L5962

Device description

Doc ID 16819 Rev 3

15/24

4

Device description

The IC includes one standby regulator, always active to guarantee the standby functions;

two switched linear regulators, managed by the I2C bus and a step-down switching voltage

regulator with selectable current limit.

4.1

Regulators

The VSTBY regulator is always active when the IC is supplied.

The other regulators can be enabled or disabled. Their outputs are automatically disabled

whenever the VBAT voltage exceeds the over-voltage shutdown threshold. Upon return from

over-voltage shutdown, the outputs recover without intervention from the system.

4.1.1

Linear regulators

VSTBY (3.3 V / 5.0 V standby)

VSTBY is a linearly regulated 3.3/5 V output. This output is enabled on battery connect. It is

supplied from the protected battery input (VBATP).

In order to select the 3.3 V output, the VSTBYSEL pin must be connected to ground.

In order to select the 5.0 V output, the VSTBYSEL pin must be connected to 5 V.

When the dropout voltage of the regulator cannot be maintained, the output shall track the

VBATP input voltage less the saturation voltage of the regulator pass element.

This regulator has a short circuit protection consisting of current limit, and thermal

shutdown. If the local die temperature exceeds the thermal shutdown detection threshold,

the output is disabled. The thermal shutdown circuitry has hysteresis such that the output is

enabled only after the die temperature falls below the thermal shutdown disable threshold.

Thermal shutdown on this output doesn't directly disable any other circuitry.

RST provides an indication that VSTBY is in regulation. It is an open drain output used to

indicate that VSTBY is in regulation (below the low-voltage threshold). RST remains low

until VSTBY achieves regulation and the RSTDLY input has charged to its threshold. For

instance, RST remains low during battery connect and disconnect and under low-voltage

battery lockout. The transition from standby mode to active mode (and vice versa) does not

cause the RST output to be triggered.

RSTDLY provides a means to delay the releasing of RST once VSTBY has achieved

regulation. It is used to delay the release of RST when VSTBY achieves regulation. This

input has a current source to charge an external capacitor and an internal pull-down to

discharge the external capacitor. The voltage on this capacitor is used to control the

operation of the RST output.

The RSTDLY pull-down is activated when a loss of regulation is detected. The input remains

low until VSTBY once again achieves regulation.

When the RSTDLY is released the current source charges the external capacitor. When the

voltage exceeds the pin's threshold, RST pin is also released, disabling its pull-down.