m56755afp Mitsumi Electronics, Corp., m56755afp Datasheet - Page 7

• Manufacturer Part Number: m56755afp
• Description: Spindle Motor Driver
• Manufacturer: Mitsumi Electronics, Corp.

REVERSE TORQUE MODE SELECT FUNCTION
At the 4 times speed and the 6 times speed CDROM drive system,
the reverse braking style has been used for the reverse torque.
However, at the 8 times speed CDROM drive system, the motor
current will be needed above 0.7A, if an user of driver IC require a
high speed access time.
If the reverse braking is used at 0.7A, the IC junction temperature
will be too much high.
Therefore, MITSUBISHI new motor driver has the braking mode
select function. This mode select function is available in order to
control flexibly in match with the situation of junction temperature.
Figure 7 shows the reverse torque mode select function table.
Figure 7.
Figure 8.
FORWARD
CURRENT
MODE2
REVERSE
TORQUE
CURRENT
BRAKING
MODE
ECR
MODE2
MODE1
CASE 1
HIGH
LOW
LOW
+1A
5.0V
3.0V
2.5V
2.0V
-1A
REVERSE AND COMMUTATED SHORT
BRAKING SELECT
0V
BRAKING MODE (ECR < EC) SELECT FUNCTION TABLE
EC PIN INPUT VOLTAGE [ECR VOLTAGE = 2.5V]
LOW
or
OPEN
HIGH
-600mA
MOTOR CURRENT [ Rsense = 0.5 ohm]
Commu-
tated short
BRAKING
COMMUTATED SHORT
BRAKING
REVERSE BRAKING
LOW or OPEN
REVERSE
BRAKING
+600mA
MOTOR
STOP
MODE1
SHORT BRAKING (2)
OUTPUT OPEN
[only inertia]
ALL SHORT
BRAKING
HIGH
FORWARD
CURRENT
REVERSE
TORQUE
CURRENT
BRAKING
MODE
ECR
MODE2
MODE1
HIGH
LOW
LOW
+1A
3.0V
2.5V
5.0V
2.0V
-1A
0V
If you hope original (the reverse braking) style, please only select
REVERSE BRAKING mode [MODE1 = LOW or OPEN and
MODE2 = HIGH] at external. If it is possible to get two more port
from com, you can flexibly control the four kinds of BRAKING
MODE. If you can only get one more port, you can control only the
MODE2. Then, you can control the two kinds of BRAKING MODE
[commutated short or reverse] under the MODE1 is set to LOW or
OPEN.
CASE 2
REVERSE AND ALL SHORT BRAKING SELECT
EC PIN INPUT VOLTAGE [ECR VOLTAGE = 2.5V]
MOTOR CURRENT
MITSUBISHI <CONTROL / DRIVER IC>
Figure 8 shows an example for the reverse torque
mode select.
The CASE1 is an controlling example for REVERSE
and COMMUTATED SHORT BRAKING.
The CASE2 is an controlling example for REVERSE
and ALL SHORT BRAKING.
ALL
SHORT
BRAKING
(Vbemf-Vd-Vsat) / Ra
Vsat ; npn transistor saturation voltage
Vd ; diode voltage
Ra ; motor inner resistance
-600mA
SPINDLE MOTOR DRIVER
REVERSE
BRAKING
+600mA
M56755AFP
MOTOR
STOP