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Component Sourcing
Buck:
Filter for voltage regulators rated between 30V-40V max input voltage (larger than expected 26V), 4A output current, and 5V output voltage
3V to 36V input voltage range
up to 95% efficiency
4A continuous output current
adjustable switching frequency
adjustable output voltage (0.8V to 30V)
Vout = 0.8 * (1 + R1/R2)
5V output requires standard resistor values of: R1 = 52.3k, R2 = 10k (recommended from datasheet) this yields around 4.984V
alternatively, R1 = 53.6k yields around 5.088V
Even better, 10.5K, 2K gives exactly 5V (strange that this was not recommended by the D.S)
“The combination of R1 and R2 should be large enough to avoid drawing excessive current from the output, which will cause power loss”
given this case: 105k and 20k would also be ideal
standard resistor values source: https://www.rfcafe.com/references/electrical/resistor-values.htm
AOZ1284PI Buck Design:
Exposed Pad (Vin Exposed pad - pin number on symbol??? is this ok in general for a vin pin to be an exposed pad?)
What should I use for switching frequency? From what I’ve seen online, higher switching frequency means I can use smaller inductors and capacitors but increases losses.
Using a 100k resistor for 500kHz of switching frequency
Soft start Pin: “A soft start process begins when the input voltage rises to 3V and voltage on EN pin is HIGH. In soft start process, a 2.5µA internal current source charges the external capacitor at SS. As the SS capacitor is charged, the voltage at SS rises. The SS voltage clamps the reference voltage of the error amplifier, therefore output voltage rising time follows the SS pin voltage. With the slow ramping up output voltage, the inrush current can be prevented. Minimum external soft-start capacitor 850pF is required, and the corresponding soft-start time is about 200µs.”
will be using 10nF cap, was available on the WARG component library (relatively similar value)
Cell Monitor IC
https://www.digikey.ca/en/products/filter/power-management-pmic/battery-management/713
https://www.digikey.ca/en/products/detail/analog-devices-inc/LTC6810IG-2-3ZZPBF/9658988
https://www.digikey.ca/en/products/detail/rochester-electronics-llc/AD7280WBSTZ-RL/12102176
3-6s cell monitoring
no ADC (connect to MCU and use that one)
Current Sense
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