Supertex inc.
High Voltage Dual EL Lamp Driver
Features
Independent input control for lamp selection
Split supply capability
Patented output timing
One miniature inductor to power both lamps
Low shutdown current
Wide input voltage range 2.0V to 5.8V
Output voltage regulation
No SCR output
Available in small packages (10-lead MSOP and
10-lead DFN/MLP)
HV841
Initial Release
General Description
The Supertex HV841 is a high voltage driver designed for driving
two EL lamps with a combined area of 3.5 square inches. The input
supply voltage range is from 2.0V to 5.8V. The device is designed to
reduce the amount of audible noise emitted by the lamp. This device
uses a single inductor and minimum number of passive components
to drive two EL lamps. The nominal regulated output voltage of
±100V is applied to the EL lamps. The chip can be enabled/ disabled
by connecting C
1
and C
2
(pins 1 and 4) to V
EN
/ Ground.
The HV841 has an internal oscillator, a switching MOSFET, and two
high voltage EL lamp drivers. An external resistor connected between
the R
SW-OSC
and the voltage supply pin V
DD
sets the frequency for the
switching MOSFET. The EL lamp driver frequency is set by dividing
the MOSFET switching frequency by 128. An external inductor is
connected between the L
X
and the V
DD
pins. Depending on the EL
lamp size, a 1.0 to 10.0nF, 200V capacitor is connected between C
S
and Ground. The two EL lamps are connected between EL
1
to Com
and EL
2
to Com.
The switching MOSFET charges the external inductor and discharges
it into the capacitor at C
S
. The voltage at C
S
increases. Once the
voltage at C
S
reaches a nominal value of 100V, the switching
MOSFET is turned off to conserve power. The outputs EL
1
to Com
and EL
2
to Com are configured as H bridges and switch in opposite
states to achieve 200V across the EL lamp.
Applications
Mobile cellular phones, dual display
Keypad and LCD backlighting
Portable instrumentation
Dual segment lamps
Hand held wireless communication devices
Typical Application Circuit
V
EN
= ON
0 = OFF
V
EN
= ON
0 = OFF
1
EL Lamp 1
1
C
1
V
DD
EL
1
EL
2
10
9
8
7
6
+
V
DD
-
C
DD
R
SW-OSC
2
3
4
5
R
SW-OSC
Com
C2
GND
C
S
L
X
EL Lamp 2
1
D
V
IN
+
C
IN
-
HV841MG-G/
HV841K6-G
~
L
X
C
S
1 The bigger sized lamp should be tied to EL1 and the smaller
sized lamp to EL2 terminals (pins 10 and 9 respectively)
NR033106
Supertex inc.
·
1235 Bordeaux Drive, Sunnyvale, CA 94089
·
Tel: (408) 222-8888
·
FAX: (408) 222-4895
·
www.supertex.com
1
HV841
Ordering Information
Package Options
DEVICE
DFN/MLP-10
1
HV841
HV841K6-G
MSOP-10
2
HV841MG-G
Absolute Maximum Ratings*
Supply Voltage, V
DD
Supply Voltage, V
CS
Operating Ambient Temperature Range
Storage Temperature Range
-0.5 to +7.5V
-0.5 to +120V
-40°C to +85°C
-65° to +150°C
1 Product supplied on 3000 piece carrier tape reels only
2 Product supplied on 2500 piece carrier tape reels only
-G indicates package is RoHS compliant (‘Green’)
*Absolute Maximum Ratings are those values beyond which damage to the
device may occur. Functional operation under these conditions is not implied.
Continuous operation of the device at the absolute rating level may affect
device reliability. All voltages are referenced to device ground, Gnd
Recommended Operating Conditions
Symbol
V
DD
T
A
Parameter
Supply Voltage
Operating Temperature
Min
2.0
-40
Typ
Max
5.8
85
Units
V
o
Conditions
C
Function Table
C
1
0
0
1
1
C
2
0
1
0
1
EL
1
Hi Z
Hi Z
ON
ON
EL
2
Hi Z
ON
Hi Z
ON
Com
Hi Z
ON
ON
ON
IC
OFF
ON
ON
ON
Pin Configuration
Pin1
C
1
1
10 EL
1
9
EL
2
8
Com
7
C
S
6
L
X
V
DD
2
R
SW-OSC
3
C
1
V
DD
R
SW-OSC
C
2
GND
HV841K6-G
EL
1
EL
2
COM
C
S
L
X
C
2
4
GND
5
HV841MG-G
(Pads are on the bottom of the package.)
Top View: MSOP-10
Top View: DFN/MLP-10
Note: Packages are not drawn to scale.
2
NR033106
Electrical Characteristics
DC Characteristics
(Over operating conditions unless otherwise specified, T = 25°C)
A
HV841
Min
-
2.0
90
180
-
Symbol Parameter
R
DS(ON)
V
DD
V
CS
V
DIFF
I
DDQ
I
DD
f
EL
f
SW
D
I
IL
I
IH
V
EN-L
V
EN-H
On-resistance of switching transistor
Input Voltage Range
Output regulation voltage
Differential output peak to peak voltage
(EL
1
to Com, EL
2
to Com)
Quiescent V
DD
supply current
Input current into the V
DD
pin
V
DIFF
output drive frequency
Switching transistor frequency
Switching Transistor Duty cycle
Input logic low current going into the
control pin
Input logic low current going into the
control pin
Logic input low voltage
Logic input high voltage
Typ
-
-
100
200
-
-
Max
6.0
5.8
110
220
150
500
190
Units
Ω
V
V
V
nA
nA
µA
Hz
kHz
%
µA
µA
V
V
Conditions
I = 100mA
---
V
DD
= 2.0V to 5.8V
V
DD
= 2.0V to 5.8V
C
1
= C
2
= 0 to 0.1V
C
1
= C
2
= 0.1 to 0.3V
V
DD
= 2.0V to 5.8V
V
IN
= 3.0V. See Figure 1.
V
IN
= 3.0V. See Figure 1.
---
V
DD
= 2.0V to 5.8V
V
DD
= 2.0V to 5.8V
---
---
-
-
215
27.5
85
-
-
0
1.5
244
31.2
-
-
-
-
-
273
34.9
89
-0.6
0.6
0.3
V
DD
Thermal Resistance
(Mounted on FR4 board, 25mm x 25mm x 1.57mm)
Package
MSOP-10
DFN/MLP-10
θ
JA
400
o
C/W
60
o
C/W
3
NR033106
Functional Block Diagram
V
DD
Lx
HV841
C
1
C
2
R
SW-OSC
C
S
Control Logic
& Switch-Osc
V
SENSE
Output
Drivers
Vcs
EL
1
+
Vcs
GND
Disable
Logic Control &
Divide by 128
Figure 1: Test Circuit
V
EN
= ON
V
EN
= ON 0 = OFF
0 = OFF
EL Lamp 1 (1.9 in
2
)
3
1
2
C
1
V
DD
+
V
DD
-
470 kΩ
0.1µF
3
4
5
R
SW-OSC
Com
C
2
GND
C
S
L
X
V
IN
+
HV841MG-G/
HV841K6-G
4.7µF
-
1 or any (equivalent or better)
>
120V, fast recovery diode
2 Murata LQH4CN331K04
3 The bigger sized lamp should be tied to EL1 and the smaller
sized lamp to EL2 terminals (pins 10 and 9 respectively)
-
V
REF
EL
1
EL
2
10
9
8
7
6
EL
2
COM
EL Lamp 2 (1.6 in
2
)
3
BAS21
1
~
330µH
2
3.3 nF, 200V
4
NR033106
HV841
Pin Configuration and Description
Pin #
1
2
Name
C
1
V
DD
Function
Enable input signal for EL lamp 1. Logic high will turn ON the EL lamp 1 and logic low will turn it OFF. Refer to the
Function Table.
Input supply voltage pin.
External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency. The external
resistor should be connected between this pin and the V
DD
pin. The EL lamp frequency is switching frequency
divided by 128.
3
R
SW-OSC
The switching frequency increases as the value of R
SW-OSC
decreases. A 470kΩ resistor will provide a switching
frequency of 31.2 kHz, and an EL lamp frequency of 244 Hz. To change the frequency to f
SW1
, the value of the
resistor R
SW-OSC1
can be determined as R
SW-OSC1
= (470k x 31.2k) / f
SW1
.
4
5
C
2
GND
Enable input signal for EL lamp 2. Logic high will turn ON the EL lamp 2 and logic low will turn it OFF. Refer to the
Function Table.
IC Ground Pin.
External inductor connection to boost the low input voltage using inductive flyback. Connect an inductor
between V
IN
and this pin. Also connect a high voltage fast recovery diode between this pin and the C
S
pin. The anode of the diode needs to be connected to the L
X
pin and the cathode to the C
S
pin. In general,
small valued inductors, which can handle more current, are more suitable for driving large sized lamps.
As the inductor value decreases, the switching frequency should be increased to avoid saturation.
When the switching MOSFET is turned ON, the inductor is being charged. When the MOSFET is turned OFF, the
energy stored in the inductor is transferred to the high voltage capacitor connected at the C
S
pin.
6
L
X
7
8
9
10
C
S
Com
EL
2
EL
1
Connect a 200V capacitor between this pin and GND. This capacitor stores the energy transferred from the
inductor.
Common connection for both EL lamps. Connect one end of both the lamps to this pin.
EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected to this pin.
EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected to this pin.
5
NR033106
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