m51971 Mitsumi Electronics, Corp., m51971 Datasheet - Page 6

• Manufacturer Part Number: m51971
• Description: Motor Speed Control
• Manufacturer: Mitsumi Electronics, Corp.

Upper side : Motor speed (FV conversion waveform of tacho-
Lower side : Supply voltage
Horizontal axis : 20 ms/div
Time constant of motor
Application Characteristics Example
100
0%
90
10
4
3
2
1
0
Output voltage range at pin
voltage characteristics
generator frequency)
4
T
a
= 75 C
Supply voltage V
100 ms
T
8
a
= 25 C
12
T
a
CC
= -20 C
(V)
9
16
– Supply
How to determine R and C
These constants determine the motor rotating speed. If the motor
rotating speed and the number of poles of tacho-generator are
assumed to be N and P, respectively, the following relational
expression is generally established. According to the required
rotating speed, select the constant in such a way that R can be
put in the range of 10k
take care for leak current that may flow on the surface of the
printed circuit board.
10000
Tacho-generator output frequency –
Connection resistance characteristics at pin
7000
5000
3000
2000
1000
120
700
500
300
200
160
–40
MITSUBISHI <CONTROL / DRIVER IC>
80
40
0
10
0
Connection resistance R (k ) at pin
NP
Buffer amplifier offset voltage –
Voltage characteristics at pin
20 30
1.20 • R • C
1
Voltage at pin
– 500k . When using a high resistance,
MOTOR SPEED CONTROL
50 70 100
1
2
M51971L/FP
8
200 300 500
V
8
V
(V)
3
CC
=9V
1
R (k )
8
1000
4
1