BQ24232: Detail of Reverse current protection

Kazuki Kuramochi

Part Number: BQ24232

Hello expert,

I'd like to know about detail of reverse current protection feature on BQ24232.
Where is this reverse current protection when we confirm block diagram?

This is because, datasheet p1 said there is reverse current protection feature on BQ24232 but I cannot found other explanation.
So I cannot understand that this RCP circuitry is protecting reverse current event on where. (e.g. output pin to input pin, or output pin to BAT pin or etc...)

I'm looking forward to hearing back from you.

Best regards,
Kazuki Kuramochi

over 3 years ago

0 Anthony P Pham over 3 years ago

TI__Mastermind 22250 points

Hi,

The reverse current is implemented through the FETs shown in the functional block diagram for the OUT to IN. Although illustrated is one FET, there are two in a back-to-back configuration at Q1.

0 Kazuki Kuramochi over 3 years ago in reply to Anthony P Pham

TI__Expert 8380 points

Hi Anthony-san,

Thank you for your explanation.

I have additional question for b2b FET RCP on BQ24232.
I guess this device cannot protect reverse current event during Q1 is turned on.

Is this correct?

Best regards,
Kazuki Kuramochi

0 Anthony P Pham over 3 years ago in reply to Kazuki Kuramochi

TI__Mastermind 22250 points

Hi Kazuki-san,

I'd have to look into extent of this if Q1 is on. Is there an expected case where reverse current is occurring? For instance, would the battery be charging?

0 Kazuki Kuramochi over 3 years ago in reply to Anthony P Pham

TI__Expert 8380 points

Hi Anthony-san,

I don't have actual case that which is causing reverse current during Q1 is turned on.
But I think your suggested case that is under charging battery will cause reverse current if higher voltage than input is applied on output side.

Actually, I just think there is the timing or situation of being disabled RCP if it is achieved by simple b2b connection FET.
So I ask this question to you.

Best regards,
Kazuki Kuramochi

0 Anthony P Pham over 3 years ago in reply to Kazuki Kuramochi

TI__Mastermind 22250 points

Hi Kazuki-san,

I'll have a reply by tomorrow to find the best way to answer this question.

0 Anthony P Pham over 3 years ago in reply to Kazuki Kuramochi

TI__Mastermind 22250 points

Hi Kazuki-san,

The back to back FETs do provide reverse current in that sense. I've provided some waveform shots that may help provide information on back to back reverse current protection for showing higher voltage at OUT than at IN

The following shows VBAT powered on without VIN supply. Reverse current protection prevents having the VIN see a voltage.

With voltage applied on the OUT pin, we see that with a high voltage at the OUT pin, the VIN is still low.

Power management

Power management forum

BQ24232: Detail of Reverse current protection