We are using boost output of PMIC to power HDMI and USB mass storage device, By default when we are turning on device we are getting 5V but after 11 sec boost output voltage becomes 3.5 v which is input voltage the PMIC .
I can clearly see at power on i am getting switching output at SWBSTLX it is getting off , when i am getting 3.6 volts.
One more observation is if i keep iMX in reset, during power ON i will get 5V till i release RESET. But if i let the board to boot up and Boot out put to become 3.6, then if if i am resetting without power off output remain fixed at 3.6 V . So i am not sure if this issue is related with some software configuration or something else? As my expectation was if i am resetting processor then PMIC initialization should happen once again and it should again output 5V for some time.
Please let me know how i should debug this issue ?
Boost output on the MMPF0100 can be selected between 5.0V/5.05V/5.10V/5.15V using the Register SWBSTCTL - ADDR 0x66, bits SWBST1VOLT.
Max load current is 500 or 600mA (depending on the input voltage), make sure, your load is not demanding more current than the boost can handle.
Note that the parasitic leakage path for a boost regulator causes the SWBSTOUT and SWBSTFB voltage to be a Schottky drop below the input voltage whenever SWBST is disabled.
Make sure SWBT1MODE and SWBSTBYMODE bits are ‘10’ (Auto (default)).
What is the input voltage for the SWBSTIN pin?
SWBSTIN range should be between 2.8V and 4.5V
If SWBST is disabled and input 3.6 V is applied at SWBSTIN pin, a parasitic leakage path for a boost regulator causes the SWBSTOUT and SWBSTFB voltage to be a Schottky drop below the input voltage whenever SWBST is disabled.
Voltage drop at Schottky diodes of around 1 mA is in the range of 0.15 V to 0.46 V.