TC1782 Scalable Pads Guidelines Description

.
TC1782 Scalable Pads
Timing and Electromagnetic Emission
AP32146
A pplication Note
V1.0 2010-01
Microcontrollers
Edition 2010-01
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2010 Infineon Technologies AG
All Rights Reserved.
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AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
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Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Table of Contents
1
Preface ................................................................................................................................................5
2
2.1
2.2
2.2.1
2.2.2
2.2.3
Introduction ........................................................................................................................................6
Pad driver scaling in detail ...................................................................................................................6
Physical basics.....................................................................................................................................7
Load charging.......................................................................................................................................7
Signal integrity......................................................................................................................................8
Power integrity / Electromagnetic emission .......................................................................................12
3
TC1782 test configuration ...............................................................................................................14
4
Specified timings .............................................................................................................................16
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
Measured timings.............................................................................................................................17
Measurement conditions and naming conventions............................................................................17
Measured rise/fall times for Class A1 drivers.....................................................................................20
Measured rise/fall times for Class A1+ drivers...................................................................................21
Measured rise/fall times for Class A2 drivers.....................................................................................23
Rise/fall time diagrams for Class A1 drivers ......................................................................................26
Rise/fall time diagrams for Class A1+ drivers ....................................................................................27
Rise/fall time diagrams for Class A2 drivers ......................................................................................29
Rise/fall time diagrams for increased capacitive loads ......................................................................33
6
6.1
6.2
6.2.1
6.2.2
6.2.3
6.3
Measured electromagnetic emission .............................................................................................37
Microcontroller operation mode..........................................................................................................37
Description of test equipment.............................................................................................................41
Conducted emission test configuration ..............................................................................................41
Radiated emission test configuration .................................................................................................41
Measurement settings........................................................................................................................42
Emission test result discussion ..........................................................................................................43
7
7.1
7.2
7.2.1
7.2.2
7.2.3
7.2.4
7.2.5
7.2.6
7.2.7
7.2.8
Recommended pad driver settings ................................................................................................51
Signal categories................................................................................................................................51
Decision tables and diagrams ............................................................................................................52
Decision table for pad class A2..........................................................................................................55
Decision table for pad class A1+........................................................................................................57
Decision table for pad class A1..........................................................................................................59
Decision diagrams for pad class A2...................................................................................................60
Decision diagrams for pad class A1+.................................................................................................65
Decision diagrams for pad class A1...................................................................................................70
Decision diagrams for weak driver at high capacitive load ................................................................75
Decision diagrams for medium driver at high capacitive load............................................................80
8
8.1
8.2
8.3
Pad Scaling Calculator (PASTOR)..................................................................................................85
Scope of the software ........................................................................................................................85
How to use PASTOR .........................................................................................................................85
PASTOR screenshots ........................................................................................................................86
Annex A: Measured rise/fall waveforms............................................................................................................90
Annex B: Glossary.............................................................................................................................................150
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Timing and Electromagnetic Emission
1
Preface
Output driver scaling, also referred to as „slew rate control“, is an effective technique to reduce the
electromagnetic emission and improve the signal integrity of an integrated circuit by reducing the driver strength
and/or smoothing the rising and falling edges of one or more pad output drivers.
Output driver scaling makes sense only when a certain margin regarding signal frequency and/or capacitive
output load is available. Any driver scaling must maintain proper signal integrity.
This application note presents a huge set of output driver characterization data plus a special software, which
shall enable the system designers to select proper driver settings to reduce the electromagnetic emission
caused by the driver switching, while maintaining the desired signal integrity. Parameters under consideration
are switching frequency, capacitive output load, pad supply voltage and ambient temperature.
Chapter 2 introduces physical basics behind the scaling.
Chapter 3 describes the TC1782 software initialization for timing and emission measurements.
Chapter 4 lists all specified timings which have been validated by measurements as documented in this
application note.
Chapter 5 provides values and comparison diagrams of measured rise/fall times under various conditions.
Chapter 6 compares several measured electromagnetic emissions under various conditions.
Chapter 7 recommends useful settings for the drivers by introducing signal categories and giving lots of
decision tables and graphs.
Chapter 8 introduces the new Microsoft Excel ™ based software PASTOR, which calculates pad driver timings
under various environmental conditions and proposes the best driver scaling under timing, EMC, load, voltage
and temperature constraints.
Annex A shows the waveforms of all measured rise/fall times.
Annex B explains all abbreviations used in this application note in a glossary.
Guideline to use this application note:
In most cases an appropriate driver setting is searched for,
based on a given signal data rate, a given capacitive load
connected to this signal, and a given maximal ambient
temperature. As a solution, the diagrams given in Chapter 7
provide the required pad driver settings. These suitable pad
driver settings lead to minimum electromagnetic emission
under the given constraints for data rate, capacitive load,
and operating temperature.
In addition, the measured values of rise and fall times for all
driver settings listed in the decision diagrams can be
referred in Chapter 5.
The impact of driver settings on electromagnetic emission
can be estimated from the diagrams in Chapter 5.
Annex A and B serve as data pool for detailled timing and
electromagnetic emission behaviour for all pad driver
settings under various temperature and capacitve load
conditions. Note that emissions are always measured at
room temperature (25°C).
Figure 1: 32-bit microcontroller TC1782
Important notes:
The information given in this application note is valid for Infineon microcontrollers of the AudoMax family,
fabricated in 90 nm CMOS technology.
Please note that all numbers given in this application note are not guaranteed in the microcontroller data
sheets. They are verified by design without being monitored during the IC fabrication process. The numbers are
based on timing measurements performed on center lot devices. Fabrication process windows may lead to
deviations of below 10%.
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
2
Introduction
The output driver scaling principle of the
TC1782 microcontroller is shown in Figure 2.
The driver configuration is possible by setting
corresponding control bits in the port-related
output control registers.
2.1
Pad driver scaling in detail
Basically, we distinguish between driver control
and edge control. Driver control bits set the
general DC driving capability of the respective
driver. Reducing the driver strength increases
the output’s internal resistance which attenuates
noise that is imported/exported via the output
line.
For a given external load, charging and
discharging time varies with the driver strength,
thus the rise/fall times will change accordingly.
For the sake of low electromagnetic emission,
low-speed signals should be driven by weak
output drivers. However, high DC-current sinks
like LEDs or power transistors may require a
stable high output current (strong driver)
although the toggle rate is very low.
The controllable output drivers of the TC1782
pins feature three differently sized transistors
(strong, medium, and weak) for each direction
(push
and
pull).
The
time
of
activating/deactivating
these
transistors
determines the output characteristics of the
respective port driver.
The strength of the driver can be selected to
adapt the driver characteristics to the
application’s requirements:
In Strong Driver Mode, the medium and strong
transistors are activated. In this mode the driver
provides maximum output current even after the
target signal level is reached.
In Medium Driver Mode, only the medium
transistor is activated while the other transistors
remain off.
In Weak Driver Mode, only the weak transistor
is activated while the other transistors remain
off. This results in smooth transitions with low
current peaks (and reduced susceptibility for
noise) on the cost of increased transition times,
i.e. slower edges, depending on the capacitive
load, and low static current.
Figure 2: Pad output driver schematic
Signal slopes or edges define the rise/fall time
for the respective output, i.e. the output transition time. Soft edges reduce the peak currents that are drawn
when changing the voltage level of an external capacitive load. For a bus interface, however, sharp edges may
still be required. Edge characteristics are controlled by the pad pre-driver which controls the final output driver
stage.
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Timing and Electromagnetic Emission
2.2
Physical basics
Two main constraints have to be met when deciding for a certain clock driver setting: signal integrity and power
integrity. Signal integrity must be maintained for all signals driven by the microcontroller. Conditions for good
signal integrity are:
-
Maximal desired signal frequency is reached.
-
Stable-Level-to-Slope ratio is high (at least 2:1, depending on protocol timing).
-
High and low signal levels are reached.
-
No overshoot or undershoot occurs.
Power integrity must be maintained to ensure proper operation and fulfil EMC requirements. Condititions for
good power integrity are:
-
Low RF noise on all power supply domains.
-
This is equivalent to low switching noise and low electromagnetic emission.
Both issues will be discussed after a general introduction to capacitive load charging.
2.2.1
Load charging
Generally, a switching transistor output stage delivers charge to its corresponding load capacitance during
rising edge and draws charge from its load capacitance during falling edge. The load capacitance is built by the
signal net (traces) on the PCB and all connected receiver input stages (ASIC input pins). Timing diagrams
normally show the signal’s voltage over time characteristics. However, the resulting timing is a result of the
electrical charge transfer to and from the load capacitance described above. Charge is transferred by flowing
current.
A bigger pad driver means a smaller resistance in the loading path of the external load. Figure 3 shows the load
current and voltage of two examples of pad drivers connected to a load of C=40pF. The strong driver has an
output resistance of 25Ω, the weak driver 50Ω. For times t<0, the output voltage is 0V. At t=0, the load
capacitor C is connected to the target output voltage U=5V via the respective driver pullup transistor. As a
reaction, the load current steps immediately to the value I=U/R. I is bigger for smaller values of R. This means
that the strong driver generates
a bigger current jump and
charges the load capacitor in a
Charging Voltage and Current at 40pF Load
shorter time.
In frequency domain, the
current peak which is resulting
from the charging of the load
capacitor and from the over- or
undershoots, causes significant
RF
energy
and
thus
electromagnetic emission on
the pad power supply. These
Application Note
0.2
4.5
0.18
4
0.16
3.5
0.14
3
0.12
2.5
0.1
2
0.08
1.5
0.06
1
0.04
0.5
0.02
0
-2.0E-09
0.0E+00
2.0E-09
4.0E-09
6.0E-09
8.0E-09
Current [A]
5
Voltage [V]
In time domain this leads to
bigger reflections for not
adapted driver impedances.
Since typical trace impedances
range from 60 to 120Ω, a
strong driver with Z=10Ω is
poorly adapted and may cause
big
voltage
overand
undershoots. A weak driver with
Z=100Ω may fit perfectly and
generate a clean voltage
switching signal without over- or
undershoots. These effects are
discussed in chapter 2.2.2.
0
1.0E-08
Time [s]
Voltage R=50Ohm
Voltage R=25Ohm
Current R=50Ohm
Current R=25Ohm
Figure 3: Current-/voltage charging curves for
different driver strengths
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effects are discussed in chapter 2.2.3.
Not only the pad driver impedance, but also the connected capacitive load determines the electromagnetic
emission amplitudes. Figure 4 illustrates the differences in charging current and voltage between a capacitive
load of 40pF and one of 20pF. In both cases, the driver impedance is set to 50Ω.
This
disadvantage
can
be
compensated by chosing a
smaller pad driver, i.e. a weaker
driver setting, causing bigger
driver impedance and thus
smaller di/dt for the charging
current.
The selection of a weaker driver
setting slows down the pad
switching time, so care must be
taken to maintain the required
signal integrity.
2.2.2
Charging Voltage and Current at 50Ohm Driver Impedance
0.2
4.5
0.18
4
0.16
3.5
0.14
3
0.12
2.5
0.1
2
0.08
1.5
0.06
1
0.04
0.5
0.02
0
-2.0E-09
0.0E+00
2.0E-09
4.0E-09
6.0E-09
8.0E-09
Current [A]
5
Voltage [V]
As expected, the charging voltage
increases faster for a smaller
load. However, the starting value
of the charging current is only
determined
by
the
driver
impedance and is thus loadindependent. The load affects
only the speed of load current
decrease. It decreases faster if
the load is smaller. This means
on the other hand a bigger di/dt
for smaller loads, resulting in
higer emission for smaller loads.
0
1.0E-08
Time [s]
Voltage Cload=40pF
Voltage Cload=20pF
Current Cload=40pF
Current Cload=20pF
Figure 4: Current-/voltage charging curves for
different capacitive loads
Signal integrity
Maintaining signal integrity means to select the rise/fall times such that all signal handshaking and data
communication timings and levels are ensured for proper system operation. This means the data interchange
between the microcontroller and external ICs (e.g. Flash memory, line drivers, receivers) runs properly.
Therefore, it has to be taken into account that CMOS transistors become slower with rising temperature. Thus
the timing of a critical signal has to be matched for proper operation at highest ambient temperature.
Depending on the application, common ambient temperature ranges are up to 85°C or up to 125°C. Several
automotive control units specify an ambient temperature range from -40°C up to 140°C. The die temperature
may reach values above 150°C during operation.
Rules:
•
Choose driver characteristics to meet the DC driving requirements. Make sure that the DC current
provided by the microcontroller’s pad drivers is sufficient to drive e.g. actuators or LEDs into the
desired logic state.
•
Choose slope settings to meet system timing constraints at the highest system temperature. Make sure
that no too strong driver settings are selected. This would lead to unnecessarily fast signal edges,
causing two disadvantages regarding electromagnetic emission: (1) The slopes are too fast and cause
undesired high emission energy at higher frequencies; (2) Over- and undershoot appears with the
danger of latchup, spikes leading to wrong logic states or increased data delays and undesired high
frequency emission.
•
If system timing requires strong drivers, consider series termination to avoid over-/undershoot at signal
transitions. The value of the termination resistor has to be chosen according the signal line impedance.
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
The following examples describe the signal integrity issues mentioned above.
Let us assume a CMOS push/pull output driver with scalable driver impedance connected to a scalable
microstrip trace on the PCB terminated by a reveiver input pin. The driver is controlled by a periodically toggling
clock with 2ns slopes at different frequencies.
This simple circuit is shown in Figure 5.
Figure 5: Signal over- and undershoots
Let us further assume the following system settings:
Driver scaling
Microstrip scaling
Clock rate scaling
20Ω
2cm long
1MHz
Strong-medium
50Ω
5cm long
10MHz
Strong-soft
100Ω
10cm long
100MHz
Medium
200Ω
20cm long
-
Weak
1000Ω
-
-
Driver name
Impedance Zdr
Strong-sharp
Please note that the “driver names” for these examples have been selected according the driver settings
implemented in the TC1782. Nevertheless, the signal shapes and timings shown in Figures 6 to 11 are based
on the simple model of Figure 5 and thus not identical to the physical realization of these drivers. For signal
shapes and signal integrity discussion of the real physical TC1782 drivers please refer to chapters 5 and 7 and
Annex A.
Figures 6, 7, 8 show the driver scaling impact on signal integrity. Stronger drivers may cause signal over- and
undershoot. Figures 9, 10, 11 show the PCB trace length impact. Driver strength should be selected to be as
weak as possible to avoid over/undershoot. Of course any timings required by communication protocols must
be maintained. Typically, weak driver settings can be used for signals up to 1MHz. Medium settings are valid
for signals in the low MHz range, whereas faster signals need strong drivers. Infineon microcontrollers refine
their strong drivers by slew-rate control like sharp/medium/soft edge, thus providing a fine tuning capability in
the high signal performance class which is especially critical for electromagnetic emission.
Figure 6: A 1MHz clock can be driven by a weak or medium driver. Any strong driver should be avoided due to
unnecessary over- and undershoots and higher electromagnetic emission.
Figure 7: A 10MHz signal cannot anymore be driven by a weak driver since the final high and low levels are
hardly reached in time. The medium driver may be possible in the shown case of a 10cm long PCB trace.
Depending on the communication protocol’s timing requirements, the strong-soft driver may be preferred due to
its slightly faster slopes. Strong-medium and strong-sharp drivers are not recommended due to resulting overand undershoot.
Figure 8: Depending on the protocol’s timing constraints, either strong-medium or strong-sharp drivers must be
used. Strong-sharp still has significant over- and undershoots, thus offers worse signal integrity, but has
steeper slopes.
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Figure 6: Signal integrity for various driver settings at 1MHz clock signal
Figure 7: Signal integrity for various driver settings at 10MHz clock signal
Figure 8: Signal integrity for various driver settings at 100MHz clock signal
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Figure 9: The PCB trace length determines the signal integrity significantly. Longer traces lead to increased
over- and undershoot due to the larger inductive and capacitive components of the trace according the
transmission line theory. This ringing effect caused by the trace length is superimposed to the ringing effect
caused by strong drivers with steep slope which was discussed in Figures 6 to 8. The strong-sharp driver
shown in Figure 9 causes significant ringing on traces longer than 5cm.
Figure 10: For strong-medium driver, the ringing is significantly reduced and the timing even for 100MHz clocks
is good up to 10cm long traces.
Figure 11: The strong-soft driver is the preferred choice for signals up to 10MHz. It cannot be used for 100MHz
clocks because due to the long slopes the target signal levels are never reached.
Figure 9: Signal integrity for strong-sharp driver at various microstrip line lengths
Figure 10: Signal integrity for strong-medium driver at various microstrip line lengths
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Timing and Electromagnetic Emission
Figure 11: Signal integrity for strong-soft driver at various microstrip line lengths
2.2.3
Power integrity / Electromagnetic emission
Any switching between low and high voltage levels generates RF noise. Responsible for this electromagnetic
energy is the dynamic current which is required to charge and discharge a lot of on-chip and off-chip nodes. In
the logic core power supply domain of a microcontroller, the millions of transistors switching nearly
simultaneously – triggered by the synchronous clock – draw lots of dynamic current from on-chip capacitors,
decoupling capacitors on
the PCB and finally the
voltage
regulator
or
battery “somewhere” in
the system. Preferrably,
most of this dynamic
switching current should
be provided by the onchip capacitors because
in that case, only a small
part of high frequency
energy is propagated
over the PCB, where it is
efficiently radiated. If a
good
RF
decoupling
concept
has
been
implemented on the PCB
(i.e.
decoupling
capacitors place close to
the
microcontroller’s
Figure 12: Spectrum envelope for different clocks and edges
power supply pins), most
of the RF current is kept
within small loops on the PCB.
For the I/O domain, the switching currents are drawn by the pad drivers. In contrast to the logic core domain, no
on-chip capacitors can be implemented on the microcontroller due to very limited area of the pad frame. For the
I/O domain, a very good external decoupling concept must be implemented on the PCB. Nevertheless, the
electromagnetic emission caused by pad drivers can in most application cases significantly reduced by using
weaker drivers. This driver selection is done by software as explained in section 2.1. From theory, the
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Timing and Electromagnetic Emission
electromagnetic emission (EME) of trapezoidal pulses (as are typical clock waveforms) is determined by the
signal frequency and the signal slopes. In the emission spectrum, the limit curve is determined by two
kneepoints which separate the limit curve in damping sections of 0dB/decade, -20dB/decade and
-40dB/decade. Figure 12 shows the kneepoint frequencies for several cases of clock frequency and clock
edges (i.e. rise/fall times). Good signal integrity is assumed when the rise and fall time takes 10% of one clock
period. Any faster edge will not improve signal integrity significantly, but leads to heavily shited damping
kneepoints towards higher frequency – see the 1ns egde examples in Figure 12.
The steeper a switching pulse is, the higher frequencies (harmonics) are required to form the rising and falling
edges. A rise time of 1ns leads to a spectrum composed from harmonics up to at least 500 MHz.
Assuming a 100MHz (10ns period) clock signal consisting of 10% rise time, 40% high level, 10% fall time and
40% low level, this clock signal already generates at least harmonics up to 500MHz.
Figure 12 indicates that not the clock frequency, but the rise/fall times determine the resulting RF spectrum.
Even if a clock driver operates at a relatively low toggle rate, it may generate the same RF spectrum as if it
would operate at a significantly higher toggle rate – as long as its rise/fall times are not adjusted to the lower
toggle rate by slowing down the transitions. For example, if the mentioned 100MHz clock driver operates at
only 10 MHz, its rise/fall times should be extended from 1 ns to 10 ns, still maintaining the 10% ratio relatively
to the clock period time. This setting will reduce the emission by 10dB at 50MHz and by more than 30dB above
300MHz.
•
General Rule: Choose driver and edge characteristics to result in lowest electromagnetic emission
while meeting all system timing requirements (i.e. good signal integrity) at given signal load and highest
system temperature.
Figure 13 refers to our pad driver and transmission line simulation model of Figure 5. It shows the simulated
electromagnetic emission at the probing point “MEAS” which is an AC-coupled test point with resistive divider to
match typical emission scales of up to 80dBµV. Important is the interpretation of relative emission reduction
potential when using weaker pad drivers.
For a 1MHz signal, Figure 6 shows that even the weakest driver delivers acceptable signal integrity. Moreover,
Figure 13 confirms that the weakest driver reduces electromagnetic emission significantly, compared to the
strong and medium settings. At 200MHz, the 1MHz harmonics are reduced by 34dB. At 100MHz, the reduction
is ca. 20dB; above ca. 450MHz, the emission stays below 10dBµV (i.e. is uncritical) for all driver settings.
Figure 13: Electromagnetic emission for various driver settings at 1MHz clock signal
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3
TC1782 test configuration
Timing measurements were performed at 3 pins, representing the 3 pad driver classes:
-
Port pin P1.13 = Class A1 pin (low speed 3.3 V LVTTL output)
-
Port pin P5.1 = Class A1+ pin (medium speed 3.3 V LVTTL output)
-
Port pin P2.0 = Class A2 pin (high speed 3.3 V LVTTL output)
Electromagnetic emission measurements were performed on the I/O supply net VDDP.
Roughly, these settings can be linked to driven data rates, as documented in Chapter 7. Note that the actual
data rate which can be driven by the selected driver depends on additional parameters like external capacitive
load, pad supply voltage and ambient temperature.
The driver settings for the respective port pins are configured by bit fields PDx in the Port Driver Mode Register,
see Table 1.
Px_PDR
Port x Pad Driver Mode Register (F000 0C40H+x*100H) Reset Value: 0000 0000H
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
0
PD7
0
PD6
0
PD5
0
PD4
r
rw
r
rw
r
rw
r
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
PD3
0
PD2
0
PD1
0
PD0
r
rw
r
rw
r
rw
r
rw
Field
PD0
Bits
[2:0]
Type
rw
PD1
[6:4]
rw
PD2
[10:8]
rw
PD3
[14:12]
rw
PD4
[18:16]
rw
PD5
[22:20]
rw
PD6
[26:24]
rw
PD7
[30:28]
rw
0
3, 7, 11,
15, 19,
23, 27, 31
r
16
0
Description
Pad Driver Mode for Px.[3:0]
(Class A1 or A2 pads; coding see Table 2)
Pad Driver Mode for Px.[7:4]
(Class A1 or A2 pads; coding see Table 2)
Pad Driver Mode for Px.[11:8]
(Class A1 or A2 pads; coding see Table 2)
Pad Driver Mode for Px.[15:12]
(Class A1 or A2 pads; coding see Table 2)
Pad Driver Mode for Px.[19:16]
(not used for 16-bit ports)
Pad Driver Mode for Px.[23:20]
(not used for 16-bit ports)
Pad Driver Mode for Px.[27:24]
(not used for 16-bit ports)
Pad Driver Mode for Px.[31:28]
(not used for 16-bit ports)
Reserved
Read as 0; should be written with 0.
Table 1: Pad driver mode register specification
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Timing and Electromagnetic Emission
Driver strength and slew rate are controlled by the bit fields in the pad driver mode register Px_PDR,
independently of input/output and pull-up/pulldown control functionality as programmed in the Pn_IOCRx
register. One Px_PDR register is assigned to each port.
Depending on the assigned pad class, the 3-bit wide pad driver mode selection bit fields PDx in the pad driver
mode registers Px_PDR make it possible to select the port line functionality as shown in Table 2:
-
Class A1 pins make it possible to select between medium and weak output drivers.
-
Class A1+ and A2 pins make it possible to select between strong/medium/weak output drivers. In case
of strong driver type, the signal transition edge can be additionally selected as soft/slow (Class A1+) or
sharp/sharp-minus/medium/medium-minus/soft (Class A2).
For details on the register structure and bit configurations please refer to the TC1782 specification.
Pad Class
A1
PDx.2
X
PDx.1
X
A1+
0
0
1
1
0
0
0
0
1
1
1
1
X
X
X
X
0
0
1
1
0
0
1
1
A2
PDx.0
0
1
0
1
0
1
0
1
0
1
X
Driver Strength
Medium driver
Weak driver
Strong driver soft edge
Strong driver slow edge
Medium driver
Weak driver
Strong driver, sharp edge
Strong driver, medium edge
Strong driver, soft edge
Strong driver, sharp-minus edge
Medium driver selected
0
1
Strong driver, medium-minus edge
Weak driver selected
Table 2: Pad Driver Mode Selection
Please note that sometimes Class A1+ and A2 drivers share the same configuration bits, thus the driver and
slew rate settings are not anymory fully individual. For these cases Table 3 lists the resulting combinations of
settings.
For details on the driver class distribution per bit please refer to the TC1782 specification.
PDx.2
PDx.1
PDx.0
A2 Driver Strength
A1+ Driver Strength
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Strong sharp
Strong medium
Strong soft
Strong sharp-minus
Medium
Medium
Strong medium-minus
Weak
Strong soft
Strong slow
Strong soft
Strong slow
Medium
Weak
Medium
Weak
Table 3: Possible Driver Strength Combinations in a Mixed Pad Group (A1+ and A2)
Application Note
15
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
4
Specified timings
Rise/fall times are specified for the TC1782 operating conditions: TJ < 150°C and VDDP = 3.3 V ± 5%.
A junction temperature TJ of 150°C corresponds to an ambient temperature of TA < 140°C. The rise/fall times
documented in chapter 5 have been characterized for ambient temperatures up to 140°C, thus fully covering
the specified operating range. In addition, worst and best case results including ± 5% variation of VDDP are
provided.
For details please refer to the TC1782 product specification.
Class
Pad driver
Load condition
Max. specified value
A1
Weak
20 pF
90 ns
A1
Weak
150 pF
350 ns
A1
Weak
20000 pF
50000 ns
A1
Medium
50 pF
40 ns
A1
Medium
150 pF
110 ns
A1
Medium
20000 pF
15000 ns
A1+
Weak
20 pF
90 ns
A1+
Weak
150 pF
350 ns
A1+
Weak
20000 pF
50000 ns
A1+
Medium
50 pF
40 ns
A1+
Medium
150 pF
110 ns
A1+
Medium
20000 pF
15000 ns
A1+
Strong slow
50 pF
28 ns
A1+
Strong soft
50 pF
16 ns
A2
Weak
20 pF
90 ns
A2
Weak
150 pF
350 ns
A2
Weak
20000 pF
50000 ns
A2
Medium
50 pF
40 ns
A2
Medium
150 pF
110 ns
A2
Medium
20000 pF
15000 ns
A2
Strong soft
50 pF
16 ns
A2
Strong medium minus
50 pF
10 ns
A2
Strong medium
50 pF
5.5 ns
A2
Strong sharp minus
50 pF
4.4 ns
A2
Strong sharp
50 pF
3.3 ns
B
Strong sharp
35 pF
2.5 ns *
B
Strong sharp
50 pF
3.3 ns *
B
Strong sharp
100 pF
6 ns *
* for I/O supply voltage VDDP ≥ 3.13V
Application Note
16
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5
Measured timings
5.1
Measurement conditions and naming conventions
The test configuration listed in chapter 3 applies. Accordingly, all timings are measured at pins P1.13 (Class
A2), P5.1 (Class A1+) and P2.0 (Class A2).
The following parameters are varied for timing measurements to reflect the PVT (process, voltage,
temperature) variations anticipated during fabrication and operation:
•
Pad supply voltage VDDP in 3 steps: 3.30V (nominal), 3.13V (-5%), 3.47V (+5%).
•
Capacitive load according TC1782 specification in 8 steps for weak and medium drivers:
10pF, 15pF, 22pF, 33pF, 47pF, 150pF, 1500pF, 20000pF
•
Capacitive load according TC1782 specification in 6 steps for strong-sharp drivers:
10pF, 15pF, 22pF, 33pF, 47pF, 100pF
•
Capacitive load according TC1782 specification in 5 steps for all strong driver settings except strongsharp: 10pF, 15pF, 22pF, 33pF, 47pF
•
Ambient
•
For rise/fall time values at other temperatures, a linear interpolation is performed.
•
Electromagnetic emission is always measured at TA=25°C.
emperature in 6 steps: -40°C, 0°C, +25°C, +40°C, +80°C, +125°C
The pad driver is loaded with the respective capacitance by connecting a lumped SMD 0805 X7R capacitor to
the port pin. The port pin is driven by either a Class A1, Class A1+ or Class A2 pad driver.
Please note that the measurement probe capacitance of 3pF must be added to the nominal load capacitors.
Therefore, total capacitance values of 13pF up to 50pF are reached. Table 4 shows the reference between real
loads and numbers given in the result diagrams. For easy reading, in all result tables and diagrams, the load
capacitances are referring to the SMD capacitor values as 10, 15, 22, 33, 47pF.
SMD load
10 pF
15 pF
22 pF
33 pF
47 pF
>50 pF
Probe capacitance
3 pF
3 pF
3 pF
3 pF
3 pF
3 pF
Resulting physical capacitance
13 pF
18 pF
25 pF
36 pF
50 pF
Respective load value +3 pF
(may be neglected for large values)
Table 4: Overview of capacitive loads used for timing measurements
Application Note
17
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Figure 14: Voltage level references for timing measurement at VDDP=3.3V
The results given in Tables 6-8 and in the diagrams of sections 4.5 to 4.8 show the measured rising and falling
edge timings. The reference points are 10% and 90% as indicated in Figure 14.
Table 5 lists all parameter variations and test names for reference. These test names are used to indicate the
driver settings and load configurations used in sections 4.5 to 4.8 4. All measurements have been performed
for VDDP=3.30V at ambient temperatures TA=-40°C, 0°C, 25°C, 40°C, 80°C and 125°C. Rise and fall time
values for other temperatures are calculated by interpolation (70°C, 85°C, 110°C) and extrapolation (140°C).
Application Note
18
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Test Name
WEA-10pF
WEA-15pF
WEA-22pF
WEA-33pF
WEA-47pF
WEA-150pF
WEA-1500pF
WEA-20nF
MED-10pF
MED-15pF
MED-22pF
MED-33pF
MED-47pF
MED-150pF
MED-1500pF
MED-20nF
SSL-10pF
SSL-15pF
SSL-22pF
SSL-33pF
SSL-47pF
SSO-10pF
SSO-15pF
SSO-22pF
SSO-33pF
SSO-47pF
SMM-10pF
SMM-15pF
SMM-22pF
SMM-33pF
SMM-47pF
SME-10pF
SME-15pF
SME-22pF
SME-33pF
SME-47pF
SSM-10pF
SSM-15pF
SSM-22pF
SSM-33pF
SSM-47pF
SSH-10pF
SSH-15pF
SSH-22pF
SSH-33pF
SSH-47pF
SSH-100pF
Driver strength
Weak
Weak
Weak
Weak
Weak
Weak
Weak
Weak
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Strong-slow
Strong-slow
Strong-slow
Strong-slow
Strong-slow
Strong-soft
Strong-soft
Strong-soft
Strong-soft
Strong-soft
Strong-medium-minus
Strong-medium-minus
Strong-medium-minus
Strong-medium-minus
Strong-medium-minus
Strong-medium
Strong-medium
Strong-medium
Strong-medium
Strong-medium
Strong-sharp-minus
Strong-sharp-minus
Strong-sharp-minus
Strong-sharp-minus
Strong-sharp-minus
Strong-sharp
Strong-sharp
Strong-sharp
Strong-sharp
Strong-sharp
Strong-sharp
Lumped load capacitance
10pF
15 pF
22 pF
33 pF
47 pF
150 pF
1500 pF
20000 pF
10pF
15 pF
22 pF
33 pF
47 pF
150 pF
1500 pF
20000 pF
10pF
15 pF
22 pF
33 pF
47 pF
10pF
15 pF
22 pF
33 pF
47 pF
10pF
15 pF
22 pF
33 pF
47 pF
10pF
15 pF
22 pF
33 pF
47 pF
10pF
15 pF
22 pF
33 pF
47 pF
10pF
15 pF
22 pF
33 pF
47 pF
100 pF
Class A1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Class A1+
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Class A2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Table 5: Abbreviations used in the timing result diagrams
Application Note
19
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Sections 5.2 to 5.4 list the measured 10% / 90% rise and fall times of all driver, load and ambient temperature
conditions, while the I/O supply is kept at nominal value VDDP=3.30V. The last row in every table (section 5.2)
lists the slowest measured rise/fall times under worst case conditions (VDDP = 3.30V-5% = 3.13V; TA=140°C).
The related waveforms are presented in Annex A.
Sections 5.5 to 5.8 show the measured rise/fall times for different combinations of ambient temperature and
capacitive load.
5.2
Measured rise/fall times for Class A1 drivers
A1 WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
30,93
38,55
34,41
42,60
36,96
45,07
38,21
47,44
42,00
52,15
46,82
55,23
48,43
56,26
49,63
62,09
CL=15pF
tR (ns) tF (ns)
39,85 46,46
44,46 51,10
47,38 54,03
49,25 56,27
53,62 62,25
59,41 67,77
61,34 69,61
62,09 71,87
CL=22pF
tR (ns) tF (ns)
41,53 48,01
45,94 52,67
48,60 55,76
50,47 57,84
55,52 63,72
61,54 70,31
63,55 72,51
64,26 73,99
150
A1 WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=150pF
tR (ns)
tF (ns)
156
129
170
138
176
143
182
149
195
161
207
174
211
178
221
185
550
CL=1500pF
tR (ns) tF (ns)
1290
845
1390
911
1420
939
1460
962
1560
1030
1670
1110
1707
1137
1763
1170
CL=20000pF
tR (ns) tF (ns)
17800 11310
18990 12030
19120 12380
19760 12840
20990 13680
22260 14890
22680 15290
23310 15487
65000
A1 MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
CL=10pF
tR (ns)
tF (ns)
10,50
11,80
11,21
12,81
12,01
13,57
12,49
14,30
13,89
15,68
15,29
17,29
15,76
17,83
CL=15pF
tR (ns) tF (ns)
13,53 14,11
14,51 15,42
15,31 16,12
15,87 16,87
17,69 18,48
19,53 20,41
20,14 21,05
16,72
20,51
WORST CASE
SPEC
18,57
21,64
CL=33pF
tR (ns) tF (ns)
51,34 55,26
56,36 60,70
59,37 64,06
61,30 66,55
68,19 73,41
75,29 79,50
77,66 81,53
79,27 86,19
CL=47pF
tR (ns) tF (ns)
67,00 66,70
73,23 72,86
76,02 76,59
78,74 79,08
84,99 86,71
94,29 95,64
97,39 98,62
99,90 100,95
CL=22pF
tR (ns) tF (ns)
13,39 14,51
14,83 16,01
15,53 16,50
16,32 17,25
17,81 18,97
19,37 20,79
19,89 21,40
CL=33pF
tR (ns) tF (ns)
16,37 16,73
18,11 18,43
19,05 19,54
19,47 19,91
21,27 21,78
23,58 24,12
24,35 24,90
CL=47pF
tR (ns) tF (ns)
21,61 20,17
23,41 21,91
24,33 22,75
25,05 23,68
27,12 25,83
29,44 28,26
30,21 29,07
20,64
25,67
31,02 29,98
50
22,11
25,96
Table 6: Pad driver class A1 – measured rise and fall times (first part)
Application Note
20
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
A1 MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=150pF
tR (ns)
tF (ns)
46,9
37,5
49,9
40,6
51,7
42,0
53,2
43,6
57,7
47,2
61,5
50,4
62,8
51,5
65,9
54,5
140
CL=1500pF
tR (ns) tF (ns)
408
256
438
272
458
283
465
291
492
311
513
329
520
335
530
350
CL=20000pF
tR (ns) tF (ns)
5190
3280
5520
3540
5700
3670
5810
3770
6180
4070
6510
4310
6620
4390
6760
4547
18000
Table 6: Pad driver class A1 – measured rise and fall times (second part)
5.3
Measured rise/fall times for Class A1+ drivers
A1+ WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
32,89
39,05
35,64
43,06
39,26
45,62
39,97
47,50
44,27
53,08
46,89
55,95
47,76
56,91
52,40
61,14
CL=15pF
tR (ns) tF (ns)
39,78
44,15
43,68
49,10
46,57
51,98
47,71
53,87
54,18
60,03
59,16
66,51
60,82
68,67
61,79
69,85
CL=22pF
tR (ns) tF (ns)
42,61
47,68
47,63
52,56
50,53
55,60
53,55
58,80
59,21
64,71
66,80
72,78
69,33
75,47
72,10
77,12
150
A1+ WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=150pF
tR (ns)
tF (ns)
163
131
175
141
181
147
190
152
200
165
214
176
219
180
231
191
550
CL=1500pF
tR (ns)
tF (ns)
1410
893
1500
952
1530
987
1570
1010
1690
1080
1780
1170
1810
1200
1863
1227
CL=20000pF
tR (ns)
tF (ns)
17210 11290
18260 11920
18810 12320
19410 12650
20380 13690
21370 14670
21700 15000
22903 15370
65000
CL=33pF
tR (ns) tF (ns)
52,51
54,41
57,76
60,53
60,61
64,07
62,63
66,16
69,46
72,63
75,43
79,07
77,42
81,22
79,34
84,04
CL=47pF
tR (ns) tF (ns)
67,17
64,99
73,73
71,74
78,04
75,67
80,64
78,87
85,87
84,03
97,12
95,39
100,87
99,18
101,78 101,24
Table 7: Pad driver class A1+ – measured rise and fall times (first part)
Application Note
21
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
A1+ MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
10,73
12,12
11,83
13,05
12,84
14,14
13,09
14,53
14,88
16,11
15,87
17,12
16,20
17,46
17,20
18,93
CL=15pF
tR (ns) tF (ns)
13,84
13,62
14,31
14,97
15,13
15,76
15,85
16,50
17,62
18,15
19,61
20,10
20,27
20,75
20,89
21,01
CL=22pF
tR (ns) tF (ns)
13,69
14,62
15,11
16,19
15,97
16,91
17,00
17,84
18,97
19,62
21,06
20,60
21,76
20,93
21,29
21,89
A1+ MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
CL=150pF
tR (ns)
tF (ns)
48,3
38,6
52,6
41,3
52,8
43,4
55,3
44,5
58,9
48,5
63,6
52,2
65,2
53,5
67,6
54,6
140
CL=1500pF
tR (ns)
tF (ns)
426
267
457
283
468
294
476
301
509
323
528
343
534
350
572
365
CL=20000pF
tR (ns)
tF (ns)
5370
3430
5720
3580
5740
3720
5860
3830
6340
4110
6670
4480
6780
4600
6997
4613
18000
A1+ STRONGSLOW
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
7,66
8,70
8,34
9,43
8,86
10,01
9,19
10,26
10,19
11,49
11,43
12,33
11,84
12,61
12,00
13,42
CL=15pF
9,22
9,83
10,13
10,77
10,44
11,17
11,03
11,79
12,18
12,95
13,48
14,31
13,91
14,76
14,84
14,93
A1+ STRONGSOFT
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
4,02
3,09
4,28
3,31
4,44
3,44
4,71
3,65
4,99
4,00
5,26
4,35
5,35
4,47
5,80
4,62
CL=15pF
5,53
3,78
5,99
4,09
6,05
4,26
6,53
4,40
6,83
4,83
7,50
5,36
7,72
5,54
7,81
5,62
WORST CASE
SPEC
CL=33pF
tR (ns) tF (ns)
16,19
16,66
18,16
18,36
19,04
19,29
19,73
20,18
21,80
22,07
23,04
23,77
23,45
24,34
24,46
25,37
CL=47pF
tR (ns) tF (ns)
20,92
19,45
23,23
21,96
24,55
23,10
25,26
23,91
27,33
26,20
30,73
29,09
31,86
30,05
32,66
30,68
50
CL=22pF
9,79
10,50
10,70
11,44
11,13
12,00
12,08
12,79
13,02
14,12
14,92
15,59
15,55
16,08
15,81
16,92
CL=33pF
11,55
11,96
12,64
13,13
13,08
13,75
13,95
14,34
15,27
15,60
16,83
17,21
17,35
17,75
17,66
17,97
CL=47pF
15,13
14,06
16,45
15,60
17,34
16,51
17,89
17,16
18,94
18,64
21,01
20,64
21,70
21,31
22,07
21,81
28
CL=22pF
6,18
4,35
6,61
4,71
6,74
4,87
7,26
5,13
7,67
5,58
8,03
6,02
8,15
6,17
8,74
6,36
CL=33pF
8,14
5,60
8,92
6,08
9,09
6,25
9,30
6,37
10,05
7,10
10,43
7,77
10,56
7,99
10,95
8,37
CL=47pF
12,11
7,53
12,75
8,27
13,24
8,66
13,42
8,93
14,21
9,85
15,15
10,77
15,46
11,08
15,60
11,05
16
Table 7: Pad driver class A1+ – measured rise and fall times (second part)
Application Note
22
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5.4
Measured rise/fall times for Class A2 drivers
A2 WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
31,49
37,86
34,97
42,55
38,13
45,44
39,89
47,41
44,25
52,84
49,07
58,66
50,68
60,60
51,57
61,75
CL=15pF
tR (ns) tF (ns)
39,13
44,44
43,71
49,20
45,94
52,15
48,22
54,90
53,95
60,06
58,31
67,12
59,76
69,47
60,62
70,45
CL=22pF
tR (ns) tF (ns)
44,86
49,72
49,52
54,50
53,18
58,53
53,91
59,50
59,49
65,60
63,41
71,47
64,72
73,43
69,66
77,57
150
A2 WEAK
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=150pF
tR (ns)
tF (ns)
149
124
162
135
168
140
171
145
184
159
200
175
205
180
220
188
550
CL=1500pF
tR (ns)
tF (ns)
1260
836
1370
905
1400
942
1420
963
1530
1050
1620
1110
1650
1130
1713
1183
CL=20000pF
tR (ns)
tF (ns)
16570 10720
17290 11510
17890 11830
18150 12210
19360 13250
20820 14140
21300 14440
22290 14870
65000
A2 MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
10,27
11,56
11,54
13,03
12,52
13,67
13,02
14,43
14,86
16,10
15,85
17,42
16,18
17,86
17,05
18,65
CL=15pF
tR (ns) tF (ns)
12,33
13,35
13,80
14,93
14,82
15,75
15,53
16,23
17,09
17,92
19,17
19,97
19,86
20,65
20,55
21,61
CL=22pF
tR (ns) tF (ns)
13,74
14,85
15,46
16,25
16,65
17,53
16,75
17,52
18,80
19,59
19,87
21,23
20,23
21,78
22,09
23,23
CL=33pF
tR (ns) tF (ns)
51,25
54,04
56,58
60,76
60,36
63,76
63,27
66,31
69,60
74,06
75,57
81,63
77,56
84,15
79,12
84,82
CL=47pF
tR (ns) tF (ns)
66,01
64,93
71,39
70,94
75,71
75,19
78,01
77,96
84,86
86,14
92,10
94,93
94,51
97,86
97,67 101,02
CL=33pF
tR (ns) tF (ns)
15,40
15,92
17,02
17,74
18,33
18,78
18,89
19,53
21,24
21,60
23,16
23,99
23,80
24,79
24,49
25,11
CL=47pF
tR (ns) tF (ns)
19,51
19,04
21,54
21,03
22,84
22,08
23,29
22,68
25,71
25,02
28,53
27,65
29,47
28,53
30,05
29,37
50
Table 8: Pad driver class A2 – measured rise and fall times (first part)
Application Note
23
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
A2 MEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=150pF
tR (ns)
tF (ns)
40,6
34,4
45,6
37,6
46,5
39,0
48,1
40,5
52,1
43,7
57,0
47,5
58,7
48,8
60,3
51,2
140
A2 STRONG-SOFT
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=1500pF
tR (ns)
tF (ns)
341
219
369
237
380
243
388
253
407
273
438
291
448
297
466
310
CL=10pF
4,55
6,10
4,98
6,52
5,38
6,79
5,69
7,15
6,48
7,86
7,18
8,54
7,41
8,77
7,60
9,12
CL=20000pF
tR (ns)
tF (ns)
5140
2810
5330
3020
5430
3110
5600
3210
5970
3480
6210
3830
6290
3950
6723
4047
18000
CL=15pF
5,08
6,78
5,55
7,43
5,98
7,53
6,30
7,87
7,14
8,53
7,80
9,29
8,02
9,54
8,15
9,80
CL=22pF
5,35
7,11
5,96
7,93
6,33
8,10
6,67
8,13
7,57
8,99
8,23
9,68
8,45
9,91
8,94 10,81
CL=33pF
5,69
7,33
6,41
7,94
6,84
8,34
7,29
8,65
8,21
9,57
9,08
10,48
9,37
10,78
9,73
11,17
CL=47pF
6,60
8,07
7,39
8,77
7,81
9,16
8,13
9,45
9,10
10,32
9,82
11,18
10,06
11,47
10,81
12,06
16
A2 STRONGCL=10pF
MEDIUM-MINUS
TA (°C) tR (ns) tF (ns)
-40
2,34
3,16
0
2,57
3,50
+25
2,76
3,70
+40
2,91
3,90
+80
3,28
4,31
+125
3,45
4,58
+140
3,51
4,67
WORST CASE
3,91
5,06
SPEC
CL=15pF
tR (ns) tF (ns)
2,65
3,63
2,90
3,96
3,11
4,19
3,27
4,36
3,65
4,72
3,82
5,07
3,88
5,19
4,22
5,42
CL=22pF
tR (ns) TA (°C)
2,87
3,92
3,22
4,35
3,42
4,57
3,56
4,64
3,98
5,09
4,32
5,53
4,43
5,68
4,79
6,17
CL=33pF
tR (ns) tF (ns)
3,23
4,21
3,58
4,64
3,81
4,89
4,01
5,10
4,50
5,65
4,95
6,17
5,10
6,34
5,24
6,47
CL=47pF
tR (ns) tF (ns)
3,85
4,89
4,24
5,32
4,51
5,58
4,69
5,74
5,19
6,32
5,69
6,80
5,86
6,96
5,95
7,27
10 tbd
A2 STRONGMEDIUM
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=15pF
tR (ns) tF (ns)
1,63
2,10
1,78
2,29
1,86
2,40
1,94
2,52
2,11
2,74
2,37
3,05
2,46
3,15
2,49
3,19
CL=22pF
tR (ns) TA (°C)
1,81
2,33
1,97
2,57
2,07
2,69
2,17
2,80
2,37
3,06
2,56
3,32
2,62
3,41
2,88
3,64
CL=33pF
tR (ns) tF (ns)
2,07
2,59
2,29
2,88
2,39
3,02
2,53
3,16
2,79
3,43
3,04
3,79
3,12
3,91
3,24
3,95
CL=47pF
tR (ns) tF (ns)
2,55
3,12
2,81
3,39
2,92
3,54
3,02
3,64
3,29
3,92
3,53
4,18
3,61
4,27
3,84
4,56
7
Application Note
CL=10pF
tR (ns)
tF (ns)
1,41
1,82
1,55
1,99
1,63
2,10
1,70
2,20
1,88
2,42
2,07
2,69
2,13
2,78
2,17
2,86
24
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Table 8: Pad driver class A2 – measured rise and fall times (second part)
A2 STRONGSHARPMINUS
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
0,93
1,35
1,01
1,48
1,07
1,55
1,15
1,63
1,29
1,78
1,39
1,85
1,42
1,87
1,52
2,07
CL=15pF
tR (ns) tF (ns)
1,14
1,59
1,24
1,73
1,31
1,81
1,39
1,88
1,51
2,01
1,70
2,22
1,76
2,29
1,78
2,33
CL=22pF
tR (ns) TA (°C)
1,31
1,78
1,46
1,94
1,52
2,02
1,62
2,15
1,78
2,24
1,95
2,45
2,01
2,52
2,13
2,66
CL=33pF
tR (ns) tF (ns)
1,60
1,98
1,75
2,18
1,81
2,25
1,94
2,38
2,14
2,60
2,28
2,84
2,33
2,92
2,44
2,96
CL=47pF
tR (ns) tF (ns)
2,06
2,42
2,24
2,62
2,31
2,71
2,43
2,80
2,63
3,07
2,94
3,37
3,04
3,47
3,13
3,59
5 tbd
A2 STRONGSHARP
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=10pF
tR (ns)
tF (ns)
0,59
0,62
0,63
0,66
0,64
0,69
0,68
0,72
0,73
0,77
0,79
0,85
0,81
0,87
0,83
0,91
CL=15pF
tR (ns) tF (ns)
0,84
0,81
0,85
0,84
0,86
0,87
0,89
0,84
0,91
0,94
0,96
1,01
0,97
1,03
1,01
1,07
CL=22pF
tR (ns) TA (°C)
1,00
1,02
1,04
1,03
1,05
1,05
1,10
1,08
1,15
1,13
1,20
1,22
1,22
1,25
1,31
1,33
CL=33pF
tR (ns) tF (ns)
1,26
1,14
1,34
1,23
1,35
1,27
1,40
1,30
1,50
1,44
1,61
1,56
1,65
1,60
1,67
1,62
2.5 tbd
CL=47pF
tR (ns) tF (ns)
1,71
1,48
1,82
1,59
1,83
1,60
1,89
1,66
2,01
1,78
2,18
1,95
2,24
2,01
2,38
2,11
3.7
A2 STRONGSHARP
TA (°C)
-40
0
+25
+40
+80
+125
+140
WORST CASE
SPEC
CL=100pF
tR (ns)
tF (ns)
3,20
2,51
3,41
2,69
3,47
2,81
3,57
2,86
3,89
3,30
4,23
3,92
4,34
4,13
4,58
4,39
7.5
Table 8: Pad driver class A2 – measured rise and fall times (third part)
Application Note
25
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5.5
Rise/fall time diagrams for Class A1 drivers
Weak Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A1
100,00
90,00
Rise/Fall Time [ns]
80,00
WEA 10 pF Rise Time
WEA 10 pF Fall Time
WEA
WEA
WEA
WEA
WEA
WEA
70,00
60,00
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
WEA 47 pF Rise Time
WEA 47 pF Fall Time
50,00
40,00
30,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 15: Rise/fall times for Class A1 weak driver setting at VDDP=3.30V
Medium Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A1
32,00
30,00
28,00
Rise/Fall Time [ns]
26,00
24,00
22,00
20,00
18,00
16,00
MED
MED
MED
MED
MED
MED
10 pF Rise Time
10 pF Fall Time
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
MED
MED
MED
MED
33 pF Rise Time
33 pF Fall Time
47 pF Rise Time
47 pF Fall Time
14,00
12,00
10,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 16: Rise/fall times for Class A1 medium driver setting at VDDP=3.30V
Application Note
26
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5.6
Rise/fall time diagrams for Class A1+ drivers
Weak Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A1+
110,00
100,00
90,00
Rise/Fall Time [ns]
WEA 10 pF Rise Time
WEA 10 pF Fall Time
80,00
WEA
WEA
WEA
WEA
WEA
WEA
70,00
60,00
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
WEA 47 pF Rise Time
WEA 47 pF Fall Time
50,00
40,00
30,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 17: Rise/fall times for Class A1+ weak driver setting at VDDP=3.30V
Medium Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A1+
32,00
30,00
28,00
26,00
MED 10 pF Rise Time
MED 10 pF Fall Time
Rise/Fall Time [ns]
24,00
MED
MED
MED
MED
MED
MED
22,00
20,00
18,00
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
MED 47 pF Rise Time
MED 47 pF Fall Time
16,00
14,00
12,00
10,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 18: Rise/fall times for Class A1+ medium driver setting at VDDP=3.30V
Application Note
27
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Strong Driver Slow-Edge Rise/Fall Times over Temperaure
3.3V Pad Supply; Pad Class A1+
22,00
21,00
20,00
19,00
18,00
SSL 10 pF Rise Time
Rise/Fall Time [ns]
17,00
SSL 10 pF
SSL 15 pF
SSL 15 pF
SSL 22 pF
SSL 22 pF
SSL 33 pF
16,00
15,00
14,00
Fall Time
Rise Time
Fall Time
Rise Time
Fall Time
Rise Time
SSL 33 pF Fall Time
SSL 47 pF Rise Time
SSL 47 pF Fall Time
13,00
12,00
11,00
10,00
9,00
8,00
7,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 19: Rise/fall times for Class A1+ strong-slow driver setting at VDDP=3.30V
Strong Driver Soft-Edge Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A1+
16,00
15,00
14,00
13,00
12,00
SSO 10 pF Rise Time
SSO 10 pF Fall Time
Rise/Fall Time [ns]
11,00
SSO 15 pF Rise Time
SSO 15 pF Fall Time
SSO 22 pF Rise Time
SSO 22 pF Fall Time
SSO 33 pF Rise Time
SSO 33 pF Fall Time
10,00
9,00
8,00
7,00
SSO 47 pF Rise Time
SSO 47 pF Fall Time
6,00
5,00
4,00
3,00
2,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 20: Rise/fall times for Class A1+ strong-soft driver setting at VDDP=3.30V
Application Note
28
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5.7
Rise/fall time diagrams for Class A2 drivers
Weak Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
100,00
90,00
Rise/Fall Time [ns]
80,00
WEA 10 pF Rise Time
WEA 10 pF Fall Time
WEA
WEA
WEA
WEA
WEA
WEA
70,00
60,00
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
WEA 47 pF Rise Time
WEA 47 pF Fall Time
50,00
40,00
30,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 21: Rise/fall times for Class A2 weak driver setting at VDDP=3.30V
Medium Driver Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
30,00
28,00
Rise/Fall Time [ns]
26,00
24,00
MED 10 pF Rise Time
MED 10 pF Fall Time
22,00
18,00
MED
MED
MED
MED
MED
MED
16,00
MED 47 pF Rise Time
MED 47 pF Fall Time
20,00
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
14,00
12,00
10,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 22: Rise/fall times for Class A2 medium driver setting at VDDP=3.30V
Application Note
29
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Strong Driver Soft-Edge Rise/Fall Times over Temperaure
3.3V Pad Supply; Pad Class A2
12,00
11,00
10,00
Rise/Fall Time [ns]
SSO 10 pF Rise Time
SSO 10 pF Fall Time
9,00
SSO 15 pF Rise Time
SSO 15 pF Fall Time
SSO 22 pF Rise Time
SSO 22 pF Fall Time
SSO 33 pF Rise Time
SSO 33 pF Fall Time
8,00
7,00
SSO 47 pF Rise Time
SSO 47 pF Fall Time
6,00
5,00
4,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 23: Rise/fall times for Class A2 strong-soft driver setting at VDDP=3.30V
Strong Driver Medium-Minus-Edge Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
7,00
6,50
Rise/Fall Time [ns]
6,00
5,50
SMM 10 pF Rise Time
SMM 10 pF Fall Time
5,00
4,00
SMM
SMM
SMM
SMM
SMM
SMM
3,50
SMM 47 pF Rise Time
SMM 47 pF Fall Time
4,50
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
3,00
2,50
2,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 24: Rise/fall times for Class A2 strong-medium-minus driver setting at VDDP=3.30V
Application Note
30
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Strong Driver Medium-Edge Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
4,50
4,00
Rise/Fall Time [ns]
3,50
SME 10 pF Rise Time
SME 10 pF Fall Time
SME
SME
SME
SME
SME
SME
3,00
2,50
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
SME 47 pF Rise Time
SME 47 pF Fall Time
2,00
1,50
1,00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 25: Rise/fall times for Class A2 strong-medium driver setting at VDDP=3.30V
Strong Driver Sharp-Minus-Edge Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
3,50
Rise/Fall Time [ns]
3,00
2,50
SSM 10 pF Rise Time
SSM 10 pF Fall Time
2,00
SSM
SSM
SSM
SSM
SSM
SSM
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
SSM 47 pF Rise Time
SSM 47 pF Fall Time
1,50
1,00
0,50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 26: Rise/fall times for Class A2 strong-sharp-minus driver setting at VDDP=3.30V
Application Note
31
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Strong Driver Sharp-Edge Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Class A2
2,50
2,00
Rise/Fall Time [ns]
SSH 10 pF Rise Time
SSH 10 pF Fall Time
SSH
SSH
SSH
SSH
SSH
SSH
1,50
15 pF Rise Time
15 pF Fall Time
22 pF Rise Time
22 pF Fall Time
33 pF Rise Time
33 pF Fall Time
SSH 47 pF Rise Time
SSM 47 pF Fall Time
1,00
0,50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 27: Rise/fall times for Class A2 strong-sharp driver setting at VDDP=3.30V
Application Note
32
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
5.8
Rise/fall time diagrams for increased capacitive loads
Weak Driver 150pF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
240
220
Rise/Fall Time [ns]
200
A2 WEA 150pF Rise Time
A2 WEA 150pF Fall Time
A1+ WEA 150pF Rise Time
A1+ WEA 150pF Fall Time
A1 WEA 150pF Rise Time
A1 WEA 150pF Fall Time
180
160
140
120
100
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 28: Rise/fall times for weak driver setting at VDDP=3.30V and 150pF load
Medium Driver 150pF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
70,0
65,0
Rise/Fall Time [ns]
60,0
55,0
A2 MED 150pF Rise Time
A2 MED 150pF Fall Time
A1+ MED 150pF Rise Time
A1+ MED 150pF Fall Time
A1 MED 150pF Rise Time
A1 MED 150pF Fall Time
50,0
45,0
40,0
35,0
30,0
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 29: Rise/fall times for medium driver setting at VDDP=3.30V and 150pF load
Application Note
33
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Weak Driver 1500pF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
1900
1800
1700
1600
Rise/Fall Time [ns]
1500
A2 WEA 1500pF Rise Time
A2 WEA 1500pF Fall Time
A1+ WEA 1500pF Rise Time
A1+ WEA 1500pF Fall Time
A1 WEA 1500pF Rise Time
A1 WEA 1500pF Fall Time
1400
1300
1200
1100
1000
900
800
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110 120
130
140
Ambient Temperature [°C]
Figure 30: Rise/fall times for weak driver setting at VDDP=3.30V and 1.5nF load
Medium Driver 1500pF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
550
500
Rise/Fall Time [ns]
450
A2 MED 1500pF Rise Time
A2 MED 1500pF Fall Time
A1+ MED 1500pF Rise Time
A1+ MED 1500pF Fall Time
A1 MED 1500pF Rise Time
A1 MED 1500pF Fall Time
400
350
300
250
200
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 31: Rise/fall times for weak driver setting at VDDP=3.30V and 1.5nF load
Application Note
34
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Weak Driver 20nF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
24000
22000
Rise/Fall Time [ns]
20000
A2 WEA 20nF Rise Time
A2 WEA 20nF Fall Time
A1+ WEA 20nF Rise Time
A1+ WEA 20nF Fall Time
A1 WEA 20nF Rise Time
A1 WEA 20nF Fall Time
18000
16000
14000
12000
10000
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 32: Rise/fall times for weak driver setting at VDDP=3.30V and 20nF load
Medium Driver 20nF Rise/Fall Times over Temperature
3.3V Pad Supply; Pad Classes A1, A1+, A2
8000
7000
Rise/Fall Time [ns]
6000
A2 MED 20nF Rise Time
A2 MED 20nF Fal lTime
A1+ MED 20nF Rise Time
A1+ MED 20nF Fall Time
A1 MED 20nF Rise Time
A1 MED 20nF Fall Time
5000
4000
3000
2000
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 33: Rise/fall times for weak driver setting at VDDP=3.30V and 20nF load
Application Note
35
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Strong Driver Sharp-Edge 100pF Rise/Fall Times over Temperature;
3.3V PadSupply; PadClass A2
4,50
Rise/Fall Time [ns]
4,00
SSH 100 pF Rise Time
SSH 100 pF Fall Time
3,50
3,00
2,50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Ambient Temperature [°C]
Figure 34: Rise/fall times for Class A2 strong-sharp driver setting at VDDP=3.30V and 100pF load
Application Note
36
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
6
Measured electromagnetic emission
6.1
Microcontroller operation mode
In addition to signal integrity, the scaling of pad drivers helps to reduce electromagnetic emission (EME)
caused by switching output pins. This is because slower signal edges produce less high frequency contents in
the emission spectra.
The following rule should be obeyed when selecting pad driver strength:
Use the weakest/slowest driver setting which provides the required signal timing at worst-case operating
conditions.
Worst-case operating conditions wrt. timing are:
-
maximal ambient temperature (+140°C)
-
minimal pad supply voltage (3.30V -5% = 3.13V)
-
realistic capacitive output load (consider trace length and structure (i.e. PCB layer stack, microstrip or
stripline, receiver input loads)
-
weak driver settings
Worst-case operating conditions wrt. electromagnetic emission are:
-
minimal ambient temperature (-40°C)
-
maximal pad supply voltage (3.30V +5% = 3.47V)
-
strong driver settings
To illustrate the benefits of driver scaling for low EME, some sample measurement results are provided.
The measurements have been performed under the following operating conditions:
All function units of the TC1782 were active according Table 9.
The pad drivers were active according Table 10. Please note that only special function drivers have been
activated; general purpose I/Os (GPIO) stayed inactive.
The pad driver settings have been varied according Table 11.
All I/Os not listed in Table 11 were inactive.
Conducted emission is measured at pad supply (VDDP) according to chapter 5.2.1.
Radiated emission is measured in mini-TEM cell according to chapter 5.2.2.
Application Note
37
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Function unit
Operating mode
Settings
PLL
• system clock generation
• system clock = 180.0 MHz
CPU
• cyclicSPRAM copy (address 0xC0000000 first 8K
to last 8K and reverse)
• module clock = 180.0 MHz
• cycle time = 1.1 µs
PCP
• 3 tasks executed in cyclic sequential order:
• task 1: PMEM read, increment, store (per pointer
over data page, address 0xF0050400); pointer
store DMI)
• task 2: 32 * 32 multiplication
• task 3: value DMI rotate
ASC0
ASC1
• 8-bit data asynchronous operation
• module clock = 80.0 MHz
• one stop bit
• baud rate = 19.231 kBaud
• receiver disabled
• deviation from 19.200 kBaud = 0.16 %
• 8-bit data synchronous operation
• module clock = 80.0 MHz
• baud rate = 10.0 MBaud
MultiCAN
• CAN0 controlled via Transmit Interrupt.
• module clock = 40.0 MHz
• CAN1 inactive, (ASC1 in use)
• baud rate = 1.0 Mbaud
• normal divider mode selected
• sample point = 65 %
• 12 time quanta before sample point
• 7 time quanta after sample point
• (re)synchronization jump width = 2
time quanta
MSC0
• single ended driver used
• module clock = 20.0 MHz
• LVDS differential Interface disabled
• baud rate = 10.0 Mbaud
• data repetition mode (content register
MSC0_DD = 0x0000A953)
MLI0
SSC0+SSC1
• normal divider mode is selected
• module clock = 20.0 MHz
• endless transmit
• baud rate = 10.0 Mbaud
• normal divider mode is selected
• module clock = 20.0 MHz
• configured as SSC master
• baud rate = 2.0 Mbaud
• transfer data width is 16 bit
• transfer/receive MSB first
• shift transmit data on the leading clock edge, latch
on trailing edge
• idle clock line is low, leading clock edge is low-tohigh transition
• slave output select leading delay: 1 SCLK periods
• slave output select trailing delay: 0 SCLK periods
• slave output select inactive delay: 1 SCLK periods
• data transmit via receive Interrupt.
Application Note
38
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
GPTA0
• normal divider mode selected
• module clock = 20.0 MHz
• GPTA running at 20 MHz, 32 GTC cells compare
a specific GT0 value and toggle their outputs
• GTO clock = 2.5 MHz
• GT1 clock = max. 3 MHz
• Out of 64 LTCs 16 are used as timer with 20 MHz,
the other 48 cells use compare.
• LTCA2 is only working when GPTA0 is active
SCU
• SYSCLK (normal mode)
• Pin 4.3 (SYSCLK) toggles at 7.5 MHz
FADC
• fractional divider mode is selected
• module clock = 32.031 MHz
• channel0 to channel3 convert continuously via
neighbour trigger
• deviation from 32.000 MHz = 0.10%
• 16 channels per autoscan
• digital clock = 80 MHz
• 10Bit resolution
• analog clock = 10 MHz
ADC0/1
Table 9: Operating modes and settings of TC1782 function units
Active pads
Pad function
Pad class
Driver config. reg.
P0.10
E-ray A data out
A2
P0_PDR.PD1
P0.11
E-ray B data out
A2
P0_PDR.PD1
P0.12
E-ray A enable out
A2
P0_PDR.PD1
P0.13
E-ray B enable out
A2
P0_PDR.PD1
P0.14
MSC CLK out
A1+
P0_PDR.PD1
P0.15
MSC data out
A1+
P0_PDR.PD1
P1.8
SSC1
A1+
P1_PDR.PDSSC1B
P1.9
SSC1
A1+
P1_PDR.PDSSC1B
P1.10
SSC1
A1+
P1_PDR.PDSSC1B
P1.11
SSC1
A1+
P1_PDR.PDSSC1B
P2.1
MLI
A2
P2_PDR.PDMSC0
P2.2
MLI
A2
P2_PDR.PDMLI0
P2.3
MLI
A2
P2_PDR.PDMLI0
P2.4
MLI
A2
P2_PDR.PD0
P2.5
MLI
A2
P2_PDR.PDMLI0
P2.6
LED driver
A2
P2_PDR.PD0
P2.7
MLI
A2
P2_PDR.PD0
P2.8
SSC_SLSO
A2
P2_PDR.PDMSC0
P2.9
SSC_SLSO
A2
P2_PDR.PDMSC0
P2.10
SSC1_Input
A1+
P2_PDR.PDSSC1
P2.11
MSC0
A1+
P2_PDR.PDSSC1
P2.12
MSC0
A1+
P2_PDR.PDSSC1
P2.13
MSC0_Input
A1
P2_PDR.PD1
P3.0
RX0DA
(A1+) pull-down
P3_PDR.PDASC0
P3.1
TX0DA
A1+
P3_PDR.PDASC0
Application Note
39
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
P3.2
SSC0
A1+
P3_PDR.PDASC0
P3.3
SSC0
(A1+) pull-down
P3_PDR.PDASC0
P3.4
SSC0
A1+
P3_PDR.PDASC0
P3.5
SSC0_SLSO
A1+
P3_PDR.PDASC0
P3.6
SSC0_SLSO
A1+
P3_PDR.PDASC0
P3.7
SSC0_SLSO
A2
P3_PDR.PDASC0
P3.8
RX1DA
A2
P3_PDR.PD1
P3.9
TX1DA
A1
P3_PDR.PD1
P3.12
RXDCAN0
(A1) pull-down
P3_PDR.PD1
P3.13
TXDCAN0
A2
P3_PDR.PD1
P3.14
RXDCAN1
(A1) pull-down
P3_PDR.PD1
P3.15
TXDCAN1
A2
P3_PDR.PD1
P4.3
SYSCLK
A2
P4_PDR.PDEXTCLK0
P5.8
MLI0_Input
A2
P5_PDR.PD2
P5.9
MLI0_Input
A2
P5_PDR.PD2
P5.10
MLI0
A2
P5_PDR.PDMLI0
P5.11
MLI0_Input
A2
P5_PDR.PD2
P5.12
MLI0
A1+
P5_PDR.PDMLI0
P5.13
MLI0
A1+
P5_PDR.PDMLI0
P5.14
MLI0_Input
A1+
P5_PDR.PD2
P5.15
MLI0
A1+
P5_PDR.PDMLI0
P6.0
MSC0
A1
P6_PDR.PD0
P6.1
MSC0
A1
P6_PDR.PD0
P6.2
MSC0
A1
P6_PDR.PD0
P6.3
MSC0
A1
P6_PDR.PD0
Table 10: Active pad drivers
Configuration name
Class A2 setting
Class A1+ setting
Class A1 setting
SSH
strong-sharp
strong-soft
medium
SSM
strong-sharp-minus
strong-soft
medium
SME
strong-medium
strong-soft
medium
SMM
strong-medium-minus
strong-soft
medium
SSO
strong-soft
strong-soft
1)
strong-slow
medium
1)
strong-slow1)
SSL
strong-slow
MED
medium
medium
medium
WEA
weak
weak
weak
Table 11: Configurations of pad scaling
Application Note
40
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
6.2
Description of test equipment
6.2.1
Conducted emission test configuration
Conducted emission is measured using the
standardized 150Ω network, see Figure 30. This
network is used for both port and power supply
emission measurements. The frequency range
is from 150kHz to 1000MHz.
For reference purpose, only the emission
measured on the supply domain VDDP is
documented. Since all digital port pin drivers are
supplied by VDDP, the electromagnetic
emission on this net is influenced significantly
by the driver setting variation. Nevertheless,
emission variations can be observed on other
power supply domains and on passive (i.e. nonswitching) pad pins as well due to RF coupling
in the microcontroller and on the test board.
However, VDDP shows the strongest link
between driver down-scaling and emission
reduction.
150Ω networks are provided for conducted
emission measurements according IEC 61967
part 4 and BISS emission test specification.
Figure 35: Conducted emission probing points
6.2.2
Radiated emission test configuration
Radiated emission is measured using the standard Mini TEM Cell according IEC 61967 part 2 and BISS
emission test specification, see Figure 31. The frequency range is from 150kHz to 1000MHz.
Figure 36: Radiated emission test setup
Application Note
41
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
6.2.3
Measurement settings
Spectrum analyzer:
Rohde & Schwarz FSP7
Frequency range:
150kHz to 1GHz
Bandwidth RBW:
10kHz
Detector type:
Peak detector
Dwell time:
10ms
Pre-Amplifier:
internal
Measurement time:
For all measurements, the emission measurement time (dwell time 10ms) at
one
frequency is longer than the test software loop duration.
Data generation software:
Rohde & Schwarz EMIPAK 9950
Environment:
Temperature 23°C ±5°C
Supply:
Nominal voltage ±5%
Application Note
42
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
6.3
Emission test result discussion
Note: To eliminate emission effects not caused by the microcontroller, the diagrams in Figures 32 to 43 cut the
frequency above 800MHz because of GSM disturbance around 900MHz.
In this section electromagnetic emissions are compared for the different driver settings explained in chapter 6.1.
The capacitive loads at all switching port pins have been 10pF (Figures 32, 33) and 47pF (Figures 34, 35),
respectively. These emission results were obtained at nominal operating conditions, i.e. room temperature
(+25°C), and 3.30V pad supply.
Result: Significant emission is caused by strong-sharp and strong-medium driver settings. Strong-soft setting
causes visible emission only in the low frequency range below 100MHz. Medium and weak settings do not
show any significant emission.
Table 12 lists average emission damping values caused by different driver settings (0 dB reference is strongsharp setting):
Driver setting
Emission damping (average approx. numbers)
Average toggling speed (1-10 MHz)
High toggling speed (>20 MHz)
Strong-sharp
0 dB
0 dB
Strong-sharp-minus
-4 dB
-6 dB
Strong-medium
-6 dB
-10 dB
Strong-medium-minus
-8 dB
-15 dB
Strong-soft
-10 dB
-20 dB
Strong-slow
-10 dB
n/a
Medium
< -10 dB (noise floor)
n/a
Weak
< -10 dB (noise floor)
n/a
Table 12: Average emission damping from driver settings
Figures 36 and 37 indicate the span of electromagnetic emission with respect to extreme values of pad supply
voltage (VDDP) and ambient temperature. Therefore, instead of really changing the ambient temperature,
VDDP was selected in a way that the resulting switching waveform was similar to the switching waveform at the
respective ambient temperature at nominal VDDP. For “SLOW” case VDDP went below 3.13V (VDDPnom -5%)
to reflect the even slower transistors switching at +140°C ambient temperature. Vice versa, the “FAST” case
was emulated by VDDP exceeding 3.47V, thus reflecting the faster transistor switching at -40°C ambient
temperature.
Result: Voltage and temperature variation within the microcontroller specification leads to maximal ca. 3dB
deviation above and below the emission at nominal conditions.
Figures 38 to 43 emphasize the benefit of the 5 available scaling steps in the Class A2 drivers. Therefore, the
toggle rate of EXTCLK at port pin P4.3 was selectedto be 22.5MHz, providing a still good signal integrity for
strong-soft driver setting, i.e. reaching the 10%/90% signal levels and staying at high/low level ca. 4 times
longer than the rise/fall times.
Result: Up to 25dB emission reduction can be obtained if the strong-soft driver setting is used instead of the
strong-sharp setting. All other strong driver settings range between these extremes.
Application Note
43
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net for all driver settings at 10pF load
VDDP = 3.30V / Ambient temperature = 25°C
30
25
dBµV
20
15
10
5
0
100
200
300
400
500
600
700
800
strong slow
medium
Frequency/MHz
strong sharp
strong sharp-minus
strong medium
strong medium-minus
strong soft
weak
Figure 37: Conducted emission spectra for different driver settings at 10pF
Conducted electromagnetic emission zoom 160MHz - 200MHz
on I/O supply net for all driver settings at 10pF load
VDDP = 3.30V / Ambient temperature = 25°C
30
25
dBµV
20
15
10
5
160
165
170
175
180
185
190
195
200
strong slow
medium
Frequency/MHz
strong sharp
strong sharp-minus
strong medium
strong medium-minus
strong soft
weak
Figure 38: Zoomed conducted noise transfer behaviour for different driver settings at 10pF
Application Note
44
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net for all driver settings at 47pF load
VDDP = 3.30V / Ambient temperature = 25°C
30
25
dBµV
20
15
10
5
0
100
200
300
400
500
600
700
800
strong slow
medium
Frequency/MHz
strong sharp
strong sharp-minus
strong medium
strong medium-minus
strong soft
weak
Figure 39: Conducted emission spectra for different driver settings at 47pF
Conducted electromagnetic emission zoom 160MHz - 200MHz
on I/O supply net for all driver settings at 47pF load
VDDP = 3.30V / Ambient temperature = 25°C
30
25
dBµV
20
15
10
5
160
165
170
175
180
185
190
195
200
strong slow
medium
Frequency/MHz
strong sharp
strong sharp-minus
strong medium
strong medium-minus
strong soft
weak
Figure 40: Zoomed conducted noise transfer behaviour for different driver settings at 47pF
Application Note
45
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net for strong sharp driver settings at 10pF load
slow (VDDP=3.13V/Ta=150°C) / nom (VDDP=3.30V/Ta=25°C) /
fast (VDDP=3.47V/Ta=-40°C)
30
25
dBµV
20
15
10
5
0
100
200
300
400
500
600
700
800
Frequency/MHz
SLOW 150°C - 3.13V
NOM 25°C - 3.30V
FAST -40°C - 3.47V
Figure 41: Conducted emission spectra for strong-sharp driver setting at 10pF and PVT variation
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net for strong sharp driver settings at 47pF load
slow (VDDP=3.13V/Ta=150°C) / nom (VDDP=3.30V/Ta=25°C) /
fast (VDDP=3.47V/Ta=-40°C)
30
25
dBµV
20
15
10
5
0
100
200
300
400
500
600
700
800
Frequency/MHz
SLOW 150°C - 3,14V
NOM 25°C - 3,3V
FAST -40°C - 3,47V
Figure 42: Conducted emission spectra for strong-sharp driver setting at 47pF and PVT variation
Application Note
46
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net for all Class A2 strong driver settings at 47pF load
VDDP = 3.30V / Ambient temperature = 25°C
40
35
dBµV
30
25
20
15
10
5
0
100
200
300
400
500
600
700
800
Frequency/MHz
strong sharp
strong sharp-minus
strong medium
strong medium-minus
strong soft
Figure 43: Conducted emission spectra for different Class A2 strong driver settings at 47pF
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net VDDP for strong sharp driver setting at 47pF load
40
35
30
dBµV
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Frequency/MHz
Figure 44: Conducted emission spectrum for strong-sharp driver setting at 47pF
Application Note
47
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net VDDP for strong sharp-minus driver setting at 47pF load
40
35
30
dBµV
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Frequency/MHz
Figure 45: Conducted emission spectrum for strong-sharp-minus driver setting at 47pF
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net VDDP for strong medium driver setting at 47pF load
40
35
30
dBµV
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Frequency/MHz
Figure 46: Conducted emission spectrum for strong-medium driver setting at 47pF
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conducted electromagnetic emission 150kHz - 800MHz on
I/O supply net VDDP for strong medium-minus driver setting at 47pF load
40
35
30
dBµV
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Frequency/MHz
Figure 47: Conducted emission spectrum for strong-medium-minus driver setting at 47pF
Conducted electromagnetic emission 150kHz - 800MHz
on I/O supply net VDDP for strong soft driver setting at 47pF load
40
35
30
dBµV
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Frequency/MHz
Figure 48: Conducted emission spectrum for strong-soft driver setting at 47pF
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Conclusion:
Generally all strong driver settings (strong-sharp, strong-sharp-minus, strong-medium, strong-medium-minus,
strong-soft) lead to considerable emission. Consequently, all “low-speed” signals up to ca. 5MHz should be
driven by medium or weak drivers. All “high-rate” signals above ca. 5MHz require strong driver settings in order
to achieve good signal integrity. However, the recommended settings depend not only on the signal’s data rate,
but significantly on the external capacitive load, the maximal ambient temperature and additional timing
protocol constraints such as maximal slew rate.
Detailed selection diagrams for the recommended driver settings depending on given data rates are provided in
Chapter 7.
Application Note
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Timing and Electromagnetic Emission
7
Recommended pad driver settings
7.1
Signal categories
In the previous chapters, many detailed data was provided for the impact of driver settings and load
capacitance on the resulting rise and fall times as well as on conducted and radiated emission.
Generally, the required signal integrity determines the selection of driver strength and slew rate for a given
toggle rate and capacitive load. However, due to the simultaneous impact on electromagnetic emission, the
weakest possible driver setting which still meets the signal integrity should be chosen.
To decide for the proper pad driver settings for a signal, its electrical characteristics should be considered. This
leads to the definition of signal categories by means of clock or data transfer (AC view) or current driving
capability (DC view). According to these views, any signal can be classified as shown in Table 13.
Signal category
Clock rate
Capacitive load
DC driving capability
System clock
>20MHz
10 … 50 pF
n/a
High-speed data line
5 … 20 MHz
10 … 50 pF
n/a
Low-speed data line
0.5 … 5 MHz
10 … 50 pF
n/a
Low-speed control line
<1 MHz
<20 pF
n/a
High-current control line
n/a
n/a
10 … 30 mA
Medium-current control line
n/a
n/a
1 … 10 mA
Low-current control line
n/a
n/a
<1 mA
Table 13: Signal categories
The following settings for pad output drivers are available, see also Table 2:
•
strong driver / sharp edge (Class A2 only)
•
strong driver / sharp-minus edge (Class A2 only)
•
strong driver / medium edge (Class A2 only)
•
strong driver / medium-minus edge (Class A2 only)
•
strong driver / soft edge (Classes A1+ and A2 only)
•
strong driver / slow edge (Class A1+ only)
•
medium driver / no edge configuration available
•
weak driver / no edge configuration available
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Driver
configuration
Edge
configuration
Signal category
Capacitive
Load
DC Current 1)
STRONG
SHARP
System clock >40MHz
Medium
2.5 / 10 mA
STRONG
MEDIUM
System clock >20MHz
Low
2.5 / 10 mA
High-speed data lines
High
High-speed data lines
Low
High-current control lines
All
Low-speed data lines
All
Medium-current control lines
All
Very low-speed control lines
All
Low-current control line
All
STRONG
MEDIUM
SOFT
none
WEAK
none
2.5 / 10 mA
1.0 / 4.0 mA
0.1 / 0.5 mA
Table 14: Recommended output driver settings
Note 1) : Two values are given for the DC current of I/O pins in the format “nominal / max mA”. The “max mA”
value can only be drawn from a pin if maximal 2 other pins in the same 16-bit port group are also driving this
maximum current. This restriction is due to danger of electromigration damage.
The following parameters determine the final selection of driver settings:
•
signal performance category (AC and DC)
•
maximal temperature
•
maximal acceptable electromagnetic emission
7.2
Decision tables and diagrams
Following the recommendations given above, the driver setting selection should be based on (1) proper signal
integrity and (2) minimal electromagnetic emission. Since electromagnetic emission increases with stronger
driver settings, the weakest driver and slew rate settings should be selected that are able to provide the rise/fall
times required for the desired signal integrity.
This chapter offers decision numbers in table and graphical format for proper driver settings at maximum clock
or data rates expected to be driven. The rise/fall times occupy 1/6th of the clock period each, see Figure 44. If
other rise/fall-to-period ratios are of interest, the given data rate values must be multiplied with “desired_ratio
divided by 1/6”, see Table 15.
Ratio rise/fall time1) to period
Multiply all given frequency values by:
1/20
0.3
1/10
0.6
1/8
0.75
1/6
1.0
1/4
1.5
Table 15: Correction factors for different edge-to-period ratios
Note
1)
: To calculate the ratio, please select the shorter one from rise and fall time.
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Figure 49: Assumed rise/fall timing conditions related to signal period T
Please note that all values given in this chapter are proposals for system application designers using Infineon
TC1782 microcontrollers in 90nm CMOS technology. They are based on timing measurements performed on
center lot devices. Thus all values are subject to less than 10% offset depending according fabrication process
variation. Additionally, pad supply voltages different from nominal conditions impact the resulting timing. The
finally selected driver setting should consider these facts.
The decision tables provided in sections 6.2.1 (pad class A2), 6.2.2 (pad class A1+) and 6.2.3 (pad class A1)
should be handled in the following way:
•
I/O supply voltage has nominal value (VDDP=3.30V) except for WORST and BEST cases.
•
Several ambient temperatures are distinguished by color:
Æ wide-spread industrial IC temperature specifications: 125°C, 110°C, 85°C, 70°C.
Æ 140°C / -40°C as maximal / minimal ambient temperatures for TC1782 during operation.
Æ 25°C as room temperature.
Æ WORST case: measured at -40°C with increased I/O supply voltage (VDDP=3.30V+5%=3.47V).
Æ BEST case: measured at 140°C with decreased I/O supply voltage (VDDP=3.30V-5%=3.13V).
•
All values are given in [MHz]; they represent the maximal data rate possible under the named
conditions in case the rise and fall time occupy 1/6 of the clock period.
•
The strong-sharp driver is additionally characterized with 100pF load according specification.
•
The weak driver is additionally characterized with 20nF load according specification.
The driver settings in the decision tables and in the decision diagrams are named as follows:
•
SSH=strong-sharp
SSM = strong-sharp-minus
SME = strong-medium
SMM = strong-medium-minus
SSO = strong-soft
SSL = strong-slow
MED = medium
WEA = weak
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Figure 45 shows an example of a decision diagram. The title of each diagram indicates the conditions (Edge-toperiod ratio, I/O voltage VDDP, ambient temperature) for the shown values:
Edge is alwaysr “T/6” (meaning the rise time and the fall time take each 1/6 of the data rate period).
Voltage indicates the I/O pad supply voltage VDDP and is nominal “3.30V”. “Best case” conditions are -40°C
and VDDP=3.13V (VDDPnom-5%); “worst case” conditions are +140°C and VDDP=3.47V (VDDPnom+5%).
Temperature indicates the ambient temperature and is one of the following values: “-40°C”, “+25°C”, “+70°C”,
“+85°C”, “+110°C”, “+125°C” or “+140°C”.
The maximal clock/data rate (“Frequency”) to meet good signal integrity is given in [MHz] for capacitive loads
from 10pF to 47pF. After selecting the crossing point of the driver load and the desired data rate, the suggested
driver can be read out of the diagram. Figure 45 gives four examples, marked with red circles A to D:
Circle A marks 2MHz data rate at 25pF load. Since the center of the circle stays below the green line, the weak
driver is recommended.
Circle B marks 4MHz at 17pF and selects the medium driver since it stays below the blue line.
Circle C marks 8MHz at 30pF and suggests the strong-soft setting (below yellow line).
Circle D marks 33MHz at 20pF and recommends the strong-medium driver (below red line).
Like in Figure 45 (Ta=+140°C), it is always recommended to take the decision diagram for the highest ambient
operating temperature of the microcontroller.
General rule: Select always the weakest possible driver which is able to toggle the maximal desired data rate at
the given external load and temperature.
Please note that according Table 3, several driver settings are available in several pad classes. Since there are
small deviations among same driver scaling in different pad classes, please refer always to the decision
diagram of the correct pad class (A1, A1+, A2).
Figure 50: Driver decision diagram example
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.1
Decision table for pad class A2
15pF
160,79
72,46
52,58
32,06
17,41
8,03
2,39
22pF
133,84
65,90
48,78
29,27
16,78
7,63
2,26
33pF
100,99
56,88
42,44
26,18
15,40
6,69
1,97
47pF 100pF 150pF
74,30 57,38
47,85
38,99
23,89
14,49
5,63
2,83
1,70
0,81
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
10pF
189,97
88,91
59,65
35,63
18,95
9,31
2,74
0,371
0,101
0,02648
0,00780
15pF
165,02
75,08
54,64
32,87
17,41
8,35
2,48
22pF
136,61
68,03
50,20
30,14
16,78
7,85
2,33
33pF
103,52
58,69
43,98
27,01
15,40
6,95
2,04
47pF 100pF 150pF
76,45 59,10
49,46
39,87
23,89
14,91
5,84
2,92
1,76
0,83
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
10pF
196,31
90,09
61,96
36,39
18,95
9,57
2,84
0,381
0,103
0,02684
0,00801
15pF
169,24
77,69
56,71
33,69
18,47
8,66
2,58
22pF
139,38
70,15
51,62
31,01
17,66
8,07
2,40
33pF
106,05
60,49
45,51
27,84
16,41
7,20
2,11
47pF 100pF 150pF
78,61 60,82
51,07
40,75
25,13
15,32
6,06
3,01
1,82
0,86
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
10pF
202,65
91,27
64,26
37,15
20,08
9,83
2,95
0,390
0,105
0,02720
0,00821
15pF
176,38
82,09
60,04
34,90
19,30
9,18
2,74
22pF
143,67
73,67
53,79
32,41
18,35
8,42
2,51
33pF
109,99
63,48
47,99
29,08
17,18
7,61
2,22
47pF 100pF 150pF
82,18 63,56
53,63
42,10
26,05
15,96
6,41
3,16
1,91
0,90
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
10pF
212,85
92,37
67,92
38,09
20,90
10,18
3,11
0,407
0,108
0,02766
0,00854
10pF
219,53
95,79
70,59
39,69
21,73
10,65
3,24
15pF
180,08
84,35
62,15
36,04
19,95
9,54
2,84
22pF
146,57
75,18
55,73
33,54
19,03
8,76
2,61
33pF
113,10
65,58
49,63
30,29
17,88
7,92
2,32
47pF 100pF 150pF
84,23 65,71
55,60
43,33
27,04
16,52
6,65
3,27
1,99
0,92
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
0,415
0,111
0,02838
0,00875
140°C
125°C
110°C
85°C
70°C
Application Note
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
Decision table for pad class A2 (continued):
10pF
242,60
107,53
79,37
45,05
24,55
12,19
3,67
15pF
192,01
92,08
69,44
39,78
22,13
10,58
3,20
22pF
158,73
82,51
61,96
36,47
20,58
9,51
2,85
33pF
123,46
74,07
55,19
34,08
19,98
8,87
2,61
47pF 100pF 150pF
91,07 72,05
61,50
47,08
29,87
18,20
7,30
3,58
2,20
0,99
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
0,439
0,119
0,03069
0,00932
10pF
268,82
123,46
91,58
52,74
27,32
14,42
4,40
15pF
199,60
104,82
79,37
45,91
24,58
12,48
3,75
22pF
163,40
93,63
71,53
42,52
23,44
11,22
3,35
33pF
132,28
84,18
64,35
39,59
22,74
10,47
3,08
47pF 100pF 150pF
97,47 78,13
68,87
53,42
34,08
20,65
8,54
4,11
2,52
1,12
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
0,489
0,132
0,03243
0,01006
10pF
174,61
77,75
56,52
31,92
17,74
8,83
2,60
15pF
156,75
70,46
51,19
30,51
16,83
7,92
2,34
22pF
124,25
60,42
44,29
26,34
S81
7,02
2,09
33pF
99,43
53,84
41,27
24,86
14,53
6,43
1,93
47pF 100pF 150pF
68,26 54,39
45,55
36,05
22,79
13,80
5,53
2,76
1,63
0,76
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
0,357
0,097
0,02474
0,00746
15pF
214,50
113,38
85,03
49,46
27,32
13,25
4,04
22pF
170,07
96,34
75,08
44,33
25,29
11,81
3,55
33pF
133,33
86,81
66,67
41,25
23,91
?T87
3,17
47pF 100pF 150pF
99,21 79,11
71,84
55,93
36,15
21,73
9,02
4,07
2,66
1,15
1500pF
20nF
SSH
SSM
SME
SMM
SSO
MED
WEA
10pF
269,69
130,21
94,16
53,76
28,99
14,56
4,53
0,502
0,137
0,03388
0,01050
25°C
-40°C
WORST
BEST
Application Note
56
V1.0, 2010-01
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.2
Decision table for pad class A1+
15pF
21,50
4,11
7,99
2,42
22pF
20,43
10,32
7,72
2,19
33pF
15,78
9,35
6,83
2,05
47pF
10,76
7,64
5,20
1,64
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
31,11
13,19
9,53
2,93
2,55
0,76
0,312
0,092
0,0246
0,00767
15pF
22,22
11,65
8,29
2,51
22pF
20,76
10,69
7,91
2,29
33pF
15,98
9,68
7,01
2,11
47pF
11,00
7,93
5,42
1,72
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
31,69
13,52
9,74
2,98
2,62
0,78
0,316
0,094
0,0250
0,00780
15pF
22,95
12,05
8,59
2,60
22pF
21,08
11,06
8,11
2,39
33pF
16,18
10,02
7,19
2,17
47pF
11,24
8,22
5,65
1,79
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
32,26
13,85
9,94
3,03
2,69
0,80
0,320
0,095
0,0254
0,00793
15pF
24,12
12,68
9,06
2,74
22pF
21,46
11,61
8,37
2,54
33pF
I139
10,59
7,45
2,27
47pF
11,65
8,73
6,04
1,92
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
33,02
14,31
10,21
3,09
2,80
0,83
0,325
0,098
0,0260
0,00812
10pF
33,90
14,94
10,63
3,23
15pF
24,68
13,19
9,41
2,86
22pF
22,04
12,11
8,71
2,64
33pF
16,92
10,92
7,73
2,35
47pF
11,90
8,93
6,22
1,97
150pF
1500pF
20nF
SSH
SSM
SME
SMM
2,88
0,84
0,333
0,101
0,0268
0,00828
10pF 15pF 22pF
SSO 37,54 27,55 24,73
SSL 16,65 14,92 13,89
MED 11,79 10,58 9,86
WEA 3,65 3,21 3,00
33pF
18,34
12,12
8,64
2,60
47pF
12,59
9,61
6,79
2,14
150pF
1500pF
20nF
3,16
0,92
0,356
0,109
0,0290
0,00886
33pF
20,48
13,94
10,00
3,06
47pF
13,76
12,04
7,97
2,48
150pF
1500pF
20nF
3,45
1,02
0,391
0,118
0,0310
0,00968
140°C
125°C
110°C
85°C
70°C
25°C
-40°C
SSO
SSL
MED
WEA
Application Note
10pF
41,46
19,16
13,75
4,27
15pF
30,14
16,95
12,04
3,78
22pF
26,97
15,87
11,40
3,50
57
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Timing and Electromagnetic Emission
Decision table for pad class A1+ (continued):
15pF
21,85
10,89
7,68
2,42
22pF
18,87
10,47
7,96
2,35
33pF
15,53
9,07
6,56
1,94
47pF
10,86
7,59
5,37
1,61
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
28,15
12,10
8,61
2,71
2,46
0,72
0,291
0,089
0,0238
0,00726
15pF
30,25
17,49
12,57
3,88
22pF
27,69
16,58
11,90
3,64
33pF
20,94
14,28
10,18
3,15
47pF
14,15
11,14
7,86
2,49
150pF
1500pF
20nF
SSO
SSL
MED
WEA
10pF
42,74
19,82
14,39
4,41
3,60
1,04
0,405
0,123
0,0319
0,01
WORST
BEST
Application Note
58
V1.0, 2010-01
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TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.3
Decision table for pad class A1
10pF 15pF 22pF 33pF 47pF
MED 8,92 7,88 7,76 6,66 5,50
WEA 2,96 2,39 2,29 2,04 1,68
150pF
2,65
0,79
1500pF
20nF
0,320 0,02515
0,104 0,00734
MED
WEA
10pF 15pF 22pF 33pF 47pF
9,35 8,17 8,02 6,91 5,66
3,02 2,46 2,37 2,10 1,74
150pF
2,71
0,81
1500pF
20nF
0,325 0,02560
0,107 0,00749
MED
WEA
10pF 15pF 22pF 33pF 47pF
9,78 8,45 8,27 7,16 5,82
3,08 2,53 2,45 2,15 1,80
150pF
2,77
0,82
1500pF
20nF
0,330 0,02606
0,109 0,00764
85°C
10pF 15pF 22pF 33pF 47pF
MED 10,48 8,90 8,67 7,57 6,08
WEA 3,15 2,64 2,58 2,25 1,90
150pF
2,86
0,85
1500pF
20nF
0,336 0,02676
0,114 0,00787
70°C
10pF 15pF 22pF 33pF 47pF
SME 10,89 9,23 9,00 7,83 6,37
SMM 3,28 2,75 2,68 2,33 1,97
150pF
2,95
0,87
1500pF
20nF
0,344 0,02740
0,114 0,00806
25°C
10pF 15pF 22pF 33pF 47pF
MED 12,28 10,34 10,10 8,53 6,85
WEA 3,70 3,08 2,99 2,60 2,18
150pF
3,22
0,95
1500pF
20nF
0,364 0,02924
0,117 0,00872
-40°C
10pF 15pF 22pF 33pF 47pF
MED 14,12 11,81 11,49 9,96 7,71
WEA 4,32 3,59 3,47 3,02 2,49
150pF
3,55
1,07
1500pF
20nF
0,408 0,03211
0,129 0,00936
10pF 15pF 22pF 33pF 47pF
8,69 7,71 7,52 6,26 5,45
2,57 2,27 2,20 1,91 1,66
150pF
2,52
0,75
1500pF
20nF
0,320 0,02464
0,094 0,00714
10pF 15pF 22pF 33pF 47pF 150pF
MED 21,87 18,36 17,56 15,19 11,66 5,50
WEA 6,75 3,20 5,36 4,68 3,78
1,63
1500pF
20nF
0,385 0,04854
0,200 0,00966
140°C
125°C
110°C
WORST
MED
WEA
BEST
Application Note
59
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.4
Decision diagrams for pad class A2
Frequency Limits, Edge=T/6, VDDP=3.13V, Ta=+140°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 51: Class A2 driver selection diagram for WORST case TA=140°C; VDDP=3.13V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+140°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 52: Class A2 driver selection diagram for TA=140°C; VDDP=3.30V; edges=1/6 period
Application Note
60
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+125°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 53: Class A2 driver selection diagram for TA=125°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+110°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 54 Class A2 driver selection diagram for TA=110°C; VDDP=3.30V; edges=1/6 period
Application Note
61
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+85°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 55: Class A2 driver selection diagram for TA=85°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+70°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 56: Class A2 driver selection diagram for TA=70°C; VDDP=3.30V; edges=1/6 period
Application Note
62
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+25°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 57: Class A2 driver selection diagram for TA=25°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=-40°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 58: Class A2 driver selection diagram for TA=-40°C; VDDP=3.30V; edges=1/6 period
Application Note
63
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.47V, Ta=-40°C
Pad Class A2
Frequency [MHz]
1000,00
SSH
SSM
SME
SMM
SSO
MED
WEA
100,00
10,00
1,00
10
20
30
40
50
60
70
80
90
100
C load [pF]
Figure 59: Class A2 driver selection diagram for BEST case TA=-40°C; VDDP=3.47V; edges=1/6 period
Application Note
64
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.5
Decision diagrams for pad class A1+
Frequency Limits, Edge=T/6, VDDP=3.13V, Ta=+140°C
Pad Class A1+
Frequency [MHz]
100,00
SSO
SSL
MED
WEA
10,00
1,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 60: Class A1+ driver selection diagram for WORST case TA=140°C; VDDP=3.13V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+140°C
Pad Class A1+
Frequency [MHz]
100,00
SSO
SSL
MED
WEA
10,00
1,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 61: Class A1+ driver selection diagram for TA=140°C; VDDP=3.30V; edges=1/6 period
Application Note
65
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+125°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 62: Class A1+ driver selection diagram for TA=125°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+110°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 63 Class A1+ driver selection diagram for TA=110°C; VDDP=3.30V; edges=1/6 period
Application Note
66
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+85°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 64: Class A1+ driver selection diagram for TA=85°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+70°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 65: Class A1+ driver selection diagram for TA=70°C; VDDP=3.30V; edges=1/6 period
Application Note
67
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+25°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 66: Class A1+ driver selection diagram for TA=25°C; VDDP=3.30V; edges=1/6 period
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=-40°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 67: Class A1+ driver selection diagram for TA=-40°C; VDDP=3.30V; edges=1/6 period
Application Note
68
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits, Edge=T/6, VDDP=3.47V, Ta=-40°C
Pad Class A1+
45,00
40,00
Frequency [MHz]
35,00
30,00
SSO
SSL
MED
WEA
25,00
20,00
15,00
10,00
5,00
0,00
10
15
20
25
30
35
40
45
C load [pF]
Figure 68: Class A1+ driver selection diagram for BEST case TA=-40°C; VDDP=3.47V; edges=1/6 period
Application Note
69
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.6
Decision diagrams for pad class A1
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.13V, Ta=+140°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 69: Class A1 driver selection diagram for WORST case TA=140°C; VDDP=3.13V; edges=1/6 period
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+140°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 70: Class A1 driver selection diagram for TA=140°C; VDDP=3.30V; edges=1/6 period
Application Note
70
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+125°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 71: Class A1 driver selection diagram for TA=125°C; VDDP=3.30V; edges=1/6 period
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+110°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 72: Class A1 driver selection diagram for TA=110°C; VDDP=3.30V; edges=1/6 period
Application Note
71
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+85°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 73: Class A1 driver selection diagram for TA=85°C; VDDP=3.30V; edges=1/6 period
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+70°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 74: Class A1 driver selection diagram for TA=70°C; VDDP=3.30V; edges=1/6 period
Application Note
72
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=+25°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 75: Class A1 driver selection diagram for TA=25°C; VDDP=3.30V; edges=1/6 period
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.30V, Ta=-40°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 76: Class A1 driver selection diagram for TA=-40°C; VDDP=3.30V; edges=1/6 period
Application Note
73
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency [MHz]
Frequency Limits, Edge=T/6, VDDP=3.47V, Ta=-40°C
Pad Class A1
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
MED
WEA
10
15
20
25
30
35
40
45
C load [pF]
Figure 77: Class A1 driver selection diagram for BEST case TA=-40°C; VDDP=3.47V; edges=1/6 period
Application Note
74
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.7
Decision diagrams for weak driver at high capacitive load
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.13V, Ta=+140°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 78: Weak driver load capability diagram for WORST case TA=140°C; VDDP=3.13V; edges=1/6 per.
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+140°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 79: Weak driver load capability diagram for TA=140°C; VDDP=3.30V; edges=1/6 period
Application Note
75
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+125°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 80: Weak driver load capability diagram for TA=125°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+110°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 81: Weak driver load capability diagram for TA=110°C; VDDP=3.30V; edges=1/6 period
Application Note
76
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+85°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 82: Weak driver load capability diagram for TA=85°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+70°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 83: Weak driver load capability diagram for TA=70°C; VDDP=3.30V; edges=1/6 period
Application Note
77
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=+25°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 84: Weak driver load capability diagram for TA=25°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.30V, Ta=-40°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 85: Weak driver load capability diagram for TA=-40°C; VDDP=3.30V; edges=1/6 period
Application Note
78
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Weak Driver, Edge=T/6, VDDP=3.47V, Ta=-40°C
Pad Classes A1, A1+, A2
10,000
Frequency [MHz]
1,000
Class A1
Class A1+
Class A2
0,100
0,010
0,001
10
100
1000
10000
100000
C load [pF]
Figure 86: Weak driver load capability diagram for BEST case TA=-40°C; VDDP=3.47V; edges=1/6 period
Application Note
79
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
7.2.8
Decision diagrams for medium driver at high capacitive load
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.13V, Ta=+140°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 87: Medium driver load capability diagram WORST case TA=140°C; VDDP=3.13V; edges=1/6 per.
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+140°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 88: Medium driver load capability diagram for TA=140°C; VDDP=3.30V; edges=1/6 period
Application Note
80
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+125°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 89: Medium driver load capability diagram for TA=125°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+110°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 90: Medium driver load capability diagram for TA=110°C; VDDP=3.30V; edges=1/6 period
Application Note
81
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+85°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 91: Medium driver load capability diagram for TA=85°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+70°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 92: Medium driver load capability diagram for TA=70°C; VDDP=3.30V; edges=1/6 period
Application Note
82
V1.0, 2010-01
AP32146
TC1782 Scalable Pads
Timing and Electromagnetic Emission
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=+25°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 93: Medium driver load capability diagram for TA=25°C; VDDP=3.30V; edges=1/6 period
Frequency Limits Medium Driver, Edge=T/6, VDDP=3.30V, Ta=-40°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 94: Medium driver load capability diagram for TA=-40°C; VDDP=3.30V; edges=1/6 period
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Frequency Limits Medium Driver, Edge=T/6, VDDP=3.47V, Ta=-40°C
Pad Classes A1, A1+, A2
100,000
Frequency [MHz]
10,000
Class A1
Class A1+
Class A2
1,000
0,100
0,010
10
100
1000
10000
100000
C load [pF]
Figure 95: Medium driver load capability diagram for BEST case TA=-40°C; VDDP=3.47V; edges=1/6 period
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8
Pad Scaling Calculator (PASTOR)
8.1
Scope of the software
For the TC1782 microcontroller, a new software is provided to calculate optimal pad driver settings depending
on electrical and environmental constraints. PASTOR displays rising and falling edge including over- and
undershoot for driver settings under these system constraints.
What you can do with PASTOR:
-
Configure the general settings of your application (capacitive load, pad supply voltage, ambient
temperature)
-
Choose a pad driver scaling and calculate how the driver behaves
-
Choose a data signal performance (either by entering rise and fall time or by entering a data rate plus
period-to-edge ratio)
-
Calculate the weakest driver setting which fulfils your system requirements
-
Display rising edge waveform including overshoot (all timings calculated as 10% to 90% level)
-
Display falling edge waveform including undershoot (all timings calculated as 90% to 10% level)
-
Save waveforms
8.2
How to use PASTOR
1) Start program
-
Launch the Excel file "Pad Scaling Calculator TC1782" and enable Macros or make sure they are
enabled.
2) Configure program
-
Click the "START" button to enter conditional parameter values.
-
Choose one of three input options by clicking on the small check box present in every option part in the
left frame:
o
Data Rate: enter your maximal expected toggle frequency (in MHz) and change the slope to
period ratio with the spinbutton. In this case the rise and fall times are considered to be
identical. For further information just click on the help button just beside. Take into
consideration that the frequency specification limit is 180 MHz.
o
Rise/Fall Times: enter the rise and the fall time (in nanoseconds). Accepted values are limited
to a realistic range wrt. the frequency limit of 180 MHz.
o
Pad Driver: in this field you can select your desired pad driver among the three existing class
A1, A1+ and A2.
-
Note: Only one of those could be selected in the same time, and only the last one ticked will be used
during the execution.
-
After option selection, you have to enter values for the load capacitor (in pF), the ambient temperature
(in degrees Celsius), and the pad supply voltage (in Volts).
-
The following restrictions apply:
o
Valid ambient temperature range is between -40 and +140 degrees Celsius.
o
Load capacitance must not exceed the specified maximal load depending on the pad driver
setting (50, 100, 20000 pF).
o
The pad supply voltage must stay within 3.3V ± 5%.
3) Calculte driver properties
-
Click the "EXE" button to start the simulation.
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-
A new window will appear (if the parameters you entered fit to the specifications):
o
It shows an estimated waveform of the rising edge for your driver.
o
You may view the falling edge waveform by clicking on "VIEW FALL TIME".
o
The values of Over and Undershoots are displayed too.
-
The displayed waveform corresponds to the weakest recommended driver matching all previously
entered conditions.
-
In case you selected a driver before, the displayed waveforms shows this driver's behaviour under the
previously entered conditions.
-
All the parameters on the left frame are now filled with values, and you can change them easily to run a
new execution.
-
Note: the slope to period ratio item is always available for value change after the first run. Thus you can
change it to see the effect on the resulting data rate
-
Note: If a warning appears next to the data rate value, it means that you exceed the frequency limit.
You can click on the warning icon to read the warning message.
4) Save waveforms:
-
8.3
Every time you run an execution, rise and fall time waveforms are saved in a folder named "Graphics":
o
This folder is automatically generated in the current directory.
o
The filename of these pictures is built with the parameters you entered.
-
By clicking the "Restart" button you will erase all these pictures and arrive on the first clean window.
-
If you decide to leave the program you can click on one of the small crosses in the window's top right
corner, or press "Exit" button which will quit Excel definitely. All waveforms are still available in the
"Graphics" directory.
-
Every new start of the program will delete all previously waveforms stored in the "Graphics" directory.
PASTOR screenshots
Figure 96 shows the start-up screen of the PASTOR calculator.
After clicking the “START” button, the PASTOR selection screen (Figure 97) appears; the user may now
change the I/O supply voltage. Valid values for capacitive load and ambient temperature must be filled into the
respective input fields.
Depending on the kind of investigation, the user has to select either “Data Rate” or “Rise/Fall Times” or “Pad
Driver” by checking one of the related boxes, and provide parameter values afterwards.
Figure 98 shows an example for user selection “Data Rate”. The appropriate driver for a 10MHz data rate
(slope-to-period ratio = 4, see Chapter 7.2), loaded with 25pF and operated at 3.3V (nominal) and 125°C
ambient temperature will be calculated after clicking the “EXE” button. Result: The medium driver provides the
required performance and lowest electromagnetic emission to fulfil 10MHz data rate under the specified
conditions.
Figure 99 shows an example for user selection “Rise/Fall Times”. The appropriate driver for a clock/data signal
of 2.5ns rise and fall time, loaded with 40pF and operated at 3.3V (nominal) and 85°C ambient temperature will
be calculated after clicking the “EXE” button. Result: The strong-sharp driver provides the required performance
to drive 40pF load at rising and falling edges (10/90%) of 2.5ns under the specified conditions. Please note that
this driver provides an even faster rise/fall time of 1.67ns; however, the next weaker driver (strong-sharp-minus)
does not fulfil the 2.5ns requirement.
By default, the rising edge including estimated overshoot is displayed. To show the falling edge including
undershoot, click on “View Fall Time”; the result for the previous example is shown in Figure 100.
Figure 101 shows an example for user selection “Driver”. This is how the class A1+ strong-slow driver performs
under the specified conditions: it can drive 20pF load with ca. 14ns rise/fall time – equivalent to 11.75MHz data
rate with a slope-to-period ratio of 6. The slope-to-period ratio can be changed to calculate other data rates. A
new ratio of 4 will allow a data rate up to 17.64MHz.
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Figure 96: PASTOR start-up screen
Figure 97: PASTOR selection screen
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Figure 98: Example for user selection “Data Rate”
Figure 99: Example for user selection “Rise/Fall Times”, displaying the rising edge
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Figure 100: Example for user selection “Rise/Fall Times”, displaying the falling edge
Figure 101: Example for user selection “Driver”
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Annex A: Measured rise/fall waveforms
Rise/fall timing diagrams are provided for selected Class A2 driver settings and capacitive loads, as listed in
Table 16. These results have been summarized in Chapter 5. This Annex A shows selected measured timing
diagrams for signal integrity reference puposes.
Driver strength
Physical load capacitor
VDDP supply voltages @ ambient temperature
Strong-sharp
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp
100 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp-minus
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp-minus
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-sharp-minus
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium-minus
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium-minus
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-medium-minus
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-soft
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-soft
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-soft
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-slow
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-slow
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Strong-slow
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
150 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
1500 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Medium
20000 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
10pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
22 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
47 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
150 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
1500 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Weak
20000 pF
3.47V@-40°C/3.30V@25°C/3.13V@125°C
Table 16: List of all timing measurement conditions provided in Annex A
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Each of the Figures 83-107 contains 6 waveforms for a given driver strength, a given VDDP supply voltage
(3.47V, 3.30V, 3.13V) and a given ambient temperature (-40°C, 25°C, 125°C). Depending on these settings,
certain clock frequencies can be driven or not.
The 6 configurations shown in one figure are distributed as indicated in Figure 82.
Rising edge
Falling edge
VDDP=3.47V
VDDP=3.47V
Ta=-40°C
Ta=-40°C
Rising edge
Falling edge
VDDP=3.30V
VDDP=3.30V
Ta=+25°C
Ta=+25°C
Rising edge
Falling edge
VDDP=3.13V
VDDP=3.13V
Ta=+125°C
Ta=+125°C
Figure 96: General grouping of waveform configurations
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Figure 97: Class A2 driver strong-sharp at 10pF load
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Figure 98: Class A2 driver strong-sharp at 22pF load
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Figure 99: Class A2 driver strong-sharp at 47pF load
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Figure 100: Class A2 driver strong-sharp at 100pF load
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Figure 101: Class A2 driver strong-sharp-minus at 10pF load
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Figure 102: Class A2 driver strong-sharp-minus at 22pF load
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Figure 103: Class A2 driver strong-sharp-minus at 47pF load
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Figure 104: Class A2 driver strong-medium at 10pF load
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Figure 105: Class A2 driver strong-medium at 22pF load
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Figure 106: Class A2 driver strong-medium at 47pF load
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Figure 107: Class A2 driver strong-medium-minus at 10pF load
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Figure 108: Class A2 driver strong-medium-minus at 22pF load
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Figure 109: Class A2 driver strong-medium-minus at 47pF load
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Figure 110: Class A2 driver strong-soft at 10pF load
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Figure 111: Class A2 driver strong-soft at 22pF load
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Figure 112: Class A2 driver strong-soft at 47pF load
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Figure 113: Class A2 driver medium at 10pF load
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Figure 114: Class A2 driver medium at 22pF load
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Figure 115: Class A2 driver medium at 47pF load
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Figure 116: Class A2 driver medium at 150pF load
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Figure 117: Class A2 driver medium at 1500pF load
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Figure 118: Class A2 driver medium at 20nF load
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Figure 119: Class A2 driver weak at 10pF load
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Figure 120: Class A2 driver weak at 22pF load
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Figure 121: Class A2 driver weak at 47pF load
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Figure 122: Class A2 driver weak at 150pF load
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Figure 123: Class A2 driver weak at 1500pF load
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Figure 124: Class A2 driver weak at 20nF load
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Figure 125: Class A1+ driver strong-soft at 10pF load
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Figure 126: Class A1+ driver strong-soft at 22pF load
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Figure 127: Class A1+ driver strong-soft at 47pF load
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Figure 128: Class A1+ driver strong-slow at 10pF load
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Figure 129: Class A1+ driver strong-slow at 22pF load
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Figure 130: Class A1+ driver strong-slow at 47pF load
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Figure 131: Class A1+ driver medium at 10pF load
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Figure 132: Class A1+ driver medium at 22pF load
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Figure 133: Class A1+ driver medium at 47pF load
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Figure 134: Class A1+ driver medium at 150pF load
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Figure 135: Class A1+ driver medium at 1500pF load
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Figure 136: Class A1+ driver medium at 20nF load
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Figure 137: Class A1+ driver weak at 10pF load
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Figure 138: Class A1+ driver weak at 22pF load
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Figure 139: Class A1+ driver weak at 47pF load
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Figure 140: Class A1+ driver weak at 150pF load
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Figure 141: Class A1+ driver weak at 1500pF load
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Figure 142: Class A1+ driver weak at 20nF load
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Figure 143: Class A1 driver medium at 10pF load
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Figure 144: Class A1 driver medium at 22pF load
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Figure 145: Class A1 driver medium at 47pF load
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Figure 146: Class A1 driver medium at 150pF load
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Figure 147: Class A1 driver medium at 1500pF load
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Figure 148: Class A1 driver medium at 20nF load
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Figure 149: Class A1 driver weak at 10pF load
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Figure 150: Class A1 driver weak at 22pF load
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Figure 151: Class A1 driver weak at 47pF load
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Figure 152: Class A1 driver weak at 150pF load
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Figure 153: Class A1 driver weak at 1500pF load
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Figure 154: Class A1 driver weak at 20nF load
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Annex B: Glossary
Cload
Load Capacitor
di/dt
Ideal capacitive load connected to an output driver
Dynamic current over time
EMC
Electromagnetic Compatibility
The ability of an electrical device to
function satisfactorily in its electromagnetic environment
(“Immunity”) without having an impermissible effect on its
environment (“Emission”).
EME
Electromagnetic Emission
Æ EMC
EXTCLK
System Clock Output
Strong output driver for the system clock
GND
Ground
Ground reference of the power supply
PI
Power Integrity
Good PI means a clean power supply system which is not
polluted by switching noise
SI
Signal Integrity
Good SI means proper signal waveform to fulfill the
required data communication
TA
Ambient Temperature
Temperature in the direct environment of the IC
tF
Fall Time
Time of the falling edge of a signal measured between
10% and 90% of the high level
tR
Rise Time
Time of the rising edge of a signal measured between
10% and 90% of the high level
VDD
Power supply voltage in general
VDDI
Core supply voltage = 1.20V nominal
VDDP
Pad supply voltage = 3.30V nominal, +/- 5%
VSS
Æ GND
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w w w . i n f i n e o n . c o m
Published by Infineon Technologies AG