ETC TMC249A-SA

TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
TMC 249/A – DATA SHEET
High Current Microstep Stepper Motor Driver
with sensorless stall detection, protection /
diagnostics and SPI Interface
TRINAMIC® Motion Control GmbH & Co KG
Sternstraße 67
D – 20357 Hamburg
GERMANY
T +49 - (0) 40 - 51 48 06 - 0
F +49 - (0) 40 - 51 48 06 - 60
WWW.TRINAMIC.COM
[email protected]
Features
The TMC249 / TMC249A (1) is a dual full bridge driver IC for bipolar stepper motor control
applications. The TMC249 is realized in a HVCMOS technology and directly drives eight external LowRDS-ON high efficiency MOSFETs. It supports more than 4000mA coil current. The low power
dissipation makes the TMC249 an optimum choice for drives, where a high reliability is desired. With
additional drivers, motor current and voltage can be increased. The integrated unique sensorless stall
detection (pat. pend.) StallGuard™ makes it a good choice for applications, where a reference point is
needed, but where a switch is not desired. Its ability to predict an overload makes the TMC249 an
optimum choice for drives, where a high reliability is desired. Internal DACs allow microstepping as
well as smart current control. The device can be controlled by a serial interface (SPI™i) or by analog /
digital input signals. Short circuit, temperature, undervoltage and overvoltage protection are
integrated.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
More than 4000mA using 8 external MOS transistors (e.g. 2.8A RMS)
Sensorless stall detection StallGuard and load measurement integrated
Control via SPI with easy-to-use 12 bit protocol or external analog / digital signals
Short circuit, overvoltage and overtemperature protection integrated
Status flags for overcurrent, open load, over temperature, temperature pre-warning, undervoltage
Integrated 4 bit DACs allow up to 16 times microstepping via SPI, any resolution via analog
control
Mixed decay feature for smooth motor operation
Slope control user programmable to reduce electromagnetic emissions
Chopper frequency programmable via a single capacitor or external clock
Current control allows cool motor and driver operation
7V to 34V motor supply voltage (A-type)
External drivers can be added for higher motor voltages and higher currents (e.g. 50V, 5A)
3.3V or 5V operation for digital part
Low power dissipation via low RDS-ON power stage
Standby and shutdown mode available
Choice of SO28 or chip size MLF package
(1) The term TMC249 in this datasheet always refers to the TMC249A and the TMC249. The major
differences in the older TMC249 are explicitly marked with “non-A-type”. The TMC249A brings a
number of enhancements and is fully backward compatible to the TMC249.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
1
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Life support policy
TRINAMIC Motion Control GmbH & Co KG does not
authorize or warrant any of its products for use in life
support systems, without the specific written consent
of TRINAMIC Motion Control GmbH & Co KG.
Life support systems are equipment intended to
support or sustain life, and whose failure to perform,
when properly used in accordance with instructions
provided, can be reasonably expected to result in
personal injury or death.
© TRINAMIC Motion Control GmbH & Co KG 2005
Information given in this data sheet is believed to be
accurate and reliable. However no responsibility is
assumed for the consequences of its use nor for any
infringement of patents or other rights of third parties,
which may result form its use.
Specifications subject to change without notice.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
2
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
3
VCC
20
GND
19
VS
18
VT
17
BL2
LB1
14
15
HB2
9
10
11
12
13
14
15
16
BL1
HB1
SPE
16
ENN
13
SCK
LB2
SRB
CSN
12
LB2
SDI
SRB
LA2
SRA
SDO
11
LB1
OSC
BL1
LA1
TMC 249-LA
8
10
-
HA2
4
SPE
HB2
HA1
3
9
HB1
2
ENN
BL2
1
8
24
21
CSN
23
INB
7
VT
22
22
SCK
ANN
25
21
INA
6
26
20
23
SDI
AGND
27
19
SLP
5
28
18
AGND
24
4
29
17
25
OSC
SDO
VS
30
GND
31
GND
INA
32
INB
-
ANN
3
VCC
HA1
26
LA2
SRA
TMC249 / 249A SO28
HA2
27
7
28
2
6
1
5
LA1
SLP
Pinning
Top view
Package codes
Type
TMC249A (2)
TMC249
TMC249A (2)
Package
SO28
SO28
QFN32, 7*7mm
Temperature range
automotive (1)
automotive (1)
automotive (1)
Lead free
Yes
From date code 05/05
Yes
Code/marking
TMC249A-SA
TMC249-SA
TMC249A-LA
(1) ICs are not tested according to automotive standards, but are usable within the complete
automotive temperature range.
(2) These devices are available in a reduced offset voltage selection grade, marked with an additional
dot.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
4
SO28 Dimensions
REF
A
B
C
D
E
F
G
H
I
K
E
F
G
C
I
D
A
K
H
B
MIN
10
17.7
7.4
MAX
10.65
18.1
7.6
1.4
2.65
0.25
0.1
0.3
0.36
0.49
0.4
1.1
1.27
All dimensions are in mm.
A
0.80
A1
0.00
0.90
1.00
0.02
0.05
-B-
0.20
7.0
E
7.0
E
0.15
BOTTOM VIEW WITH TYPE C ID
2
1
RADIUS
D2
5.00
5.15
5.25
E2
5.00
5.15
5.25
L
0.45
0.55
0.65
b
0.25
0.30
0.35
aaa C 2x
N N-1
TOP VIEW
ccc C
NX
0.08 C
SEATING
PLANE
SIDE VIEW
0.65
-C-
A3
0.03
D
e
D/2
INDEX AREA
(D/2 xE/2)
aaa C 2x
L1
D
MAX
A
A3
NOM
E/2
MIN
A1
REF
-A-
QFN32 Dimensions
D2
D2/2
All dimensions are in mm.
-B-
INDEX AREA
(D/2 xE/2)
L1
2
1
N N-1
NXb
6
SEE
DETAIL B
-A-
SEE
DETAIL B
E2
e
E2/2
NXL
Datum A or B
ddd
BTM VIEW
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
5
bbb
e/2
C A B
C
e
Terminal Tip
DETAIL B
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
5
Application Circuit / Block Diagram
+VM
BL1
BL2
220nF
VS
TMC249
OSC
OSC
HA1
Current Controlled
Gate Drivers
PWM-CTRL
+VCC
Undervoltage
100nF
Temperature
HA2
P
N
[PHB]
SDO
Parallel
Control
[ERR]
CSN
N
LA1
RS
0
Load
mesurement
SDI
Control & Diagnosis
[PHA]
SPIInterface
SCK
P
Coil A
LA2
SRA
[MDBN]
RSH
VT
1nF
VCC
100µF
DAC
4
1
INA
REFSEL
VREF
DAC
INB
4
1
0
SRB
RS
PWM-CTRL
Current Controlled
Gate Drivers
LB1
ENN
VCC/2
REFSEL
LB2
N
N
Coil B
HB2
P
P
HB1
SPE
ANN
AGND
GND
SLP
[MDAN]
stand alone mode
RSLP
[...]: function in stand alone mode
Pin Functions
Pin
Function
Pin
Function
VS
Motor supply voltage
VT
Short to GND detection comparator –
connect to VS if not used
VCC
3.0-5.5V supply voltage for analog GND
and logic circuits
Digital / Power ground
AGND
Analog ground (Reference for SRA, OSC
SRB, OSC, SLP, INA, INB, SLP)
Oscillator capacitor or external clock
input for chopper
INA
Analog current control phase A
INB
Analog current control input phase B
SCK
Clock input of serial interface
SDO
Data output of serial interface (tristate)
SDI
Data input of serial interface
CSN
Chip select input of serial interface
ENN
Device enable (low active), and SPE
overvoltage shutdown input
Enable SPI mode (high active). Tie to
GND for non-SPI applications
ANN
Enable analog current control via SLP
INA and INB (low active)
Slope control resistor. Tie to GND for
fastest slope
BL1, BL2
Digital blank time select
Bridge A/B current sense resistor input
SRA, SRB
HA1, HA2, Outputs for high side P-channel LA1, LA2,
HB1, HB2 transistors
LB1, LB2
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
Outputs for
transistors
low
side
N-channel
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
6
Selecting Power Transistors
Selection of power transistors for the TMC249 depends on required current, voltage and thermal
conditions. Driving transistors directly with the TMC249 is only limited by the gate capacity of these
transistors. If the total gate charge is too high, slope time increases and leads to a higher switching
power dissipation. Typical applications can reach a current in excess of 4A, while the maximum
voltage is limited to 30V. A total gate charge of below 10nC per transistor is recommended. The table
below shows a choice of transistors which can be driven directly by the TMC249. The maximum
application current mainly is a function of cooling and environment temperature. The given values are
more conservative. Peak currents typically can be higher by a factor of 1.5 for a limited time.
List of recommended transistors
Manufacturer
and type
Siliconix
SI 7501DN
Siliconix
SI 4539ADY
Siliconix
SI 5504
IRF 9952
(/ IRF 7509)
Siliconix
SI 1901
Fairchild Semi
FDS 8333C
Package
(#Trans)
PPack
(1N,1P)
SO8
(1N,1P)
1206-8
(1N,1P)
SO8
(1N,1P)
SOT363-6
(2P)
SO8
(1N,1P)
Volts N-type
Volts P-type
30V
30V
30V
30V
30V
30V
30V
30V
30V
RDSON
[Ohm]
0.03
0.05
0.04
0.06
0.09
0.17
0.10
0.25
0.48
Total gate
charge [nC]
5.0
8.0
7.5
9.0
3.0
3.2
4.5
4.0
0.8
Typical maximum
Remark
application current
4000mA
(1)
3500mA
30V
30V
0.08
0.13
2.9
3.0
3000mA
6000mA (2 devices
in parallel)
2000mA
2500mA
200mA unipolar
(1) These transistor types have a very high drain to gate capacity (P-channel), which may introduce
destructive current impulses into the HA/HB outputs by forcing them above the power supply level,
depending on the low-side slope. To ensure reliability, connect one ZHCS1000 SOT23 or an SS16 1A
schottky diode or similar to both HA and HB outputs against VS to protect them.
Layout Considerations
For optimal operation of the circuit a careful board layout is important, because of the combination of
high current chopper operation coupled with high accuracy threshold comparators. Please pay special
attention to massive grounding. Depending on the required motor current, either a single massive
ground plane or a ground plane plus star connection of the power traces may be used. The schematic
shows how the high current paths can be routed separately, so that the chopper current does not flow
through the system’s GND-plane. Tie the TMC249’s AGND and GND to the GND plane. Additionally,
use enough filtering capacitors located near to the board’s power supply input and small ceramic
capacitors near to the power supply connections of the TMC249. Use low inductance sense resistors,
or add a ceramic capacitor in parallel to each resistor to avoid high voltage spikes. In some
applications it may become necessary to introduce additional RC-filtering into the SRA / SRB line, as
optional voltage
shown in the schematic, to prevent spikes from
divider
VS
triggering the short circuit protection or the
chopper comparator. If you want to take
100nF
R
VT
advantage of the thermal protection and
+VM
100R
diagnosis, ensure, that the power transistors
GND
are very close to the package, and that there is
TMC249/
Bridge A
Bridge B
optional filter
a good thermal contact between the TMC249
TMC239A
SRA
C
and the external transistors. Please be aware,
100R
SRB
that long or thin traces to the sense resistors
R
R
100R
may add substantial resistance and thus
3.3 GND
10nF
reduce output current. The same is valid for the
AGND
GNDhigh side shunt resistor.
Plane
RSH
DIV
VM
SA
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
SB
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
7
Using additional Power Drivers
For higher voltage and higher output current it is possible to add external MOSFET gate drivers. Both,
dedicated transistor drivers are suitable, as well as a circuit based on standard HCMOS drivers. It is
important to understand the function of dedicated gate drivers for N-channel transistors: Since the
chopping also can be stopped in open load conditions, the gate drive circuit for the upper transistors
should allow for continuous ON conditions. In the schematic below this is satisfied by attaching a weak
additional charge pump oscillator and pumping the VS up to the high voltage supply. Do not enable
the TMC249, before the gate driver capacitors are charged to an appropriate voltage. A current
sensing comparator in the VM line pulling down the VT pin by some 100mV on overcurrent can be
added, if required. Since the TMC249 in this application can not sense switch-off of the transistor
gates to ensure break-before-make operation, the break before-make-delays have to be set by
capacitive loading of its transistor drive outputs. The capacitors CdHS and CdLS are charged /
discharged with the nominal gate current. The opposite output is not enabled, before the switching-off
output has been discharged to 0.5V. To calculate the timing, refer to the required logic levels of the
attached power driver, resp. the attached PMOS. For CdHS and CdLS 470pF give about 100ns. Both
circuits do not show decoupling capacitors and further details.
+12V
VS
VT
LED
grn*
to other
bridges
HA1
22K
small signal PMOS, e.g. BSS84
High current, high
voltage MOS, e.g.
SI4450
1µF
2n2
12V
N
HS-Driver
N
390R
1K
TMC249/
TMC239
+VM e.g. 50V
C-Pump
20kHz
ICM7555
CDHS
470p
Coil
LA1
LSDriver
N
390R
N
CDLS
470p
IR2101
SRA
RS
100R
4.7nF
opt.
*) The LED increases break-before-make
time and may be bridged if not desired
SLP
Set HS and LS
current to 10mA
10K
+VS 7..15V
+VM 20..60V
VS
1K
VCC
120R
High voltage logic
level MOS bridge
1/2 74HC244
on high side
VT
P
1K
CDHS
HA1
LM337
HV
55V low current
N-MOS
390R
OUT
/OE
GND
VM-5.2V
IN
TMC249/
TMC239
P
100R
ADJ
+5V
Coil
VCC
1/2 74HC244
on low side
LA1
1K
CDLS
100R
N
N
/OE
GND
SRA
RS
SLP
15K
set to 7 mA highside drive current
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Control via the SPI Interface
The SPI data word sets the current and polarity for both coils. By applying consecutive values,
describing a sine and a cosine wave, the motor can be driven in microsteps. Every microstep is
initiated by its own telegram. Please refer to the description of the analog mode for details on the
waveforms required. The SPI interface timing is described in the timing section. We recommend the
TMC428 to automatically generate the required telegrams and motor ramps for up to three motors.
Serial data word transmitted to TMC249
(MSB transmitted first)
Bit
Name
Function
Remark
11
MDA
mixed decay enable phase A
“1” = mixed decay
10
CA3
current bridge A.3
MSB
9
CA2
current bridge A.2
8
CA1
current bridge A.1
7
CA0
current bridge A.0
LSB
6
PHA
polarity bridge A
“0” = current flow from OA1 to OA2
5
MDB
mixed decay enable phase B
“1” = mixed decay
4
CB3
current bridge B.3
MSB
3
CB2
current bridge B.2
2
CB1
current bridge B.1
1
CB0
current bridge B.0
LSB
0
PHB
polarity bridge B
“0” = current flow from OB1 to OB2
Serial data word transmitted from TMC249
(MSB transmitted first)
Bit
Name
Function
Remark
11
LD2
load indicator bit 2
MSB
10
LD1
load indicator bit 1
9
LD0
load indicator bit 0
8
1
always “1”
7
OT
overtemperature
6
OTPW temperature prewarning
“1” = prewarning temperature exceeded
5
UV
driver undervoltage
“1” = undervoltage on VS
4
OCHS
overcurrent high side
3 PWM cycles with overcurrent within 63 PWM cycles
3
OLB
open load bridge B
no PWM switch off for 14 oscillator cycles
2
OLA
open load bridge A
no PWM switch off for 14 oscillator cycles
1
OCB
overcurrent bridge B low side
3 PWM cycles with overcurrent within 63 PWM cycles
0
OCA
overcurrent bridge A low side
3 PWM cycles with overcurrent within 63 PWM cycles
LSB
“1” = chip off due to overtemperature
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
8
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
9
Typical winding current values
Current setting Percentage of
CA3..0 / CB3..0 current
Typical trip voltage of the current sense comparator
(internal reference or analog input voltage of 2V is used)
0000
0%
0V
0001
6.7%
23 mV
0010
13.3%
45 mV
...
(bridge continuously in slow decay condition)
...
1110
93.3%
317 mV
1111
100%
340 mV
The current values correspond to a standard 4 Bit DAC, where 100%=15/16. The contents of all
registers is cleared to “0” on power-on reset or disable via the ENN pin, bringing the IC to a low power
standby mode. All SPI inputs have Schmitt-Trigger function.
Base current control via INA and INB in SPI mode
In SPI mode, the IC can use an external reference voltage for each DAC. This allows the adaptation to
different motors. This mode is enabled by tying pin ANN to GND. A 2.0V input voltage gives full scale
current of 100%. In this case, the typical trip voltage of the current sense comparator is determined by
the input voltage and the DAC current setting (see table above) as follows:
VTRIP,A = 0.17 VINA × “percentage SPI current setting A”
VTRIP,B = 0.17 VINB × “percentage SPI current setting B”
A maximum of 3.0V VIN is possible. Multiply the percentage of base current setting and the DAC table
to get the overall coil current. It is advised to operate at a high base current setting, to reduce the
effects of noise voltages. This feature allows a high resolution setting of the required motor current
using an external DAC or PWM-DAC (see schematic for examples).
using PWM signal
8 level via R2R-DAC
2 level control
INA
µCPort .2
100K
R1
51K
47K
R2
INB
100nF
µCPort .1
10nF
100K
51K
AGND
+VCC
µCPWM
µCPort .0
100K
µCPort
51K
ANN
Controlling the power down mode via the SPI interface
Bit
Standard
function
Control
word
function
11
10
9
8
7
6
5
4
3
2
1
0
MxA CA3 CA2 CA1 CA0 PhA MxB CB3 CB2 CB1 CB0 PhB
-
0
0
0
0
-
-
0
0
0
0
-
Enable standby mode and clear
error flags
Programming current value “0000” for both coils at a time clears the overcurrent flags and switches
the TMC249 into a low current standby mode with coils switched off.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Open load detection
Open load is signaled, whenever there are more than 14 oscillator cycles without PWM switch off.
Note that open load detection is not possible while coil current is set to “0000”, because the chopper is
off in this condition. The open load flag will then always be read as inactive (“0”). During overcurrent
and undervoltage or overtemperature conditions, the open load flags also become active!
Due to their principle, the open load flags not only signal an open load condition, but also a torque loss
of the motor, especially at high motor velocities. To detect only an interruption of the connection to the
motor, it is advised to evaluate the flags during stand still or during low velocities only (e.g. for the first
or last steps of a movement).
Standby and shutdown mode
The circuit can be put into a low power standby mode by the user, or, automatically goes to standby
on Vcc undervoltage conditions. Before entering standby mode, the TMC249 switches off all power
transistors, and holds their gates in a disable condition using high ohmic resistors. In standby mode
the oscillator becomes disabled and the oscillator pin is held at a low state. The standby mode is
available via the interface in SPI-mode and via the ENN pin in non-SPI mode.
The shutdown mode even reduces supply current further. It can only be entered in SPI-mode by
pulling the ENN pin high. In shutdown additionally all internal reference voltages become switched off
and the SPI circuit is held in reset.
Power saving
The possibility to control the output current can dramatically save energy, reduce heat generation and
increase precision by reducing thermal stress on the motor and attached mechanical components.
Just reduce motor current during stand still: Even a slight reduction of the coil currents to 70% of the
current of the last step of the movement, halves power consumption! In typical applications a 50%
current reduction during stand still is reasonable.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
10
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
11
Stall Detection
Using the sensorless load measurement
The TMC249 provides a patented sensorless load measurement, which allows a digital read out of the
mechanical load on the motor via the serial interface. To get a readout value, just drive the motor
using sine commutation and mixed decay switched off. The load measurement then is available as a
three bit load indicator during normal motion of the motor. A higher mechanical load on the motor
results in a lower readout value. The value is updated once per fullstep.
Since the load detection is based on the motor’s back EMF, the readout results depend on several
factors:
- Motor velocity: A higher velocity leads to a higher readout value
- Motor resonance: Motor resonances cause a high dynamic load on the motor, and thus
measurement may give unsatisfactory results.
- Motor acceleration: Acceleration phases also produce dynamic load on the motor.
- Mixed decay setting: For load measurement mixed decay has to be off for some time before
the zero crossing of the coil current. If mixed decay is used, and the mixed decay period is
extended towards the zero crossing, the load indicator value decreases.
Implementing sensorless stall detection
The sensorless stall detection typically is used, to detect the reference point without the usage of a
switch or photo interrupter. Therefore the actuator is driven to a mechanical stop, e.g. one end point in
a spindle type actuator. As soon as the stop is hit, the motor stalls. Without stall detection, this would
give an audible humming noise and vibrations, which could damage mechanics.
To get a reliable stall detection, follow these steps:
1. Choose a motor velocity for reference movement. Use a medium velocity which is far enough
away from mechanical resonance frequencies. In some applications even motor start / stop
frequency may be used. With this the motor can stop within one fullstep if a stall is detected.
2. Use a sine stepping pattern and switch off mixed decay (at least 1 to 3 microsteps before zero
crossing of the wave). Monitor the load indicator during movement. It should show a stable
readout value in the range 3 to 7 (LMOVE). If the readout is high (>5), the mixed decay portion
may be increased, if desired.
3. Choose a threshold value LSTALL between 0 and LMOVE - 1.
4. Monitor the load indicator during each reference search movement, as soon as the desired
velocity is reached. Readout is required at least once per fullstep. If the readout value at one
fullstep is below or equal to LSTALL, stop the motor.
5. If the motor stops during normal movement without hitting the mechanical stop, decrease
LSTALL. If the stall condition is not detected at once, when the motor stalls, increase LSTALL.
v(t)
a_
m
ax
v_max
t
load
indicator
acceleration
constant velocity
max
stall
LMOVE
LSTALL
stall threshold
min
t
acceleration
jerk
stall detected!
vibration
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Protection Functions
Overcurrent protection and diagnosis
The TMC249 uses the current sense resistors on the low side to detect an overcurrent: Whenever a
voltage above 0.61V is detected, the PWM cycle is terminated at once and all transistors of the bridge
are switched off for the rest of the PWM cycle. The error counter is increased by one. If the error
counter reaches 3, the bridge remains switched off for 63 PWM cycles and the error flag is read as
“active”. The user can clear the error condition in advance by clearing the error flag. The error counter
is cleared, whenever there are more than 63 PWM cycles without overcurrent. There is one error
counter for each of the low side bridges, and one for the high side. The overcurrent detection is
inactive during the blank pulse time for each bridge, to suppress spikes which can occur during
switching.
The high side comparator detects a short to GND or an overcurrent, whenever the voltage between
VS and VT becomes higher than 0.15 V at any time, except for the blank time period which is logically
ORed for both bridges. Here all transistors become switched off for the rest of the PWM cycle,
because the bridge with the failure is unknown.
The overcurrent flags can be cleared by disabling and re-enabling the chip either via the ENN pin or
by sending a telegram with both current control words set to “0000”. In high side overcurrent
conditions the user can determine which bridge sees the overcurrent, by selectively switching on only
one of the bridges with each polarity (therefore the other bridge should remain programmed to
“0000”).
Overtemperature protection and diagnosis
The circuit switches off all output power transistors during an overtemperature condition. The overtemperature flag should be monitored to detect this condition. The circuit resumes operation after cool
down below the temperature threshold. However, operation near the overtemperature threshold
should be avoided, if a high lifetime is desired.
Overvoltage protection and ENN pin behavior
During disable conditions the circuit switches off all output power transistors and goes into a low
current shutdown mode. All register contents is cleared to “0”, and all status flags are cleared. The
circuit in this condition can also stand a higher voltage, because the voltage then is not limited by the
maximum power MOSFET voltage. The enable pin ENN provides a fixed threshold of ½ VCC to allow a
simple overvoltage protection up to 40V using an external voltage divider (see schematic).
+VM
R1
for switch off at 26 - 29V:
at VCC=5V: R1=100K; R2=10K
at VCC=3.3V: R1=160K; R2=10K
ENN
R2
µC-Port (opt.)
low=Enable,
high=Disable
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
12
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Chopper Principle
Chopper cycle / Using the mixed decay feature
The TMC249 uses a quiet fixed frequency chopper. Both coils are chopped with a phase shift of 180
degrees. The mixed decay option is realized as a self stabilizing system (pat. fi.), by shortening the
fast decay phase, if the ON phase becomes longer. It is advised to enable the mixed decay for each
phase during the second half of each microstepping half-wave, when the current is meant to
decrease. This leads to less motor resonance, especially at medium velocities. With low velocities or
during standstill mixed decay should be switched off. In applications requiring high resolution, or using
low inductivity motors, the mixed decay mode can also be enabled continuously, to reduce the
minimum motor current which can be achieved. When mixed decay mode is continuously on or when
using high inductivity motors at low supply voltage, it is advised to raise the chopper frequency to
36kHz, because the half chopper frequency could be audible under these conditions.
target current phase A
actual current phase A
on
slow decay
on
fast decay
slow decay
oscillator clock
resp. external clock
mixed decay disabled
mixed decay enabled
When polarity is changed on one bridge, the PWM cycle on that bridge becomes restarted at once.
Fast decay switches off both upper transistors, while enabling the lower transistor opposite to the
selected polarity. Slow decay always enables both lower side transistors.
Blank Time
The TMC249 uses a digital blanking pulse for the current chopper comparators. This prevents current
spikes, which can occur during switching action due to capacitive loading, from terminating the
chopper cycle. The lowest possible blanking time gives the best results for microstepping: A long
blank time leads to a long minimum turn-on time, thus giving an increased lower limit for the current.
Please remark, that the blank time should cover both, switch-off time of the lower side transistors and
turn-on time of the upper side transistors plus some time for the current to settle. Thus the complete
switching duration should never exceed 1.5µs. With slow external power stages it will become
necessary to add additional RC-filtering for the sense resistor inputs.
The TMC249 allows to adapt the blank time to the load conditions and to the selected slope in four
steps (the effective resulting blank times are about 200ns shorter in the non-A-type):
Blank time settings
BL2
BL1
Typical blank time
GND
GND
0.6 µs
GND
VCC
0.9 µs
VCC
GND
1.2 µs
VCC
VCC
1.5 µs
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
13
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Classical non-SPI control mode (stand alone mode)
The driver can be controlled by analog current control signals and digital phase signals. To enable this
mode, tie pin SPE to GND. In this mode, the SPI interface is disabled and the SPI input pins have
alternate functions. The internal DACs are forced to “1111”.
Pin functions in stand alone mode
Pin
Stand alone
mode name
Function in stand alone mode
SPE
(GND)
Tie to GND to enable stand alone mode
ANN
MDAN
Enable mixed decay for bridge A (low = enable)
SCK
MDBN
Enable mixed decay for bridge B (low = enable)
SDI
PHA
Polarity bridge A (low = current flow from output OA1 to OA2)
CSN
PHB
Polarity bridge B (low = current flow from output OB1 to OB2)
SDO
ERR
Error output (high = overcurrent on any bridge, or overtemperature). In this
mode, the pin is never tristated.
ENN
ENN
Standby mode (high active), high causes a low power mode of the device.
Setting this pin high also resets all error conditions.
INA,
INB
INA,
INB
Current control for bridge A, resp. bridge B. Refer to AGND. The sense
resistor trip voltage is 0.34V when the input voltage is 2.0V. Maximum input
voltage is 3.0V.
Input signals for microstep control in stand alone mode
Attention: When transferring these waves to SPI operation, please remark, that the mixed decay bits
are inverted when compared to stand alone mode.
INA
INB
90°
180°
270°
360°
PHA
(SDI)
PHB
(CSN)
MDAN
(ANN)
MDBN
(SCK)
Use dotted line to improve performance
at medium velocities
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
14
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Unipolar Operation
The TMC249 can also be used in an unipolar motor application with microstepping. In this
configuration, only the four upper power transistors are required.
Differences of short circuit behavior in unipolar operation mode
Since there is no possibility to disable a short to VS condition, the circuit is not completely short circuit
proof. In a low cost application a motor short would be covered, just using the bottom sense resistors
(see schematic).
Differences in chopper cycle in unipolar operation mode
In unipolar mode, one of the upper side transistors is chopped, depending on the phase polarity. Slow
decay mode always means, that both transistors are disabled. There is no difference between slow
and fast decay mode, and the mixed decay control bits are “don’t care”. The transistors have to stand
an off voltage, which is slightly higher than the double of the supply voltage. Voltage decay in the coil
can be adapted to the application by adding additional diodes and a zener diode to feed back coil
current in flyback conditions to the supply.
+VM
HA1
HA2
TMC249/
TMC239
P
P
One coil of
the motor
LA2
LA1
SRA
RS
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
15
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Calculation of the external components
Sense Resistor
Choose an appropriate sense resistor (RS) to set the desired motor current. The maximum motor
current is reached, when the coil current setting is programmed to “1111”. This results in a current
sense trip voltage of 0.34V when the internal reference or a reference voltage of 2V is used.
When operating your motor in fullstep mode, the maximum motor current is as specified by the
manufacturer. When operating in sinestep mode, multiply this value by 1.41 for the maximum current
(Imax).
RS = VTRIP / Imax
In a typical application:
RS = 0.34V / Imax
RS:
VTRIP:
Imax:
Current sense resistor of bridge A, B
Programmed trip voltage of the current sense comparators
Desired maximum coil current
Examples for sense resistor settings
Imax
723mA
1030mA
1545mA
2267mA
3400mA
RS
0.47Ω
0.33Ω
0.22Ω
0.15Ω
0.10Ω
High side overcurrent detection resistor RSH
The TMC249 detects an overcurrent to ground, when the voltage between VS and VT exceeds
150mV. The high side overcurrent detection resistor should be chosen in a way that 100mV voltage
drop are not exceeded between VS and VT, when both coils draw the maximum current. In a sinestep
application, this is when sine and cosine wave have their highest sum, i.e. at 45 degrees,
corresponding to 1.41 times the maximum current setting for one coil. In a fullstep application this is
the double coil current.
In a microstep application:
RSH = 0.1V / (1.41 × Imax)
In a fullstep application:
RSH = 0.1V / (2 × Imax)
RSH:
Imax:
High side overcurrent detection resistor
Maximum coil current
However, if the user desires to use higher resistance values, a voltage divider in the range of 10Ω to
100Ω can be used for VT. This might also be desired to limit the peak short to GND current, as
described in the following chapter.
Attention: A careful PCB layout is required for the sense resistor traces and for the RSH traces.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
16
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Making the circuit short circuit proof
In practical applications, a short circuit does not describe a static condition, but can be of very different
nature. It typically involves inductive, resistive and capacitive components. Worst events are
unclamped switching events, because huge voltages can build up in inductive components and result
in a high energy spark going into the driver, which can destroy the power transistors. The same is true
when disconnecting a motor during operation: Never disconnect the motor during operation!
There is no absolute protection against random short circuit conditions, but pre-cautions can be taken
to improve robustness of the circuit:
In a short condition, the current can become very high before it is interrupted by the short detection,
due to the blanking during switching and internal delays. The high-side transistors allow a high current
flowing for the selected blank time. The lower the external inductivity, the faster the current climbs. If
inductive components are involved in the short, the same current will shoot through the low-side
resistor and cause a high negative voltage spike at the sense resistor. Both, the high current and the
voltage spikes are a danger for the driver.
Thus there are a three things to be done, if short circuits are expected:
1. Protect SRA/SRB inputs using a series resistance
2. Increase RSH to limit maximum transistor current: Use same value as for sense resistors
3. Use as short as possible blank time
The second measure effectively limits short circuit current, because the upper driver transistor with its
fixed ON gate voltage of 6V forms a constant current source together with its internal resistance and
RSH. A positive side effect is, that only one type of low ohmic resistor is required. The drawback is, that
power dissipation increases. A high side short detection resistor of 0.33 Ohms limits maximum high
side transistor current to typically 4A. The schematic shows the modifications to be done.
However, the effectiveness of these measures should be tested in the given application.
VS
R2
RSH
100nF
VT
+VM
100R
GND
RSH=RSA=RSB
Microstep: R2 = 27R
Fullstep: R2 = 18R
CVM
SRA
100R
SRB
100R
RSA
RSB
GND
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
17
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Oscillator Capacitor
The PWM oscillator frequency can be set by an external capacitor. The internal oscillator uses a 28kΩ
resistor to charge / discharge the external capacitor to a trip voltage of 2/3 Vcc respectively 1/3 Vcc. It
can be overdriven using an external CMOS level square wave signal. Do not set the frequency higher
than 100kHz and do not leave the OSC terminal open! The two bridges are chopped with a phase shift
of 180 degrees at the positive and at the negative edge of the clock signal.
1
fOSC ≈
40 µs × COSC [nF]
fOSC:
COSC:
PWM oscillator frequency
Oscillator capacitor in nF
Table of oscillator frequencies
fOSC typ.
16.7kHz
20.8kHz
25.0kHz
30.5kHz
36.8kHz
44.6kHz
COSC
1.5nF
1.2nF
1.0nF
820pF
680pF
560pF
Please remark, that an unnecessary high frequency leads to high switching losses in the power
transistors and in the motor. For most applications a chopper frequency slightly above audible range is
sufficient. When audible noise occurs in an application, especially with mixed decay continuously
enabled, the chopper frequency should be two times the audible range.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
18
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
19
Slope Control Resistor
The output-voltage slope of the full bridge is controlled by a constant current gate charge / discharge
of the MOSFETs. The charge / discharge current for the MOSFETs can be controlled by an external
resistor: A reference current is generated by internally pulling the SLP-Pin to 1.25V via an integrated
4.7KΩ resistor. This current is used to generate the current for switching ON and OFF the power
transistors. (In non-A-type the low side slopes are fixed to typ. +/-15mA corresponding to a 5KΩ to
10KΩ slope control resistor!)
The gate-driver output current can be set in range of 2mA to 25mA by an external resistor:
RSLP [kΩ] ≈
RSLP:
IOUT:
123
− 4.7
IOUT [mA]
Slope control resistor
Controlled output current of the low-side MOSFET driver
The SLP-pin can directly be connected to AGND for the fastest output-voltage slope (respectively
maximum output current).
Please remark, that there is a trade off between reduced electromagnetic emissions (slow slope) and
high efficiency because of low dynamic losses (fast slope). Typical slope times range between 100ns
and 500ns. Slope times below 100ns are not recommended, because they superimpose additional
stress on the power transistors while bringing only very slight improvement in power dissipation.
For applications where electromagnetic emission is very critical, it might be necessary to add
additional LC (or capacitor only) filtering on the motor connections.
For these applications emission is lower, if only slow decay operation is used.
25
IHDON
20
15
-IHDOFF /
+/-ILD
10
5
0
0
2
5
10
RSLP [KOhm]
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
20
50
100
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
20
Absolute Maximum Ratings
The maximum ratings may not be exceeded under any circumstances.
Symbol Parameter
Min
Max
Unit
VS
Supply voltage
36
V
VSM
Supply and bridge voltage max. 20000s
40
V
VCC
Logic supply voltage
6.0
V
IOP
Gate driver peak current (1)
50
mA
IOC
Gate driver continuous current
5
mA
VI
Logic input voltage
-0.3
VCC+0.3V
V
VIA
Analog input voltage
-0.3
VCC+0.3V
V
IIO
Maximum current to / from digital pins
+/-10
mA
VS-1V
VS+0.3V
V
-0.5
and analog inputs
VVT
Short-to-ground detector input voltage
TJ
Junction temperature
-40
150 (1)
°C
TSTG
Storage temperature
-55
150
°C
(1) Internally limited
Electrical Characteristics
Operational Range
Symbol Parameter
Min
Max
Unit
TAI
Ambient temperature industrial (1)
-25
125
°C
TAA
Ambient temperature automotive
-40
125
°C
TJ
Junction temperature
-40
140
°C
VS
Bridge supply voltage (A-type)
7
34
V
VS
Bridge supply voltage (non-A-type)
7
30
V
VCC
Logic supply voltage
3.0
5.5
V
fCLK
Chopper clock frequency
100
kHz
RSLP
Slope control resistor
470
KΩ
0
(1) The circuit can be operated up to 140°C, but output power derates.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
21
DC Characteristics
DC characteristics contain the spread of values guaranteed within the specified supply voltage and
temperature range unless otherwise specified. Typical characteristics represent the average value of
all parts.
Logic supply voltage: VCC = 3.0 V ... 5.5 V,
Junction temperature: TJ = -40°C … 140°C,
Bridge supply voltage : VS = 7 V…34 V
(unless otherwise specified)
Symbol
ILDON
ILDOFF5
ILDOFF3
ILDON
ILDOFF
IHDON
IHDOFF
Parameter
Conditions
Min
Typ
Max
Unit
Gate drive current
low side switch ON (non-A-type)
VLD < 4V
10
15
25
mA
Gate drive current
low side switch OFF (non-Atype)
VLD > 3V
-15
-25
-35
mA
Gate drive current
low side switch OFF (non-Atype)
VLD > 3V
-10
-15
-20
mA
Gate drive current
low side switch ON (A-type)
VS > 8V, RSLP= 0K
15
25
40
mA
VLD < 4V
Gate drive current
low side switch OFF (A-type)
-15
-25
-40
mA
VLD > 4V
-15
-25
-40
mA
15
30
40
mA
70
100
130
%
-5.1
-6.0
-8.0
V
5.1
6.0
8.0
V
0
-0.5
V
0
0.5
V
16
20
V
Gate drive current
high side switch ON
Gate drive current
high side switch OFF
∆ISET
Deviation of Current Setting with
Respect to Characterization
Curve 1)
VGH1
Gate drive voltage high side ON
VCC = 5V
VCC = 3.3V
VS > 8V, RSLP= 0K
VS > 8V, RSLP= 0K
VS - VHD < 4V
VS > 8V, RSLP= 0K
VS - VHD > 4V
Deviation from
standard value,
10kΩ<RSLP<75kΩ
VS > 8V
relative to VS
VGL1
Gate drive voltage low side ON
VS > 8V
VGH0
Gate drive voltage high side
OFF
relative to VS
VGL0
Gate drive voltage low side OFF
VGCL
Gate driver clamping voltage
-IH / IL = 20mA
VGCLI
Gate driver inverse clamping
voltage
-IH / IL = -20mA
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
12
-0.8
V
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
Symbol
Parameter
Conditions
22
Min
Typ
Max
Unit
VCCUV
VCC undervoltage
2.5
2.7
2.9
V
VCCOK
VCC voltage o.k.
2.7
2.9
3.0
V
0.85
1.35
mA
0.45
0.75
mA
37
70
µA
ICC
VCC supply current
fosc = 25 kHz
ICCSTB
VCC supply current standby
ICCSD
VCC supply current shutdown
VSUV
VS undervoltage
5.5
5.9
6.2
V
VCCOK
VS voltage o.k.
6.1
6.4
6.7
V
ENN = 1
VS supply current with maximum VS = 14V,
current setting (static state)
R = 0K
6
ISSD
VS supply current shutdown or
standby
28
VIH
High input voltage
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
VIL
ISSM
mA
SLP
VS = 14V
50
µA
2.2
VCC +
0.3 V
V
Low input voltage
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
-0.3
0.7
V
VIHYS
Input voltage hysteresis
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
100
300
500
mV
VOH
High output voltage
(output SDO)
-IOH = 1mA
VCC –
0.6
VCC –
0.2
VCC
V
VOL
Low output voltage
(output SDO)
IOL = 1mA
0
0.1
0.4
V
-IISL
Low input current
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
VI = 0
VCC = 3.3V
VCC = 5.0V
2
70
µA
µA
µA
10
25
VENNH
High input voltage threshold
(input ENN)
VEHYS
Input voltage hysteresis
(input ENN)
VOSCH
High input voltage threshold
(input OSC)
tbd
2/3 VCC
tbd
V
VOSCL
Low input voltage threshold
(input OSC)
tbd
1/3 VCC
tbd
V
VVTD
VT threshold voltage
(referenced to VS)
-130
-155
-180
mV
VTRIP
SRA / SRB voltage at
DAC=”1111”
315
350
385
mV
VSRS
SRA / SRB overcurrent detection
threshold
570
615
660
mV
VSROFFS1 SRA / SRB comparator offset
voltage (Standard device)
-10
0
10
mV
VSROFFS2 SRA / SRB comparator offset
voltage (Selected device)
-6
0
6
mV
175
264
360
kΩ
RINAB
INA / INB input resistance
1/2 VCC
0.1
VENNH
internal ref. or
2V at INA / INB
Vin ≤ 3 V
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
23
AC Characteristics
AC characteristics contain the spread of values guaranteed within the specified supply voltage and
temperature range unless otherwise specified. Typical characteristics represent the average value of
all parts.
Logic supply voltage: VCC = 3.3V,
Bridge supply voltage: VS = 14.0V,
Ambient temperature: TA = 27°C,
External MOSFET gate charge = 3.2nC
Symbol Parameter
fOSC
Oscillator frequency
using internal oscillator
TBL
TONMIN
Conditions
Min
Typ
Max
Unit
COSC = 1nF
±1%
20
25
31
kHz
1.35
1.5
1.65
µs
Effective Blank time
BL1, BL2 = VCC
Minimum PWM on-time
BL1, BL2 =
GND
0.7
µs
Thermal Protection
Symbol
TJOT
TJOTHYS
TJWT
TJWTHYS
Parameter
Conditions
Thermal shutdown
Min
Typ
Max
Unit
145
155
165
°C
TJOT hysteresis
Prewarning temperature
TJWT hysteresis
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
15
135
145
15
°C
155
°C
°C
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
24
SPI Interface Timing
tES
ENN
CSN
t1
tCL
tCH
t1
t1
SCK
tDU
bit11
SDI
tDH
bit10
bit0
tD
SDO
tZC
bit11
bit10
bit0
Propagation Times
(3.0 V ≤ VCC ≤ 5.5 V, -40°C ≤ Tj ≤ 150°C; VIH = 2.8V, VIL = 0.5V; tr, tf = 10ns; CL = 50pF,
unless otherwise specified)
Symbol
fSCK
Parameter
SCK frequency
Conditions
Min
ENN = 0
DC
Typ
Max
Unit
4
MHz
t1
SCK stable before and after
CSN change
50
ns
tCH
Width of SCK high pulse
100
ns
tCL
Width of SCK low pulse
100
ns
tDSU
SDI setup time
40
ns
tDH
SDI hold time
50
ns
tD
SDO delay time
tZC
CSN high
impedance
tES
ENN to SCK setup time
tPD
CSN high to output change
delay
to
CL = 50pF
SDO
high
40
100
ns
50
ns
30
ns
3
µs
SDO is tristated whenever ENN is inactive (high) or CSN is inactive (high).
Using the SPI interface
The SPI interface allows either cascading of multiple devices, giving a longer shift register, or working
with a separate chip select signal for each device, paralleling all other lines. Even when there is only
one device attached to a CPU, the CPU can communicate with it using a 16 bit transmission. In this
case, the upper 4 bits are dummy bits.
SPI Filter
To prevent spikes from changing the SPI settings, SPI data words are only accepted, if their length is
at least 12 bit.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005)
25
Application Note: Extending the Microstep Resolution
For some applications it might be desired to have a higher microstep resolution, while keeping the
advantages of control via the serial interface. The following schematic shows a solution, which adds
two LSBs by selectively pulling up the SRA / SRB pin by a small voltage difference. Please remark,
that the lower two bits are inverted in the depicted circuit. A full scale sense voltage of 340mV is
assumed. The circuit still takes advantage of completely switching off of the coils when the internal
DAC bits are set to “0000”. This results in the following comparator trip voltages:
Current setting Trip voltage
(MSB first)
0000xx
0V
000111
5.8 mV
000110
11.5 mV
000101
17.3 mV
000100
23 mV
...
111101
334.2 mV
111100
340 mV
SPI bit
DAC bit
SPI bit
DAC bit
15
/B1
7
A2
14
/B0
6
PHA
13
/A1
5
MDB
12
/A0
4
B5
11
MDA
3
B4
10
A5
2
B3
9
A4
1
B2
SCK
SCK
SDI
SDI
TMC236 /
TMC239
SRA
SDO
110R
4.7nF
opt.
CSN
/CS
47K
47K
RS
47K
+VCC
100K
/OE
C2
/MR
C1
DS1D
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
/DACA.0
/DACA.1
/DACB.0
/DACB.1
Free for
second
TMC239
Q7'
74HC595
Vcc = 5V
C
SDO
Q
D
1/2 74HC74
i
Note: Use a 74HC4094
instead of the HC595 to get
rid of the HC74 and inverter
SPI is a trademark of Motorola
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
8
A3
0
PHB