Panasonic BB-HCM381A Service Manual page 79

PWM signal from MAIN board is compared with HALL OUT signal in Drive AMP (IC1010), and drives Iris
in LENS UNIT as ALC_MAIN [+] signal so that the difference between PWM and HALL OUT may be zero.
HALL OUT signal is produced by IC1007 from HALL_OUT [+]/HALL_OUT [-] signal, which are produced
depending on the Iris position in LENS UNIT, and generates voltage as large as Iris opens. The
HALL_OUT signal is transferred to MAIN board as the information for Iris position and also, its AC
component is transferred through C1032 to IC1010 for stabilization of Iris drive, and then a stabilized
signal is produced. This stabilized signal is added to HALL OUT signal.
In DC bias Generator (IC1008), DC voltage is generated by I2CBUS signal (SCL, SDA) from MAIN board,
and the voltage will apply to PWM signal bias voltage (4pin output), OP amp bias (+1.3V: 3pin output),
HALL bias circuit (IC1007) (1pin output) for HALL device bias voltage generation in LENS UNIT and
HALL OUT signal DC level decision (2pin output).
15.1.3.2. Zoom Motor Drive Block
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