STA5620

Functional description

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3.9

Power control modes

Three different power control modes can be chosen by means of the CHIP_EN and the

RF_EN pins. If the CHIP_EN pin is forced low the device goes to stand-by mode with very

low power consumption. On the other hand, if CHIP_EN is set high, two scenarios are

possible:

1.

IIf RF_EN = 0 the crystal oscillator and only one output buffer are enabled,

XTAL_CLK if MODE = 1 or GPS_CLK if MODE = 0;

2.

If RF_EN = 1 the whole chip is active and functional.

Only if MODE = 0 the XTAL_CLK output is disabled.

A logic reset of the SPI registers is generated by the low to high transitions of the CHIP_EN

pin. External pin strapping dominates until some SPI commands reverse the priority and

overrides the strapping until next reset.