SI7300A Sanken Electric Co., SI7300A Datasheet - Page 3

• Manufacturer Part Number: SI7300A
• Description: Unipolar Driver ICs
• Manufacturer: Sanken Electric Co.

SI-7300 and SI-7330A
Application Note
The output current, lo is fixed by the following circuit ele-
ments:
To operate a motor at maximum current level, set Rx =
infinity (open). Based on the specifications of SI-7300A, its
output current lo can be seen as:
To compute lo when different values are used for Rs and
V
ripple value I
computed as follows:
The graph of this equation is shown below.
CC2
Determining the output
current I
R
V
R
lo (rms value): 535 to 625 mA
l
l
OH(max)
OH(min)
, use the approximation formula below. The maximum
CC2
S
X
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
3
2
1
0
SI-7300A Output current I
0
SI-7330A Output current I
: Current detection resistor
: Supply voltage
: Variable current resistor
0
.
=
.
=
.
.
RS
R
O
I
OH
1
1
OH
S
(motor coil current)
of the output current waveform can be
(0.233•V
(0.214•V
Current detection resistor Rs ( )
Waveform of output current
Current detection resistor Rs ( )
1
1
CC2
CC2
OH
OH
I
I
–0.026) [A]
–0.021) [A]
vs. Current detection resistor Rs
vs. Current detection resistor Rs
OH(max)
OH(min)
2
2
Rs
Rs
1
1
(0.233V
(0.214V
3
3
CC2
CC2
–0.026)
–0.021)
4
4
The SI-7300A can be operated in power down mode. The
circuit is shown below. When transistor Tr is switched on,
the reference voltage drops and the output current can be
decreased.
The graph shows the relation-
ship between frequency and
pull-out torque of SI-7300A.
Power down mode
Example of a Frequency vs.
Torque characteristic
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
3
2
1
0
0
0
SI-7300A Output current I
SI-7330A Output current I
Variable current resistor Rx (k )
1
1
Variable current resistor Rx (k )
Rx
Tr
OH
OH
2
2
vs. Variable current resistor R
vs. Variable current resistor R
2
SI-7300A
*
I
I
OH(max)
OH(min)
SI-7300A Pull-out torque out
Rx : k
Response frequency f (pps)
vs. Response frequency
5
4
3
2
1
0
500
Rs
Rs
1
1
3
Motor
V
I
2-phase excitation
V
3
O
23PM-C108
(Fixed)
CC1
Z
=1.2A/
4.843+
5.165+
=60V
=30V
1.131
1.107
1000
4.9
5.1
Rx
Rx
V
V
CC2
CC2
– 0.026
– 0.021
4
4
X
X
5000
31