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, Inc.
MIC4827
Ordering Information
Part Number
Standard
MIC4827BMM
Pb-Free
MIC4827YMM
–40° to +85°C
8-Pin MSOP
Ambient Temp. Range
Package
Pin Configuration
8-Pin MSOP (MM)
Pin Description
Pin Number
1
2
Pin Name
VDD
RSW
Pin Function
Supply (Input): 1.8V to 5.5V.
Switcher Resistor (External Component): Set switch frequency of the internal
power MOSFET by connecting an external resistor to VDD. Connecting the
external resistor to GND disables the switch oscillator and shuts down the
device.
EL Resistor (External Component): Set EL frequency of the internal H-bridge
driver by connecting an external resistor to VDD. Connecting the external
resistor to GND disables the EL oscillator.
Ground Return.
Switch Node (Input): Internal high-voltage power MOSFET drain.
Regulated Boost Output (External Component): Connect the output capacitor of
the boost regulator and connect to the cathode of the diode.
EL Output: Connect to one end of the EL lamp. Polarity is not important.
EL Output: Connect to the other end of the EL lamp. Polarity is not important.
3
REL
4
5
6
7
8
GND
SW
CS
VB
VA
July 2009
2
M9999-070709-A
(408) 955-1690
Micrel, Inc.
MIC4827
(1)
Absolute Maximum Ratings
Operating Ratings
(2)
Supply Voltage (V
DD
).................................... +1.8V to +5.5V
Lamp Drive Frequency (f
EL
) ....................... 60Hz to 1000Hz
Switching Transistor Frequency (f
SW
) ........8KHz to 200KHz
Ambient Temperature (T
A
) .......................... –40°C to +85°C
Junction Thermal Resistance
PDIP (θ
JA
) ........................................................206°C/W
Supply Voltage (V
DD
)............................................–0.5 to 6V
Output Voltage (V
CS
) ........................................–0.5 to 100V
Freq. Control Voltage (V
RSW
, V
REL
)....... –0.5 to (V
DD
+ 0.3V)
Power Dissipation @ T
A
= 85°C ..............................200mW
Storage Temperature (T
s
) .........................–65°C to +150°C
EDS Rating
(3)
Electrical Characteristics
(4)
V
IN
= V
DD
= 3.0V; R
SW
= 560KΩ; R
EL
= 1.0MΩ; T
A
= 25°C,
bold
values indicate –40°C< T
A
< +85°C, unless noted.
Symbol
R
DS(ON)
V
CS
V
A
– V
B
V
EN-L
V
EN-H
I
SD
I
VDD
I
CS
I
IN
f
EL
f
SW
D
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended.
4. Specification for packaged product only.
5. Shutdown current is defined as the sum of current going into pin 1, 5, and 6 when the device is disabled.
Parameter
On-resistance of switching
transistor
Output voltage regulation
Output peak-to-peak voltage
Input low voltage (turn-off)
Input high voltage (turn-on)
Shutdown current,
Note 5
Input supply current
Boosted supply current
Input current including inductor
current
V
A
– V
B
output drive frequency
Switching transistor frequency
Switching transistor duty cycle
Condition
I
SW
= 100mA, V
CS
= 85V
V
DD
= 1.8V to 5.5V
V
DD
= 1.8V to 5.5V
V
DD
= 1.8V to 5.5V
V
DD
= 1.8V to 5.5V
R
SW
= LOW; R
EL
= LOW;
V
DD
= 5.5V
R
SW
= HIGH; R
EL
= HIGH;
V
CS
= 85V; V
A
, V
B
OPEN
R
SW
= HIGH; R
EL
= HIGH;
V
CS
= 85V; V
A
, V
B
OPEN
V
IN
= V
DD
= 1.8V
(See Test Circuit)
Min
Typ
3.8
Max
7.0
95
97
190
194
0.5
Units
Ω
V
V
V
V
V
V
85
83
170
166
V
DD
–
0.5
90
180
0.01
21
200
28
285
53
360
66
90
0.1
0.5
75
400
µA
µA
µA
µA
mA
435
79
Hz
kHz
%
July 2009
3
M9999-070709-A
(408) 955-1690
Micrel, Inc.
MIC4827
Test Circuit
V
IN
C
IN
10µF
1
L1
220µH
D1
BAV20WS
C
OUT
0.033µF/100V
5
6
8
7
MIC4827
562k
VDD
RSW
REL
GND
SW
CS
VA
VB
2
3.32M
3
4
10nF
July 2009
4
M9999-070709-A
(408) 955-1690
Micrel, Inc.
MIC4827
Typical Characteristics
5
4
3
2
1
0
1
2
345
INPUT VOLTAGE (V)
6
100
EL FREQUENCY (Hz)
6
SWITCHING FREQUENCY (kHz)
7
SWITCH RESISTANCE (
Ω)
Switch Resistance
vs. Input Voltage
1000
Switching Frequency
vs. Switch Resistor
10000
EL Frequency
vs. EL Resistor
1000
10
100
1
100
100
0
10000
SWITCH RESISTOR (k
Ω)
10
0.1
1
EL RESISTOR (M
Ω)
10
SWITCHING FREQUENCY (Hz)
120
100
80
60
40
20
Switching Frequency
vs. Input Voltage
R
SW
= 332k
R
SW
= 442k
R
SW
= 562k
400
350
EL FREQUENCY (Hz)
300
250
200
150
100
50
0
12345
EL Frequency
vs. Input Voltage
120
FREQUENCY (KHz)
100
80
60
40
20
Switching Frequency
vs. Temperature
R
SW
= 332k
R
SW
= 442k
R
SW
= 562k
R
EL
= 1M
R
EL
= 2M
R
EL
= 3.32M
6
INPUT VOLTAGE (V)
0
12345
INPUT VOLTAGE (V)
6
V
IN
= 3.0V
0
-40 -20 0 20 40 60 80 100
TEMPERATURE
°C)
(
July 2009
5
M9999-070709-A
(408) 955-1690
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