ETC TS88915T

Features
•
•
•
•
•
•
•
•
•
•
•
Vcc = 5V ± 5%
Military Temperature Range
Fully Compatible with the TS68040
Five Low Skew Outputs
– Five Outputs (Q0-Q4) with Output-to-Output Skew < 500 ps Each Being Phase End
Frequency Locked to the SYNC Input
Three Additional Outputs are Available:
– The 2X_Q Output Runs Twice the System “Q” Frequency
– The Q/2 Output Runs At 1/2 the System “Q” Frequency
– The Q5 Output is Inverted (180° Phase Shift)
Two Selectable Clock Inputs
– Two Selectable CLOCK Inputs are Available for Test or Redundancy Purposes
– Test Mode Pin (PLL_EN) Provided for Low Frequency Testing
– All Outputs Can Go Into High Impedance (3-state) for Board Test Purposes
Input Frequency Range From 5 MHz to 2X_Q FMAX
Three Input/Output Ratios
– Input/Output Phase-locked Frequency Ratios of 1:2, 1:1 and 2:1 are Available
Low Part-to-part Skew
– The Phase Variation from Part-to-part Between the SYNC and FEEDBACK Inputs is
Less than 550 ps (Derived From the tPD Specification, which Defines the
Part-to-part Skew)
CMOS and TTL Compatible
– All Outputs Can Drive Either CMOS or TTL Inputs
– All Inputs are TTL-level Compatible
LOCK Indicator (LOCK) Indicates a Phase-locked State
Low Skew
CMOS PLL
Clock Driver
Tri-State 70 and
100 MHz
Versions
TS88915T
Description
The TS88915T Clock Driver utilizes a phazed-locked loop (PLL) technology to lock its
low skew outputs’ frequency and phase onto an input reference clock. It is designed to
provide clock distribution for high performance microprocessors such as TS68040,
TSPC603E,TSPC603P,TSPC603R, PCI bridge, RAM’s, MMU’s.
Screening/Quality
This Product is Manufactured:
•
Based Upon the Generic Flow of MIL-STD-883
•
or According to Atmel-Grenoble Standard
R suffix
PGA 29
Ceramic Pin Grid Array
W suffix
LDCC 28
Leaded Ceramic Chip Carrier
Rev. 2122A–HIREL–06/02
1
Introduction
The TS88915T is a CMOS PLL Clock Driver using phase-locked loop (PLL) technology.
The PLL allows the high current and low skew outputs to lock onto a single input and
distribute it with essentially zero delay to multiple components on a board. The PLL also
allows the TS88915T to multiply a low frequency input clock and distribute it locally at a
higher (2X) system frequency. Multiple 88915’s can lock onto a single reference clock,
which is ideal for applications when a central system clock must be distributed synchronously to multiple boards (see Figure 12).
Figure 1. TS88915T Block Diagram (All Versions)
LOCK
FEEDBACK
SYNC[0]
SYNC[1]
0
M
U
1 X
PHASE/FREQ.
DETECTOR
CHARGE PUMP/
LOOP FILTER
EXT. REC NETWORK
(RC1 pin)
REF_SEL
PLL_EN
VOLTAGE
CONTROLLED
OSCILLATOR
0
1
2X_Q
MUX
D
(÷1)
DIVIDE
BY TWO
(÷2)
1
Q
CP
R
M
U
0 X
Q
D
Q
CP
Q
R
FREQ_SEL
Q0
Q1
OE/RST
D
Q
CP
R
D
R
D
R
D
R
2
R
Q5
Q
Q
D
Q4
Q
Q
CP
Q3
Q
Q
CP
CP
Q
Q
CP
Q2
Q/2
Q
TS88915T
2122A–HIREL–06/02
TS88915T
Pin Assignments
29-lead Pin Grid Array
(PGA)
Figure 2. 29-lead PGA (Bottom View)
F
F/SL
Q0
VCC
GND
GNDA
SYC1
GND
Q1
P/EN
LOCK
VCCA
RC1
GND
Q2
SYC0
R/SL
Q3
VCC
FDBK
RST
Q5
VCC
Q/2
GND
NC
VCC
GND
Q4
Q*2
1
2
3
E
D
TS88915T
(BOTTOM VIEW)
C
B
A
28-lead Ceramic Leaded
Chip Carrier (LDCC)
4
5
6
Figure 3. 28-lead LDCC (Top View)
OE/RST VCC Q5 GND Q4
FEEDBACK
5
REF_SEL
6
SYNC[0]
7
4
3
2
1
28
VCC 2X_Q
27
26 25
TS88915T
(TOP VIEW)
Q/2
24
GND
23
Q3
22
VCC
VCC (AN)
8
RC1
9
21
Q2
GND (AN)
10
20
GND
SYNC[1]
11
19
LOCK
12
13
14
15
FREQ_SEL GND Q0 VCC
16
17
18
Q1 GND PLL_EN
3
2122A–HIREL–06/02
Signal Description
Table 1. Signal Index
Pin Name
Num
I/O
Signal Function
SYNC[0]
1
Input
Reference Clock Input
SYNC[1]
1
Input
Reference Clock Input
REF_SEL
1
Input
Chooses Reference Between SYNC[0] and SYNC[1]
FREQ_SEL
1
Input
Doubles VCO Internal Frequency
FEEDBACK
1
Input
Feedback Input to Phase Detector
RC1
1
Input
Input for External RC Network
Q(0-4)
5
Output
Clock Output (Locked to SYNC)
Q5
1
Output
Inverse of Clock Output
2x_Q
1
Output
2 x Clock Output (Q) Frequency (Synchronous)
Q/2
1
Output
Clock Output (Q) Frequency ÷ 2 (Synchronous)
LOCK
1
Output
Indicates Phase Lock has been Achieved (High when Locked)
OE/RST
1
Input
Output Enable/Asynchronous Reset (Active Low)
PLL_EN
1
Input
Disables Phase-lock for Low Frequency Testing
VCC, GND
11
Power
Power and Ground pins
Pins 8 and 10 are “analog” supply pins for internal PLL only
Scope
This drawing describes the specific requirements for the clock driver TS88915T, in compliance with MIL-STD-883 class B or Atmel standard screening.
Applicable
Documents
1. MIL-STD-883: Test methods and procedures for electronics.
2. MIL-PRF-38535 appendix A: General specifications for microcircuits.
Requirements
General
The microcircuits are in accordance with the applicable documents and as specified
herein.
Design and Construction
Terminal Connections
Depending on the package, the terminal connections shall be as shown in Figure 2 and
Figure 3.
Lead Material and Finish
Lead material and finish shall be as specified in MIL-STD-1835 (see “Package Mechanical Data” on page 17).
Package
The macrocircuits are packaged in hermetically sealed ceramic packages, which conform to case outlines of MIL-STD-1835, but “Package Mechanical Data” on page 17.
The precise case outlines are described at the end of the specification (see “Package
Mechanical Data” on page 178) and into MIL-STD-1835.
4
TS88915T
2122A–HIREL–06/02
TS88915T
Absolute Maximum
Ratings
Stresses above the absolute maximum rating may cause permanent damage to the
device. Extended operation at the maximum levels may degrade performance and affect
reliability.
Table 2. Absolute Maximum Rating for the TS88915T
Parameter
Symbol
Min
Max
Unit
Supply Voltage
VCC
-0.5
6.0
V
Input Voltage
Vin
-0.5
VCC +
0.5
V
Storage Temperature Range
Tstg
-65
+150
°C
Power Dissipation
PGA Package
LDCC Package
PD
500
mW
7
7
°C/W
Thermal Resistance Junction-Case
PGA29
LDCC28
Note:
ΘJC
-
Functional operating conditions are given in AC and DC electrical specifications.
Stresses beyond the absolute maximums listed may affect device reliability or cause permanent damage to the device.
Caution: Input voltage must not be greater than the supply voltage by more than 2.5V at
all times including during power-on reset.
Mechanical and
Environment
The microcircuits shall meet all environmental requirements of either MIL-STD-883 for
class B devices or for Atmel standard screening.
Marking
The document that defines the markings is identified in the related reference documents. Each microcircuit is legible and permanently marked with the following
information as minimum:
•
Atmel Logo
•
Manufacturer’s Part Number
•
Class B Identification
•
Date-code of Inspection Lot
•
ESD Identifier If Available
•
Country of Manufacturing
Electrical
Characteristics
General Requirements
All static and dynamic electrical characteristics specified for inspection purposes and the
relevant measurement conditions are given below:
•
Table Static Electrical Characteristics for the Electrical Variants
•
Table Dynamic Electrical Characteristics for TS88915T (70 MHz and 100 MHz
Versions)
5
2122A–HIREL–06/02
Static Characteristics
DC Electrical Characteristics
(Voltages Referenced to GND) Tc = -55°C to +125°C for 70 MHz and 100 MHz version; VCC = 5.0V ± 5%
Symbol
Parameter
Test Conditions
Limits
Unit
VIH
Minimum High-Level Input Voltage
Vout = 0.1V or VCC - 0.1V
2.0
V
VIL
Maximum Low-Level Input Voltage
Vout = 0.1V or VCC - 0.1V
0.8
V
VOH
Minimum High-Level Output Voltage
Vin = VIH or VIL, IOH = -36 mA(1)
4.01
4.51
V
V
Vin = VIH or VIL, IOL = 15 mA(6)
0.44(4)
0.50(5)
0.20
VI = VCC or GND, VCCmax
±1.0
µA
(2)
mA
VCCmin
VCCmax
Vin = VIH or VIL, IOL = 36 mA(1)
Maximum Low-Level Output Voltage
VOL
Iin
Maximum Input Leakage Current
ICCT
Maximum ICC/Input
VI = VCC - 2.1V, VCCmax
ICC
Maximum Quiescent Supply Current (per
package)
VI = VCC or GND, VCCmax
IOZ
Notes: 1.
2.
3.
4.
5.
6.
2.0
Maximum Tri-State Leakage Current
VI = VIH or VIL,VO = VCC or GND, VCCmax
IOL and IOH are 12 mA and -12 mA respectively for the LOCK output.
The PLL_EN input pin is not guaranteed to meet this specification.
Maximum test duration is 2.0 ms, one output loaded at a time.
Specification value for static tests at 25°C and at minimum rated operating temperature.
Specification value for static tests at maximum rated operating temperature.
Specifications values which can be used for compability with the Power PC.
1.0
mA
$50
µA
Capacitance and Power Specifications
Symbol
Parameter
Typical Values
Unit
Conditions
CIN
Input Capacitance
10
pF
VCC = 5.0V
CPD
Power Dissipation Capacitance
40
pF
VCC = 5.0V
PD1
Power Dissipation at 50 MHz with 50Ω Thevenin
Termination
23 mW/Output
184 mW/Device
mW
VCC = 5.0V
T = 25°C
57 mW/Output
456 mW/Device
mW
VCC = 5.0V
T = 25°C
PD2
Note:
Power Dissipation at 50 MHz with 50Ω Parallel
Termination to GND
1. PD1 and PD2 mW/Output are for a ‘Q’ output.
Dynamic Characteristics
(Tc = -55°C to +125°C, VCC = 5.0V ± 5%)
Frequency Specifications
Guaranteed Minimum
Symbol
fmax(1)
Note:
6
Parameter
Maximum Operating Frequency (2X_Q Output)
88915T-70
88915T-100
Unit
70
100
MHz
Maximum Operating Frequency (Q0-Q4, Q5 Outputs)
35
50
MHz
1. Maximum Operating Frequency is guaranteed with the part in a phase-locked condition, and all outputs loaded with 50Ω terminated to VCC/2.
TS88915T
2122A–HIREL–06/02
TS88915T
SYNC Input Timing Requirements
Minimum
Symbol
Parameter
tRISE/FALL, SYNC Inputs
tCYCLE, SYNC Inputs
88915T-70
88915T-100
Maximum
Unit
–
–
3.0
ns
28.5(1)
20.0(1)
200(2)
ns
Rise/Fall Time, SYNC Inputs
From 0.8 to 2.0V
Input Clock Period, SYNC Inputs
Duty Cycle SYNC Inputs
Input Duty Cycle, SYNC Inputs
50% ± 25%
Notes: 1. These tCYCLE minimum values are valid when ‘Q’ output is feed back and connected to the FEEDBACK pin.
2. Information in Table 1 and in Note 3 of the AC specification notes describe this specification and its limits depending on what
output is feed back, and if FREQ_SEL is high or low.
AC Characteristics (Tc = -55°C to +125°C, VCC = 5.0V ± 5%, Load = 50Ω terminated to VCC/2)
Symbol
Parameter
Min
Max
Unit
tRISE/FALL
Outputs
Rise/Fall Time, All Outputs
(Between 0.2 VCC and 0.8 VCC)
1.0
2.5
ns
Into a 50Ω Load
Terminated to
VCC/2
tRISE/FALL(1)
2X_Q Output
Rise/Fall Time into a 20 pF Load, with
Termination(2)
0.5
1.6
ns
tRISE: 0.8V - 2.0V
tFALL: 2.0V - 0.8V
tPULSE WIDTH(1)
(Q0-Q4, Q5,
Q/2)
Output Pulse Width: Q0, Q1, Q2, Q3, Q4,
Q5, Q/2 at VCC/2
0.5tCYCLE - 0.5(2)
0.5tCYCLE + 0.5(2)
ns
Into a 50Ω Load
Terminated to
VCC/2
tPULSE WIDTH(1)
(2X_Q Output)
Output Pulse Width:
2X_Q at 1.5V
40 MHz
50 MHz
66 MHz
100 MHz
0.5tCYCLE - 1.5(2)
0.5tCYCLE - 1.0
0.5tCYCLE - 0.5
0.5tCYCLE - 0.5
0.5tCYCLE + 1.5(2)
0.5tCYCLE + 1.0
0.5tCYCLE + 0.5
0.5tCYCLE + 0.5
ns
Must use
termination(2)
tPULSE WIDTH(1)
(2X_Q Output)
Output Pulse Width:
2X_Q at VCC/2
40-49 MHz
50-65 MHz
66-100
MHz
0.5tCYCLE - 1.5(2)
0.5tCYCLE - 1.0
0.5tCYCLE - 0.5
0.5tCYCLE + 1.5(2)
0.5tCYCLE + 1.0
0.5tCYCLE + 0.5
ns
Into a 50Ω Load
Terminated to
VCC/2
tPD(1)(3)
SYNC Feedback
SYNC Input to Feedback
Delay (Measured at SYNC0
or 1 and FEEDBACK input
pins)
ns
See Note 4 and
Figure 6 for
detailed
explanation
(With 1 MΩ from RC1 to An VCC)
70 MHz
100 MHz
-1.05
-0.40
-1.05
-0.30
Conditions
(With 1 MΩ from RC1 to An GND)
+1.25
+3.25
tSKEWr (1)(4)
(Rising)(5)
Output-to-Output Skew between Outputs
Q0-Q4, Q/2 (Rising edges only)
–
500
ps
All Outputs into a
matched 50Ω
load Terminated
to VCC/2
tSKEWf (1)(4)
(Falling)
Output-to-Output Skew between Outputs
Q0-Q4 (Falling edges only)
–
750
ps
All Outputs into a
matched 50Ω
load Terminated
to VCC/2
tSKEWall (1)(4)
(Falling)
Output-to-Output Skew 2X_Q, Q/2, Q0-Q4
Rising, Q5 Falling
–
750
ps
All Outputs into a
matched 50Ω
load Terminated
to VCC/2
7
2122A–HIREL–06/02
AC Characteristics (Tc = -55°C to +125°C, VCC = 5.0V ± 5%, Load = 50Ω terminated to VCC/2) (Continued)
Symbol
tLOCK
(5)
tPZL
tPHZ, tPLZ
Notes:
Parameter
Min
Max
Unit
Time required to acquire Phase-Lock from
time SYNC inputs signal is received
1.0
10
ms
Also time to lock
indicator High
Output Enable Time OE/RST to 2X_Q, Q0Q4, Q5 and Q/2
3.0
14
ns
Measured with
the PLL_EN pin
Low
3.0
14
ns
Measured with
the PLL_EN pin
Low
These specifications are not tested, they are guaranteed by statistical characterization. See General AC specification
Note 1.
tCYCLE in this specification is 1/Frequency at which the particular output is running.
The TPD specification’s min/max values may shift closer to zero of a larger pull up resistor is used.
Under equally loaded conditions and at a fixed temperature and voltage.
With VCC fully powered-on, and an output properly connected to the FEEDBACK pin. tLOCK maximum is with C1 = 0.1 µF,
tLOCK minimum is with C1 = 0.01 µF.
Output Disable Time OE/RST to 2X_Q, Q0Q4, Q5 and Q/2
1.
2.
3.
4.
5.
Conditions
Figure 4. Output/Input Switching Waveforms and Timing Diagrams
(These waveforms represent the hook-up configuration of Figure 8)
SYNC INPUT
(SYNC[1] or
SYNC[0])
tCYCLE SYNC INPUT
tPD
FEEDBACK
INPUT
Q/2 OUTPUT
tSKEWall
tSKEWr
tSKEWf
tSKEWr
Q0-Q4
OUTPUTS
tCYCLE "Q" OUTPUTS
Q5 OUTPUT
2X_Q OUTPUT
8
TS88915T
2122A–HIREL–06/02
TS88915T
Application
Information
General AC Specification 1. Several specifications can only be measured when the TS88915T is in phaselocked operation. TS88915T units are fabricated with key transistor properties
Notes
intentionally varied to create a 14 cell designed experimental matrix.
2. These two specs (tRISE/FALL and tPULSE WIDTH 2X_Q output) guarantee that the
TS88915T meets the 33 MHz TS68040 P-Clock input specification (at 66 MHz).
For these two specs to be guaranteed by Atmel, the termination scheme shown
below in Figure 5 must be used.
Figure 5. TS68040 P-Clock Input Termination Scheme
TS88915
2X_Q
Output
Rs
Rs = Z0-7Ω
Z0 (CLOCK TRACE)
TS68040
P_Clock
Input
Rp
Rp = 1.5Z0
3. To meet the 25 MHz TS68040 P-clock input specification (2 x Q tpulse width at
50 MHz) FREQ-SEL must be low. This configuration improve the accuracy of the
88915T duty cycle.
4. The wiring diagrams and explanations in Figure 8, Figure 9 and Figure 10 demonstrate the input and output frequency relationships for three possible feedback
configurations. The allowable SYNC input range for each case is also indicated.
There are two allowable SYNC frequency ranges, depending whether
FREQ_SEL is high or low. Although not shown, it is possible to feed back the Q5
output, thus creating a 180° phase shift between the SYNC input and the “Q”
outputs. Table 3 below summarizes the allowable SYNC frequency range for
each possible configuration.
Table 3. Allowable SYNC Input Frequency Range for Different Feedback Configurations
FREQ_SEL
Level
FEEDBACK
Output
Allowable SYNC Input
Frequency Range (MHz)
Corresponding VCO
Frequency Range
Phase Relationships of the
“Q” Outputs to Rising
SYNC Edge
HIGH
HIGH
HIGH
HIGH
Q/2
any “Q” (Q0-Q4)
Q5
2X_Q
5 to (2X_Q FMAX Spec)/4
10 to (2X_Q FMAX Spec)/2
10 to (2X_Q FMAX Spec)/2
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
0°
0°
180°
0°
LOW
LOW
LOW
LOW
Q/2
any “Q” (Q0-Q4)
Q5
2X_Q
2.5 to (2X_Q FMAX Spec)/8
5 to (2X_Q FMAX Spec)/4
5 to (2X_Q FMAX Spec)/4
10 to (2X_Q FMAX Spec)/2
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
20 to (2X_Q FMAX Spec)
0°
0°
180°
0°
9
2122A–HIREL–06/02
5. A 1 MΩ resistor tied to either Analog VCC or Analog GND as shown in Figure 5 is
required to ensure no jitter is present on the TS88915T outputs. This technique
causes a phase offset between the SYNC input and the output connected to the
FEEDBACK input, measured at the input pins. The TPD spec describes how this
offset varies with process, temperature and voltage. The specs are arrived at by
measuring the phase relationship for the 14 lots described in Note 1 while the
part was in phase-locked operation. The actual measurements are made with 10
MHz SYNC input (1.0 ns edge rate from 0.8V - 2.0V) with the Q/2 output feed
back. The phase measurements are made at 1.5V. The Q/2 output is terminated
at the FEEDBACK input with 100Ω to VCC and 100Ω to GND.
Figure 6. Depiction of the Fixed SYNC to Feedback Offset (tPD) Which is Present When a 1 MΩ Resistor is Tied to VCC
or GND
EXTERNAL LOOP
FILTER
RC1
330Ω
0.1 µF
RC1
1 MΩ
REFERENCE
RESISTOR
R2
1 MΩ
REFERENCE
RESISTOR
C1
R2
C1
330Ω
0.1 µF
ANALOG GND
With the 1 MΩ resistor tied in this fashion, the tPD
specification measured at the input pins is:
With the 1 MΩ resistor tied in this fashion, the tPD
specification measured at the input pins is:
tPD = 2.25 ns ± 1.0 ns
tPD = -0.775 ns ± 0.275 ns
3.0V
SYNC INPUT
SYNC INPUT
2.25 ns OFFSET
FEEDBACK OUTPUT
5.0V
3.0V
-0.775 ns OFFSET
5.0V
FEEDBACK OUTPUT
6. The tSKEWr specification guarantees that the rising edges of outputs Q/2, Q0, Q1,
Q2, Q3 and Q4 will always fall within a 500 ps window within one part. However,
if the relative position of each output within this window is not specified, the
500 ps window must be added to each side of the tPD specification limits to calculate the total part-to-part skew. For this reason the absolute distribution of
these outputs is provided in Table 4. When taking the skew data, Q0 was used
as a reference, so all measurements are relative to this output. The information
in Table 4 is derived from measurements taken from the 14 process lots
described in Note 1, over the temperature and voltage range.
10
TS88915T
2122A–HIREL–06/02
TS88915T
Table 4. Relative Position of Outputs Q/2, Q0-Q4, 2X_Q,Within the 500 ps tSKEWr Spec
Window
Output
(ps)
+
(ps)
Q0
Q1
Q2
Q3
Q4
Q/2
2X_Q
0
-72
-44
-40
-274
-16
-633
0
40
275
255
-34
250
-35
7. Calculation of Total Output-to-Output skew Between Multiple Parts (Part-to-Part
Skew)
By combining the tPD specification and the information in Note 5, the worst case
Output-to-Output skew between multiple TS88915’s connected in parallel can be
calculated. This calculation assumes that all parts have a common SYNC input
clock with equal delay that input signal to each part. This skew value is valid at
the TS88915 output pins only (equally loaded), it does not include PCB trace
delays due to varying loads.With a 1 MΩ resistor tied to analog VCC as shown in
Note 4, the tPD spec. limits between SYNC and the Q/2 output (connected to the
FEEDBACK pin) are -1.05 ns and -0.5 ns. To calculate the skew of any given
output between two or more parts, the absolute value of the distribution of that
output given in Table 4 must be subtracted and added to the lower and upper tPD
spec limits respectively. For output Q2, [276-(-44)] = 320 ps is the absolute value
of the distribution. Therefore [-1.05 - 0.32] = -1.37 ns is the lower tPD limit, and [0.5 + 0.32] = -0.18 ns is the upper limit. Therefore the worst case skew of output
Q2 between any number of part is [(-1.37)-(-0.18)] = 1.19 ns. Q2 has the worst
case skew distribution of any output, so 1.2 ns is the absolute worst case Output-to-Output skew between multiple parts.
8. Note 4 explains that the tPD specification was measured and is guaranteed for
the configuration of the Q/2 output connected to the FEEDBACK pin and the
SYNC input running at 10 MHz. The fixed offset (tPD) as described above has
some dependence on the input frequency and what frequency the VCO is running. The graphs of Figure 6 demonstrate this dependence. The data presented
in Figure 6 is from devices representing process extremes, and the measurements were also taken at the voltage extremes (VCC = 5.25V and 4.75V).
Therefore the data in Figure 6 is a realistic representation of the variation of tPD.
11
2122A–HIREL–06/02
Figure 7.
-0.50
-0.50
-0.75
tPD
-1.00
SYNC to
FEEDBACK
(ns)
tPD
SYNC to
FEEDBACK -1.00
(ns)
-1.50
-1.25
-1.50
2.5
-2.00
5.0
7.5
10.0
12.5
15.0
2.5 5.0 7.5 10 12.5 15 17.5 20 22.5 25 27.5
17.5
SYNC INPUT FREQUENCY (MHz)
SYNC INPUT FREQUENCY (MHz)
tPD versus Frequency for Q/2 output feed back,
including process and voltage variation at 25°C
(with 1 MΩ resistor tied to analog VCC)
tPD
SYNC to
FEEDBACK
(ns)
tPD versus Frequency for Q4 output feed back,
including process and voltage variation at 25°C
(with 1 MΩ resistor tied to analog VCC)
3.5
3.5
3.0
3.0
2.5
2.5
tPD
SYNC to
FEEDBACK
(ns)
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.5
2.5
5.0
7.5
10.0
12.5
15.0
17.5
SYNC INPUT FREQUENCY (MHz)
tPD versus Frequency for Q/2 output feed back,
including process and voltage variation at 25°C
(with 1 MΩ resistor tied to analog GND)
0
5
10
15
25
20
SYNC INPUT FREQUENCY (MHz)
tPD versus Frequency for Q4 output feed back,
including process and voltage variation at 25°C
(with 1 MΩ resistor tied to analog GND)
9. The Lock indicator pin (LOCK) will reliably indicate a phase-locked condition at
SYNC input frequencies down to 10 MHz. At frequencies below 10 MHz, the frequency of correction pulses going into the phase detector from the SYNC and
FEEDBACK pins may not be sufficient to allow the lock indicator circuitry to
accurately predict a phase-locked condition. The TS88915T is guaranteed to
provide stable phase-locked operation down to the appropriate minimum input
frequency given in Table 3, even though the LOCK pin may be low at frequencies below 10 MHz.
Timing Notes
1. The TS88915T aligns rising edges of the FEEDBACK input and the SYNC input,
therefore the SYNC input does not require a 50% duty cycle.
2. All skew specs are measured between VCC/2 crossing point of the appropriate
output edges. All skews are specified as ‘windows’, not as a “deviation around a
center point”.
3. If a “Q” output is connected to the FEEDBACK input (this situation is not shown),
the “Q” output frequency would match the SYNC input frequency, the 2X_Q out-
12
TS88915T
2122A–HIREL–06/02
TS88915T
put would run twice the SYNC frequency, and the Q/2 output would run at half
the SYNC frequency. See Figure 7, Figure 8 and Figure 9 below.
Figure 8. Wiring Diagram and Frequency Relationship with Q/2 Output Feed Back
100 MHz SIGNAL
25 MHz FEEDBACK SIGNAL
HIGH
RST
Q5
Q4
2X_Q
FEEDBACK
LOW
CRYSTAL 25 MHz INPUT
OSC.
EXTERNAL
LOOP
FILTER
Q/2
REF_SEL
50 MHz
"Q"
CLOCK
OUTPUTS
SYNC[0]
ANALOG VCC
Q3
RC1
Q2
ANALOG GND
FQ_SEL
Q0
Q1
PLL_EN
HIGH
HIGH
Figure 9. Wiring Diagram and Frequency Relationship with Q4 Output Feed Back
100 MHz SIGNAL
50 MHz FEEDBACK SIGNAL
HIGH
RST
Q5
Q4
2X_Q
FEEDBACK
LOW
Q/2
25 MHz
SIGNAL
REF_SEL
CRYSTAL 50 MHz INPUT
OSC.
EXTERNAL
LOOP
FILTER
50 MHz
"Q"
CLOCK
OUTPUTS
SYNC[0]
ANALOG VCC
Q3
RC1
Q2
ANALOG GND
FQ_SEL
Q0
Q1
PLL_EN
HIGH
HIGH
Figure 10. Wiring Diagram and Frequency Relationship with 2X_Q Output Feed Back
100 MHz FEEDBACK SIGNAL
HIGH
RST
Q5
Q4
FEEDBACK
LOW
Q/2
25 MHz
SIGNAL
REF_SEL
CRYSTAL 100 MHz INPUT
SYNC[0]
OSC.
EXTERNAL
LOOP
FILTER
2X_Q
Q3
ANALOG VCC
Q2
RC1
50 MHz
"Q"
CLOCK
OUTPUTS
ANALOG GND
FQ_SEL
HIGH
Q0
Q1
PLL_EN
HIGH
13
2122A–HIREL–06/02
Notes Concerning Loop
Filter and Board Layout
Issues
1. Figure 10 shows a loop filter and analog isolation scheme which will be effective
in most applications. The following guidelines should be followed to ensure stable and jitter-free operation:
2. All loop filter and analog isolation components should be tied as close to the
package as possible. Stray current passing through the parasitics of long traces
can cause undesirable voltage transients at the RC1 pin.
3. The 47Ω resistors, the 10 µF low frequency bypass capacitor, and the 0.1 µF
high frequency bypass capacitor form a wide bandwidth filter that will minimize
the 88915T’s sensitivity to voltage transients from the system digital VCC supply
and ground planes. This filter will typically ensure that a 100 mV step deviation
on the digital VCC supply will cause no more than 100 ps phase deviation on the
88915T outputs. A 250 mV step deviation on VCC using the recommended filter
values should cause no more than a 250 ps phase deviation; if a 25 µF bypass
capacitor is used (instead of 1 µF) a 250 mV VCC step should cause no more
than a 100 ps phase deviation. If good bypass techniques are used on a board
design near components which may cause digital VCC and ground noise, the
above described VCC step deviations should not occur at the 88915T’s digital VCC
supply. The purpose of the bypass filtering scheme shown in Figure 10 is to give
the 88915T additional protection from the power supply and ground plane transients that can occur in a high frequency, high speed digital system.
4. There are no special requirements set forth for the loop filter resistors (1 MΩ and
330Ω). The loop filter capacitor (0.1 µF) can be a ceramic chip capacitor, the
same as a standard bypass capacitor.
5. The 1 MΩ reference resistor injects current into the internal charge pump of the
PLL, causing a fixed offset between the outputs and the SYNC input. This also
prevents excessive jitter caused by inherent PLL dead-band. If the VCO (2X_Q
output) is running above 40 MHz, the 1 MΩ resistor provides the correct amount
of current injection into the charge pump (2-3 µA). For the 70 and 100 MHz versions, if the VCO is running below 40 MHz, a 1.5 MΩ resistor should be used
(instead of 1 MΩ).
6. In addition to the bypass capacitors used in the analog filter of Figure 10, there
should be a 0.1 µF bypass capacitor between each of the other (digital) four VCC
pins and the board ground plane. This will reduce output switching noise caused
by the 88915T outputs, in addition to reducing potential for noise in the ‘analog’
section of the chip. These bypass capacitors should also be tied as close to the
package as possible.
14
TS88915T
2122A–HIREL–06/02
TS88915T
Figure 11. Recommended Loop Filter and Analog Isolation Scheme for the TS88915T
BOARD VCC
47Ω
ANALOG VCC
10 µF LOW
FREQ BYPASS
0.1 µF HIGH
FREQ
BYPASS
1 MΩ
ANALOG LOOP FILTER/FCO
SECTION OF THE TS88915T
(NOT DRAWN TO SCALE)
330Ω
RC1
ANALOG GND
47Ω
Note:
A separate analog power supply is not necessary and should not be used. Following these prescribed guidelines is all that is
necessary to use the TS88915T in a normal digital environment.
Figure 12. Representation of a Potential Multi-Processing Application Utilizing the
TS88915T for Frequency Multiplication and Low Board-to-board Skew
CLOCK
at f
TS88915T
PLL
2f
CMMU
CMMU
CPU
CMMU
CMMU
CMMU
CMMU
CMMU
CPU
CMMU
CMMU
CMMU
CPU
CARD
SYSTEM
CLOCK
SOURCE
CPU
CARD
TS88915T
PLL
DISTRIBUTE
CLOCK at f
2f
CLOCK at 2f
AT POINT OF USE
TS88915T
PLL
2f
MEMORY
CONTROL
MEMORY
CARDS
CLOCK at 2f
AT POINT OF USE
15
2122A–HIREL–06/02
TS88915T System Level
Testing Functionality
Tri-State functionality has been added to the TS88915T to ease system board testing.
Bringing the OE/RST pin low will put all outputs (except for LOCK) into a high impedance state. As long as the PLL_EN pin is low, the Q0-Q4, Q5 and Q/2 outputs will
remain in the low state after the OE/RST until a falling SYNC edge is seen. The 2X_Q
output will be the inverse of the SYNC signal in this mode. If the tri-state functionality will
be used, a pull-up or a pull-down resistor must be tied to the FEEDBACK input pin to
prevent it from floating when the feedback output goes into high impedance.
With the PLL_EN pin low the selected SYNC signal is gated directly into the signal clock
distribution network, bypassing and disabling the VCO. In this mode the outputs are
directly driven by the SYNC input (per the block diagram). This mode can also be used
for low frequency board testing.
Note: If the outputs are put into 3-state during normal PLL operation, the loop will be
broken and phase-lock will be lost. It will take a maximum of 10 ms (tLOCK spec) to
regain phase-lock after the OE/RST pin goes back high.
Preparation For
Delivery
Packaging
Microcircuits are prepared for delivery in accordance with MIL-PRF-38535.
Certificate of Compliance Atmel offers a certificate of compliances with each shipment of parts, affirming the products are in compliance either with MIL-STD-883 and guarantying the parameters not
tested at temperature extremes for the entire temperature range.
Handling
16
MOS devices must be handled with certain precautions to avoid damage due to accumulation of static charge. Input protection devices have been designed in the chip to
minimize the effect of this static buildup. However, the following handling practices are
recommended:
•
Devices Should Be Handled On Benches With Conductive And Grounded Surfaces
•
Ground Test Equipment, Tools And Operator
•
Do Not Handle Devices By The Leads.
•
Store Devices In Conductive Foam Or Carriers.
•
Avoid Use Of Plastic, Rubber, Or Silk In Mos Areas.
•
Maintain Relative Humidity Above 50 Percent If Practical.
TS88915T
2122A–HIREL–06/02
TS88915T
Package Mechanical
Data
29-pin PGA
Inches
Millimeters
Dim
Min
Max
Min
Max
A
0.594
0.606
15.087
15.392
C
-
0.107
-
2.72
D
0.17
0.19
4.32
4.83
E
0.045
0.055
1.143
1.397
F
0.045
0.055
1.143
1.397
G
H
0.100 BSC
0.017
2.54 BSC
0.019
0.43
0.48
17
2122A–HIREL–06/02
28-pin LDCC
Note:
This package is pin compatible with PLCC
Ordering Information
TS88915T M
R
B/T
70
Maximum Output Frequency :
70: 70 MHz
100: 100 MHz
Device Type
Temperature range : Tc
Screening level :
M : -55, +125°C
V : -40, +85°C
__ : Standard
B/T: according to MIL-STD-883
D/T: Burn-in
Package :
R: PGA
W: LDCC
Note:
18
For availability of the different versions, contact your Atmel sales office.
TS88915T
2122A–HIREL–06/02
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© Atmel Corporation 2002.
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2122A–HIREL–06/02
0M