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)
Applications
Mobile cellular phones, dual display
Keypad and LCD backlighting
Portable instrumentation
Dual segment lamps
Hand held wireless communication devices
General Description
The Supertex HV839 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 90V is applied to
the EL lamps. The two EL lamps can be turned ON
and OFF by the two logic input control pins, C
1
and
C
2
. The device is disabled when both C
1
and C
2
(pins 1 and 4) are at logic low.
The HV839 has an internal oscillator, a switching
MOSFET, and two high voltage EL lamp drivers. An
external resistor connected between the R
SW-OSC
pin
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, 100V 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 90V, 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 180V across the
EL lamp.
Typical Application Circuit
HV839
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HV839
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1 Product supplied on 3000 piece carrier tape reels only
2 Product supplied on 2500 piece carrier tape reels onl
y
G indicates package is RoHS compliant - "Green"
Pin Configuration
Ordering Information
Package Options
Device
DFN/MLP10
1
MSOP10
2
HV839 HV839K6-G HV839MG-G
Absolute Maximum Ratings*
Supply Voltage, V
DD
-0.5V to 7.5V
Output Voltage, V
CS
-0.5V to 120V
Operating Temperature Range
-40C to 85C
Storage temperature
-65C to 150C
*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 Parameter
Min Typ Max Units
Conditions
V
DD
Supply
Voltage
2.0 5.8 V
T
A
Operating
Temperature
-40 85 C
Function Table
C
1
C
2
EL
1
EL
2
Com IC
0
0
Hi Z
Hi Z
Hi Z
OFF
0 1
Hi
Z
ON
ON
ON
1 0 ON Hi
Z ON ON
1 1 ON ON ON ON
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Electrical Characteristics
DC Characteristics
(Over recommended operating conditions unless otherwise specified, T
A
= 25C)
Symbol Parameter
Min Typ Max Units Conditions
R
DS(ON)
On-resistance of switching
transistor
6.0
I = 100mA
V
DD
Input Voltage Range
2.0
5.8
V
Vcs
Output regulation voltage
80
90
100
V
V
DD
= 2.0V to 5.8V
V
DIFF
Differential output peak to peak
voltage (EL
1
to Com, EL
2
to Com)
160 180 200 V V
DD
= 2.0V to 5.8V
150
nA
C
1
= C
2
= 0 to 0.1V
I
DDQ
Quiescent
V
DD
supply current
500
nA
C
1
= C
2
= 0.1 to 0.3V
I
DD
Input current into the V
DD
pin
190
A
V
DD
= 2.0V to 5.8V
60
V
IN
= 3.0V, See Figure 1.
T
A
= -40
C to +85
C
I
IN
Input current including inductor
current when driving both lamps
45 53
mA
V
IN
= 3.0V, See Figure 1.
T
A
= +25
C
V
CS
Output voltage on V
CS
when
driving both lamps
76.2 V V
IN
= 3.0V. See Figure 1.
V
DIFF
Differential output peak to peak
voltage across each lamp (EL
1
to
Com, EL
2
to Com)
152.4
V V
IN
= 3.0V. See Figure 1.
f
EL
V
DIFF
output drive frequency
440
500
560
Hz
V
IN
= 3.0V. See Figure 1.
f
SW
Switching transistor frequency
56.3
64.0
71.7
kHz
V
IN
= 3.0V. See Figure 1.
f
SW Drift
Switching transistor frequency
drift
5.0
kHz
T
A
= -40
C to +85
C
D
Switching Transistor Duty cycle
85
89
%
I
IL
Input logic low current going into
the control pin
-0.6
A
V
DD
= 2.0V to 5.8V
I
IH
Input logic low current going into
the control pin
0.6
A
V
DD
= 2.0V to 5.8V
V
EN-L
Logic input low voltage
0
0.3
V
V
EN-H
Logic input high voltage
1.5
V
DD
V
Thermal Resistance
(Mounted on FR4 board, 25mm x 25mm x 1.57mm)
Package
ja
MSOP-10 400
C/W
DFN/MLP-10 60
C/W
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Functional Block Diagram
Figure 1: Test Circuit
Device Lamp
V
IN
= V
DD
I
IN
V
CS
f
EL
Brightness
EL1 29.6mA
85.8
13.68ft-lm
HV839MG-G
or
HV839K6-G
Both EL1 and EL2 ON
3.0V
45.0mA 76.2
500Hz
12.66ft-lm
Vcs
Vcs
Output
Drivers
Vsense
-
+
Vref
Control Logic
& Switch Osc
Disable
Logic Control &
Divide by 128
EL
1
EL
2
COM
R
SW-OSC
C
S
Lx
V
DD
C
1
C
2
GND
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Typical HV839 Performance Curves
(EL
1
Lamp = 1.3in
2
, EL
2
= Lamp = 0.93in
2
, V
DD
= 3.0V)
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Pin Configuration and Description
Pin #
Name
Function
1 C
1
Enable input signal for EL lamp 1. Logic high will turn ON the EL lamp 1 and logic low will
turn it OFF. Refer Function Table.
2 V
DD
Input supply voltage pin.
3 R
SW-OSC
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.
The switching frequency increases as the value of R
SW-OSC
decreases. A 220k
resistor will
provide a switching frequency of 64.0 kHz, and an EL lamp frequency of 500 Hz.
To change the frequency to f
EL1
, the value of the resistor R
SW-OSC1
can be determined as
R
SW-OSC1
= (220 x 500) / f
EL1
k
.
4 C
2
Enable input signal for EL lamp 2. Logic high will turn ON the EL lamp 2 and logic low will
turn it OFF. Refer Function Table.
5
GND
IC Ground Pin.
6 L
X
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.
7 C
S
Connect a 100V capacitor between this pin and GND. This capacitor stores the energy
transferred from the inductor.
8
Com
Common connection for both EL lamps. Connect one end of both the lamps to this pin.
9 EL
2
EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be
connected to this pin.
10 EL
1
EL lamp 1 connection. For optimum performance, the larger of the two lamps should be
connected to this pin.
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Split Supply Configuration
The HV839 can be used in applications operating from a battery where a regulated voltage is available. This is
shown in Figure 2. The regulated voltage can be used to drive the internal logic of HV839. The amount of current
used to drive the internal logic is less than 190
A. Therefore, the regulated voltage could easily provide the current
without being loaded down.
Figure 2: Split Supply Configuration
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Audible Noise Reduction
This section describes a method (patented) developed at Supertex to reduce the audible noise emitted by the EL
lamps used in application sensitive to audible noise. The waveform takes the shape of approximately 2RC time
constants for rising and 2RC time constants for falling, where C is the capacitance of the EL lamp, and R is the
external resistor, R
SER
connected in series with the EL lamp.
Figure 3 shows a general circuit schematic that uses the series resistors, R
SER1
and R
SER2
, for each of the EL lamps.
R
SER1
and R
SER2
are connected in series with the EL lamp. The audible noise can be set a desirable level by
selecting the resistances for R
SER1
and R
SER2
. It is important to note that addition of these external resistors will
reduce the voltage across the EL lamp, and hence the brightness of the EL lamp.
Figure 3: Typical Application Circuit For Audible Noise Reduction
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