LM25066 I2C Power

Adrian Soltero

Intellectual 1135 points

Other Parts Discussed in Thread: LM25056, LM25061, LM25066

Hi,

Is it possible to power the I2C bus so it can be accessed before the 12 V (input) is applied?

Thanks,

Adrian

over 12 years ago

0 Dennis Hudgins over 12 years ago

TI__Prodigy 375 points

Adrian,

The I2C digital core is powered off the chip VDD. Unfortunately a reverse body diode prohibits powering VDD externally before VIN is applied. So it is not possible to have the digital core operating prior to VIN.

If you are interested in Telemetry only, the LM25056 can allow the VDD to be powered externally before VIN. If you need a hot-swap with this I would recommend the LM25061.

Regards,

Dennis

0 Adrian Soltero over 12 years ago in reply to Dennis Hudgins

TI__Intellectual 1135 points

Thanks for the help Dennis.

-Adrian

0 LeonardEllis over 10 years ago in reply to Dennis Hudgins

TI__Guru 71526 points

Dennis,

What about the loading on the SDA, SCL pins when the LM25066 is not powered-ON? Are these signal basically open-drain'high impedance, or will the signals be pulled-down? Since these follow a bus standard, I would imagine they are high-impedance, but it is not specified in the datasheet.

-Leonard

0 Michael Hartshorne over 10 years ago in reply to LeonardEllis

TI__Genius 12105 points

Leonard,

The SDA and SCL pins are true open collector on the LM25066. The device will not pull down the bus lines if VIN is at GND.

Regards,

MIke

Power management

Power management forum

LM25066 I2C Power