A8603KESTR-R datasheet(21/42 Pages) ALLEGRO

21 / 42 page

Multiple-Output Regulator for

Automotive LCD Displays

A8603

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

OUT

A8603

COMP

PGND

DMOS

Slope-

comp

Oscillator

Enable

PWM

Control

Multi-input

Transconductance

Ampliﬁer

AVDD

VGL

VGH

OCP

OVP

AGND

Figure 8: Boost Controller Circuit

The boost controller is protected against overvoltage and overcur-

rent fault conditions.

• The Switch OVP threshold, VSW(OVP), is internally set

at approximately 21 V typical. Under normal operating

conditions, the boost output voltage should always be lower

than 18 V, so only in the event of a fault will SW_OVP be

tripped (for example: boost diode open or VOUT pin open

during startup).

• The switch current is protected by a cycle-by-cycle current

limit (ISWILIM , 2.6 A typical). In the event of a heavy

load or during a transient, the SW peak current may reach

SWILIM level momentarily. In this case, the present on-time

is truncated immediately, but no signal is generated on the

FAULT pin. The switching will continue with the same period.

• In the event of a catastrophic failure (such as shorted

inductor), the SW current may exceed SWILIM2, which is

150% of the SWILIM threshold. In this case, the IC is shut

down immediately.

It is important to note that the A8603 cannot protect the input cur-

rent in case there is a short from boost output to GND. To do so

requires the use of an input disconnect switch.

A8603KESTR-R Datasheet(PDF) 21 Page - Allegro MicroSystems

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