Power Supply Circuit; Motor Drive Circuit - Brother P-touch BB4 Service Manual

3.2.9

Power Supply Circuit

Figure 3.2-12 shows a power supply circuit.
The 3-terminal regulator (RH5RL33A) stabilizes the battery output, producing the 3.3V
power source. Capacitor C13 is for the logic circuit and C5 is for driving the thermal head
and DC motor.

3.2.10 Motor Drive Circuit

Figure 3.2-13 shows the drive circuit of the DC motor which feeds tape.
Through P10, the CPU produces a start/stop control signal to the motor drive circuit.
Figure 3.2-14 shows waveforms of control signal and motor drive current.
Electronic governor IC (U4: BA6220) controls this circuit to keep the rotation speed of the
DC motor constant even if the power supply voltage (V
Figure 3.2-12 Power Supply Circuit
Figure 3.2-13 Motor Drive Circuit
III - 10
) varies.
BT