Datasheet

ST7538Q Auxiliary analog and digital functions
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6.11 5V and 3.3V voltage regulators and power good function
ST7538Q has an embedded 5V linear regulator externally available to supply the application
circuitry.
The linear regulator has a very low quiescent current (50µA) and a current capability of
50mA. The regulator is protected against short circuitry events.
The DVdd pin can act either as 3.3V Voltage Output or as Input Digital Supply. When the
DVdd pin is externally forced to 5V all the Digital I/Os operate at 5V, otherwise all the Digital
I/Os are internally supplied at 3.3V. The DVdd pin can also source 3.3V voltage to supply
external components. The 3.3V linear regulator has a very low quiescent current (50µA) and
a current capability of 50mA. The regulator is protected against short circuitry events.
If AVdd and DVdd pins are connected to VDC pin, the 5V regulator maximum current
capability rises to 100mA
When the regulator Voltages are above of the power good thresholds V
PG
(see Table 4),
Power Good line is forced high, while is forced low at startup and when VDC or DVdd falls
below V
PG
- V
PGHYS
Voltage.
Figure 23. Power good function
PG OK
250mV
Time
Time
V
DC
/DV
DD
4.5V/3.125V
PG
D03IN1411