MIC4827
Low Input Voltage, 180V
PP
Output Voltage,
EL Driver
General Description
Micrel’s MIC4827 is a high output voltage, DC to AC con-
verter, designed for driving EL (Electroluminescent) lamps.
The device operates from an input voltage range of 1.8V to
5.5V, making it suitable for 1-cell Li-Ion and 2- or 3-
cellalkaline/NiCad/NiMH
battery
applications.
The
MIC4827 converts a low voltage DC input to a 180V
PP
AC
output signal that drives the EL lamp.
The MIC4827 is comprised of two stages: a boost stage,
and an H-bridge, lamp driver, stage. The boost stage steps
the input voltage up to +90V. The H-bridge stage then
alternately switches the +90V output to each terminal of
the EL lamp, thus creating a 180V
PP
AC signal to drive the
EL lamp and generate light.
The MIC4827 features separate oscillators for the boost-
and H-bridge stages. External resistors independently set
the operating frequency of each stage. This flexibility
allows the EL lamp circuit to be optimized for maximum
efficiency and brightness.
The MIC4827 uses a single inductor and a minimum
number of external components, making it ideal for
portable, space-sensitive applications.
The MIC4827 is available in an 8-pin MSOP package with
an ambient temperature range of –40°C to +85°C.
Features
•
1.8V to 5.5V DC input voltage
•
180V
PP
regulated AC output waveform
•
Independently adjustable EL lamp frequency
•
Independently adjustable boost converter frequency
•
0.1µA shutdown current
Applications
•
LCD panel backlight
•
Cellular phones
•
PDAs
•
Pager
•
Calculators
•
Remote controls
•
Portable phones
Typical Application
V
B
V
A
(50V/div) (50V/div)
V
A—
V
B
(50V/div)
V
IN
C
IN
10µF
1
L1
220µH
D1
BAV20WS
C
OUT
0.033µF/100V
5
6
8
7
MIC4827
332k
3.32M
VDD
RSW
REL
GND
SW
CS
VA
VB
2
3
4
TIME (2ms/div)
2in
2
EL LAMP
High Voltage EL Driver
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2009
M9999-070709-A
(408) 955-1690
MICREL [ MICREL SEMICONDUCTOR ]
