TMC249-SA

TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 1 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 INFO@TRINAMIC.COM 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 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 2 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 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 3 Pinning GND GND 26 VCC SLP LA1 LA2 SRA OSC SDO SDI SCK CSN ENN SPE BL1 SRB LB2 LB1 1 2 28 27 HA2 HA1 ANN AGND SLP INA INB VCC GND VS VT BL2 HB1 HB2 AGND ANN HA1 HA2 LA1 LA2 SRA 1 INA INB TMC249 / 249A SO28 3 4 5 6 7 8 9 10 11 12 13 14 26 25 24 23 22 21 20 19 18 17 16 15 32 31 - 30 29 28 27 VS 25 24 23 22 20 19 18 VT BL2 HB1 HB2 LB1 LB2 SRB TMC 249-LA 5 6 9 10 11 12 13 14 15 16 SCK SPE SDI OSC CSN SDO 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 ENN BL1 17 21 2 3 4 7 8 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 4 SO28 Dimensions C I A H K REF A B C D E F G H I K 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 G B D F E All dimensions are in mm. QFN32 Dimensions REF A A1 A3 L1 D E D2 E2 L b e 5.00 5.00 0.45 0.25 0.03 7.0 7.0 5.15 5.15 0.55 0.30 0.65 5.25 5.25 0.65 0.35 NX ccc C 0.08 C aaa C 2x TOP VIEW MIN 0.80 0.00 NOM 0.90 0.02 0.20 MAX 1.00 0.05 INDEX AREA (D/2 xE/2) D D/2 -A- -B- E/2 BOTTOM VIEW WITH TYPE C ID aaa C 2x 0.15 E 2 1 RADIUS N N-1 A SIDE VIEW A1 D2 A3 SEATING PLANE -C- All dimensions are in mm. D2/2 NXL Datum A or B e E2/2 E2 -BSEE DETAIL B 2 1 INDEX AREA (D/2 xE/2) N N-1 -A6 SEE DETAIL B NXb bbb ddd BTM VIEW 5 CAB C e e/2 Terminal Tip DETAIL B Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG L1 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 5 Application Circuit / Block Diagram +VM BL1 BL2 VS 220nF 100µF RSH TMC249 OSC 1nF VT OSC Current Controlled Gate Drivers HA1 +VCC VCC 100nF PWM-CTRL Undervoltage HA2 P P Coil A Temperature LA2 N N LA1 SRA RS SPIInterface [MDBN] SCK Control & Diagnosis 0 Load mesurement [PHA] SDI DAC 4 1 INA REFSEL VREF INB Parallel Control [ERR] SDO DAC 4 1 [PHB] CSN 0 SRB RS LB1 Current Controlled Gate Drivers PWM-CTRL LB2 N N Coil B ENN VCC/2 HB2 P P REFSEL HB1 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 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. Tie to GND for fastest slope Bridge A/B current sense resistor input Outputs for transistors low side N-channel 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 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 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 30V 30V RDSON [Ohm] 0.03 0.05 0.04 0.06 0.09 0.17 0.10 0.25 0.48 0.08 0.13 Total gate charge [nC] 5.0 8.0 7.5 9.0 3.0 3.2 4.5 4.0 0.8 2.9 3.0 Typical maximum Remark application current 4000mA (1) 3500mA 2000mA 2500mA 200mA unipolar 3000mA 6000mA (2 devices in parallel) (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 DIV RSH VM SA SB Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG 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 LED grn* VT to other bridges C-Pump 20kHz ICM7555 +VM e.g. 50V 22K 2n2 1µF 12V HS-Driver CDHS 470p HA1 small signal PMOS, e.g. BSS84 1K High current, high voltage MOS, e.g. SI4450 N 390R N Coil TMC249/ TMC239 LA1 CDLS 470p LSDriver 390R N N IR2101 SRA 100R 4.7nF opt. *) The LED increases break-before-make time and may be bridged if not desired RS SLP 10K Set HS and LS current to 10mA +VS 7..15V VS 1K VT 120R VCC 1/2 74HC244 on high side +VM 20..60V High voltage logic level MOS bridge P CDHS HA1 55V low current N-MOS 1K ADJ LM337 HV IN 1/2 74HC244 on low side LA1 1K CDLS /OE GND SRA 100R 390R /OE GND VM-5.2V 100R P OUT +5V VCC Coil TMC249/ TMC239 N N 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) 8 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 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 TMC249 (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 © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 9 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 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 INA µCPWM INB 47K 100nF 10nF 51K AGND 100K 100K 51K 8 level via R2R-DAC µCPort .2 2 level control +VCC R1 R2 µCPort .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 µCPort .0 µCPort 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) 10 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 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) 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 © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 12 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 for switch off at 26 - 29V: at VCC=5V: R1=100K; R2=10K at VCC=3.3V: R1=160K; R2=10K R1 ENN R2 µC-Port (opt.) low=Enable, high=Disable Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 13 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 GND GND VCC VCC BL1 GND VCC GND VCC Typical blank time 0.6 µs 0.9 µs 1.2 µs 1.5 µs Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 14 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 © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 15 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 P P TMC249/ TMC239 LA2 One coil of the motor LA1 RS SRA Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 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 0.47Ω 0.33Ω 0.22Ω 0.15Ω 0.10Ω Imax 723mA 1030mA 1545mA 2267mA 3400mA 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 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 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 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 100nF VT R2 RSH 100R GND +VM 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 TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 18 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 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] ≈ 123 − 4.7 IOUT [mA] RSLP: IOUT: 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 20 IHDON 15 -IHDOFF / +/-ILD 10 5 0 0 2 5 10 RSLP [KOhm] 20 50 100 Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG 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 VS VSM VCC IOP IOC VI VIA IIO Supply voltage Supply and bridge voltage max. 20000s Logic supply voltage Gate driver peak current (1) Gate driver continuous current 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 40 6.0 50 5 VCC+0.3V VCC+0.3V +/-10 Unit V V V mA mA V V 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 30 5.5 100 470 Unit °C °C °C V V V kHz KΩ (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 Parameter Gate drive current low side switch ON (non-A-type) Gate drive current low side switch OFF (non-Atype) Gate drive current low side switch OFF (non-Atype) Gate drive current low side switch ON (A-type) Gate drive current low side switch OFF (A-type) Gate drive current high side switch ON Gate drive current high side switch OFF Deviation of Current Setting with Respect to Characterization Curve 1) Gate drive voltage high side ON Conditions VLD < 4V Min 10 Typ 15 Max 25 Unit mA ILDOFF5 VLD > 3V VCC = 5V VLD > 3V VCC = 3.3V VS > 8V, RSLP= 0K VLD < 4V VS > 8V, RSLP= 0K VLD > 4V VS > 8V, RSLP= 0K VS - VHD < 4V VS > 8V, RSLP= 0K VS - VHD > 4V Deviation from standard value, 10kΩ 8V relative to VS 5.1 6.0 0 0 8.0 -0.5 0.5 20 V V V V V -IH / IL = 20mA -IH / IL = -20mA 12 16 -0.8 Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 22 Symbol VCCUV VCCOK ICC ICCSTB ICCSD VSUV VCCOK ISSM ISSD VIH VIL VIHYS VOH VOL -IISL Parameter VCC undervoltage VCC voltage o.k. VCC supply current VCC supply current standby VCC supply current shutdown VS undervoltage VS voltage o.k. Conditions Min 2.5 2.7 Typ 2.7 2.9 0.85 0.45 Max 2.9 3.0 1.35 0.75 70 6.2 6.7 Unit V V mA mA µA V V mA fosc = 25 kHz ENN = 1 5.5 6.1 37 5.9 6.4 6 28 2.2 -0.3 100 300 VCC – 0.2 0.1 VS supply current with maximum VS = 14V, current setting (static state) R = 0K SLP 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 (input ENN) 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 VS = 14V 50 VCC + 0.3 V 0.7 500 VCC 0.4 70 µA V V mV V V µA µA µA -IOH = 1mA IOL = 1mA VI = 0 VCC = 3.3V VCC = 5.0V VCC – 0.6 0 2 10 25 1/2 VCC 0.1 VENNH tbd tbd -130 2/3 VCC 1/3 VCC -155 350 615 0 0 264 tbd tbd -180 385 660 10 6 360 VENNH VEHYS VOSCH VOSCL VVTD VTRIP VSRS V V mV mV mV mV mV kΩ internal ref. or 2V at INA / INB 315 570 -10 -6 VSROFFS1 SRA / SRB comparator offset voltage (Standard device) VSROFFS2 SRA / SRB comparator offset voltage (Selected device) RINAB INA / INB input resistance Vin ≤ 3 V 175 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 Effective Blank time Minimum PWM on-time Conditions COSC = 1nF ±1% BL1, BL2 = VCC BL1, BL2 = GND Min 20 Typ 25 Max 31 Unit kHz 1.35 1.5 0.7 1.65 µs µs 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 © 2005, TRINAMIC Motion Control GmbH & Co KG TMC249 / TMC249A DATA SHEET (V2.02 / Aug 12th, 2005) 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, -40°C ≤ Tj ≤ 150°C; VIH = 2.8V, VIL = 0.5V; tr, tf = 10ns; CL = 50pF, unless otherwise specified) Symbol fSCK t1 tCH tCL tDSU tDH tD tZC tES tPD 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 impedance to SDO high CL = 50pF 50 30 3 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 µs ENN to SCK setup time CSN high to output change delay 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 000111 000110 000101 000100 ... 111101 111100 SPI bit DAC bit SPI bit DAC bit 15 /B1 7 A2 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 0V 5.8 mV 11.5 mV 17.3 mV 23 mV SCK 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 i SPI is a trademark of Motorola Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG