imp803 ETC-unknow, imp803 Datasheet - Page 4

• Manufacturer Part Number: imp803
• Description: High-voltage Lamp Driver
• Manufacturer: ETC-unknow

The IMP803 generates high voltages and caution should
be exercised.
4
Pin Descriptions
External Components
High Voltages Present
I M P 8 0 3
I M P 8 0 3
Resistor R
Capacitor C
Resistor R
Lamp, R
Inductor L
1
2
3
4
5
6
7
8
Diode
CL
SW
EL
S
R
R
GND
SW-OSC
EL-OSC
V
C
L
V
V
DD
X
A
S
B
Catch diode. A fast reverse recovery diode, with BV > 100, such as a 1N4148.
This is the high voltage capacitor that stores the inductive energy transferred through the
catch diode. A 100 volt capacitor between 10nF and 100nF is recommended.
The EL lamp oscillator frequency setting resistor. This resistor, connected between the
R
as R
Lamp color is also determined by this frequency. A 2MΩ resistor between the R
V
Switching Oscillator frequency setting resistor. The switching oscillator resistor is connected
between the R
to the resistor value, dropping as the resistance increases.
The inductor provides the voltage boost needed by means of inductive “flyback”. The internal
MOSFET switch alternately opens and closes the ground connection for the inductor at the
L
diode and the current will pass through the storage capacitor C
Smaller inductors are preferred to prevent saturation. As the value of the inductor
increases (and the series DC resistance of the inductor decreases), the switching frequency
set by R
can handle more current are more desirable when larger area EL lamps must be driven.
An external resistor (R
currents during lamp commutation.
X
DD
EL-OSC
pin. When this internal switch opens, the inductor potential will forward-bias the catch
supply results in a lamp frequency around 350Hz: a 1MΩ resistor will give ≈700Hz.
EL
increases, the EL lamp frequency decreases along with the current drawn by the lamp.
pin and V
SW
Positive voltage supply for the IMP803. Inductor L may be connected here or to a
separate unregulated supply.
Switch-mode resistor pin. Switching frequency is determined by an external resistor, R
Boost converter storage capacitor. The voltage across the EL lamp is equal to twice the
voltage at C
Connection to flyback inductance, L.
Ground pin.
EL lamp drive. The lamp is connected in a high-voltage bridge circuit with V
the complementary connection to V
thus two times V
EL lamp drive. (See above)
The EL lamp oscillator frequency setting pin. The oscillator frequency is controlled
by external resistor R
should be increased to prevent saturation. In general, smaller value inductors that
SW-OSC
408-432-9100/www.impweb.com
DD
, provides an oscillator frequency inversely proportional to R
S
pin and the V
.
CL
) in series with the lamp will protect the output drivers from high transient
CS
.
EL
.
DD
supply. The switching frequency is inversely proportional
A
. The peak-to-peak AC voltage across the EL lamp is
S
, charging it to a high voltage.
EL-OSC
EL
;
B
© 2000 IMP, Inc.
providing
pin and the
SW
.