BQ25713B: BQ25713 OTG Not Starting up at low battery capacity

Andrew Boss32

Part Number: BQ25713B
Other Parts Discussed in Thread: BQ25713

I am using a BQ25713 in a 1S cell design that is quite similar to the TI evaluation board (schematic screenshot below). OTG starts up fine (to 5.3 V) when the battery capacity is > 40%, but will momentarily start and immediately shut down when the battery capacity gets to be below 40%, even with no load connected. SYS is stable before/during/after enabling OTG. Any suggestions?

over 5 years ago

0 Kedar Manishankar over 5 years ago

TI__Mastermind 24075 points

Hi Andrew,

This is from the datasheet regarding VBAT for OTG

0 Andrew Boss32 over 5 years ago in reply to Kedar Manishankar

Prodigy 130 points

Can you provide a page number? The link did not show up properly.

0 Kedar Manishankar over 5 years ago in reply to Andrew Boss32

TI__Mastermind 24075 points

Hi Andrew,

Sorry about that. Page 13 of the datasheet under BATTERY UNDER VOLTAGE LOCKOUT COMPARATOR. It is the VBAT_OTGEN and VBAT_OTGENZ parameters

0 Andrew Boss32 over 5 years ago in reply to Kedar Manishankar

Prodigy 130 points

Thanks Kedar. I went ahead and read out the contents of the ADCVSYSVBAT register and am receiving 0x8080. With a 64 mV LSB, this corresponds to 8192 mV for SYS and VBAT. However, when I measure the voltage at the SRN and SRP pins with a DMM with respect to ground, I am measuring 3.41 V (a single cell config.). I verified that the ADCOPTION register is loaded with 0x40 at address 0x3B and loaded with 0x03 at address 0x3A. Not sure why there is a measurement error.

0 Andrew Boss32 over 5 years ago in reply to Andrew Boss32

Prodigy 130 points

Kedar,

Please disregard. I now realize these registers have a 2.88 V offset. Thus a reading of 0x80 would correspond to 3.39 V and would fall within the VBAT_OT GEN VBAT OTG enable rising threshold for VSRN rising.

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BQ25713B: BQ25713 OTG Not Starting up at low battery capacity