L6460 datasheet(48/139 Pages) STMICROELECTRONICS

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Linear main regulator

L6460

48/139

Doc ID 17713 Rev 1

Linear main regulator

The linear main regulator is directly powered by VSupply voltage and it is one of the

regulators that L6460 could consider as a system regulator. This means that the voltage

generated by this regulator is not used to power any internal circuit, but L6460 will check

that the feedback voltage VLINmain_FB is in the good value range before enabling all its

internal functions. When an under-voltage event (with a duration longer than period tprim_uv

defined by the deglitch filter) is detected during normal operation, L6460 will enter in reset

state and it will signal this event to the microcontroller by pulling low the nRESET pin and

disabling most of its internal blocks.

Here are summarized the primary features of the regulator:

–

Regulated output voltage from 0.8V to VSupply-2V with a maximum load of 10mA.

–

Band gap generated internal reference voltage.

–

Short circuit protected (output current is clamped to 22mA typ).

–

Under voltage signal (both continuous and latched) accessible through serial

interface.

–

Low power dissipation mode.

The internal series element is a P-channel MOS device. The voltage regulator will regulate

its output so that feedback pin equals VLINmain_FB, therefore the regulated voltage can be

calculated using the formula:

VLINmain_OUT = VLINmain_ref *(Ra+Rb)/Rb

Figure 9.

Linear main regulator

To extend the output current capability this regulator can be used as a controller for an

external active component able to provide higher current (i.e. a Darlington device); the

external power element allows the handling of an higher current since it dissipates the

power externally (the power dissipated by a linear driver supplied at VSupply and regulating a

voltage VLINmain_OUT with an output current IOUT is about: Pd= (VSupply-VLINmain_OUT)*IOUT.

VLINmain_ref

Body Diode

Vsupply

VLINmain_OUT

VLINmain_FB

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