BQ24172: there is no charging current when connected the battery(no load)

Sherry Liang

Part Number: BQ24172

I’m writing you to ask a question about BQ24172, the question is that there is no charging current when connected the battery.

The figure 1 is pin-STATE’s waveform, The figure 2 is pin-SW’s waveform, figure 3:pin-ACDRV, figure 4: pin-REGN

The figure 5 is customer’s schematic.(there is a thermistor in the pin-TS, and he replaced it with a 10k resistor. But he didn’t mark it in the schematic.)

In addition, he connected pin-TTC to pin-VREF.

Could you please help check it and give a solution about it？

Thank you very much!

There are some new developments. When connected TTC to GND, there is a charging current. But I don't know the reason,

could you please help explain it?

Thanks & Best Regards,

Sherry

over 7 years ago

0 Ning T over 7 years ago

TI__Guru 57651 points

The schematic provided does not follow design guidelines. Please make corrections per the Typical Application Schematics on the datasheet and test again. Thanks!

Scanned from a Followme printer.pdf

Please click "This Resolved my issue" button if this post answer your question.

0 Sherry Liang over 7 years ago in reply to Ning T

TI__Genius 10255 points

There are some new developments. When connected TTC to GND, there is a charging current. But I don't know the reason,

could you please help explain it?

Thanks & Best Regards,

Sherry

0 Ning T over 7 years ago in reply to Sherry Liang

TI__Guru 57651 points

Pulling the TTC pin to AGND disables both termination and fast charge safety timer. Since termination is disabled, the charger is in charging mode and tries to regulate VBAT voltage all the time unless other conditions described in 9.3.9 Enable and Disable Charging on page 17 of the d/s are met. Thanks!
Please click "This Resolved my issue" button if this post answer your question.

0 Sherry Liang over 7 years ago in reply to Ning T

TI__Genius 10255 points

Yes, but why no charging current when pulling the TTC to VREF?

0 Ning T over 7 years ago in reply to Sherry Liang

TI__Guru 57651 points

What do you mean “When connected TTC to GND, there is a charging current.”? Was the device charging normally? TTC does not impact on normal charging operation. If TTC=GND may charge normally, then TTC=VREF should also charge normally. Thanks!
Please click "This Resolved my issue" button if this post answer your question.

0 Sherry Liang over 7 years ago in reply to Ning T

TI__Genius 10255 points

Sorry, maybe I didn’t express it clearly.
The current situation is that when the customer connects the TTC to the VREF, there is no charging current. When the TTC is connected to the ground, there is charging current. I don't know why, so I would like to ask you what may be the cause of this failure?

Thank you!

0 Ning T over 7 years ago in reply to Sherry Liang

TI__Guru 57651 points

As explained earlier, TTC connection does not impact on normal charging operation. If TTC=GND may charge normally, then TTC=VREF should also charge normally. When TTC=GND, are you sure it is charging normally? Please provide waveforms for STAT, SW, PVCC, VBAT and IBAT. Thanks!

0 Sherry Liang over 7 years ago in reply to Ning T

TI__Genius 10255 points

Hi，

When TCC=VREF, the waveforms are as follows,

STAT

PVCC

VBAT

VREF

0 Ning T over 7 years ago in reply to Sherry Liang

TI__Guru 57651 points

You have posted the same waveforms for TTC=VREF already. The blinking STAT pin indicates fault status. Please measure the voltages for all pins of the device and identify the fault condition. Thanks!

0 Sherry Liang over 7 years ago in reply to Ning T

TI__Genius 10255 points

When TTC=VREF,

ACDRV

ACP

AVCC

PVCC

REGN

SYS

TTC

0 Ning T over 7 years ago in reply to Sherry Liang

TI__Guru 57651 points

The same waveforms posted again and again do not provide enough information for debug. Please take additional information such as the voltages for all pins of the device and identify the fault condition. Thanks!
Please click "This Resolved my issue" button if this post answer your question.

0 Ning T over 6 years ago in reply to Ning T

TI__Guru 57651 points

We haven’t heard back from you for a while, the thread is considered solved and closed. Thanks!
Please click "This Resolved my issue" button if this post answer your question.

Power management

Power management forum

BQ24172: there is no charging current when connected the battery(no load)