MIC4834
Low Noise Dual 220 V
PP
EL Driver
General Description
The MIC4834 is a low noise dual Electroluminescent (EL)
Panel driver used in backlighting applications. The
MIC4834 converts a low DC voltage to a high DC voltage
using a boost converter and then alternates the high DC
voltage across the EL panels using an H-bridge. The
MIC4834 incorporates internal wave-shaping circuitry
specifically designed to reduce audible noise emitted by
EL panels. With only one inductor the MIC4834 can drive
two outputs and requires a minimum number of passive
components. It features an operating input voltage range
of 2.3V to 5.8V, making it suitable for 1-cell Li-ion and 2- or
3-cell alkaline/NiCad/NiMH battery applications.
The MIC4834 features separate oscillators for the boost
and H-bridge stages. The boost frequency may be
adjusted with an external resistor to optimize efficiency
and brightness. The H-bridge frequency is internally preset
to 225Hz, to reduce the number of external components
and layout space.
The MIC4834 is available in 10 pin 3mmx3mm MLF
®
package as well as MSOP-10L, and has an operating
junction temperature range of –40°C to +125°C.
Features
•
•
•
•
•
•
•
•
•
Drives two EL panels, up to 3 in
2
each at full
brightness
220V
PP
regulated AC output waveform
2.3V to 5.8V DC input voltage
Wave-shaping circuit to reduce audible noise
Adjustable boost converter frequency
Single inductor to power both panels
0.1µA typical shutdown current
Package options
−
10-pin 3mmx3mm MLF
®
−
10-pin MSOP
–40
o
C to +125
o
C junction temperature range
Applications
•
•
•
•
•
•
•
Mobile phones
MP3/portable media players (PMP)
Clocks/ watches
Remote controls
Cordless phones
GPS devices
PDAs
_________________________________________________________________________________________________
Typical Application
Low Noise Dual EL Driver
MLF and MicroLead Frame are registered trademark of Amkor Technologies
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
October 2008
M9999-100808-A
Micrel
MIC4834
Ordering Information
Part Number
MIC4834YML
MIC4834YMM
Package
10 pin (3mm x 3mm) MLF
®
10-Pin MSOP
Operating Junction Temp Range
-40ºC to +125ºC
-40ºC to +125ºC
Lead Finish
Pb-free / RoHS-Compliant
Pb-free / RoHS-Compliant
Pin Configuration
®
10-Pin MLF - Top View
10-Pin MSOP – Top View
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
EPad
Pin Name
ENA
VDD
RSW
ENB
GND
SW
CS
COM
ELB
ELA
HS Pad
Pin Function
EL Panel A Enable Pin: Logic high enables ELA and logic low disables ELA output.
DC Input Supply Voltage: 2.3V to 5.8V
RSW pin: Sets internal boost converter switch frequency by connecting an external
resistor (R
SW
) to VDD. Connecting the R
SW
resistor to GND shuts down the device.
EL Panel B enable pin: Logic high enables ELB and logic low disables ELB output.
Ground.
Switch Node: Drain of internal high-voltage power MOSFET for boost circuit.
Regulated Boost Output: Connect to the output capacitor of the boost regulator and
to the cathode of the diode.
EL output: Common EL output terminal to both ELA and ELB. Connect one end of
each EL panel to this pin.
EL Panel B output: Connect the other end of the EL panel B to this pin.
EL Panel A output: Connect the other end of the EL panel A to this pin.
Heat Sink Pad. Connect to ground externally. MLF® package only.
October 2008
2
M9999-100908-A
Micrel
MIC4834
Absolute Maximum Rating
(1)
Supply voltage (V
DD
) ....................................... -0.5V to 6.5V
Output voltage (V
CS
)...................................... -0.5V to 130V
Switch Node (V
SW
) ......................................... -0.5V to 130V
Enable Voltage (V
RSW
, V
ENA,
V
ENB
)................... -0.5V to 6.5V
Ambient Storage Temperature (T
S
) ........... -65ºC to +150ºC
ESD Rating
(3) ...........................................................................
ESD Sensitive
Operating Range
(2)
Supply Voltage (V
DD
) ........................................2.3V to 5.8V
Switching MOSFET Frequency (f
SW
) ........ 35kHz to 350kHz
Enable Voltage (V
RSW
, V
ENA,
, V
ENB
) ....................... 0V to V
DD
Junction Temperature Range (T
J
) ............. -40°C to +125°C
Package Thermal Impedance
3mm x 3mm MLF
®
(θ
JA
)……………………........ 60°C/W
MSOP (θ
JA
)……………………......................... 206°C/W
Electrical Characteristics
(4)
T
A
= 25
o
C, V
DD
= 3.0V unless otherwise noted.
Bold
values indicate -40°C
≤
T
J
≤
85°C.
Symbol
V
DD
I
DD
I
SD
R
DS
(ON)
V
CS
Parameter
Supply Voltage Range
Input Supply Current
Shutdown Current
On-resistance Of Switching Transistor
Output voltage Regulation
V
RSW
= High; V
CS
= 105V;
ELA, ELB, COM = Open
V
RSW
= Low; V
DD
= 5.8V
I
SW
= 100mA, V
CS
= 105V
V
DD
= 2.3V to 5.8v
V
DD
= 3.0V
(R
SW
= 1.3MΩ )
f
Sw
Boost Switching Frequency
V
DD
= 3.0V
(R
SW
= 450kΩ)
V
DD
= 3.0V
(R
SW
= 125kΩ)
f
EL
D
I
OUT
V
ENA
,
V
ENB
V
HYS
I
ENA
,
I
ENB
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. Human body model, 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
Condition
Min
2.3
Typ
Max
5.8
Units
V
µA
µA
Ω
V
kHz
kHz
kHz
Hz
%
mA
V
mV
µA
152
0.1
6.0
90
25
75
250
165
80
2.5
0.4
20
50
0.1
5
109
35
100
350
225
220
1
12.0
120
45
125
450
285
95
7.5
1.2
150
1
ELA, ELB and COM Drive Frequency
Switching Transistor Duty Cycle
Output Current Drive Limit
Enable Logic Threshold
Enable Logic Hysteresis
Enable Input Current
V
DD
= 3.0V
ELA, ELB, COM = Open
October 2008
3
M9999-100908-A
Micrel
MIC4834
Typical Characteristics
Switching Frequency
vs SW Resistor
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
400
350
300
250
200
150
100
50
0
140
120
100
Recommended Switching
Frequency Vs. Total Lamp Size
INPUT CURRENT (mA)
40
35
30
25
20
15
10
5
f
SW
Total Input Current
vs. Input Voltage
f
EL
= 225Hz
= 2.2nF
= 94kHz
C
f
OUT
SW
80
60
40
20
0
0
1
2
3
4
5
2
Size = 2in
2
= 116kHz
2
200
400
600
800
1000
1200
1400
0
6
SWITCHING RESISTOR (kOhm)
TOTAL LAMP SIZE (in )
Size = 1in
0
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
60
INPUT CURRENT (mA)
55
50
45
40
35
30
25
f
SW
Total Input Current
vs. Input Voltage
f
EL
= 225Hz
INPUT CURRENT (mA)
= 2.2nF
C
90
85
80
75
70
65
60
Total Input Current
vs. Input Voltage
f
EL
= 225Hz
C
f
OUT
120
100
CS VOLTAGE (V)
80
60
40
f
CS Voltage
vs. Input Voltage
OUT
= 2.2nF
f
SW
= 62kHz
Size = 4in
2
SW
= 42kHz
2
Size = 6in
= 82kHz
2
Size = 3in
20
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
55
50 f = 50kHz
SW
45
Size = 5in
2
40
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
SW
= 45kHz
20 f
EL
= 225Hz
C
OUT
= 2.2nF
0
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
Output Voltage
vs. Input Voltage
240
OUTPUT VOLTAGE (V
P-P
)
200
BRIGHTNESS (lux)
160
120
80 f
= 45kHz
16
14
12
10
8
6
4
2
Brightness
vs. Input Voltage
SW
40 f
EL
= 225Hz
C
= 2.2nF
OUT
0
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
Distance = 2 in
f
SW
= 135kHz
f
EL
= 225Hz
L = 220µH
0
2 2.5 3 3.5 4 4.5 5 5.5 6
INPUT VOLTAGE (V)
October 2008
4
M9999-100908-A
Micrel
MIC4834
Functional Diagram
Figure 1. MIC4834 Block Diagram
Functional Description
Overview
The MIC4834 is a high-voltage dual output EL driver with
a peak-to-peak AC output voltage of 220V capable of
driving two 3 in
2
EL panels. The MIC4834 drives EL
panels by converting a low DC input voltage to a high
DC high output voltage using the boost regulator circuit
and then alternating the high DC voltage across the EL
panel using an H-Bridge. Input supply current for the
MIC4834 is typically 152µA. The high voltage EL driver
has two internal oscillators to control the boost switching
frequency and the H-bridge driver frequency. The
internal boost oscillator frequency can be individually
October 2008
5
programmed through an external resistor to maximize
efficiency and brightness of the EL panel. The H-bridge
frequency is internally fixed at 225Hz to reduce external
component count.
R
egulation
Referring to Figure 1, power is initially applied to V
DD
.
When the internal feedback voltage is less than the
reference voltage, the internal comparator enables
switching in the boost circuit. When the boost regulator
is switching, current flows through the inductor into the
switch. The switching MOSFET will typically turn on for
90% of the switching period. During the on-time, energy
M9999-100908-A
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