STK531U3xx series Application Note www.onsemi.com 1. Product synopsis This application handbook is intended to provide practical guidelines for the STK531U3xx series use. The STK531U3xx series is Intelligent Power Module (IPM) based upon ONs Insulated Metal Substrate Technology (IMST) for 3-phase motor drives which contain the main power circuitry and the supporting control circuitry. The key functions are outlined below: Highly integrated device containing all High Voltage (HV) control from HV-DC to 3-phase outputs in a single small SIP module. Output stage uses IGBT/FRD technology and implements Under Voltage Protection (UVP) and Over Current Protection (OCP) with a Fault Detection output flag. Internal Boost diodes are provided for high side gate boost drive. Externally accessible embedded thermistor for substrate temperature measurement. All control inputs and status outputs are at low voltage levels directly compatible with microcontrollers. Single control power supply due to Internal bootstrap circuit for high side pre-driver circuit. Mounting points are available on SIP package A simplified block diagram of a motor control system is shown in Figure 1. Intelligent Power Module Figure 1. Motor Control System Block Diagram Semiconductor Components Industries, LLC, 2014 Nov, 2014 1/22 Rev.1 STK531U3xx series Application Note 2. Product description Table1. gives an overview of the available devices, for a detailed description of the packages refer to Chapter 6. Device Feature Package Voltage (VCEmax.) Current (Ic) Peak current (Ic) Isolation voltage Shunt resistance STK531U369A-E STK531U394A-E single shunt SIP05 – horizontal pins 600V 10A 15A 20A 30A 2000V 33mΩ 25mΩ Table 1. Device Overview VB3(1) W,VS3(2) VB2(5) V,VS2(6) VB1(9) U,VS1(10) P(13) DB DB DB U.V. U.V. U.V. Shunt-Resistor N(16) RCIN(28) Latch time TH(29) Level Shifter Level Shifter Level Shifter HIN1(17) HIN2(18) HIN3(19) Logic Logic Logic LIN1(20) LIN2(21) LIN3(22) FAULT(23) ISO(24) Latch VDD(25) VSS(26) Over-Current Thermistor Latch time is 18ms to 80ms ( Automatic reset ) VDD-UnderVoltage ISD(27) Figure 2. STK531U3xx series equivalent circuits The high side drive is used with a bootstrap circuit to generate the higher voltage needed for gate drive. The Boost diodes are internal to the part and sourced from VDD (15V). There is an internal level shift circuit for the high side drive signals allowing all control signals to be driven directly from Vss levels common with the control circuit such as the microcontroller without requiring external level shift such as opto isolators. 2/22 STK531U3xx series Application Note 3. Performance test guidelines The following Chapter gives performance test method shown in Figures 3 to 7. 3.1. Switching time definition and performance test method trr 10% 90% VCE 90% 10% Io td(ON) 10% td(OFF) tr tf tOFF tON IN Figure 3. Switching time definition Ex) Lower side U phase measurement VB1 P VD1=15V U,VS1 VB2 VD2=15V V,VS2 U,VS1 VB3 Vcc CS VD3=15V W,VS3 VDD Io VD4=15V Input signal N LIN1 VSS ISD Figure 4. Evaluation circuit (Inductive load) IPM Ho HIN1,2,3 CS VCC Driver U,V,W LIN1,2,3 Lo Input signal Io Input signal Io Figure 5. Switching loss circuit 3/22 STK531U3xx series Application Note IPM Ho HIN1,2,3 CS VCC Driver U,V,W LIN1,2,3 Lo Input signal Io Input signal Io Figure 6. R.B.SOA circuit IPM Ho HIN1,2,3 CS VCC Driver U,V,W LIN1,2,3 Lo Input signal Io Input signal Io Figure 7. S.C.SOA circuit 4/22 STK531U3xx series Application Note 3.2. Thermistor Characteristics An integrated thermistor is used to sense the internal module temperature its electrical characteristic is outlined below. Parameter Resistance Symbol R25 Condition Tc=25°C R100 Tc=100°C Resistance B-Constant(25-50°C) B Temperature Range Min 99 Typ. 100 Max 101 Unit kΩ 5.18 5.38 5.60 kΩ 4208 4250 4293 K °C -40 +125 Table 2. NTC Thermistor value R25 is the value of the integrated NTC thermistor at Tc=25 °C. The resistance value is 100kΩ±1% and the value of the B-Constant (25-50°C) is 4250K±1%. The temperature depended value is calculated as shown in the formula. 𝐑(𝐭) = 𝐑 𝟐𝟓 × 𝟏 𝟏 𝐁(𝐓−𝟐𝟗𝟖) 𝐞 The resulting in the NTC values over temperatures Thermistor resistance - Case temperature Thermistor resistance [kΩ] 10000 min 1000 typ max 100 10 1 -50 0 50 100 150 Case temperature [˚C] Figure 8. typical NTC value over temperature 5/22 STK531U3xx series Application Note 4. Protective functions and Operation Sequence This chapter describes the protection features. over current protection short circuit protection under Voltage Lockout (UVLO) protection cross conduction prevention 4.1. Over current protection Over current protection is implemented by measuring the voltage across a shunt resistor to the negative supply terminal. In case of an OCP fault the gate drivers are shut down internally and the external Fault signal becomes active (low). The trip level of the over current protection current is programmable with an external resistance RSD between the ISD and VSS terminals as shown in over current protection Figure 9. Shunt resistor N Protection circuit VSS RSD ISD Figure 9. over current protection circuit Once activated by a fault condition the FAULT signal output returns to inactive (and is pulled high by the external resistor) when the fault condition is over and the fault clear time (FLTCLR) has passed. This implies that the system microcontroller needs to disable all input signals to the module by driving them low upon detection of a fault condition. The OCP trip level is programmed within the default or lower levels by an external resistor (RSD) between the ISD and VSD pins according to Figure 10 and 11. When the default level is used both terminals must be shorted e.g. by a 0Ω resistor. Note 1: One should be aware that the “N“ and the “VSS” pins are internally connected. Therefore an external short between these pins can cause the OCP level to be lower than desired. Note 2: In order to prevent false OCP events due to switching noise and recovery current – a blanking time of some microseconds is implemented. This blanking time will also filter repetitive short high current pulses without tripping the OCP. 6/22 STK531U3xx series Application Note External Resistance Over Current Protection (ISD) [A] (RSD) [Ω] min typ max 0 18.1 20.5 22.9 200 16.7 18.8 21.1 390 15.9 18.0 20.1 560 15.5 17.4 19.5 1000 14.8 16.6 18.6 2200 14.0 15.8 17.6 4700 13.6 15.3 17.0 10000 13.3 15.0 16.7 Open 13.1 14.7 16.4 Figure 10. STK531U36xA-E RSD values and resulting ISD curve External Resistance Over Current Protection (ISD) [A] (RSD) [Ω] min typ max 0 22.0 24.8 27.8 200 21.0 23.7 26.5 390 20.4 23.0 25.7 560 20.0 22.6 25.2 1000 19.4 21.8 24.3 2200 18.6 20.9 23.3 4700 18.1 20.3 22.6 10000 17.7 20.0 22.2 Open 17.4 19.6 21.8 Figure 11. STK531U39xA-E RSD values and resulting ISD curve HIN/LIN Protection state Set Reset HVG/LVG Normal operation Over current detection Over current IGBT turn off Output Current Ic (A) Over current reference voltage Voltage of Shunt resistor RC circuit time constant Fault output Fault output Figure 12. Over current protection Timing chart 7/22 STK531U3xx series Application Note 4.2. Under Voltage Lockout Protection The UVLO protection is designed to prevent unexpected operating behavior as described in Table 3. Both High-side and Low-side have UV protecting function. However the fault signal output only corresponds to the Low-side UVLO Protection. During the UVLO state the fault output is continuously driven (low). VDD Voltage (typ. Value) Operation behavior < 12.5V As the voltage is lower than the UVLO threshold the control circuit is not fully turned on. A perfect functionality cannot be guaranteed. 12.5 V – 13.5 V IGBTs can work, however conduction and switching losses increase due to low voltage gate signal. 13.5 V – 16.5 V Recommended conditions 16.5 V – 20.0 V IGBTs can work. Switching speed is faster and saturation current higher, increasing short-circuit broken risk. > 20.0 V Control circuit is destroyed. Absolute max. rating is 20 V. Table 3. Module operation according to control supply voltage The sequence of events in case of a low side UVLO event (IGBTs turned off and active fault output) is shown in Figure 13. Figure 14 shows the same for a high side UVLO (IGBTs turned off and no fault output). LIN Protection state Reset Set Reset Control supply voltage VD Under voltage reset Under voltage trip Normal operation Output Current Ic (A) After the voltage level reaches UV reset, the circuits start to operate when next input is applied . IGBT turn off Fault output Fault output Figure 13. Low side UVLO timing chart 8/22 STK531U3xx series Application Note Figure 14. High side UVLO timing chart 4.3. Cross conduction prevention The STK531U3xx series module implement a cross conduction prevention logic at the pre-driver to avoid simultaneous drive of the low- and high-side IGBTs as shown in Figure 15. Figure 15. Cross Input Conduction Prevention In case of both high and low side drive inputs are active (high) the logic prevents both gates from being driven – a corresponding timing diagram can be found in Figure 16 below. 9/22 STK531U3xx series Application Note HIN LIN Shoot-Through Prevention HVG Normal operation Normal operation LVG VDD Fault output Keeping high level output ( No Fault output ) Figure 16. cross conduction prevention timing diagram Even so cross conduction on the IGBTs due to incorrect external driving signals is prevented by the circuitry the driving signals (HIN and LIN) need to include a “dead time”. This period where both inputs are inactive between either one becoming active is required due to the internal delays within the IGBTs. Figure 17 shows the delay from the HIN-input via the internal HVG to high side IGBT, the similar path for the low side and the resulting minimum dead time which is equal to the potential shoot through period: HIN LIN tON High Side IGBT Low Side IGBT tOFF Shoot-Trough Period Dead time = tOFF-tON Figure 17. Shoot Trough Period 10/22 STK531U3xx series Application Note 5. PCB design and mounting guidelines This chapter provides guidelines for an optimized design and PCB layout as well as module mounting recommendations to appropriately handle and assemble the IPM. 5.1. Application (schematic) design The following figures 18 gives an overview of the external circuitry’s functionality when designing with the STK531U3xx series module. Figure 18. STK531U3xx series application circuit Figure 19. PCB design reference 11/22 STK531U3xx series Application Note 5.2. Pin by pin design and usage notes This section provides pin by pin PCB layout recommendations and usage notes. For a complete list of module pins refer to the datasheet or Chapter 6. P, N These pins are connected with the main DC power supply. The applied voltage is up to the Vcc level. Overvoltage on these pins could be generated by voltage spikes during switching at the floating inductance of the wiring. To avoid this behavior the wire traces need to be as short as possible to reduce the floating inductance. In addition a snubber capacitor needs to be placed as close as possible to these pins to stabilize the voltage and absorb voltage surges. U, V, W These terminals are the output pins for connecting the 3-phase motor. They share the same GND potential with each of the high side control power supplies. Therefore they are also used to connect the GND of the of the bootstrap capacitors. These bootstrap capacitors should be placed as close to the module as possible. VDD, VSS These pins connect with the circuitry of the internal protection and pre-drivers for the low -side power elements and also with the control power supply of the logic circuitry. Voltage to input these terminals is monitored by the under voltage protection circuit. The VSS terminal is the reference voltage for the control inputs signals as well as Fault and ISO. VSS is connected with the “N“ terminal internally. The main circuit does typically not draw current from VSS. When the “N“ and “VSS” pins are connected externally care must be taken to select a single connection point as close as possible to the IC. In case of multiple connections to these pins and longer traces being used, the overcurrent protection level may become low. Therefor this should be avoided. VB1, VB2, VB3 The VBx pins are internally connected to the positive supply of the high-side drivers. The supply needs to be floating and electrically isolated. The boot-strap circuit shown in Figure 20 forms this power supply individually for every phase. Due to integrated boot resistor and diode (RB & DB) only an external boot capacitor (CB) is required. CB is charged when the following two conditions are met. ① Low-side signal is input ② Motor terminal voltage is low level The capacitor is discharged while the high-side driver is activated. Thus CB needs to be selected taking the maximum on time of the high side and the switching frequency into account. 12/22 STK531U3xx series Application Note CB DB Driver RB VDD Driver Figure 20. Boot Strap Circuit The voltages on the high side drivers are individually monitored by the under voltage protection circuit. In case an UVP event is detected on a phase its operation is stopped. Typically a CB value of less or equal 47uF (±20%) is used. In case the CB value needs to be higher an external resistor (of apx. 20Ω or less) should be used in series with the capacitor to avoid high currents which can cause malfunction of the IPM. HIN1, LIN1, HIN2, LIN2, HIN3, LIN3 These pins are the control inputs for the power stages. The inputs on HIN1/HIN2/HIN3 control the high-side transistors of U/V/W, and the inputs on LIN1/LIN2/LIN3 control the low-side transistors of U/V/W respectively. The input are active high and the input thresholds VIH and VIL are 5V compatible to allow direct control with a microcontroller system Simultaneous activation of both low and high side is prevented internally to avoid shoot through at the power stage. However, due to IGBT switching delays the control signals must include a dead-time. The equivalent input stage circuit is shown in Figure 21. IN 33k VSS Figure 21. Internal Input Circuit For fail safe operation the control inputs are internally tied to VSS via a 33kΩ (typ) resistor. To avoid switching captured by external wiring to influence the module behavior an additional external low-ohmic pull-down resistor with a value of 2.2kΩ-3.3kΩ should be used. The output might not respond when the width of the input pulse is less than 1µs (both ON and OFF). 13/22 STK531U3xx series Application Note Fault The Fault pin is an active low output (open-drain output). It is used to indicate an internal fault condition of the module. The structure is shown in Figure 22. The sink current of IoSD during an active fault is nominal 2mA @ 0.1V. Depending on the interface supply voltage the external pull-up resistor (RP) needs to be selected to set the low voltage below the VIL trip level. For the commonly used supplies VP: VP = 15V -> RP >= 20kΩ VP = 5V -> RP>= 6.8kΩ VP VDD RP FAULT VSS Figure 22. Fault Connection For a detailed description of the fault operation refer to Chapter 4. Note: The Fault signal does not latch permanently. After the protection event ended and the fault clear time(min. 18ms) passed, the module operation is automatically re-started. Therefore the input needs to be driven low externally activated as soon as a fault is detected. ISO The ISO pin allows monitoring the output voltage of the integrated current sense amplifier. This pin is usually left unconnected. Any external circuitry needs to have an impedeance higher than 5.6kΩ. Note: In case this pin is shorted to VSS – current sensing will not function. Figure 23. The output current (Io) vs ISO characteristics (STK531U36xA-E) TH An internal thermistor to sense the substrate temperature is connected between TH and VSS. By connecting an external pull-up resistor to arbitrary voltage, the module temperature can be monitored. Please refer to heading 3.2 for details of the thermistor. Note: This is the only means to monitor the substrate temperature indirectly. 14/22 STK531U3xx series Application Note RCIN This pin is used to the set the fault clear time. It is recommended to leave this pin open to select the default fault clear time of 18 ms. VDD RF RCIN CF PreDriver IC VSS Figure 24. RCIN Circuit To shorten the fault clear time, connect an external resistor RF between VDD and RCIN. To lengthen the fault clear time, connect an external capacitor CF between RCIN and VSS. 5.3. Heat sink mounting and torque If a heat sink is used, insufficiently secure or inappropriate mounting can lead to a failure of the heat sink to dissipate heat adequately. This can lead to an inability of the device to provide its inherent performance, a serious reduction in reliability, or even destruction, burst and burn of the device due to overheating. The following general points should be observed when mounting IPM on a heat sink: 1. Verify the following points related to the heat sink: - There must be no burrs on aluminum or copper heat sinks. - Screw holes must be countersunk. - There must be no unevenness in the heat sink surface that contacts IPM. - There must be no contamination on the heat sink surface that contacts IPM. 2. Highly thermal conductive silicone grease needs to be applied to the whole back (aluminum substrate side) uniformly, and mount IPM on a heat sink. Upon re-mounting apply silicone grease(100um to 200um) again uniformly. 3. For an intimate contact between the IPM and the heat sink, the mounting screws should be tightened gradually and sequentially while a left/right balance in pressure is maintained. Either a bind head screw or a truss head screw is recommended. Please do not use tapping screw. We recommend using a flat washer in order to prevent slack. The standard heat sink mounting condition of STK531U3xx series is as follows. 15/22 STK531U3xx series Application Note Table 4. heat sink mounting Fig 2 : size of washer t D d Fig 3 : About uniformly application Steps to mount an IPM on a heat sink 1st: Temporarily tighten maintaining a left/right balance. 2nd : Finally tighten maintaining a left/right balance. 16/22 STK531U3xx series Application Note 5.4. Mounting and PCB considerations In designs in which the printed circuit board and the heat sink are mounted to the chassis independently, use a mechanical design which avoids a gap between IPM and the heat sink, or which avoids stress to the lead frame of IPM by an assembly that a moving IPM is forcibly fixed to the heat sink with a screw. IPM Figure 25. Fix to Heat Sink Maintain a separation distance of at least 1.5 mm between the IPM case and the printed circuit board. In particular, avoid mounting techniques in which the IPM substrate or case directly contacts the printed circuit board. Do not mount IPM with a tilted orientation. This can result in stress being applied to the lead frame and IPM substrate could short out tracks on the printed circuit board. Always mount the IPM vertically. If stress is given by compulsory correction of a lead frame after the mounting, a lead frame may drop out. Be careful of this point. IPM When designing the PCB layout take care that the bent part portion of the lead frame pins does not short-circuit to VIA holes or tracks on the PCB. IPM Since the use of sockets to mount IPM can result in poor contact with IPM leads, we strongly recommend making direct connections to PCB. 17/22 STK531U3xx series Application Note IPMs are flame retardant. However, under certain conditions, it may burn, and poisonous gas may be generated or it may explode. Therefore, the mounting structure of the IPM should also be flame retardant. Mounting on a Printed Circuit Board 1. Align the lead frame with the holes in the printed circuit board and do not use excessive force when inserting the pins into the printed circuit board. To avoid bending the lead frames, do not try to force pins into the printed circuit board unreasonably. 2. Do not insert IPM into printed circuit board with an incorrect orientation, i.e. be sure to prevent reverse insertion. IPM may be destroyed, exploded, burned or suffer a reduction in their operating lifetime by this mistake. 3. Do not bend the lead frame. 5.5. Cleaning IPM has a structure that is unable to withstand cleaning. As a basic policy, do not clean independent IPM or printed circuit boards on which an IPM is mounted. 6. Package Outline STK531U3xx series is SIP05 package. (Single-inline-package) Every second pin is bent forward to form two rows on the PCB see Figure 26. 6.1. Package outline and dimension Missing pin: 3,4,7,8,11,12,14,15 note1: No.1 pin identification mark (mirror surface) note2: Model number note3: Lot code * The form of a character in this drawing differs from that of IPM. Figure 26. STK531U3xx series Package Outline 18/22 STK531U3xx series Application Note 6.2. Pin Out Description Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Name VB3 W, VS3 NA NA VB2 V,VS2 NA NA VB1 U,VS1 NA NA P NA NA N HIN1 HIN2 HIN3 LIN1 LIN2 LIN3 Fault ISO VDD VSS ISD RCIN TH Description High Side Floating Supply Voltage 3 Output 3 - High Side Floating Supply Offset Voltage none none High Side Floating Supply voltage 2 Output 2 - High Side Floating Supply Offset Voltage none none High Side Floating Supply voltage 1 Output 1 - High Side Floating Supply Offset Voltage none none Positive Bus Input Voltage none none Negative Bus Input Voltage Logic Input High Side Gate Driver - Phase 1 Logic Input High Side Gate Driver - Phase 2 Logic Input High Side Gate Driver - Phase 3 Logic Input Low Side Gate Driver - Phase 1 Logic Input Low Side Gate Driver - Phase 2 Logic Input Low Side Gate Driver - Phase 3 Fault Signal Output Current Sensing Monitor +15V Control Power Supply Negative Control Power Supply Over Current Protection Setting Fault Clear Time Setting Temperature Monitor 19/22 STK531U3xx series Application Note 7. Demo Board The demo board consists of the minimum required components such as snubber capacitor and bootstrap circuit elements of STK531U3xx series. Figure 27. Evaluation board schematic Length : 96mm Side : 128mm Thickness : 1.6mm Rigid double-sided substrate Material : FR-4 Both sides resist coating Copper foil thickness : 70um Surface Back side Figure 28. Evaluation board PCB layout (TOP view) 20/22 STK531U3xx series Application Note Red frame: Connector For the connection to the control part Vext terminal is connected pull-up resister IPM from TH and fault. Please impress arbitrary voltage to this terminal. W V Blue frame: Test pins For monitoring each control signal U VSS Purple frame: Low pass filter and pull-down Vext resistor for control terminal VDD ISO ISD RCIN TH - Low pass filter is composed of resistor of 100Ω, and capacitor of 100pF. 0Ω 10kΩ 10kΩ FAULT - Pull-down resistor 3.3kΩ is for prevention of malfunction by external wiring. LIN3 LIN2 LIN1 HIN3 HIN2 HIN1 3.3kΩ 100Ω Brown frame - 100pF Vext VSS VDD ISO ISD RCIN TH NC FAULT LIN3 LIN2 LIN1 HIN3 HIN2 HIN1 VSS NC NC NC NC + ISD VSS Pull-down R(0Ω) for ISD TH Evaluation Board Pull-up R(10kΩ) for TH Vext Pull-up R(10kΩ) for Fault Fault Figure 29. Description of each pin Green frame: U,V,W terminal Please connect to the motor. Orange frame: +, - terminal Please connect to DC power supply. IPM W Motor V U VSS VDD ISO ISD RCIN TH FAULT 0Ω 10kΩ 10kΩ LIN3 LIN2 LIN1 HIN3 HIN2 HIN1 100Ω 3.3kΩ Logic Vext 100pF DC 15V Vext VSS VDD ISO ISD RCIN TH NC FAULT LIN3 LIN2 LIN1 HIN3 HIN2 HIN1 VSS NC NC NC NC - + DC power supply Evaluation Board Figure 30. Evaluation board instructions 21/22 STK531U3xx series Application Note Operation procedure Step1: Please connect IPM, each power supply, logic parts, and the motor to the evaluation board, and confirm that each power supply is OFF at this time. Step2: Please impress the power supply of DC15V. Step3: Please perform a voltage setup according to specifications, and impress the power supply between the "+" and the "-" terminal. Step4: By inputting signal to the logic part, IPM control is started. (Therefore, please set electric charge to the boot-strap capacitor of upper side to turn on lower side IGBT before running.) * When turning off the power supply part and the logic part, please carry out in the reverse order to above steps. ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC) or its subsidiariesin the United States and/or other countries. SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf . SCILLC reserves the right to make changes without further notice to any products herein. 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