Operating mode

L5962

18/24

Doc ID 16819 Rev 3

5

Operating mode

When a power source is connected to the IC, the internal circuitry begins to establish

internal bias, the bandgap reference voltage, and other related functions. The standby

(VSTBY) regulator and battery detection are functional.

The standby mode is activated when the enable (EN) input is asserted low.

When the enable (EN) input is set high (EN =1: active mode.), the IC exits the standby mode

and enters the active mode.

During active mode, I2C interface is activated and all functions are operational. The IC

remains in active mode until either the standby regulator falls out of regulation (where the IC

enters the low-voltage reset state) or until the enable (EN) input is brought back to 0 V

(where the IC enters the standby state).

5.1

Battery detection

The operating voltage for VLR1, high side drivers and battery warnings is provided by VBAT

pin. This input is also used as reference to detect an over-voltage or an under-voltage

condition. When such condition is detected, the VBATVW output is pulled down. The

overvoltage detection circuit has hysteresis for noise rejection.

Two external resistors (Rext1, Rext2), whose values are lower than 100 kohm, are

connected to the LWIN (low warning input) pin to give the possibility to trim the threshold at

which the low voltage warning comparator triggers. When LVWIN voltage is below the input

voltage threshold (1.25 V typ), the VBATW (battery voltage warning) output is pulled down

and a low-voltage warning is indicated. When no external resistor network is connected to

LVWIN, the detector sets the threshold to a nominal 7.5 V.

No external interaction is required to reset the output state, because it is automatically reset

when the fault condition is removed.

Figure 4 shows an high level block diagram of the low-voltage warning circuit. VBAT is

divided by two internal resistors (Rint1, Rint2) and two external programming resistors

(Rext1, Rext2). When VBAT decreases so that LVWIN voltage gets lower than the internal

reference (VBG), VBATW is pulled down to ground.

Figure 4.

Low voltage warning high level block diagram

VBAT

Rint1 =13.89 M ohm

Rint2 = 2.83 M ohm

Rext1

Rext2

VBATW

VBG

LVWIN

comparator