Tool/software:
Hello -
I am working on a design for the DRV8428E to drive two single coil latching relays (one coil between AOUT1 /2 the other between BOUT1/2).
VM (supply) = 24V. Relay coil is 60-70 ohm each. 99% of the time the relay is not being energized, and we will hold EN low for both outputs via MCU. We don't plan to use the sleep function.
Logic voltage is 1.8V.
I have a few questions:
1) Please confirm there is nowhere we need to tie 1.8V logic onto the DRV8428E? I see we need 0.1uF between DVDD & GND for the internal 5V regulator.
2) Please confirm we can tie nSleep to 1.8V if we don't want to sleep the DRV.
3) The relays will be pulsed for 50-100mS each, by setting IN high or low depending on whether Set or Reset function is required, and then bringing EN high. After 50-100mS, EN will be brought low again. I do not believe we need any decay for this application, so should we tie the TOFF/DECAY pin to GND?
4) Regarding the VM caps: I see the datasheet calls out 0.01uF X7R ceramic, can a 0.1uF X7R be used for decoupling or is the smaller 0.01uF value recommended (we use 0.1uF's everywhere else on the schematic, so it's just to avoid adding another unique part to the BOM). For the bulk capacitor, can you recommend a size? I was thinking around 47uF 35V electrolytic. (note: only one relay will ever be energized at a time, never simultaneously). Does this value seem high enough or should we go closer to 100uF?
Thank you.
