
LB8656FN, LB8656W
No.7897-15/16
Continued from preceding page.
Due to the above considerations, the capacitor connected to the FC pin must be set to a value (in the range 0.0015F to
0.033F) that is as small as possible while still preventing oscillations, especially in applications that require
high-speed shutter operation.
(8) Notes on shutter drive regeneration mode
Regeneration mode (IN5/IN6 = high/high) in the shutter modes is provided to regenerate (slow decay) the coil current
within the output H bridge by switching from the shutter close state (IN5/IN6 = low/high) and gradually attenuate the
coil current. (See the following figures.)
(a)Shutter close state (IN5/IN6 = low/high)
(b)Regeneration mode (IN5/IN6 = high/high)
Although the output current is brought up to the target constant current value from the output current zero state in
shutter control when operation is switched from the standby state to shutter close (or open), since the IC internal
constant current control amplifier output goes to the full drive state when in the regenerative state described above,
when switching from regenerate to shutter close (or open), operation has a form in which the current falls from full
drive state to the target constant current value. Therefore, in constant current control, to switch from regenerate to
shutter close (or open), a temporary standby state is inserted and then the state is switched to the target state.
The figure below presents an example of the operating sequence.
(9) Ground wiring and the power supply capacitors
Capacitors must be connected to PGND (two places) and SGND as close to the IC as possible and they must be
connected as close to the power supply pins as possible for each power supply.
OUT6
OUT5
OUT6
OUT5
ILB01640
IN6
IN5
Standby
Close
Open
Regenerative
Standby
ILB01641