Additional features and protections

L6928

10/16

Doc ID 11051 Rev 6

5

Additional features and protections

5.1

DROPOUT operation

The Li-Ion battery voltage ranges from approximately 3 V and 4.1 V - 4.2 V (depending on

the anode material). In case the regulated output voltage is from 2.5 V and 3.3 V, it can be

that, close to the end of the battery life, the battery voltage goes down to the regulated one.

In this case the device stops to switch, working at 100% of duty cycle, so minimizing the

dropout voltage and the device losses.

5.2

PGOOD (Power Good output)

with a threshold set at 90% of the of reference voltage (0.6 V). Since the output voltage is

The internal comparator is triggered and the PGOOD pin is pulled down.

The pin is an open drain output and so, a pull up resistor should be connected to him.

If the feature is not required, the pin can be left floating.

5.3

Adjustable output voltage

The output voltage can be adjusted by an external resistor divider from a minimum value of

0.6 V up to the input voltage. The output voltage value is given by:

Equation 4

5.4

OVP (Overvoltage protection)

The device has an internal overvoltage protection circuit to protect the load.

If the voltage at the feedback pin goes higher than an internal threshold set 10% (typ) higher

than the reference voltage, the low side power MOSFET is turned on until the feedback

voltage goes lower than the reference one.

During the overvoltage circuit intervention, the zero crossing comparator is disabled so that

the device is also able to sink current.

5.5

Thermal shutdown

The device has also a thermal shutdown protection activated when the junction temperature

reaches 150 °C. In this case both the high side MOSFET and the low side one are turned

off. Once the junction temperature goes back lower than 95 °C, the device restarts the

normal operation.

V

OUT

0.6

1

R

2

R

1

-------

+

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=