BQ4050: Interfacing with BQ25703A

Fabian Luttenberger

Prodigy 235 points

Part Number: BQ4050
Other Parts Discussed in Thread: BQ25703A, , BQ78350, BQ34110

Hello,

the BQ4050 is a SMBus device. Can it interface with the BQ25703A charger, which uses I2C?

There is a developmentboard (without documentation) available that uses these two devices:

http://www.ti.com/lit/df/tidrzn1/tidrzn1.pdf

Can you also recommend an I2C alternative to BQ4050?

BR,

Fabian

over 6 years ago

0 Batt over 6 years ago

TI__Mastermind 42535 points

Hi Fabian,

SMBUS is a subset of the i2c protocol. Technically the gauge should be able to talk to it. For compatibility, please read this,

Currently we don't have direct substitutes for the bq4050, you may try the bq78350 which is SMBUS based or the bq34110 which is i2c based but is quite different.

0 Fabian Luttenberger over 6 years ago in reply to Batt

Prodigy 235 points

Hi Batt,

thanks for the paper.

TI has an evaluation board (tidrzn1) that has both, BQ25703A (I2C) and BQ4050 (SMBus). However, in this forum post, BQ4050 with I2C was not recommended:
https://e2e.ti.com/support/power-management/f/196/p/757507/2798580?tisearch=e2e-sitesearch&keymatch=bq4050%20i2c#2798580

So is it now safe to use both?

BR,

Fabian

0 Batt over 6 years ago in reply to Fabian Luttenberger

TI__Mastermind 42535 points

Hi Fabian,

What I wanted to say there was that this device is an SMBUS device, it has much stricter timing requirements than i2c, which is the superset protocol. The design may work depending on if your device adheres to the timing requirements.

That's why I attached the other document explaining what can work and what may not work.

0 Fabian Luttenberger over 6 years ago in reply to Batt

Prodigy 235 points

Hi Batt!

The bq4050 has internal pulldown resistors at SMB pins. When using I2C, external pull-up resistors (3.3V supply) will still be required, correct?

Br,

Fabian

0 Batt over 6 years ago in reply to Fabian Luttenberger

TI__Mastermind 42535 points

Hi Fabian,

That is correct.

Power management

Power management forum

BQ4050: Interfacing with BQ25703A