mm1538 Mitsumi Electronics, Corp., mm1538 Datasheet - Page 21

• Manufacturer Part Number: mm1538
• Description: 4-ch Motor Driver For Portable Cd Players
• Manufacturer: Mitsumi Electronics, Corp.

MITSUMI
3 DC-DC converter block
(1) Output voltage
(2) Short protect function
(3) Soft start function
(4) Power off function
· 3.2V typ. voltage multiplier circuit can be constructed using external components. This voltage can be
· When the error amplifier output(6PIN)has switched to the high-level state,SPRT(8PIN)is charged, and when
· The soft start function operates when a capacitor is connected between DEAD(4PIN)and GND.
· When low-level is applied to OFF(40PIN), SPRT(8PIN)is charged, and when the voltage reaches 1.2V typ. ,
varied with the addition of an external resistor. The setting method is as follows.
the voltage reaches 1.2V typ. , the SW(5PIN)switching stops.The time until switching stops is set by the
capacitor connected to SPRT(8PIN)according to the following formula.
Also, the maximum duty can be varied by connecting a resistor to 4PIN.
the SW(5PIN)switching stops. The time until switching stops is set by the capacitor connected to
SPRT(8PIN)according to the following formula.
VSYS1=1.2
t=CDEAD
t=CSPRT
t=CSPRT
R1
R2
I
V
R (sec) (R=65kΩ)
OFF
TH
ISPRT
R1 · R3
V
R1+R3
TH
(sec) (V
R2 · R4
R2+R4
(sec) (V
VSYS1
+
TH
R2 · R4
R2+R4
EI
=1.2V, I
12
7
TH
=1.2V, ISPRT=10µA)
(V)
OFF
=20µA)
R3
R4
1.2V
4-ch Motor Driver for Portable CD Players MM1538
R1=external resistor
R2=external resistor
R3=35kΩ
R4=21kΩ