MIC4827
Micrel
MIC4827
Low Input Voltage, 180V
PP
Output Voltage, EL Driver
Final Information
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-cell
alkaline/NiCad/NiMH battery applications. The MIC4827 con-
verts 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
LCD panel backlight
Cellular phones
PDAs
Pagers
Calculators
Remote controls
Portable phones
Applications
Ordering Information
Part Number
MIC4827BMM
Ambient Temp. Range
–40°C to +85°C
Package
MSOP-8
Typical Application
C
OUT
0.033µF/100V
5
6
8
1
VDD
RSW
REL
GND
SW
CS
VA
VB
332k
3.32M
2
3
4
2in
2
EL LAMP
TIME (2ms/div)
High Voltage EL Driver
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
September 2001
1
V
A
— V
B
(50V/div)
7
V
B
(50V/div)
C
IN
10µF
MIC4827
V
A
(50V/div)
V
IN
L1
220µH
D1
1N4148
MIC4827