ZHCSFP7A November 2016 – February 2017 TAS2557
The TAS2557 requires four power supplies:
The decoupling capacitors for the power supplies should be placed close to the device terminals. For VBAT, IOVDD, DVDD and AVDD, a small decoupling capacitor of 0.1 µF should be placed close to the device terminals. Refer to Figure 43 for the schematic.
The following power sequence should be followed for power up and power down. If the recommended sequence is not followed there can be large current in device due to faults in level shifters and diodes becoming forward biased. The Tdelay between power supplies should be large enough for the power rails to settle.
When the supplies have settled, the /RESET terminal can be set HIGH to operate the device. Additionally the /RESET pin can be tied to IOVDD and the internal DVDD POR will perform a reset of the device. After a hardware or software reset additional commands to the device should be delayed for 100uS to allow the OTP to load. The above sequence should be completed before any I2C operation.