D365A Datasheet, PDF (10/12 Pages) List of Unclassifed Manufacturers – Electroluminescent Lamp Driver IC

IV. Controlling EL Brightness Through Clock Pulse Width Modulation
Pulse-width modulation of an external clock signal that controls the inductor oscillating frequency may also be used to
regulate the brightness of an EL lamp. In this circuit, when the positive duty cycle of the external clock is at 25%, the
lamp is at full brightness. Incremental dimming occurs as the positive duty cycle is increased to as high as 75%. This
scheme may also be used inversely to regulate lamp brightness over the life of the battery or to compensate for lamp
aging. In these cases, positive duty cycle may be incrementally increased as part of a feedback control in the application.
(Note: Operation at duty cycles higher than 75% or lower than 25% is not recommended.)
L
1.0V Min
0.2V Max
pnp transistor
V+
HF CLK
0.1 µF V+
1 L+
L- 8
2 BASE VOUT 7
3 CHF
GND 6
4 V+ _D365
E5
ON
OFF
EL Lamp
V. Two-Level Dimming Control
Two level dimming may be achieved with the circuit below. When DIM is low, the external PNP transistor is saturated
and the EL lamp runs at full brightness. When DIM is high, the external PNP turns off and the 47Ω resistor reduces the
voltage at (V+) and dims the EL lamp.
L
pnp transistor
V+
CHF
capacitor
0.1 µF
1 L+
L- 8
2 BASE VOUT 7
3 CHF
GND 6
4 V+ _D365
E5
ON
OFF
EL Lamp
47 Ω
1k_Ω
DIM
2N3906
V_bat
10