AM5901AF44 datasheet(15/19 Pages) BCDSEMI

15 / 19 page

Data Sheet

Mar. 2007 Rev. 1. 3

BCD Semiconductor Manufacturing Limited

4-CHANNEL MOTOR DRIVER WITH POWER CONTROLLER

AM5901A

3. Soft-Start Function

The soft-start is functioned by putting a capacitor

between

DEAD

terminal

and

GND,

the

maximum duty can be changed by attaching a

resistance to pin 4.

t = CDEAD * R (sec)

(R=65k

Ω)

4. Power-Off Operation

SPRT terminal is charged by setting OFF

terminal to "L". Then, switching of SW terminal

is terminated when the voltage of the SPRT

terminal has reached 1.245V (Typ.). Time to

disable switching depends on a capacitor of the

SPRT terminal and it can be calculated by the

expression:

t = CSPRT * VTH/IOFF (sec)

(VTH = 1.245V, IHV = 20µA)

5. Over-Voltage Protection Operation

When the voltage applied to BSEN terminal has

been 8.4V (Typ.), SPRT terminal is charged.

Then, switching of SW terminal is terminated

when the voltage of the SPRT terminal has

reached

1.245V

(Typ.).

Time

disable

switching depends on a capacitor of SPRT

terminal and it can be calculated by the

expression:

t = CSPRT * VTH/IHV (sec)

(VTH = 1.245V, IHV = 20µA)

PWM Power Supply Driver Circuit

This circuit detects a maximum output level of

drivers of four channels and performs the PWM

supply of load drive power supply. This circuit

uses

PNP

transistor,

Schottky

Diode

and

capacitor as external component.

"Empty" Detector Unit

When the voltage applied to BSEN terminal has

reached the detecting voltage or less. EMP

terminal varies from "H" to "L" (open collector

output). Hysteresis of 50mV (Typ.) is set to the

detecting

voltage

prevent

the

output

chattering.

The

detecting

voltage

varies

depending on SEL terminal as follows:

SEL Pin

Detecting

Voltage

Return

Voltage

2.2V (Typ.)

2.25V (Typ.)

High-Z

1.8V (Typ.)

1.85V (Typ.)

Application Information (Continued)

PSW

PWMFIL

47 F

2200pF

10pF

100k

HVcc

SBD

0.1 F

33 H

Ω

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