BQ25890: VBUS voltage

liping pan

Intellectual 460 points

Part Number: BQ25890

I short D+ and D-. The IC detect it as USB DCP (3.25A).

If I connect the VBUS = 12V, what will hapen? Can it still works?

over 1 year ago

0 James Steenbock over 1 year ago

TI__Genius 15215 points

Hi liping,

Yes, the charger will work with 12V at VBUS after shorting D+/D-. By shorting D+/D- you are forcing the charger to detect USB DCP which will set the proper input current limit (3.25A).

Regards,

James

0 liping pan over 1 year ago in reply to James Steenbock

Intellectual 460 points

Then,wha's the difference between below two mode?

0 James Steenbock over 1 year ago in reply to liping pan

TI__Genius 15215 points

Hi liping,

The Adjustable High Voltage DCP is part of the handshake process described in the datasheet section below. If you have D+/D- shorted, this process results in USB DCP regardless of the voltage at VBUS. The Adjustable HVDCP is used with specific chargers that can respond to the handshake communication. However keep in mind that the BQ25890 may not automatically work with any HVDCP adapter you find.

For more details take a look at these threads below:

Thread 1

Thread 2

Regards,

James

0 liping pan over 1 year ago in reply to James Steenbock

Intellectual 460 points

1) USB DCP can only works with a fixed VBUS voltage from adpater, right? It can be 5V or 12V?

2) MaxCharge is one type of Adjustable HVDCP. The VBUS can be adjusted from 5V to 9V/12V step by step based on handshake, right?

0 liping pan over 1 year ago in reply to liping pan

Intellectual 460 points

If yes, then what's the benif of use MaxCharge?

If I want to a fast charge with big current, I just a apdater with 12V, isn't it more convenient?

+1 James Steenbock over 1 year ago in reply to liping pan

TI__Genius 15215 points

Hi liping,

1) USB DCP detection depends on the adapter's internal D+/D- connections. The DCP detection does not take VBUS voltage into account so 5V and 12V would both work.

2) MaxCharge adapters are not easily available so I wouldn't recommend this, but they would be compatible with the handshake process.

A 12V DCP adapter would be a good solution for high voltage / high current charging applications using our device.

Regards,

James

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BQ25890: VBUS voltage