MIC4826
Micrel
MIC4826
Low Input Voltage, 160V
PP
Output Voltage, EL Driver
General Description
Micrel’s MIC4826 is a high output voltage, DC to AC converter,
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 MIC4826 converts
a low voltage DC input to a 160V
PP
AC output signal that
drives the EL lamp.
The MIC4826 is comprised of two stages: a boost stage, and
an H-bridge, lamp driver, stage. The boost stage steps the
input voltage up to +80V. The H-bridge stage then alternately
switches the +80V output to each terminal of the EL lamp,
thus creating a 160V
PP
AC signal to drive the EL lamp and
generate light.
The MIC4826 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 MIC4826 uses a single inductor and a minimum number
of external components, making it ideal for portable, space-
sensitive applications.
The MIC4826 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
160V
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
Standard
Pb-Free
MIC4826BMM
Temp. Range
–40°C to +85°C
Package
MSOP-8
MIC4826YMM
Typical Application
L1
220µH
MIC4826
1
442k
2M
VDD
RSW
REL
GND
SW
CS
VA
VB
5
6
8
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
March 2009
1
V
A
Ð V
B
(50V/div)
7
V
B
(50V/div)
C
IN
10µF
C
OUT
0.01µF/100V
V
A
(50V/div)
V
IN
D1
BAV19WS
V
IN
= 3.0V
L = 220µH½
C
OUT
= 0.01µF
Lamp = 2in
2
½
R
SW
= 332k½
R
EL
= 3.32M
MIC4826
MIC4826
Micrel
Pin Configuration
VDD 1
RSW 2
REL 3
GND 4
8 VA
7 VB
6 CS
5 SW
8-Pin MSOP Package (MM)
Pin Description
Pin Number
1
2
Pin Name
VDD
RSW
Pin Function
Supply (Input): 1.8V to 5.5V for internal circuitry.
Switch 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 shutdown 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 to the output ca-
pacitor 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
MIC4826
2
March 2009
MIC4826
Micrel
Absolute Maximum Rating
(Note 1)
Supply Voltage (V
DD
).......................................–0.5V to +6V
Output Voltage (V
CS
) ...................................–0.5V to +100V
Frequency Control Voltage (V
RSW
, V
REL
) ... –0.5V to (V
DD
+ 0.3V)
Power Dissipation @ T
A
= 85°C ..............................
200mW
Storage Temperature (T
S
) ........................ –65°C to +150°C
ESD Rating
..............................................................
Note 3
Operating Ratings
(Note 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
Package Thermal Resistance
8-pin MSOP
(θ
JA
) ..............................................
206°C/W
Electrical Characteristics
V
IN
= V
DD
= 3.0V, R
SW
= 560KΩ,
R
EL
= 1.0MΩ. T
A
= 25°C unless otherwise specified.
Bold
values indicate
-40°C
≤ T
A
≤ +85°C
Symbol
R
DS(ON)
V
CS
Parameter
Condition
Min
75
73
150
146
V
DD
–0.5
160
Typ
3.8
80
Max
7.0
85
87
170
174
0.5
0.01
21
200
28
285
53
360
66
90
435
79
0.1
0.5
75
400
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 4
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
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended.
Shutdown current is defined as the sum of current going into pin 1, 5, and 6 when the device is disabled.
Units
Ω
V
V
V
V
V
V
µA
µA
µA
µA
mA
Hz
kHz
%
V
DD
= 1.8V to 5.5V
V
DD
= 1.8V to 5.5V
V
DD
= 1.8V to 5.5V
I
SW
= 100 mA, V
CS
= 75V
V
A
– V
B
V
EN-L
I
SD
V
EN-H
R
SW
= LOW; R
EL
= LOW;
V
DD
= 5.5V
R
SW
= HIGH; R
EL
= HIGH;
V
CS
= 75V; V
A
, V
B
OPEN
V
DD
= 1.8V to 5.5V
I
VDD
I
CS
I
IN
f
EL
D
R
SW
= HIGH; R
EL
= HIGH;
V
CS
= 75V; V
A
, V
B
OPEN
V
IN
= V
DD
= 1.8V
(See Test Circuit)
f
SW
Note 1.
Note 2.
Note 3.
Note 4.
Test Circuit
V
IN
L1
220µH
MIC4826
1
D1
BAV19WS
C
OUT
0.01µF/100V
5
6
8
7
C
IN
10µF
442k
2M
VDD
RSW
REL
GND
SW
CS
VA
VB
2
3
4
100Ω
10nF
March 2009
3
MIC4826
MIC4826
Micrel
Typical Characteristics
Total Input Current
vs. Input Voltage
R
SW
50
INPUT CURRENT (mA)
45
40
35
30
25
20
15
10
5
0
0
= 562k, R
EL
= 1M
50
INPUT CURRENT (mA)
Total Input Current
vs. Temperature
R = 562k
45
SW
R
EL
= 1M
40
35
30
25
20
200
Output Voltage
vs. Input Voltage
R
= 442k
EL
V
A
–V
B
(V
PP
)
R
= 442k
SW
R = 2M
R
SW
= 442k
R
EL
= 2M
180
R
SW
= 2M
EL
160
140
120
R
SW
= 562k
R
EL
= 1M
R
= 332k
SW
R = 3.32M
EL
Lamp =
L = 220µH
D = BAV19WS
C
= 0.1µF
OUT
2in
2
1
2
3
4
5
INPUT VOLTAGE (V)
6
V = 3.0V
15
IN
Lamp = 2in
2
10 R = 332k
SW
L = 220µH
D = BAV19WS
5 R = 3.32M
EL
C
OUT
= 0.1µF
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
100
R = 332k
SW
80
R
EL
= 3.32M
60
40
Lamp = 2in
2
L = 220µH
D = BAV19WS
C
= 0.1µF
OUT
20
0
1
2
3
4
5
INPUT VOLTAGE (V)
6
OUTPUT VOLTAGE (V
PP
)
200
180
Output Voltage
vs. Temperature
100
90
80
70
60
50
40
Output Voltage Regulation
vs. Input Voltage
R
= 442k
SW
R = 2M
EL
100
90
CS Voltage
vs. Temperature
160
140 R = 332k
R
SW
= 442k
SW
120 R = 3.32M
R
EL
= 2M
EL
100
R
SW
= 562k
80
V = 3.0V
R
EL
= 1M
IN
60
40
L = 220µH
C
OUT
= 0.1µF
20
D = BAV19WS
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Lamp = 2in
2
V
CS
(V)
R
SW
= 562k
R = 1M
EL
R
= 332k
SW
R = 3.32M
EL
30
20
10
0
1
Lamp = 2in
2
L = 220µH
C
OUT
= 0.01µF
2
3
4
5
INPUT VOLTAGE (V)
6
80
70 R = 332k
SW
R
SW
= 442k
60 R
EL
= 3.32M
R
EL
= 2M
50
40
R
SW
= 562k
V = 3.0V
IN
30
R
EL
= 1M
Lamp = 2in
2
20
L = 220µH
C
OUT
= 0.1µF
10
D = BAV19WS
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
5
4
3
2
1
0
1
2
3
4
5
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
V
CS
(V
AVG
)
10000
EL Frequency
vs. EL Resistor
1000
10
100
1
100
1000
10000
SWITCH RESISTOR (kΩ)
10
0.1
1
EL RESISTOR (MΩ)
10
SWITCHING FREQUENCY (Hz)
120
100
80
60
40
20
0
1
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
1
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
2
3
4
5
INPUT VOLTAGE (V)
6
V
IN
= 3.0V
2
3
4
5
INPUT VOLTAGE (V)
6
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
MIC4826
4
March 2009
MIC4826
Micrel
400
350
FREQUENCY (KHz)
300
250
200
150
100
50
EL Frequency
vs. Temperature
R
SW
=1M
OUTPUT VOLTAGE (V
PP
)
180
160
140
120
100
80
60
40
20
0
0
1
Output Voltage
vs. Lamp Size
INPUT CURRENT (mA)
R
SW
= 332k
R
EL
= 3.32M
20
18
16
14
12
10
8
6
4
2
0
0
Total Input Current
vs. Lamp Size
R
SW
= 332k
R
EL
= 3.32M
R
SW
= 2M
R
SW
= 3.32M
V
IN
= 3.0V
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
V
IN
= 3.0V
L = 220µH
C
OUT
= 0.1µF
D = BAV19WS
2
3
4
5
6
LAMP SIZE (sq. in.)
7
V
IN
= 3.0V
L = 220µH
D = BAV19WS
C
OUT
= 0.1µF
1
2
3
4
5
6
LAMP SIZE (sq. in.)
7
March 2009
5
MIC4826
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