BQ25790: BQ25792 custom circuit design does not charge

Nishant Sood

Part Number: BQ25790
Other Parts Discussed in Thread: BQ25792

Tool/software:

Below is my custom schematics for BQ25792 for a single cell LIPO configured with a external resistor for charging single cell LIPO, I have been configuring the IC on boot with writing to 0x2E address, value: 0xB8 and writing to 0x14 address, value: 0x36 to activate ADC readings for battery voltage etc.
The problem is that I'm not able to charge the lipo, please help in putting the IC to charge the single cell LIPO.

over 1 year ago

0 Jeff F over 1 year ago

TI__Guru**** 170516 points

Hi Nishant,

Per the table below, PMID needs at least 4uF of ceramic capacitance after derating for applied voltage and temperature.

BATP is the sense line for BAT pin, which connects to battery B+, not SYS. With no shipFET, BATP connects to BAT=B+ through 100ohm resistor.

Regards,

Jeff

0 Nishant Sood over 1 year ago in reply to Jeff F

Intellectual 260 points

Yes, About B+ I corrected the schematics I do have it connected to B+ not Sys.Not sure about the PMID input capacitor, 4uF ..

0 Nishant Sood over 1 year ago in reply to Jeff F

Intellectual 260 points

@Jeff F About the PMID, can having just decoupling capacitance in terms of 100nF when Im not even using that output going to cause NOT charging on the IC?!

0 Jeff F over 1 year ago in reply to Nishant Sood

TI__Guru**** 170516 points

Hi Nishant,

Yes. PMID is the input to the converter. Capacitance on that pin is required. The IC may even be damaged without it.

Regards,

Jeff

0 Nishant Sood over 1 year ago in reply to Jeff F

Intellectual 260 points

Everything else looks fine!?

0 Jeff F over 1 year ago in reply to Nishant Sood

TI__Guru**** 170516 points

HI Nishant,

STAT and INT are open drain so need a pull up. Other than that, I don't see any issues. Please follow the datasheet recommended PCB layout.

Regards,

Jeff

0 Nishant Sood over 1 year ago in reply to Jeff F

Intellectual 260 points

HI Jeff,

Thanks again. I'm operating with a very small custom board so won't be able to add STAT & INT pullups. Only need the SYS regulation(which already works) and charging with PLUGIN registers working for now, with those functionalities in mind, is the schematics ok!?

0 Jeff F over 1 year ago in reply to Nishant Sood

TI__Guru**** 170516 points

Hi Nishant,

Other than PMID cap, I see no other obvious errors.

Regards,

Jeff

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BQ25790: BQ25792 custom circuit design does not charge