STK541UC62K-E Application Note www.onsemi.com 1. Product synopsis This application handbook is intended to provide practical guidelines for the STK541UC62K-E use. The STK541UC62K-E 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 1/18 Rev.1 STK541UC62K-E Application Note 2. Product description Table1. gives an overview, 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 STK541UC62K-E single shunt SIP1 – Vertical pins 600V 10A 20A 2000V 33mΩ Table 1. Device Overview VB1(7) U(8) VB2(4) V(5) VB3(1) W(2) P(10) U.V. U.V. U.V. Shunt Resistor N(12) Thermistor VTH (13) Level Level Level Shifter Shifter Shifter HIN1(15) HIN2(16) HIN3(17) LIN1(18) Logic Logic Logic LIN2(19) LIN3(20) FLTEN(21) ISO(22) VDD(14) VSS(23) Latch Latch Time About 9ms ( Automatic Reset ) Over-Current VDD-Under Voltage Figure 2. STK541UC62K-E 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. 2/18 STK541UC62K-E 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 Figure 3. Switching time definition Ex) Lower side U phase measurement VB1 P VD1=15V U VB2 VD2=15V V U Vcc VB3 CS VD3=15V W VDD Io VD4=15V Input signal N LIN1 VSS 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 3/18 STK541UC62K-E 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 4/18 STK541UC62K-E Application Note 3.2. Thermistor Characteristics The thermistor is built-in between VTH and VSS. This is used to sense internal module temperature. Its characteristic is outlined below. Parameter Resistance Resistance B-Constant(25-50°C) Symbol R25 Condition Tc=25°C R100 Tc=100°C B Temperature Range Min 97 Typ. 100 Max 103 Unit kΩ 5.07 5.38 5.71 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±3% 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 5/18 STK541UC62K-E 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). 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. 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. Figure 9. Over current protection Timing chart 6/18 STK541UC62K-E Application Note 4.2. Under Voltage Lockout Protection The UVLO protection is designed to prevent unexpected operating behavior as described in Table 2. 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 2. 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 10. Figure 11 shows the same for a high side UVLO (IGBTs turned off and no fault output). Figure 10. Low side UVLO timing chart 7/18 STK541UC62K-E Application Note Figure 11. High side UVLO timing chart 4.3. Cross conduction prevention The STK541UC62K-E 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 12. Figure 12. Cross Input Conduction Prevention In case of both high and low side drive inputs are active (Low) the logic prevents both gates from being driven – a corresponding timing diagram can be found in Figure 13 below. 8/18 STK541UC62K-E Application Note Figure 13. 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 14 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: Figure 14. Shoot Trough Period 9/18 STK541UC62K-E 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 figure 15 gives an overview of the external circuitry’s functionality when designing with the STK541UC62K-E module. Figure 15. STK541UC62K-E application circuit Figure 16. PCB design reference 10/18 STK541UC62K-E 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 17 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. 11/18 STK541UC62K-E Application Note CB DB Driver RB VDD Driver Figure 17. 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 Low 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 18. VDD 100kΩ IN VSS Figure 18. Internal Input Circuit For fail safe operation the control inputs are internally tied to VDD via a 100kΩ (typ) resistor. The output might not respond when the width of the input pulse is less than 1µs (both ON and OFF). 12/18 STK541UC62K-E Application Note FLTEN The FLTEN pin is an active low input and open-drain output. It is used to indicate an internal fault condition of the module and also can be used to disable the module operation. The I/O structure is shown in Figure 19. 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 FLTEN VSS Figure 19. FLTEN Connection For a detailed description of the fault operation refer to Chapter 4. Note: The Fault signal does not latch permanently. The modules operation is automatically re-started after the causing protection event end and after the minimum of the fault timeout(6ms). Therefore the input needs to be driven low externally activated as soon as a fault is detected. 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. 0.8 ISO output voltage (V) ISO 0.6 0.4 0.2 0 0 5 10 15 20 Output current Io (A) Figure 20. The output current (Io) vs ISO characteristics 13/18 STK541UC62K-E Application Note VTH An internal thermistor to sense the substrate temperature is connected between VTH and VSS. By connecting an external pull-up resistor to this pin, 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. 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 an STK541UC62K-E is as follows. Table 3. heat sink mounting 14/18 STK541UC62K-E Application Note 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. 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 21. 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. 15/18 STK541UC62K-E Application Note 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. 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. 16/18 STK541UC62K-E Application Note 6. Package Outline The package of STK541UC62K-E is SIP1 (Single-inline-package) shown in Figure 22. 6.1. Package outline and dimension missing pin: 3,6,9,11 note1: No.1 pin identification mark note2: Model number note3: Lot code * The form of a character in this drawing differs from that of IPM. Figure 22. STK541UC62K-E Package Outline 17/18 STK541UC62K-E 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 Name VB3 W NA VB2 V NA VB1 U NA P NA N VTH VDD HIN1 HIN2 HIN3 LIN1 LIN2 LIN3 FLTEN ISO VSS Description High Side Floating Supply Voltage 3 Output 3 - High Side Floating Supply Offset Voltage none High Side Floating Supply voltage 2 Output 2 - High Side Floating Supply Offset Voltage none High Side Floating Supply voltage 1 Output 1 - High Side Floating Supply Offset Voltage none Positive Bus Input Voltage none Negative Bus Input Voltage Temperature Monitor +15V Control Power Supply 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 Enable input / Fault output Current Sensing Monitor Negative Control Power Supply 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. 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