January 2005

7

MIC4827

MIC4827

Micrel

EL Frequency

The EL lamp frequency is controlled via an external resistor

connected between REL pin and VDD pin of the device. The

lamp frequency increases the resistor value decreases. For

resistor value selections, see the “Typical Characteristics: EL

Frequency vs. EL Resistor” or use the equation below. The

switching frequency range is 60Hz to 1000Hz, with an accu-

racy of ±20%.

f

(Hz)

360

R(M )

EL

EL

=

Ω

TIME (2ms/div)

V

L = 220µH

C

R

R

Figure 3. 180Hz Output Waveform

In general, as the EL lamp frequency increases, the amount

of current drawn from the battery will increase. The color of

the EL lamp and the intensity are dependent upon its fre-

quency.

TIME (2ms/div)

Figure 4. 360Hz Output Waveform

Enable Function

The enable function of the MIC4827 is implemented by

switching the R

When R

the EL oscillators are disabled; therefore the EL driver be-

comes disabled. When these resistors connect to V

the oscillators will function and the EL driver is enabled.