Supertex inc.
Supertex inc.
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: (408) 222-8888
FAX: (408) 222-4895
www.supertex.com
1
NR040306
HV859
Initial Release
Features
Patented audible noise reduction
Patented lamp aging compensation
210 V
PP
output voltage for higher brightness
Patented output timing for high effi ciency
Single cell lithium ion compatible
150nA shutdown current
Wide input voltage range 1.8V to 5.0V
Separately adjustable lamp and converter
frequencies
Output voltage regulation
Split supply capability
Applications
LCD backlighting
Mobile Cellular Phone keypads
PDAs
Handheld wireless communication products
Global Positioning Systems (GPS)
General Description
The Supertex HV859 is a high voltage driver designed for
driving Electroluminescent (EL) lamps of up to 5 square
inches. The input supply voltage range is from 1.8V to 5.0V.
The device uses a single inductor and a minimum number of
passive components. The nominal regulated output voltage
that is applied to the EL lamp is 105V. The chip can be
enabled/disabled by connecting the resistor on R
SW-OSC
to V
DD
/
ground.
The HV859 has two internal oscillators, a switching MOSFET,
and a high voltage EL lamp driver. The frequency for the
switching MOSFET is set by an external resistor connected
between the R
SW-OSC
pin and the supply pin V
DD
. The EL lamp
driver frequency is set by an external resistor connected
between R
EL-OSC
pin and the V
DD
pin. An external inductor is
connected between the L
X
and V
DD
pins or V
IN
for split supply
applications. A 0.003-0.1F capacitor is connected between
C
S
and ground. The EL lamp is connected between V
A
and
V
B
.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at C
S
. The voltage at C
S
will start
to increase. Once the voltage at C
S
reaches a nominal value
of 105V, the switching MOSFET is turned OFF to conserve
power. The outputs V
A
and V
B
are confi gured as an H bridge
and are switching in opposite states to achieve 105V across
the EL lamp.
Typical Application Circuit
High Voltage EL Lamp Driver for Low Noise Applications
1
2
3
4
8
7
6
5
V
DD
R
SW-osc
V
B
R
EL-osc
GND
V
A
L
X
C
S
D
+
-
+
-
V
DD
V
IN
C
DD
C
IN
R
SW
R
EL
C
S
R
SER
HV859MG/
HV859K7
L
X
EL Lamp
Enable
ON = V
DD
OFF = 0V
2
NR040306
HV859
Ordering Information
Device
Package Options
MSOP-8
1
DFN/MLP-8
2
HV859
HV859MG-G
HV859K7-G
1. Product supplied on 2,500 piece carrier tape reels only
2. Product supplied on 3,000 piece carrier tape reels only
-G indicates package is RoHS compliant (`Green')
Absolute Maximum Ratings*
V
DD
, Supply Voltage
-0.5V to 6.5V
Operating Temperature
-40C to +85C
Storage Temperature
-65C to +150C
Power Dissipation MSOP-8
300mW
Power Dissipation DFN/MLP-8
1.6W
V
CS
, Output Voltage
-0.5V to +130V
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Electrical Characteristics
DC Characteristics
(Over recommended operating conditions unless otherwise specifi ed V
IN
= V
DD
= 3.3V, T
A
=25C)
*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.
Pin Confi guration
1
2
3
4
8
7
6
5
V
DD
R
SW-OSC
R
EL-OSC
GND
1
2
3
4
8
7
6
5
MSOP-8
DFN/
MLP-8
V
A
V
B
C
S
L
X
V
A
V
B
C
S
L
X
V
DD
R
SW-OSC
R
EL-OSC
GND
HV859MG
HV859K7
Top View*
(Pads are on the bottom of the package)
*Drawings are not to scale.
R
DS(ON)
On-resistance of switching transistor
-
-
6.0
I = 100mA
V
CS
Max. output regulation voltage
95
105
115
V
V
DD
= 1.8V to 5.0V
V
A
V
B
Peak to Peak output voltage
190
210
230
V
V
DD
= 1.8V to 5.0V
I
DDQ
Quiescent V
DD
supply current
-
-
150
nA
Rsw-osc = Low
I
DD
Input current going into the V
DD
pin
-
-
150
A
V
DD
= 1.8V to 5.0V. See Figure 1.
I
IN
Input current including inductor current
-
26
35
mA
See Figure 1.*
V
CS
Output voltage on V
CS
-
90
-
V
See Figure 1.
F
EL
EL lamp frequency
205
-
275
Hz
See Figure 1.
Fsw
Switching transistor frequency
-
77
-
kHz
---
D
Switching transistor duty cycle
-
88
-
%
See Figure 1.
* The inductor used is a 220H Murata inductor, max DC resistance of 8.4, part # LQH32CN221K21.
V
DD
Supply voltage
1.8
-
5.0
V
---
f
EL
Output drive frequency
-
-
1
kHz
---
T
A
Operating Temperature
-40
-
+85
C
---
EN-L
Logic input low voltage
0
-
0.2
V
V
DD
= 1.8V to 5.0V
EN-H
Logic input high voltage
V
DD
- 0.2
-
V
DD
V
V
DD
= 1.8V to 5.0V
Enable/Disable Function Table
Recommended Operating Conditions
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Package
ja
MSOP-8
330 C/W
DFN/MLP-8
60 C/W
Thermal Resistance
3
NR040306
HV859
Functional Block Diagram
Figure 1: Typical Application/Test Circuit
Q
Q
Q
Q
-
+
V
DD
GND
Disable
V
DD
R
SW-OSC
V
B
V
A
C
S
L
X
R
SW-OSC
V
REF
High
Voltage
Level
Trans-
lators
V
SENSE
C
Switch
OSC
Switch
OSC
1
2
3
4
8
7
6
5
+
-
V
DD
R
SW-osc
V
B
R
EL-osc
GND
V
A
L
X
C
S
V
DD
V
DD
= V
IN
HV859MG/
HV859K7
Enable Signal
ON = V
DD
OFF = 0V
560k
2.0M
1.0F
220H*
2.0k
10nF
Equivalent to 3.0in
2
lamp
BAS21**
3.3nF
200V
* Murata Inductor - LQH32CN221K21
** BAS21 - General Purpose HV diode
4
NR040306
HV859
External Component Description
External Component
Selection Guide Line
Diode
Fast reverse recovery diode, BAS21 diode or equivalent.
C
S
Capacitor
0.003F to 0.1F, 200V capacitor to GND is used to store the energy transferred from the inductor.
R
EL
Resistor
The EL lamp frequency is controlled via an external R
EL
resistor connected between R
EL-OSC
and V
DD
of the
device. The lamp frequency increases as R
EL
decreases. As the EL lamp frequency increases, the amount
of current drawn from the battery will increase and the output voltage V
CS
will decrease. The color of the EL
lamp is dependent upon its frequency.
A 2M resistor would provide lamp frequency of 205 to 275Hz. Decreasing the R
EL
resistor by a factor of 2
will increase the lamp frequency by a factor of 2.
R
SW
Resistor
The switching frequency of the converter is controlled via an external resistor, R
SW
between R
SW-OSC
and V
DD
of the device. The switching frequency increases as R
SW
decreases. With a given inductor, as the switching
frequency increases, the amount of current drawn from the battery will decrease and the output voltage,
V
CS
, will also decrease.
Lx Inductor
The inductor L
X
is used to boost the low input voltage by inductive fl yback. When the internal switch is
on, the inductor is being charged. When the internal switch is off, the charge stored in the inductor will be
transferred to the high voltage capacitor C
S
. The energy stored in the capacitor is connected to the internal
H-bridge, and therefore to the EL lamp. In general, smaller value inductors, which can handle more current,
are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency of
the inductor (controlled by R
SW
) should be increased to avoid saturation.
A 220H Murata (LQH32CN221) inductor with 8.4 series DC resistance is typically recommended. For
inductors with the same inductance value, but with lower series DC resistance, lower R
SW
resistor value is
needed to prevent high current draw and inductor saturation.
Lamp
As the EL lamp size increases, more current will be drawn from the battery to maintain high voltage across
the EL lamp. The input power, (V
IN
x I
IN
), will also increase. If the input power is greater than the power
dissipation of the package, an external resistor in series with one side of the lamp is recommended to help
reduce the package power dissipation.
Split Supply Confi guration
Figure 2: Split Supply and Enable/Disable Confi guration
1
2
3
4
8
7
6
5
+
-
V
DD
R
SW-osc
V
B
R
EL-osc
GND
V
A
L
X
C
S
Regulated Voltage = V
DD
V
IN
HV859MG/
HV859K7
Enable Signal
ON = V
DD
OFF = 0V
R
EL
C
IN
L
X
EL Lamp
D
C
S
R
SW
The HV859 can also be used for handheld devices operating from
a battery where a regulated voltage is available. This is shown in
Figure 2. The regulated voltage can be used to run the internal logic
of the HV859. The amount of current necessary to run the internal
logic is 150A Max at a V
DD
of 3.0V. Therefore, the regulated voltage
could easily provide the current without being loaded down.
The HV859 can be easily enabled and disabled via a logic control
signal on the R
SW
and R
EL
resistors as shown in Figure 2 below.
The control signal can be from a microprocessor. R
SW
and R
EL
are
typically very high values. Therefore, only 10's of microamperes
will be drawn from the logic signal when it is at a logic high (enable)
state. When the microprocessor signal is high the device is enabled,
and when the signal is low, it is disabled.
5
NR040306
HV859
Figure 3: Typical Application Circuit for Audible Noise reduction
1
2
3
4
8
7
6
5
V
DD
R
SW-osc
V
B
R
EL-osc
GND
V
A
L
X
C
S
D
+
-
+
-
V
DD
V
IN
C
DD
C
IN
R
SW
R
EL
C
S
R
SER
HV859MG/
HV859K7
L
X
EL Lamp
Enable
ON = V
DD
OFF = 0V
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. Figure 3 shows a general
circuit schematic that uses the resistor, R
SER
, connected in series
with the EL lamp
How to Minimize EL Lamp Audible Noise:
The EL lamp, when lit, emits an audible noise. This is due to EL
lamp construction and it creates a major problem for applications
where the EL lamp can be close to the ear such as cellular phones.
The noisiest waveform is a square wave and the quietest waveform
has been assumed to be a sine wave.
After extensive research, Supertex has developed a waveform
that is quieter than a sine wave. 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. This waveform has been proven to generate less noise than
a sine wave.
The audible noise from the EL lamp can be set at a desired level
based on the series resistor value used with the lamp. It is important
to note that use of this resistor will reduce the voltage across the
lamp. Reduction of voltage across the lamp will also have another
effect on the over all performance of the Supertex EL drivers, age
compensation (patented). This addresses a very important issue,
EL lamp life that most mobile phone manufacturers are concerned
about.
As EL lamp ages, its brightness is reduced and its capacitance is
diminished. By using the RC model to reduce the audible noise
emitted by the EL lamp, the voltage across the lamp will increase
as its capacitance diminishes. Hence the increase in voltage will
compensate for the reduction of the brightness. As a result, it will
extend the EL lamp's half-life (half the original brightness).
Effect of Series Resistor on EL Lamp Audible
Noise and Brightness:
Increasing the value of the series resistor with the lamp will reduce
the EL lamp audible noise as well as its brightness. This is due to
the fact that the output voltage across the lamp will be reduced and
the output waveform will have rounder edges.
Supertex inc.
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 222-8888 / FAX: (408) 222-4895
www.supertex.com
2006 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited.
Supertex inc.
does not recommend the use of its products in life support applications, and will not knowingly sell its products for use in such applications, unless it receives an adequate
"product liability indemnification insurance agreement". Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of the devices
determined defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest
product specifications, refer to the Supertex website: http//www.supertex.com.
6
Doc.# DSFP - HV859
NR040306
HV859
8-Lead MSOP Package Outline (MG)
3.0 3
12 4
B
0.013 0.005
(0.330 0.127)
D
0.116 0.004
(2.946 0.102)
E
0.118 0.004
(3.000 0.102)
H
0.193 0.006
(4.902 0.152)
A
1
0.004 0.002
(0.102 0.051)
A
0.040 0.003
(1.016 0.076)
BSC
0.0256
(0.650)
e
0.0215 0.006
(0.546 0.152)
L
0.006 0.0003
(0.152 0.0076)
C
Note: Circle (e.g. B ) indicates JEDEC Reference.
Dimensions in Inches
(Dimensions in Millimeters)
Measurement Legend =
Full Circle,
or Half Circle,
8-Lead DFN/MLP Package Outline (K7)
Bottom View
Top View
Side View
1.500
3.00
1.500
3.00
1.40
1.80
0.65
0.20
Pin #1 Index
All dimensions are in millimeters
Legend: min
max
1.55
2.40
0.23
0.37
0.20
0.40
0.70
0.80
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