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LP55231: Battery powered configuration and digital IO interfaces

Gregoire TYROU
Prodigy 105 points
Part Number: LP55231
Other Parts Discussed in Thread: TXS0102

Hello,

We are a startup creating a product which will feature 3 lp55231 led drivers.

We intend to power those lp55231 with the Li-ion battery, so Vdd will be somewhere between 3.1 and 4.2 V. Our plan is to use the typical application described in Section 8.2.1 of the spec.

We are unclear about the digital IO level in such configuration though. The spec is unclear, it refers to some VEN level, but the spec does not explain what this VEN voltage is. (See section 6.9 of the spec).

So how should we connect the I2C bus and GPIOs to our host ? Our host digital IO interface is 3.3V. Should we use a level shifter such as LSF010x, powered by Battery on one end and 3.3V on the other end ?

(our host cannot support voltage levels greater than 3.5V)

Please advise,

Thanks.

  • 0
    TI__Mastermind 22746 points
    hi,

    I dread is a typo... for the EN makes sense the values listed in datasheet, while for the interface normally those percentages (20 and 80%) refer to VDD... while the abs max is VDD+0,3V, indicating there is an ESD diode from the pins to the VDD...
    anyway normally you don't care becasue as I2C bus you pull up the lines (to VDD)...
    the real problem is that you can damage the GPIO of the host when the battery is full, since the only limitation to the current is the mentioned pull-up (plus the battery will be quickly drained out)...
    I would recommend the TXS0102 that is better for open-drain (I2C)...

    KR
    Vincenzo