LM5056A: Bit Bank I2C

Kuan Wei Chen (Kevin Chen)

Part Number: LM5056A
Other Parts Discussed in Thread: INA282, INA240, INA193, ADS1113, INA226

Dear Team,

The I2C read mode of the LM5056A is bit bank I2C is not a regular regular I2C. Dell said that their OS6 code does not support bit banks, so Dell asks us to find out if there is no pin to pin. If there is no pin to pin, please help recommend a suitable one.

I check on the TI.com website, it seems this one is the only solution to measure voltage up to 80V.

Because they use this device to measure 54V rail.

Or they need to use a different approach?

Kevin

over 5 years ago

0 Ian Williams over 5 years ago

TI__Mastermind 27715 points

Hello Kevin,

It is true that the LM5056A utilizes a PMBus interface, which is not the same as I2C. However at the moment it is our only digital output current sense amplifier that can support an input common-mode voltage of 54V. Is a digital output required? If not, many more devices are available, including the INA240, INA282, INA193, and others.

Best regards,

Ian Williams
Applications Manager
Current & Magnetic Sensing

0 Kuan Wei Chen (Kevin Chen) over 5 years ago in reply to Ian Williams

TI__Genius 9710 points

Dear Ian,
Thanks for the information.
If the customer use INA240, which ADC or device you will suggest to transfer the analog signal to I2C?
BR
Kevin

0 Ian Williams over 5 years ago in reply to Kuan Wei Chen (Kevin Chen)

TI__Mastermind 27715 points

Hi Kevin,

I'm not an ADC expert, but a 16-bit I2C delta-sigma ADC like ADS1113 looks like a good option.

Best regards,

Ian Williams

0 Kuan Wei Chen (Kevin Chen) over 5 years ago in reply to Ian Williams

TI__Genius 9710 points

Dear Ian,

Really appreciated.
How about using two INA226 for current and voltage?

BR
Kevin

0 Kuan Wei Chen (Kevin Chen) over 5 years ago in reply to Kuan Wei Chen (Kevin Chen)

TI__Genius 9710 points

Sorry, it should be one INA226 for both voltage and current

0 Kuan Wei Chen (Kevin Chen) over 5 years ago in reply to Kuan Wei Chen (Kevin Chen)

TI__Genius 9710 points

Can I use resister to have 0.5*54V for Vbus pin?

0 Patrick Simmons over 5 years ago in reply to Kuan Wei Chen (Kevin Chen)

TI__Mastermind 25045 points

Hey Kevin,

I presume you are wanting to use a voltage divider to divide the 54V bus voltage down to 27V to feed into the INA226 VBUS pin. You can do that. However, you need to be careful with the resistors. The divider resistor between VBUS and ground should be at least 10x smaller than the VBUS input impedance (830kohm) to get close to the expected 27V at the input. However, by using such a small resistor for the divider you will increase the amount of current pulled from your supply on an order of 100s of ua or a few mA which may go undetected if you are doing a high side current measurement..

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LM5056A: Bit Bank I2C