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Simplify Charge Pump and Depletion Mode FET (U4)
Original parts
Charge pump switch regulator
Depletion mode FET
New Change
Find closed switch to replace the two components
Part requirement
Normally closed relay
Form B (Form C can work)
https://forum.digikey.com/t/understanding-form-a-form-b-form-c-contact-configuration/811
Support
151.5V + safety factor (x1.5)
0.5A
Ratings at 60C
Controllable
Can close on-demand or
Closes when car close
Implementation
Existing parts
Remove
Charge pump and corresponding capacitors
Pull-down resistor
Keep
LED and resistor
Current limiting resistor
Relay
For lower current parts
Add a series resistor to discharge path for lower current
Drawback
Slower to discharge (0.25s)
For lower voltage parts
Use relay in parallel
Less preferrable
Drawback
Expensive
May not share load equally (reduce one relay lifespan quicker)
Part Search
Types of relay
Solid-state relay
https://www.digikey.ca/en/products/detail/
ixysintegratedcircuits-divisionPM1206654953- 600V
400V and 0.5A
AC(0.3A at 60C)
Datasheet below
- AC
https://www.digikeymouser.ca/en/products/detail/ixys-integrated-circuits-division/CPC1963G/2417218
600V and 0.5A
ProductDetail/Panasonic-Industrial-Devices/AQZ404?qs=Wn4D5qJAqBJmKpb9gy8Awg%3D%3D (mouser link)
- 600V
Need lower current part implementation
https://www.digikey.ca/en/products/detail/
panasonicelectricworksAQZ204/646377 Preferring this one?400V and 0.5A
Datasheet below
https://www.mouser.ca/ProductDetail/Panasonic-Industrial-Devices/AQZ204?qs=Wn4D5qJAqBLvGIN%2FDTrEgw%3D%3D (mouser link)60V and 3.25A (2.5A at 60C)
Need lower voltage parts
Current amount a little overkill
Smaller changes
Removing:
Fan control
Remove fan connector
Remove entire fan control sheet
Thermistor
Remove thermistor connector
Remove entire thermistor sheet
Add jumpers near AND gate to skip it
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