AD9522-4: Does high-low-high pulse at reset pin (pin 23) after power-up is needed to be done externally or it is done internally by the chip itself?
The AD9522 series of devices have a Power-on Reset (POR) function which issues an internal reset which performs the same functionality as an external reset (i.e. high-low-high pulse at pin 23). Therefore, there is no explicit need for the user to issue a reset after power up.
You can read about this in the datasheet under Reset Modes -> Power-on Reset, but I have copied the applicable text here.
"During chip power-up, a power-on reset pulse is issued when VS reaches ~2.6 V (<2.8 V) and restores the chip either to the setting stored in EEPROM (with the EEPROM pin = 1) or to the on-chip setting (with the EEPROM pin = 0). At power-on, the AD9522 also executes a SYNC operation, ~50 ms after the supply reaches ~2.4 V, which brings the outputs into phase alignment according to the default settings. It takes ~70 ms for the outputs to begin toggling after the power-on reset pulse signal is internally generated."
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