SiDB766761 Vishay Siliconix Temperature Sensing MOSFET Evaluation Board FEATURES Turns Off MOSFET Before TJ Exceeds 175_C Rating 5-V Logic Level Operation of Control Circuit 12-V Battery Level Operation of Power MOSFET Circuit Sense Diode Bias Current, IF = 250 A Built-In Hysterisis to Ensure Jitter Free Operation Cyclic Operation of MOSFET (Turn-On and Turn-Off) Under Continuous Fault Condition D Flexibility to Set MOSFET Turn-Off Temperature D D D D D D ORDERING INFORMATION: SiDB766761 DESCRIPTION The Vishay Siliconix SUB60N04-15LT, temperature sensing MOSFET, provides the capabilities to sense the junction temperature, TJ, and implement self-protection in a control circuit. An electrically isolated poly-silicon diode, which is located in the close proximity to MOSFET junction on the same die, facilitates temperature sensing. The forward voltage drop of sense diode has a negative temperature co-efficient of approximately −2mV/_C. In other words, the forward voltage drop of the sense diode is inversely proportional to the MOSFET junction temperature. This evaluation board demonstrates the self-protection feature in a control circuit, using SUB60N04-15LT, the temperature sensing MOSFET. The cyclic turn-off and turn-on of the MOSFET under the fault condition protects it from catastrophic failure. The appendix includes, a schematic diagram, test setup, bill-of-materials, and PCB layouts. Using this information, one can incorporate the basic control scheme described here, in any core system design of an application. The demonstration board layout is available in Gerber file format. Contact your Vishay Siliconix sales representative/ distributor for a copy. CIRCUIT DESCRIPTION The schematic diagram shown in Appendix (A) is a simple comparator circuit that uses a low cost op-amp, LMV321. This IC is identified as “U1.” The op-amp output Pin 4 provides gate drive approximately 4.8 V through resistor R6 to the temperature sensing MOSFET, Q1. The latter in turn controls the “load” connected between its drain, Pin 3, and +12 V. The voltage divider, resistors R1 and R2, establishes reference voltage VREF = 490 mV. 5-V logic level input at the INPUT terminal provides the bias current, IF = 250 A, for the sense diode on Pins 2 and 4 of Q1. The op-amp is configured for non-inverting mode by connecting the sense diode forward voltage drop to Pin 1, the “+” input through resistors R7. The feedback resistor R4 establishes 20-mV hysteresis on R7 to ensure jitter free operation. Resistor R5 facilitates monitoring of gate drive signal. Resistor RG when connected to the MOSFET gate via jumper J2, cuts down the MOSFET gate drive to 2.8 V and shifts the MOSFET operation to linear mode. The peripheral capacitors C1 through C5 are for power supply filter and noise suppression. S D2PAK-5L T1 G 1 2 3 4 5 G D T1 Document Number: 72800 18-Mar-04 S D1 D2 T2 D T2 P-Channel MOSFET www.vishay.com 1 SiDB766761 Vishay Siliconix TEST SETUP (a) Laboratory Equipment D Connect the jumper J1. This provides 5-V logic level signal on the INPUT terminal. Observe V(G) = 4.8 V (approximately) The MOSFET turns on. The current flows through the load (lighted lamp, if a lamp load is used). (b) Fault Condition This configuration facilitates testing with two laboratory power supplies. Refer to Appendix (B). A 5-V/2-A regulated power supply between +5 and GND powers up the control circuit. A separate 12-V/20-A power supply between +12 V and GND powers the load and MOSFET drain Pin 3 and source Pin 5. Remove the jumper 3. Thereby, the 5-V logic level power supply, VLL, for the control circuit is independent of over load or shorted load on MOSFET side. Diodes D1 and D2 prevent reverse current flow in case of accidental connection of both power supplies when the jumper J3 is not removed. Connect a suitable load that would draw about 1 A, e.g. a lamp (12 V, 1 A) or a resistor (12 , 25 W) between terminal +12 V and load. (b) Field Simulated Testing Using a 12-V battery can simulate field level testing. This power source on the load side is capable of supplying continuous over load/short circuit current. In other words, the battery will have the capacity to maintain the terminal voltage of the 12-V even under short circuit conditions. Connect the battery between +12 V and GND. In this case, a separate 5-V logic level power supply is not required. The jumper J3 must be in place. The latter provides the 5-V logic level, VLL, to the control circuit via on-board voltage regulator LM2937. The IC is identified as Q2. D Connect the jumper J4, Which is an external shorting link (not supplied), to short-circuit the load. Monitor V(G) = 4.8 V, the MOSFET is still in “on” state. Observe excessive current flow from the 12-V supply. The MOSFET starts heating up. After sometime, the MOSFET turns off, monitor V(G) = 0 (< 0.2 V). The load current drops to zero. The MOSFET starts cooling down. The MOSFET turns on again when cooling is complete. Observe V(G) = 4.8 V and the load current flow from the power supply. D The cycle repeats as long as jumper J4 is connected across the +12 V and load terminals and the setup is powered. D Removing jumper J4 restores normal operation. The MOSFET maintains an “on” state with jumper J1 in place, with 5 V at the INPUT terminal. ACCELERATED TESTING Jumper J2 facilitates accelerated testing. Now the actual gate voltage drops to 2.8 V because of voltage divider formed at the MOSFET gate Pin 1, by resistors R6 and RG. Refer to the schematic diagram in Appendix (A). This drives the MOSFET in linear mode, resulting in accelerated heating of the MOSFET and faster turn off. The cycle time of fault condition is reduced. SUMMARY OPERATION Either step (a) or step (B) of the Test Setup enables the testing and demonstration of the self-protection feature as follows: (a) Normal Operation D D D D Remove jumpers J1 and J2. Power-up the circuit Connect the Oscilloscope or DMM to monitoring Pin G. Observe V(G) = 0 (or <0.2 V), MOSFET in “off” state. No current flow in the load. www.vishay.com 2 The evaluation board shows implementation of a self-protecting feature in a control circuit for a high-side connected floating load, using the temperature sensing MOSFET, SUB60N04-15LT The circuit operation, under normal and fault conditions, demonstrates that the MOSFET can provide the desired load control function and also sustain continuous fault condition while exhibiting a self-protection feature. The basic control circuit can be easily incorporated into the core design of an application using the information provided in the Appendix. For additional information on temperature sensing MOSFETs and actual design example refer to application note AN820 available via the Vishay web site, www.vishay.com. Document Number: 72800 18-Mar-04 SiDB766761 Vishay Siliconix APPENDIX A: SCHEMATIC DIAGRAM J3 Q2 LM2937IMP-5.0 3 C2 1000 F 25 V C3 0.1 F 25 V C5 0.1 F 1 JUMPER Terminal GND − U1 1 + R7 10 k 1% R3, 18 k 5 3 C1 560 pF Signal Ground 2 2 D2 1N5819M C4 0.1 F 25 V 4 2 LMV321M5 1 Screw LOAD Terminal Q1 2 1 LIMIT R2 22 k 1% J4 Gate 2 J2 1 3 R6, 560 R4, 560 k, 1% Screw +12 V Terminal 2 R5, 18 k 490 mV 2 Terminal INPUT 1 1 C6 10 F R1 200 k 1% J1 VIN GND SUB60N04-15LT D1 1N5819M VOUT 3 Terminals VLL Terminal +5 V RG 820 4 5 Power Ground GND Screw Terminal APPENDIX B: TEST SETUP Jumper J3 To Power The EVB From 12-V Power Supply or Battery (In The Absence of 5-V Power Supply) Jumper J4 Load Shorting Link V(LL) 5 V Regulated Power Supply Lamp Load + − − Jumper J1 To Continuously Input 5-V Signal Document Number: 72800 18-Mar-04 12-V Automotive Battery or Power Supply Jumper J2 To Operate MOSFET at 2.8 V Connect to Oscilloscope to Monitor MOSFET Status www.vishay.com 3 SiDB766761 Vishay Siliconix 1399 (mil) APPENDIX C: LAYOUT 2000 (mil) FIGURE 3. Silk Screen FIGURE 4. Top Layer FIGURE 5. Bottom Layer www.vishay.com 4 Document Number: 72800 18-Mar-04 SiDB766761 Vishay Siliconix EVALUATION BOARD DISCLAIMER Vishay Siliconix (Vishay) provides this evaluation board (EVB) under the following conditions: The EVB is intended for DEMONSTRATION OR ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered to be fit for commercial use. Vishay assumes no liability for application assistance, customer product design, infringement of patents, or software performance. Please read the EVB datasheet carefully; it contains important information for its use. The user assumes all responsibility and liability for safe and proper handling of the EVB and to take any and all appropriate precautions concerning electrostatic discharge. Further, the user indemnifies Vishay from all claims arising from handling or use. The EVB is not regulatory-compliant or agency-certified. Any user handling the product must have electronics training and observe good laboratory practice standards. THE EVB IS PROVIDED AS IS, WHERE IS, WITH NO WARRANTIES WHATSOEVER, EITHER EXPRESSED, IMPLIED, OR STATUTORY, AND SPECIFICALLY EXCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The EVB is not provided exclusively to the user and Vishay may supply the EVB to other users. No license is granted under any patent right or any other intellectual property right of Vishay. APPENDIX D: BILL-OF-MATERIAL Item Qty Designator Description Footprint Part Number Manufacturer 1 1 R1 200-k Resistor, 1% 805 CRCW0805, 200 k, 1% Vishay Dale 2 1 R2 22-k Resistor, 1% 805 CRCW0805, 22 k, 1% Vishay Dale 3 2 R3, R5 18-k Resistor, 5% 805 CRCW0805, 18 k, 5% Vishay Dale 4 1 R4 560-k Resistor, 1% 805 CRCW0805, 560 k, 1% Vishay Dale 5 1 R6 560- Resistor, 5% 805 CRCW0805, 560 , 5% Vishay Dale 6 1 R7 10-k Resistor, 1% 805 CRCW0805,10 k, 1% Vishay Dale 7 1 RG 820- Resistor, 5% 805 CRCW0805, 820 , 5% Vishay Dale 8 1 C1 560-pF/25-V Ceramic Capacitor 805 VJ0805Y561JXAA Vishay Vitramon 9 1 C2 1000-F/25-V, Electrolytic Capacitor RB-0.2/0.4 10 3 C3, C4, C5 0.1-F/25-V, Ceramic Capacitor 805 VJ0805Y104JXAA Vishay Vitramon 11 1 C6 10-F/25-V, Ceramic Capacitor 2512 VJ2225V106MXAA Vishay Vitramon 12 2 D1, D2 1N5819M, Schottky Diode, 40 V, 1 A, SOD87 MELF 13 1 Q1 SUB60N04-15LT, Temperture Sense MOSFET, 40 V D2PAK-5L SUB60N04-15LT Vishay Siliconix 14 1 Q2 LM2937IMP-5.0, IC, 5 V, 500 mA, LDO VREG SOT-223 15 1 U1 LMV321M5, IC, Low Voltage Op Amp SC70-5 16 3 J1, J2, J3 Jumper Pins SIP-2 929834-02-36-ND Digi-Key 17 3 JMP Shunt Jumper Shunts A26228-ND Digi-Key 18 2 +5 V, GND In Board Pins TURRET V1055-ND Digi-Key 19 2 IN, G Press-In Terminal TURRET V1073-ND Digi-Key 20 3 +12 V. Load, GND Terminal, 12-V, GND LOADCON 7693-ND Digi-Key 21 1 PCB Evaluation PC Board TSM1 Vishay Siliconix Document Number: 72800 18-Mar-04 www.vishay.com 5