View TMC24606_4306088.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
1
TMC 246/A - DATA SHEET
High Current Microstep Stepper Motor Driver with sensorless stall detection, protection / diagnosis and SPI Interface
TRINAMIC(R) Motion Control GmbH & Co KG Sternstrae 67 D - 20357 Hamburg GERMANY T +49 - (0) 40 - 51 48 06 - 0 F +49 - (0) 40 - 51 48 06 - 60 WWW.TRINAMIC.COM INFO@TRINAMIC.COM
Features
The TMC246 / TMC246A (1) is a dual full bridge driver IC for bipolar stepper motor control applications. The integrated unique sensorless stall detection (pat. pend.) StallGuardTM 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 TMC246 an optimum choice for drives, where a high reliability is desired. The TMC246 is realized in a HVCMOS technology combined with Low-RDS-ON high efficiency MOSFETs (pat. pend.). It allows to drive a coil current of up to 1500mA even at high environment temperatures. Its low current consumption and high efficiency together with the miniature package make it a perfect solution for embedded motion control and for battery powered devices. Internal DACs allow microstepping as well as smart current control. The device can be controlled by a serial interface (SPITMi) or by analog / digital input signals. Short circuit, temperature, undervoltage and overvoltage protection are integrated. * * * * * * * * * * * * * * Sensorless stall detection StallGuardTM 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) Up to 1500mA output current and more than 800mA at 105C 3.3V or 5V operation for digital part Low power dissipation via low RDS-ON power stage Standby and shutdown mode available
(1) The term TMC246 in this datasheet always refers to the TMC246A and the TMC246. The major differences in the older TMC246 are explicitly marked with "non-A-type". The TMC246A brings a number of enhancements and is fully backward compatible to the TMC246.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
2
FEATURES ............................................................................................................................................1 PINNING.................................................................................................................................................5 PACKAGE CODES...................................................................................................................................5 PQFP44 DIMENSIONS ..........................................................................................................................6 APPLICATION CIRCUIT / BLOCK DIAGRAM .....................................................................................7 PIN FUNCTIONS.....................................................................................................................................7 LAYOUT CONSIDERATIONS ...............................................................................................................8 CONTROL VIA THE SPI INTERFACE ..................................................................................................9 SERIAL DATA WORD TRANSMITTED TO TMC246 ......................................................................................9 SERIAL DATA WORD TRANSMITTED FROM TMC246..................................................................................9 TYPICAL WINDING CURRENT VALUES .....................................................................................................10 BASE CURRENT CONTROL VIA INA AND INB IN SPI MODE......................................................................10 CONTROLLING THE POWER DOWN MODE VIA THE SPI INTERFACE ...........................................................10 OPEN LOAD DETECTION .......................................................................................................................11 STANDBY AND SHUTDOWN MODE ..........................................................................................................11 POWER SAVING ...................................................................................................................................11 STALL DETECTION ............................................................................................................................12 USING THE SENSORLESS LOAD MEASUREMENT .....................................................................................12 IMPLEMENTING SENSORLESS STALL DETECTION ....................................................................................12 PROTECTION FUNCTIONS................................................................................................................13 OVERCURRENT PROTECTION AND DIAGNOSIS........................................................................................13 OVERTEMPERATURE PROTECTION AND DIAGNOSIS ................................................................................13 OVERVOLTAGE PROTECTION AND ENN PIN BEHAVIOR ...........................................................................13 CHOPPER PRINCIPLE........................................................................................................................14 CHOPPER CYCLE / USING THE MIXED DECAY FEATURE ...........................................................................14 BLANK TIME ........................................................................................................................................14 BLANK TIME SETTINGS .........................................................................................................................14 CLASSICAL NON-SPI CONTROL MODE (STAND ALONE MODE) ................................................15 PIN FUNCTIONS IN STAND ALONE MODE .................................................................................................15 INPUT SIGNALS FOR MICROSTEP CONTROL IN STAND ALONE MODE..........................................................15 CALCULATION OF THE EXTERNAL COMPONENTS......................................................................16 SENSE RESISTOR................................................................................................................................16 EXAMPLES FOR SENSE RESISTOR SETTINGS..........................................................................................16 HIGH SIDE OVERCURRENT DETECTION RESISTOR RSH ............................................................................16 MAKING THE CIRCUIT SHORT CIRCUIT PROOF.........................................................................................17 OSCILLATOR CAPACITOR .....................................................................................................................18 TABLE OF OSCILLATOR FREQUENCIES ...................................................................................................18 PULLUP RESISTORS ON UNUSED INPUTS ...............................................................................................18 SLOPE CONTROL RESISTOR ................................................................................................................19 EXAMPLE FOR SLOPE SETTINGS ...........................................................................................................19 ABSOLUTE MAXIMUM RATINGS......................................................................................................20 ELECTRICAL CHARACTERISTICS ...................................................................................................20 OPERATIONAL RANGE .........................................................................................................................20 DC CHARACTERISTICS ........................................................................................................................21 AC CHARACTERISTICS ........................................................................................................................22 THERMAL PROTECTION........................................................................................................................22 THERMAL CHARACTERISTICS ...............................................................................................................23 TYPICAL POWER DISSIPATION AT HIGH LOAD / HIGH TEMPERATURE ........................................................23 Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
3
SPI INTERFACE TIMING.....................................................................................................................24 PROPAGATION TIMES ..........................................................................................................................24 USING THE SPI INTERFACE ..................................................................................................................24 SPI FILTER .........................................................................................................................................24 ESD PROTECTION..............................................................................................................................25 APPLICATION NOTE: EXTENDING THE MICROSTEP RESOLUTION ...........................................26
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
4
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.
(c) 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 (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
5
Pinning
AGND
GND
VCC
SLP
INA
INB
VS
36
VT
35
-
-
44
43
42
41
40
39
38
37
ANN OA1
34
-
1 2 3
33 32
BL2 OB1
31 30
VSA OA2
4 5 6 7
VSB OB2
TMC 246 / 236A QFP44
29 28 27
OA1
8 26 25 24
OB1
9 10
BRA OA2
BRB OB2
11
23
12
13
14
15
16
17
18
19
20
21
GND
CSN
ENN
SRA
SCK
SPE
BL1
SDO
Package codes Type TMC246A TMC246 Package PQFP44 PQFP44 Temperature range automotive (1) automotive (1) Lead free (ROHS) Yes From date code 30/04 Code/marking TMC246A-PA TMC246-PA
(1) ICs are not tested according to automotive standards, but are usable within the complete automotive temperature range.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
OSC
SRB
SDI
22
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
6
PQFP44 Dimensions REF A C D E F G H I K L MIN. 12 10 1 0.09 0.05 0.30 0.45 0.8 0 0.08 1.6 0.2 0.15 0.45 0.75 MAX.
E
G
I
C D
F
All dimensions are in mm. L: Co-planarity of pins
A
H
K
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
7
Application Circuit / Block Diagram
+VM
BL1
BL2
VS
220nF
100F
RSH
TMC246
OSC 1nF
VT
OSC Current Controlled Gate Drivers
VSA
+VCC
VCC
PWM-CTRL
Undervoltage
P
P
OA1 Coil A
100nF
OA2
Temperature
N
N
BRA RS
SPIInterface
[MDBN]
SCK
Control & Diagnosis
Load mesurement
0
SRA
[PHA]
SDI
DAC
4
1 INA REFSEL VREF INB
Parallel Control
[ERR]
SDO
DAC
4
1
[PHB]
CSN
0
SRB RS BRB
Current Controlled Gate Drivers
PWM-CTRL
N
N
ENN
OB1 Coil B
OB2
VCC/2
P
P
REFSEL
VSB
SPE
ANN [MDAN]
AGND
GND
SLP
stand alone mode
RSLP [...]: function in stand alone mode
Pin Functions Pin VS VCC AGND INA SCK SDI ENN ANN BL1, BL2 OA1, OA2 VSA, VSB Function Motor supply voltage Pin VT Function Short to GND detection comparator - connect to VS if not used Digital / Power ground Oscillator capacitor or external clock input for chopper Analog current control input phase B Data output of serial interface (tristate) Chip select input of serial interface Enable SPI mode (high active). Tie to GND for non-SPI applications Slope control resistor. Bridge A/B current sense resistor input Output of full-bridge B Bridge A/B sense resistor
3.0-5.5V supply voltage for analog GND and logic circuits Analog ground (Reference for SRA, OSC SRB, OSC, SLP, INA, INB, SLP) Analog current control phase A Clock input of serial interface Data input of serial interface INB SDO CSN
Device enable (low active), and SPE overvoltage shutdown input Enable analog current control via SLP INA and INB (low active) Digital blank time select Output of full-bridge A Supply voltage for bridge A/B SRA, SRB OB1, OB2 BRA, BRB
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
8
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 a 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 TMC246'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 TMC246. 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 VT and SRA / SRB line, as shown in the schematic, to prevent spikes from triggering the short circuit protection or the chopper comparator. Be sure to connect all pins of the PQFP package for each of the double/quad output pins externally. Each two of these output pins should be treated as if they were fused to a single wide pin (as shown in the drawing). Each two pins are used as cooling fin for one of the eight integrated output power transistors. Use massive motor current traces on all these pins and multiple vias, if the output trace is changed to a different layer near the package. A symmetrical layout on all of the OA and OB pins is required, to ensure proper heat dissipation on all output transistors. Otherwise proper function of the thermal protection can not be guaranteed! A multi-layer PCB shows superior thermal performance, because it allows usage of a massive GND plane, which will act as a heat spreader. The heat will be coupled vertically from the output traces to the GND plane, since vertical heat distribution in PCBs is quite effective. Heat dissipation can be improved by attaching a heat sink to the package directly. Please be aware, that long or thin traces to the sense resistors may add substantial resistance and thus reduce output current. The same is valid for the high side shunt resistor. Use short and straight traces to avoid parasitic inductivities, because these can generate large voltage spikes and EMV problems.
optional voltage divider
100nF VT 100R GND RDIV RSH
VS
+VM
VSA
TMC236/ TMC246
VSB
BRA
CVM
BRB
SRA
optional filter
100R
SRB 100R 3.3 10nF AGND
RSA
RSB
GND
GNDPlane
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
9
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 TMC246 (MSB transmitted first) Bit 11 10 9 8 7 6 5 4 3 2 1 0 Name MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB Function mixed decay enable phase A current bridge A.3 current bridge A.2 current bridge A.1 current bridge A.0 polarity bridge A mixed decay enable phase B current bridge B.3 current bridge B.2 current bridge B.1 current bridge B.0 polarity bridge B LSB "0" = current flow from OB1 to OB2 LSB "0" = current flow from OA1 to OA2 "1" = mixed decay MSB Remark "1" = mixed decay MSB
Serial data word transmitted from TMC246 (MSB transmitted first) Bit 11 10 9 8 7 6 5 4 3 2 1 0 Name LD2 LD1 LD0 1 OT UV OCHS OLB OLA OCB OCA Function load indicator bit 2 load indicator bit 1 load indicator bit 0 always "1" overtemperature driver undervoltage overcurrent high side open load bridge B open load bridge A overcurrent bridge B low side overcurrent bridge A low side "1" = chip off due to overtemperature "1" = prewarning temperature exceeded "1" = undervoltage on VS 3 PWM cycles with overcurrent within 63 PWM cycles no PWM switch off for 14 oscillator cycles no PWM switch off for 14 oscillator cycles 3 PWM cycles with overcurrent within 63 PWM cycles 3 PWM cycles with overcurrent within 63 PWM cycles LSB Remark MSB
OTPW temperature prewarning
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
10
Typical winding current values Current setting Percentage of CA3..0 / CB3..0 current 0000 0001 0010 ... 1110 1111 0% 6.7% 13.3% ... 93.3% 100% 317 mV 340 mV Typical trip voltage of the current sense comparator (internal reference or analog input voltage of 2V is used) 0V 23 mV 45 mV (bridge continuously in slow decay condition)
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 chip 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 x "percentage SPI current setting A" VTRIP,B = 0.17 VINB x "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
INA CPWM INB 47K 100nF 10nF 51K AGND 100K 100K 51K
8 level via R2R-DAC
CPort .2
2 level control
+VCC
R1 R2
CPort .1
Controlling the power down mode via the SPI interface
Bit Standard function Control word function
11
10
9
8
7
6
51K
ANN
100K
CPort .0 CPort
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 TMC246 into a low current standby mode with coils switched off.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
11
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 TMC246 switches off all power driver outputs. 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 (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
12
Stall Detection
Using the sensorless load measurement The TMC246 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. The load detection is based on the motor's back EMF, thus the level depends 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. Attention: Do not read out the value within one chopper period plus 8 microseconds after toggling one of the phase polarities! 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)
v_max
a_ m ax
t
load indicator max
acceleration
constant velocity
stall
LMOVE LSTALL t
stall threshold min
acceleration jerk
stall detected! vibration
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
13
Protection Functions
Overcurrent protection and diagnosis The TMC246 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 1/2 VCC to allow a simple overvoltage protection up to 40V using an external voltage divider (see schematic).
+VM
for switch off at 26 - 29V: at VCC=5V: R1=100K; R2=10K at VCC=3.3V: R1=160K; R2=10K R1 ENN R2
C-Port (opt.) low=Enable, high=Disable
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
14
Chopper Principle
Chopper cycle / Using the mixed decay feature The TMC246 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 TMC246 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 1.5s. The TMC246 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 GND GND VCC VCC BL1 GND VCC GND VCC Typical blank time 0.6 s 0.9 s 1.2 s 1.5 s
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
15
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 SPE ANN SCK SDI CSN SDO ENN INA, INB Stand alone mode name (GND) MDAN MDBN PHA PHB ERR ENN INA, INB Function in stand alone mode Tie to GND to enable stand alone mode Enable mixed decay for bridge A (low = enable) Enable mixed decay for bridge B (low = enable) Polarity bridge A (low = current flow from output OA1 to OA2) Polarity bridge B (low = current flow from output OB1 to OB2) Error output (high = overcurrent on any bridge, or overtemperature). In this mode, the pin is never tristated. Standby mode (high active), high causes a low power mode of the device. Setting this pin high also resets all error conditions. 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 (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
16
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 RS 0.47 0.43 0.39 0.33 0.27 0.22 Imax 723mA 790mA 870mA 1030mA 1259mA 1545mA
High side overcurrent detection resistor RSH The TMC246 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 x Imax) In a fullstep application: RSH = 0.1V / (2 x 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 10 to 100 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 (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
17
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 allows up to 10A 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 two 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 7V 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 slightly. 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
100nF VT
RDIV RSH 100R
+VM
GND
RSH=RSA=RSB
RDIV values for Microstep: Fullstep: internal reference 27R 18R INA/INB up to3V 18R 12R
CVM
SRA 100R SRB 100R RSA RSB
GND
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
18
Oscillator Capacitor The PWM oscillator frequency can be set by an external capacitor. The internal oscillator uses a 28k 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 s x 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. For most applications we recommend a frequency of 36.8kHz. Pullup resistors on unused inputs The digital inputs all have integrated pull-up resistors, except for the ENN input, which is in fact an analog input. Thus, there are no external pull-up resistors required for unused digital inputs which are meant to be positive.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
19
Slope Control Resistor The output-voltage slope of the full bridge outputs can be controlled to reduce noise on the power supply and on the motor lines and thus electromagnetic emission of the circuit. It is controlled by an external resistor at the SLP pin. Operational range: 0k RSLP 100k The SLP-pin can directly be connected to AGND for the fastest output-voltage slope (respectively maximum output current). In most applications a minimum external resistance of 10 K is recommended to avoid unnecessary high switching spikes. Only for non-A-types the slope on the lower transistors is fixed (corresponding to a 5K to 10K slope control resistor). 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. Please remark, that there is a trade off between reduced electromagnetic emissions (slow slope) and high efficiency because of low dynamic losses (fast slope). The following table and graph depict typical behavior measured from 15% of output voltage to 85% of output voltage. However, the actual values measured in an application depend on multiple parameters and may stray in a user application. Example for slope settings tSLP typ. 30ns 60ns 110ns 245ns 460ns RSLP 2.2K 10K 22K 51K 100K
tSLP [ns] @ 24V tSLP [ns] @ 10V
500
200
100
50
20
10 0 1 2 5 10 RSLP in KOhm 20 50 100
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
20
Absolute Maximum Ratings
The maximum ratings may not be exceeded under any circumstances. Symbol Parameter VS VS VMD VTR VTR VCC IOP IOC Supply voltage (A-type) Supply voltage (non-A-type) Supply and bridge voltage max. 20000s (non-A-type: device disabled) Power transistor voltage VOA-VBRA, VOBVBRB, VSA-VOA, VSB-VOB (A-type) Power transistor voltage VOA-VBRA, VOBVBRB, VSA-VOA, VSB-VOB (non-A-type) Logic supply voltage Output peak current (10s pulse) Output current (continuous, one bridge) TA 85C TA 105C TA 125C VI VIA IIO Logic input voltage Analog input voltage Maximum current to / from digital pins and analog inputs VVT TJ TSTG Short-to-ground detector input voltage Junction temperature Storage temperature VS-1V -40 -55 VS+0.3V 150 (1) 150 V C C -0.3 -0.3 -0.5 Min Max 36 30 40 40 30 6.0 +/-7 1500 1000 800 VCC+0.3V VCC+0.3V +/-10 V V mA Unit V V V V V V A mA
(1) Internally limited
Electrical Characteristics
Operational Range Symbol Parameter TAI TAA TJ VS VS VCC fCLK RSLP Ambient temperature industrial (1) Ambient temperature automotive Junction temperature Bridge supply voltage (A-type) Bridge supply voltage (non-A-type) Logic supply voltage Chopper clock frequency Slope control resistor 0 Min -25 -40 -40 7 7 3.0 Max 125 125 140 34 28.5 5.5 50 110 Unit C C C V V V kHz K
(1) The circuit can be operated up to 140C, but output power derates.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
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 = -40C ... 150C, Bridge supply voltage : VS = 7 V ... 34 V (unless otherwise specified) Symbol ROUT,Sink Parameter RDSON of sink-transistor Conditions TJ = 25C VS 8V TJ = 25C VS 8V TJ =150C VS 8V TJ =150C VS 8V TJ = 25C IOXX = 1.05A 2.5 2.7 fosc = 25 kHz Min Typ 0.12 0.22 0.20 0.37 0.84 2.7 2.9 0.85 0.45 ENN = 1 5.5 6.1 VS = 14V, RSLP = 0K VS = 14V 2.2 -0.3 100 -IOH = 1mA IOL = 1mA VI = 0 VCC = 3.3V VCC = 5.0V VCC - 0.6 0 2 10 25 1/2 VCC 0.1 300 VCC - 0.2 0.1 28 50 VCC + 0.3 V 0.7 500 VCC 0.4 70 A V V mV V V A A A 37 5.9 6.4 6 Max 0.19 0.36 0.26 0.47 1.12 2.9 3.0 1.35 0.75 70 6.2 6.7 Unit V V V mA mA A V V mA
ROUT,Source RDSON of source-transistor ROUT,Sink RDSON of sink-transistor max.
ROUT,Source RDSON of source-transistor max. VDIO VCCUV VCCOK ICC ICCSTB ICCSD VSUV VCCOK ISSM Diode forward voltages of Oxx MOSFET diodes VCC undervoltage VCC voltage o.k. VCC supply current VCC supply current standby VCC supply current shutdown VS undervoltage VS voltage o.k. VS supply current with fastest slope setting (static state) VS supply current shutdown or standby High input voltage (SDI, SCK, CSN, BL1, BL2, SPE, ANN) Low input voltage (SDI, SCK, CSN, BL1, BL2, SPE, ANN) Input voltage hysteresis (SDI, SCK, CSN, BL1, BL2, SPE, ANN) High output voltage (output SDO) Low output voltage (output SDO) Low input current (SDI, SCK, CSN, BL1, BL2, SPE, ANN) High input voltage threshold (input ENN) Input voltage hysteresis
ISSD VIH VIL VIHYS VOH VOL -IISL
VENNH VEHYS
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
22
(input ENN) VOSCH VOSCL VVTD VTRIP VSRS VSROFFS RINAB High input voltage threshold (input OSC) Low input voltage threshold (input OSC) VT threshold voltage (referenced to VS) SRA / SRB voltage at DAC="1111" SRA / SRB overcurrent detection threshold SRA / SRB comparator offset voltage INA / INB input resistance Vin 3 V internal ref. or 2V at INA / INB tbd tbd -130 315 570 -10 175
VENNH 2/3 VCC 1/3 VCC -155 350 615 0 264 tbd tbd -180 385 660 10 300 V V mV mV mV mV k
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. Bridge supply voltage: VS = 14.0V, Logic supply voltage: VCC = 5.0V, Ambient temperature: TA = 27C Symbol Parameter fOSC Oscillator frequency using internal oscillator tRS, tFS Rise and fall time of outputs Oxx with RSLP=0 Rise and fall time of outputs Oxx with RSLP = 25K Rise and fall time of outputs Oxx with RSLP = 50K Effective Blank time Minimum PWM on-time Conditions COSC = 1nF 1% Vo 15% to 85% IOXX = 800mA Vo 15% to 85% IOXX = 800mA Vo 15% to 85% IOXX = 800mA BL1, BL2 = VCC BL1, BL2 = GND 1.35 1.5 0.7 1.65 s s 250 ns 125 ns Min 20 Typ 25 Max 31 Unit kHz
25
ns
tRS, tFS
tRS, tFS
TBL TONMIN
Thermal Protection Symbol TJOT TJOTHYS TJWT TJWTHYS Parameter Thermal shutdown TJOT hysteresis Prewarning temperature TJWT hysteresis 135 Conditions Min 145 Typ 155 15 145 15 155 Max 165 Unit C C C C
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
23
Thermal Characteristics Symbol RTHA12 RTHA22 RTHA14 RTHA24 Parameter Thermal resistance bridge transistor junction to ambient, one bridge chopping, fixed polarity Thermal resistance bridge transistor junction to ambient, two bridges chopping, fixed polarity Thermal resistance bridge transistor junction to ambient, one bridge chopping, fixed polarity Thermal resistance bridge transistor junction to ambient, two bridges chopping, fixed polarity Conditions soldered to 2 layer PCB soldered to 2 layer PCB soldered to 4 layer PCB (pessimistic) soldered to 4 layer PCB (pessimistic) Typ 88 68 84 51 Unit K/W K/W K/W K/W
Typical Power Dissipation at high load / high temperature Coil: Chopping with: LW = 10mH, RW = 5.0 tDUTY = 33% ON, only slow decay Motor supply Slope voltage tSLP VM 16 V 16 V 14 V 14 V 28 V 28 V 400 ns 400 ns 60ns 60ns 60ns 60ns Chopper frequency fCHOP 25 KHz 25 KHz 20 KHz 20 KHz 25 KHz 25 KHz Typ total power dissipation PD 490 mW 450 mW 350 mW 340 mW 1000 mW 1100 mW
Current Current Ambient both brid- one bridge temperature ges on on TA 560 mA 560 mA 1000 mA 800 mA 800 mA 1500 mA 105 C 105 C 125 C 125 C 70 C 70 C
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
24
SPI Interface Timing
tES ENN CSN t1 SCK tDU SDI SDO bit11 tD bit11 bit10 bit0 tDH bit0 tZC bit10 tCL tCH t1 t1
Propagation Times (3.0 V VCC 5.5 V, -40C Tj 150C; VIH = 2.8V, VIL = 0.5V; tr, tf = 10ns; CL = 50pF, unless otherwise specified) Symbol fSCK t1 tCH tCL tDU tDH tD tZC tES tPD tLD Parameter SCK frequency SCK stable before and after CSN change Width of SCK high pulse Width of SCK low pulse SDI setup time SDI hold time SDO delay time CSN high to SDO high impedance ENN to SCK setup time CSN high to OA / OB output polarity change delay Load indicator valid after OA / OB output polarity change **) CL = 50pF *) 50 30 3 5 tOSC + 4 7 Conditions ENN = 0 Min DC 50 100 100 40 50 40 100 Typ Max 4 Unit MHz ns ns ns ns ns ns ns ns s s
*) SDO is tristated whenever ENN is inactive (high) or CSN is inactive (high). **) Whenever the PHA / PHB polarity is changed, the chopper is restarted for that phase. However, the chopper does not switch on, when the SRA resp. SRB comparator threshold is exceeded upon the start of a chopper period.
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 (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
25
ESD Protection
Please be aware, that the TMC246 is an ESD sensitive device due to integrated high performance MOS transistors.
ESD sensitive device If the ICs are manually handled before / during soldering, special precautions have to be taken to avoid ESD voltages above 100V HBM (Human body model). For automated SMD equipment the internal device protection is specified with 1000V CDM (charged device model), tbf.
When soldered to the application board, all inputs and outputs withstand at least 1000V HBM.
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)
26
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 000111 000110 000101 000100 ... 111101 111100 SPI bit DAC bit SPI bit DAC bit 15 /B1 7 A2
SCK
0V 5.8 mV 11.5 mV 17.3 mV 23 mV 334.2 mV 340 mV 14 /B0 6 PHA 13 /A1 5 MDB 12 /A0 4 B5 11 MDA 3 B4 10 A5 2 B3 9 A4 1 B2 8 A3 0 PHB
SCK
SDI
SDI
TMC236 / TMC239
SRA 110R 4.7nF opt.
SDO
/CS
CSN
47K
47K
RS
47K
+VCC
100K
/OE C2 /MR C1 DS1D Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q7' /DACA.0 /DACA.1 /DACB.0 /DACB.1
Free for second TMC239
74HC595
C SDO Q D
Vcc = 5V
1/2 74HC74
Note: Use a 74HC4094 instead of the HC595 to get rid of the HC74 and inverter
Please see the FAQ document for more application information.
i
SPI is a trademark of Motorola
Copyright (c) 2005, TRINAMIC Motion Control GmbH & Co KG

▲Up To Search▲

Price & Availability of TMC24606

	To Download TMC24606 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .