Boost output of PMIC PF0100

[aabhishekoct18]

Hi Team 

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. 

[aabhishekoct18]

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 ?

[reyes]

Hi,

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

Regards,

Jose
NXP Semiconductors

[aabhishekoct18]

Hi Jose

Input voltage of SWBSTIN pin is 3.6 V.

How device will behave if SWBST is disabled and input 3.6 V is applied

at SWBSTIN pin ?

[reyes]

Hi,

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.

Regards,

Jose