TCA9517: is it possible to use TCA9157/TC9803 with VCC on both side the same (VCCa = VCCb)

Gil Melamud

Part Number: TCA9517

hello

we are starting a design and we want to include TCA 9517 ( or TCA 9803) as a level shifter for I2c bus.

in one of the use cases we will have VCC1 = 3.3v and VCC2 = 1.8v

in other use case we will have VCC1=VCC2=3.3v (the system will go a full reset between the two caes)

there might even be a case where VCC1=VCC2=1.8v

so I have two questions:

1. is it o.k to use the shifter with both sides have same VCC

2. can the master (direction of the clock signal) be on both sides in this case?

thanks

Gil

0 Clemens Ladisch over 3 years ago

Guru 243180 points

During operation of the TCA9517, V_CCA must not be larger than V_CCB, and V_CCB must be at least 2.7 V.

The TCA980x does not have these restrictions.

I²C signals are bidirectional; on the electrical level, it does not matter which device is master or slave.

0 Gil Melamud over 3 years ago in reply to Clemens Ladisch

thank you for the reply

VCCA must not be larger than VCCB, >> can it be the same ? (as long as both >2.7) for example VCCa = VCCb = 3.3v

0 Clemens Ladisch over 3 years ago in reply to Gil Melamud

Guru 243180 points

Yes.

0 Gil Melamud over 3 years ago in reply to Clemens Ladisch

thank you very much for your help

thanks

Gil

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