Detailed description

L6920DB

10/16

5.3

Shutdown

In shutdown mode (SHDN pulled low) all internal circuitries are turned off, minimizing the

Both switches are turned off, and the low battery comparator output is forced in high

impedance state.

The synchronous switch body diode causes a parasitic path between power supply and

output that can't be avoided also in shutdown.

5.4

Low battery detection

The L6920DB includes a low battery detector comparator.

the threshold slowly. The LBO is an open drain output so a pull up resistor is required for a

proper use.

5.5

Low battery input

It is possible to fix, using an external resistor divider, the LBO threshold, in order to adapt

the LBO detection at the correct input source, by the following equation:

Equation 2

5.6

Reverse polarity

A protection circuit has been implemented to avoid that L6920DB and the battery are

destroyed in case of wrong battery insertion.

In addition, this circuit has been designed so that the current required by the battery is zero

also in reverse polarity.

If a battery can be inserted in reverse direction, a non polarized capacitor should be

installed in location of C2.

5.7

Output voltage selection

Output voltage must be selected acting on FB pin.

Three choices are available: fixed 3.3V, 5V or adjustable output set via an external resistor

divider.

V

batt-th

1.23V

=

1

R1

R2

--------

+

⎝⎠

⎛⎞

⋅