Hi!
I designed a circuit utilizing the ADJ version of the AD2503 buck-boost converter using the Buck-Boost Designer Tool. The output VOUT is approx. 5.4V.
Unfortunately when powering up with no load and pulling EN to VIN the output voltage stays at 0V. At VIN = 3.7V the input current is approx. 250 mA which is not what I expected. I tried PWM and PSM mode but this had no effect. Could the output capacitance be too large? (The capacitance value was suggested by the Designer Tool.)
I measured the resistance of several nodes on the board and wondered if this could be the source of the error:
R(Vin to GND) >= 2 Meg Ohm (looks reasonably)
R(Vout to GND) >= 30 kOhm (looks reasonably because of the feedback network)
Are the switch nodes shorted to GND when the part is not powered up?
R(SW1 to GND) = 0.2 Ohms
R(SW2 to GND) = 0.2 Ohms
I don't have a eval board of this device. Thank you for pointing me into the right direction.
Comment values that looks reasonably or suspiciously.
[edited by: myorbit at 7:06 AM (GMT -4) on 22 Jul 2022]