D372A Datasheet, PDF (9/12 Pages) List of Unclassifed Manufacturers – Electroluminescent Lamp Driver IC

D372 Design Ideas
I. Lamp Frequency Control With an External Clock Signal
An external clock signal may be used to control the EL lamp frequency (LF) by applying the clock signal to the CLF pin.
The oscillator frequency can be varied to synchronize the inverter with other elements in the application. An internal
divider network in the IC divides the clock signal by two. The recommended clocking frequencies range from 500Hz
to 1kHz and result in an EL lamp frequency range of 250Hz to 500Hz respectively. The amplitude of the clock signal
typically ranges from 1.0V to V+.
Vbat
0.1µ F
on
off
1 V+
LF CLK
1V ^50%DC
2 CLF
0V
3 CHF
CHF
4E
5 GND
Rd
Rd 10
EL2 9
EL1 8
Cs
Cs 7
L+ 6
L
D372A
EL Lamp
Vbat
II. Controlling EL Brightness Through Clock Pulse Width Modulation
An external clock signal may be used to control the inductor oscillating frequency (HF). Pulse width modulation of the
external clock signal may be used to regulate the brightness of an EL lamp. In this circuit, when the positive duty cycle
of the external clock is at 20%, the lamp is at full brightness. Incremental dimming occurs as the positive duty cycle is
increased to as high as 85%. This scheme may also be used inversely to regulate lamp brightness over the life of the
battery or to compensate for lamp aging. (Note: Operation at duty cycles higher than 85% and lower than 20% is not
recommended.) The recommended clocking frequency ranges from 10kHz to 24kHz, and the amplitude of the clock
signal typically ranges from 1.0V to V+.
Vbat
0.1µF
on
off
1 V+
CLF
2 CLF
1V
3 CHF
0V
HF CLK
4 ^{20%-85% +DC} _E
5 GND
Rd
Rd 10
EL2 9
EL1 8
Cs
Cs 7
L+ 6
D372A
L
EL Lamp
Vbat
10