LB8653T, LB8653FN

No.7982-11/14

Application Design Notes

(1) Constant-voltage setting for OUT1 to OUT6

“H” output voltage for OUT1 and OUT2 can be set by the VC1 pin input voltage.

The setting formula is as follows:

(OUT1/2 output voltage) = (VC1 input voltage)

×5.27

Correspondingly, OUT3 and OUT4 can be set by VC2, and OUT5 and OUT6 can be set by VC3.

The setting formula is as follows:

(OUT3/4 output voltage) = (VC2 input voltage)

×5.27

(OUT5/6 output voltage) = (VC3 input voltage)

×5.27

In addition, if the right side setting of the above formula exceeds the supply voltage (VB),

the output voltage is saturated.

(2) Output pin oscillation prevention capacitor for OUT1 to OUT6 constant-voltage control.

For constant-voltage control of OUT1 to OUT6, a capacitor must be placed between OUT pins in order to prevent

oscillation.

Test capacitor values between 0.01

µF to 0.1µF and choose a value that does not cause output oscillation problems.

However, for the saturated drive, no oscillation prevention capacitor is necessary.

(3) Constant-current setting between OUT7 and OUT8

Constant-current setting between OUT7 and OUT8 depends on the IC pin input voltage and IM pin connection

resistance (current detection resistor).

As shown in the block diagram, the output current is controlled so that the IC pin input voltage can be equal to the

voltage generated on the current detection resistor which is connected between IM and GND.

The formula for output current is as follows:

(Output current) = (IC input pin voltage)

÷ (current detection resistance)

In addition, since the constant-current control block is connected to PGND inside the IC, when the voltage is

supplied to the IC pin with partial resistance, GND side of the resistor must be connected to PGND.

(4) Fast charge/discharge circuit for the FC pin

In order to support high speed shutter control (sequential shutter), a built-in fast charge/fast discharge circuit is

implemented in the shutter control block (OUT7, OUT8).