Im trying to use two 16 channel LED drivers to drive 32 mosfets, im not understanding the datasheet about current sinking, maximum voltages etc.

Are they meant to drive the LEDs by themselves?

Basically im trying to multiply number of PWM pins on my MCU, and want to use 32 mosfets 5A current each to drive bigger lamps.

I know there are basic shift registers, but I cant use PWM with them?? Are there other ICs to achieve this?


closed as unclear what you're asking by Elliot Alderson, pipe, Bimpelrekkie, Finbarr, winny Dec 21 '18 at 9:25

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    \$\begingroup\$ What LED drivers? What MOSFETs? What circuit?? You can't multiply number of PWM pins on my MCU it is unclear what you mean. \$\endgroup\$ – Bimpelrekkie Dec 20 '18 at 14:19
  • \$\begingroup\$ For those kinds of currents, you need a current controlled driver per LED to keep the LED from heating up and then drawing more current and going into thermal runaway and burning up. \$\endgroup\$ – CrossRoads Dec 20 '18 at 14:22
  • \$\begingroup\$ Well at least you have the datasheet available. My crystal ball tells me, that the LED driver is meant to drive LEDs and not MOSFETs, but the weather is not nice today and it told me different yesterday. \$\endgroup\$ – Arsenal Dec 20 '18 at 14:23
  • \$\begingroup\$ 1. Any, any, any... With shift registers chained and connected to SPI I can get lots of IO's but as far as I know I cant use those outputs to generate PWM signals. 2. all the current is running through mosfet so I don't know what you mean? 3. isn't it the same if I drive 20mA led or a signal to a mosfet?? \$\endgroup\$ – Seeker Dec 20 '18 at 16:01
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    \$\begingroup\$ Please reread Bimpeirekkie's comment. Then act on it. To repeat the salient portions: "What LED drivers? What MOSFETs? What circuit??" Stop jerking us around - provide links to the parts you're talking about, and use the schematic editor to provide a sample schematic. \$\endgroup\$ – WhatRoughBeast Dec 20 '18 at 17:36

Here are examples of 500mA constant current LED drivers. Looks like most need a PWM input to control dimming. https://www.digikey.com/products/en/integrated-circuits-ics/pmic-led-drivers/745?FV=7b80001%2C1f140000%2Cffe002e9&quantity=0&ColumnSort=1000011&page=1&stock=1&k=led+driver&pageSize=25&pkeyword=led+driver If you paired these with SX1509 to create the PWM signals, that might do what you want https://www.digikey.com/product-detail/en/semtech-corporation/SX1509BIULTRT/SX1509BIULCT-ND/2295548

  • \$\begingroup\$ Are you suggesting he use ten 500 mA drivers in parallel to drive one 5 Amp LED? That's 320 drivers. Try LM3409. \$\endgroup\$ – Misunderstood Dec 20 '18 at 21:26
  • \$\begingroup\$ No, somehow I had 500mA on the brain vs 5A. Good catch. \$\endgroup\$ – CrossRoads Dec 21 '18 at 13:10

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