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MM1538

4-ch Motor Driver for Portable CD Players

Mitsumi 

MITSUMI

4ch Moter driver IC for Portable CD Player

Circuit operation

1 H-bridge driver block

(1) Gain setting

· The driver input resistance (ch 1,3 and 4) are 11kΩ typ. ,ch2 is 7.5kΩ typ. . Set the gain according to the

following formula.

ch1

ch2

GV=20log

ch3

55k

(db)

11k+R

R:Externally-connected input

ch2

GV=20log

110k (db)

7.5k+R

· The driver output stage power supply is HVcc(36PIN), and the bridge circuit power supply is VSYS2

(15PIN). Connect a bypass capacitor between these two power supplies(approximately 0.1µF).

(2) Mute function

· Of the four drivers,ch1 has a brake function,and the other channels have a mute function.

· When BRAKE1(23PIN)is set to high level, both ch1 outputs go low level, and the circuit enters brake mode.

· When MUTE2(21PIN)is set to high level, the ch2 output is muted.

· When MUTE34(19PIN)is set to high level, the ch3 and 4 outputs are muted.

(3) Vref drop mute

· When the voltage applied to Vref(16PIN)is 1.0V or less typ. , the driver outputs are set to high impedance.

(4) Thermal shutdown

· When the chip temperature reaches 150°C typ. the output current is cut. The chip starts operating again at

about 120°C typ. .

2 PWM power supply drive block

· This detects the maximun output level from among the four channels, and supplies the load drive power

supply(36PIN)for the PWM. The external components are a PNP transistor, coil, Schottky diode,and

capacitor.

10pF

BATT

100kΩ

2200pF

47kΩ

44

37

PWMFIL PSW

33µH

SBD

47µF

0.1µF

36

HVCC

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