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We use the component PCA9535EMTTXG in our design of a telematics device component. Normally our unit and your component is permanently powered. Nevertheless we provide a reset where we switch off power of our external I2C devices, e.g. also the PCA9535 component which is normally powered by 3V. Using this reset the voltage level is less than 5 mV on all pins of PCA9535. According specification the voltage must be less than 0.2 V. Unfortunately there is no timing for reset specified as well as for startup. The timing seems to be very device specific. We have observed error conditions when the component answers I2C commands correctly but the command has no effect (e.g. setting an output will be acknowledge but the output level does not change)! Some PCA9535 components work after few milliseconds after power-up (<10 ms) some other seems to require much more time (>105 ms). Currently we use a voltage-off time of 100 ms and we wait 150 ms after power-on until we start I2C communication with the device. Which timing do you recommend to us. Please forward the question to the right person if this is not the right forum. Thank you.

The time required before I2C commands can be interpreted correctly by the PCA9535E: I/O Port Expander depends more on the slew rate of rising Vcc rather than a fixed time. We recommend a Vcc rise slew rate somewhere between 150 us / V to 1.5 ms / V. A Vcc slew rate of 150 us / V translates to a trise of 450 us while 1.5 ms / V translates to a trise of 4.5 ms. For the conditions above, we would recommend a wait time of 10 ms after power on before accessing the device. If your rising Vcc slew rate satisfies these conditions, a wait time of 150 ms is more than enough time. Answered by:
ON Semiconductor
2013-11-12 10:17:07.724