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| WEBENCH® Tools/TPS92515HV-Q1: Designing a driver with EMI filtering for driving high current leds | |
| Part Number: TPS92515HV-Q1 Tool/software: WEBENCH® Design Tools Unfortunately, the Webench tool is not available for this part. I'm looking to use this part in a circuit with CISPR 25 Class 5 Noise filtering for driving 9 high power LEDs @ 2A the LED's Vf range: Forward Voltage VF min 2.3 | 3.0 | 3.0 | 3.0 V V VF max 3.6 | 3.9 | 3.9 | 3.9 V V total 31.5|34.2|34.2|34.2 V They're multi-die LEDs and I know I'll have to have 4 individual drivers and 2 designs they are tested with a 20ms pulse. I want to use an AVR (ATmega328P) to control the driver and blink the LEDs in different fashions I'm still a student and trying to make my mark in the industry with an amazing product. Thanks in advance! | |
| Hello, CISPR 25 level 5 is difficult to reach. Look at PMP15004. This design meets CISPR 25 level 3. I placed an enclosure around it, bypassed the input and output and reached CISPR 25 Class 5 with our internal testing. Your input voltage must be higher since the output voltage is much higher. If your design is run at 100% duty cycle it will be a difficult task. Also, what duty cycle are you pulsing at? What is your input voltage range? The more information the better we can help. Best Regards, | |
| The Voltage range is an Automotive 12Vdc so a range from Vmin ~11V up to Vmax~14Vdc I'm open to other IC suggestions I need min CISPR class 3 filtering but the higher the better. Each led needs 2A. so the theoretical options are: A) Drive them in series and have 2A @ 31.5v (R) / 34.2v (W,B,G) B) Drive them in parallel and have 18A @ 3.5v (R)/ 3.8 V (W,B,G) C) Drive them series parallel 3x3 and have 6A @ 10.2v (R)/11.4v (W,B,G) I'm learning more every day! recently turned my life around and am committed to this project! your time will never be wasted! Thanks again! | |
| Hello Tim, I would look at the TPS92691 or TPS92692 used as a boost converter for 31.5V or 34.2V at 2A. Probably the best route as long as the input voltage cannot go higher than the output. The LM3409 can be used at 6A as a buck converter though I don't see this as being a viable solution since the output can be higher voltage than the input. Also there are tolerances and temperature to take into account, the LED isn't a fixed voltage drop, it will go up at colder temperatures. The TPS92640/641 can be used at 18A as a buck converter, this design will be a bit more difficult since the currents are high. If it is automotive the TPS92640/641 is not automotive grade. Best Regards, | |
| I'm going to give the TPS92692 a shot! do you have any ready-made filtered circuits that I can use for now until I put together my own detailed one? Do I need/ would it be helpful to have a voltage regulator on in Vin to bring the 11v-14v to a stable 12vdc? | |
| Hello Tim, If you read through the datasheet you will see this part was intended to run from a car battery including cold crank. Pre-regulating at that level will not buy you anything except added complexity. The TPS92692 EVM has filtering to meet Class 3 CISPR 25, this is without an enclosure. Most likely you will need an enclosure to pass Class 5, especially at you power level. If you look at some of the TIDAs they have filters that can meet CISPR 25 Class 5 levels. Check TPS92682 for this. This part has SPI interface so it requires communication however, the power designs are boost, boost to battery which should yield similar EMI results. Note as the power level goes up the filtering for the fundamental frequency will also have to go up. Best Regards, | |