Technical Note
6/10
BA6950FS, BA6951FS
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2011.05 - Rev.C
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●External application components
1) Resistor for the current sensing, R5
This is a current sensing resistor, care must be taken to avoid changes in the ground wire pattern in any external
connected component.
2) Control amplifier gain setting resistor, R1
VCTL pin voltage is buffered to RC pin, and the control gain - V
CTLGA
- can be set by connecting R1. The current
decided here is output to RT1 pin.
3) Control amplifier phase compensation capacitor, C1
This phase compensation capacitor for the control amplifier. Please monitor the RT1 pin voltage and confirm no
oscillation. About 33pF is recommended.
4) Current feedback amplifier gain setting resistor, R4
CS1 pin voltage (the motor current detection) is buffered to CS2 pin - BA6950FS.
ATC pin voltage (the motor current detection) is buffered to CS pin - BA6951FS.
The current feedback gain can be set by R4 connecting to CS2 or CS pin. The current decided here is output to RT2
pin.
5) Pre-amplifier gain setting resistor, R2, R3
These resistors are to add the control amplifier output and the current feedback amplifier output. This amplifier has
about fourfold gain.
6) Pre-amplifier phase compensation capacitor, C2
Please connect the capacitor about 0.1µF as the phase compensation of the pre-amplifier, and monitor the driver
output no oscillation.
7) Stabilization capacitor for the power supply line, C5, C6
Please connect the capacitor of 1μF to 100μF for the stabilization of the power supply line, and confirm the motor
operation.
8) Phase compensating capacitor, C3, C4
Noise is generated in output pins or oscillation results in accord with the set mounting state such as power supply
circuit, motor characteristics, PCB pattern artwork, etc. As noise oscillation measures, connect 0.01μF to 0.1μF
capacitors.
9) Torque limiter setting, TL pin, BA6951FS only
The motor current is limited so that ATC pin voltage should not exceed TL pin voltage.
●Functional descriptions
Table 3 Logic table
FIN RIN M1 M2 Operation
L L OPEN* OPEN* Stop (idling)
H L L H Forward (M2 > M1)
L H H L Reverse (M1 > M2)
H H L L Brake (stop)
* OPEN is the off state of all output transistors. Please note that this is the state of the connected diodes, which differs from that of the mechanical relay.
