User's Manual

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USERS MANUAL

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Document number Revision

1/198 17-5/FCP 101 3317 Uen A

6 Rudimentary Circuit Functions

This section contains some rudimentary circuit functions for the sequencing of powering

the modem up and down.

6.1 Power On Sequence

This sequence illustrates the power on procedure.

Figure 6-1 Power On Sequence

Sequence Detail:

1 VIN and 3V3 are supplied to the modem by the host. These two voltages can be

supplied simultaneously when the Daughter Card is required to be powered on.

Both voltages must be present before the power on sequence is initiated for the

Daughter Card to function correctly.

2 Once VIN and 3V3 voltages are applied the host can enable power up by

asserting power enable signal P_EN. The power up process will begin.

3 VREF may be used as an indicator that the modems regulators are powered.

POn

is typically less than 70 ms