S2-LP datasheet(48/90 Pages) STMICROELECTRONICS

48 / 90 page

Operating modes

S2-LP

48/90

DocID029944 Rev 1

Operating modes

The S2-LP is provided with a built-in main controller which controls the switching between

the two main operating modes: transmitter (TX) and receiver (RX), driven by SPI

commands.

In shutdown condition (the S2-LP can be switched on/off with the external pin SDN), no

internal supply is generated, and all stored data and configurations are lost.

From shutdown, the S2-LP can be switched on going to READY state, where the reference

clock signal is available.

From READY state, the S2-LP can be moved to LOCK state to generate the high precision

LO signal and then in TX or RX modes. Switching from RX to TX and vice versa can

happen only by passing through the LOCK state. This operation is managed by the main

controller through a single user command (TX or RX). At the end of the operations, the S2-

LP can return to READY state or can go to SLEEP state, having a very low power

consumption.

SLEEP state can be configured to retain the FIFOs content or not enabling very low power

mode. If also no wake up timer is required, the S2-LP can be moved from READY to

STANDBY state, which has the lowest possible current consumption.

Figure 9: State diagram

Three states: READY, STANDBY and LOCK may be defined as stable state.

All other states are transient, which means that, in a typical configuration, the controller

remains in those states, at most for any timeout timer duration. Also the READY and LOCK

states behave as transients when they are not directly accessed with the specific

commands (for example, when LOCK is temporarily used before reaching the TX or RX

states).

S2-LP 数据表(PDF) 48 Page - STMicroelectronics