CMD8649 Datasheet, PDF (6/8 Pages) Ceramate Technical – Lens Motor Driver for Digital Still Camera

CMD8649
(Preliminary)
Lens Motor Driver for Digital Still Camera
(2) Rapid charge and discharge circuits (FC1, OUT9, OUT10)
SH control blocks (OUT9 - OUT10) incorporate rapid charge and discharge circuits to enable high-speed control of the shutter
and a rapid discharge circuit to enable consecutive filming.
As these circuits are not built into AE control blocks (OUT11 to OUT12), use OUT9 and OUT10 blocks for shutter drive.
(3) Rise compensation function (ISH, OUT9, OUT10)
ISH
Coil current
Rise compensation
VCC high (without ISH capacitor)
VCC low (without ISH capacitor)
Rise compensation coil current
ISH discharge
SH closing
Setting the input voltage of ISH pin larger than the coil time constant by means of an external CR enables application of rise
compensation to the coil waveform, ensuring stable shutter operation against fluctuation of power supply.
(Note) In ISH rise compensation, the rise waveform of coil current during VCC power reduction in the condition without
ISH capacitor is checked. The capacity is determined so that the time constant becomes lower than this waveform.
Note that the rise compensation capacitor is not necessary when the rise compensation function is not necessary, for example,
when the stable supply voltage is supplied.
(4) Phase compensation capacitors (FC1, 2)
Set FC1 and 2 capacitors to the capacitance value within the range of 0.01 to 0.1µF that does not present an oscillation problem
to the output. Particularly when a coil with high impedance is to be used, it is necessary to provide an allowance to the
capacitance. As the constant-current control block is connected to PGND in IC, connect the GND side of FC1 and 2
capacitors to PGND.
(5) Constant-voltage control oscillation preventive capacitors (OUT1 to 8)
For constant-voltage control, it is necessary to insert a capacitor between OUT pins to prevent oscillation. Set the capacitor
within a range of 0.01µF to 0.1µF that does not present an oscillation problem to the output. This oscillation preventive
capacitor is not necessary when drive is made in the saturated condition.
(6) Capacitors for GND wiring and each power line (PGND, SGND, VCC, VB1, 1, VDD)
Connect PGND (two points) and SGND near IC and insert a capacitor directly near the power pin for each power supply.
* All specs and applications shown above subject to change without prior notice.
1F-5 NO.66 SEC.2 NAN-KAN RD ., LUCHU , TAOYUAN, TAIWAN
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Rev 0.1 Mar. 3,2004