CPC6826 Datasheet, PDF (10/12 Pages) Clare, Inc. – High Voltage EL Lamp Driver

CPC6826
4.3 Switch Oscillator Frequency
An external resistor connected between pin 2, R_SW,
and pin 1, V_DD, controls the frequency of the Switch
Oscillator. Switching frequency increases as the
resistor value decreases. For resistor value selections,
please refer to the typical characteristics graph:
Switching Frequency vs. Switch Resistor. Note
that switch accuracy is +/-20% due to the internal RC
network.
CPC6826
Switching Frequency
vs. Switch Resistor
1000
100
10
1
100
1000
10000
4.4 Switcher Duty Cycle
Clare’s CPC6826 driver is designed to generate a
fixed duty cycle with a nominal 88% on-time. In
addition, this circuit generates an adjustable converter
frequency via R_SW to turn on and off the high voltage
power MOSFET. This drive method helps to eliminate
RFI that can cause problems in portable wireless
devices. The waveform on pin 5 (L_X) shows a typical
switch oscillator frequency of 79.6KHz.
CH1: 50V/Div
Time: 2μs/Div
Frequency = 79.6KHz
RSW = 560KΩ
REL = 1MΩ
LX = 220μH
EL Lamp = 1.6 in2
10
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