ROHM BA6438S Datasheet

BA6438S

Motor driver ICs

3-phase motor driver

BA6438S

The BA6438S is a 3-phase, full-wave, pseudo-linear motor driver suited for VCR capstan motors. The IC has a torque
ripple cancellation circuit to reduce wow and flutter, and an output transistor saturation prevention circuit that provides
superb motor control over a wide range of current. The built-in motor power switching regulator allows applications with
low power consumption

Applications

!

3-phase VCR capstan motors

Features

!

1) 3-phase, full-wave, pseudo-linear drive system.

2) Torque ripple cancellation circuit.

3) Reversal brake based on the detection of motor
direction.

4) Output transistor (high-and low-sides) saturation
prevention circuit

5) Motor power switching regulator with oscillation circuit.

6) Output-to-GND short-circuit detection.

7) Available in SDIP 24-pin power package (with radiation
fins).

Absolute maximum ratings

!

Parameter Symbol Limits Unit

Applied voltage
Applied voltage
Power dissipation
Operating temperature
Storage temperature
Allowable output current

1 Reduced by 16mW for each increase in Ta of 1°C over 25°C.

∗

2 Should not exceed the ASO value.

∗

Recommended operating conditions

!

Parameter Symbol Min. Typ. Max. Unit
Operating power supply voltage
Operating power supply voltage

(Ta = 25°C)

V

CC

M

V

Pd
Topr −10 ∼ +75
Tstg −40 ∼ +150
I

Opeak

(Ta = 25°C)

V

V

7V

24 V

1

∗

2000

2

∗

1.7

CC

M

456 V
31223 V

mW

°C
°C

A

Motor driver ICs

Block diagram

!

CC

V

Hall

Hall

Hall

TORQUE

COMMAND

H1+Hall

10

9

−

H1

+

H2

8
7

−

H2

+

H3

6
5

−

H3

4

C

H

P

E

C

17
16

E

CR

RIPPLE

CANCELLATION

12

GND

V

CC

Amp.

CONTROL

SIGNAL

DIRECTION

AGC

TL CS

20 22

11

MOTOR

MOTOR

DIRECTION

DET

SETTING

P SIGNAL COMBINER

TSD

SHORT

CIRCUIT

OUTPUT

SATURATION

P

PCV

18

SIGNAL V

19

V

CC

ED / S

MOTOR DIRECTION SWITCHING

SWITCHING

REGULATOR

DET.

OSC

C

I

21

15

OUTPUT

SATURATION

OSC

M

V

24

A1

23

A2

3

A3

1

ATC

2

13
14

CC

REG
VS

MOTOR V

BA6438S

CC

Motor driver ICs

Pin descriptions

!

BA6438S

Pin No.

Pin name Function

1A3
2 ATC
3A2
4 PCH
5H3
6H3
7H2
8H2

9H1
10 H1
11

−

+

−

+

−

+

ED / S
12 GND
13 REG
14 V

S

15 OSC
16 ECR
17 EC
18 PCV
19 V

CC

20 TL
21 PCI
22 CS
23 A1
24 V

M

Motor output
Driver ground
Motor output
Hall amplifier AGC phase compensation
Hall signal input
Hall signal input
Hall signal input
Hall signal input
Hall signal input
Hall signal input
Forward when LOW; stop when MEDIUM; reverse when HIGH
Signal ground
Switching regulator output (sink output)
High-side saturation detection output
Oscillator capacitor connection
Torque control reference voltage input
Torque control signal input
Phase compensation for preventing driver high-side saturation
Signal power supply
Torque limiter
Phase compensation for preventing driver low-side saturation
Current sensing input
Motor output
Motor power supply

Electrical characteristics

!

Parameter Symbol Min. Typ. Max. Unit Conditions

Torque control input / output gain
Ripple cancel ratio

Output high level voltage
Output low level voltage
Oscillator frequency
Saturation detection output gain
Regulator current capacity

Not designed for radiation resistance.

(unless otherwise noted, Ta = 25°C, VCC = 5V, VM = 12V)

G

io

0.25 0.31 0.36 −

V

V
V
f

OSC

G

REGO

I

RCC

OH

OL

us

4.6 6.4 7.2 %

1.1 1.5 1.9 V I

0.95 1.3 1.65 V I
100 135 160 kHz C = 470pF

5.0 6.5 8.0 −−
30 −−mA

C =

2.2→2.1V,

E

=

L, L, H

Input

=

L, L, H→L, M, H

Input

O =

0.8A

O =

0.8A

V

O =

5V