Supertex inc.
Supertex inc.
www.supertex.com
HV857
Doc.# DSFP-HV857
A062013
Features
►Patented audible noise reduction
►Patented lamp aging compensation
►190 VPP output voltage for higher brightness
►Patented output timing for high efciency
►Single cell lithium ion compatible
►150nA shutdown current
►Wide input voltage range 1.8 to 5.0V
►Separately adjustable lamp and converter
frequencies
►Output voltage regulation
►Split supply capability
►Available in 8-Lead MSOP and DFN packages
Applications
►LCD backlighting
►Mobile Cellular Phone
►PDAs
►Handheld wireless communication products
►Global Positioning Systems (GPS)
General Description
The Supertex HV857 is a high voltage driver designed for driving
Electroluminescent (EL) lamps of up to 5.0 square inches. The
input supply voltage range is from 1.8 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 ±95V. The chip can be enabled/disabled by connecting the
resistor on RSW-Osc to VDD/GND.
The HV857 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 RSW-Osc pin and the supply pin VDD. The EL lamp driver
frequency is set by an external resistor connected between REL-
Osc pin and VDD pin. An external inductor is connected between
the LX and VDD pins or VIN for split supply applications. A 0.003-
0.1µF capacitor is connected between CS and ground. The EL
lamp is connected between VA and VB.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at CS. The voltage at CS will start
to increase. Once the voltage at CS reaches a nominal value of
95V, the switching MOSFET is turned OFF to conserve power. The
outputs VA and VB are congured as an H bridge and are switching
in opposite states to achieve ±95V across the EL lamp.
Typical Application Circuit
Low Noise, High Voltage
EL Lamp Driver IC
EL Lamp
+
_ CS
VIN
LX
CIN
Enable Signal
ON = VDD
OFF = 0
D
+
_
VDD CDD
RSW
REL
1
2
3
4
8
7
6
5
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
HV857
2
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
Absolute Maximum Ratings
Parameter Value
Supply voltage, VDD -0.5V to 6.5V
Operating temperature -40°C to +85°C
Storage temperature -65°C to +150°C
DFN-8 power dissipation 1.6W
MSOP-8 power dissipation 300mW
Output voltage, VCS -0.5 to +120V
Absolute Maximum Ratings are those values beyond which damage to the
device may occur. Functional operation under these conditions is not im-
plied. Continuous operation of the device at the absolute rating level may
affect device reliability. All voltages are referenced to device ground.
Pin Conguration
8-Lead MSOP
(top view)
Pads are at the bottom of the package.
Exposed center pad is at ground potential.
8-Lead DFN
(top view)
1
2
3
4
8
7
6
5
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
1
2
3
4
8
7
6
5
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
Typical Thermal Resistance
Package θja
8-Lead DFN 37OC/W
8-Lead MSOP 171OC/W
Mounted on FR4 board, 25mm x 25mm x 1.57mm
Sym Parameter Min Typ Max Units Conditions
VDD Supply voltage 1.8 - 5.0 V ---
fEL Operating drive frequency - - 1.0 kHz ---
TAOperating temperature -40 - +85 OC ---
Recommended Operating Conditions
Sym Parameter Min Typ Max Units Conditions
EN-L Logic input low voltage 0 - 0.2 V VDD = 1.8 to 5.0V
EN-H Logic input high voltage VDD - 0.2 - VDD V VDD = 1.8 to 5.0V
Enable/Disable Function Table
Sym Parameter Min Typ Max Units Conditions
RDS(ON) On-resistance of switching transistor - - 6.0 ΩI = 100mA
VCS Max. output regulation voltage 85 95 105 V VDD=1.8 to 5.0V
DC Electrical Characteristics (Over recommended operating conditions unless otherwise specied, TA = 25°C)
Product Marking
H857
YWLL
Y = Last Digit of Year Sealed
W = Code for Week Sealed
L = Lot Number
= “Green” Packaging
L = Lot Number
YY = Year Sealed
WW = Week Sealed
= “Green” Packaging
H857
LLLL
YYWW
Top Marking
Bottom Marking
8-Lead DFN
8-Lead MSOP
Package may or may not include the following marks: Si or
Package may or may not include the following marks: Si or
Ordering Information
Part Number Package Packing
HV857K7-G 8-Lead DFN 3000/Reel
HV857MG-G 8-Lead MSOP 2500/Reel
-G denotes a lead (Pb)-free / RoHS compliant package
3
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
Block Diagram
* The inductor used is a 220µH Murata inductor, max DC resistance of 8.4Ω, part # LQH32CN221K21.
Figure 1: Typical Application/ Test Circuit
DC Electrical Characteristics (cont.)
Sym Parameter Min Typ Max Units Conditions
VA – VBPeak to Peak output voltage 170 190 210 V VDD=1.8 to 5.0V
IDDQ Quiescent VDD supply current - - 150 nA RSW-Osc = Low
IDD Input current going into the VDD pin - - 150 µA VDD= 1.8 to 5.0V. See Figure 1
IIN Input current including inductor current - 20 25 mA See Figure 1*
VCS Output voltage on VCS - 84 - V See Figure 1
fEL EL lamp frequency 205 240 275 Hz See Figure 1
fSW Switching transistor frequency - 80 - kHz See Figure 1
DSwitching transistor duty cycle - 88 - % See Figure 1
C
+
_
V
REF
Disable High
Voltage
Level
Translator
GND
VDD
Q
Q
Q
VA
CS
LX
VB
Q
RSW-Osc
REL-Osc
V
SENSE
EL
Osc
V
DD
Switch
Osc
220µH*
3.3nF
100V
560kΩ
2.0MΩ
BAS21
* Murata Inductor LQH32CN221K21
HV857
ON = VDD
OFF = 0V
Enable Signal
+
-
V
IN
4.7µF
+
-
V
DD
0.1µF
2.0kΩ
Equivalent to 3.0in2 lamp
10nF
1
2
3
4
8
7
6
5
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
HV857
4
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
Typical Performance
Device Lamp Size VDD = VIN IIN VCS fEL Brightness
HV857MG-G 3.0in23.3V 20.0mA 84V 240Hz 6.0ft-lm
Typical Performance Curves for Figure 1 (EL Lamp = 3.0in2, VDD = 3.0V)
IIN, VCS, Brightness vs Inductor Value
0
10
20
30
40
50
60
70
80
90
100
100 200 300 400 500 600
Inductor Value (µH)
0
1
2
3
4
5
6
7
Brightness
V
CS
I
IN
vs V
IN
13
15
17
19
21
23
25
V
IN
(V)
VCS (V)
lIN (mA)
Brightness (ft-lm)
lIN (mA)
l
IN
(mA), V
CS
(V)
Brightness (ft-Im)
Brightness vs V
IN
1
2
3
4
5
6
7
1.5 2.5 3.5 4.5 5.5
V
IN
(V)
I
IN
vs V
CS
14
16
18
20
22
24
55 65 75 85 95
V
CS
(V)
VCS vs VIN
55
65
75
85
95
V
IN
(V)
l
IN
1.5 2.5 3.5 4.5 5.5 1.5 2.5 3.5 4.5 5.5
5
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
External Component Description
External
Component Description
Diode Fast reverse recovery diode, BAS21 diode or equivalent.
CS Capacitor 0.003µF to 0.1µF, 100V capacitor to GND is used to store the energy transferred from the inductor.
REL Resistor
The EL lamp frequency is controlled via an external REL resistor connected between REL-Osc and VDD
of the device. The lamp frequency increases as REL decreases. As the EL lamp frequency increases,
the amount of current drawn from the battery will increase and the output voltage VCS will decrease. The
color of the EL lamp is dependent upon its frequency.
A 2MΩ resistor would provide lamp frequency of 205 to 275Hz. Decreasing the REL resistor by a factor
of 2 will increase the lamp frequency by a factor of 2.
fEL = (2MΩ)(240Hz)
REL
RSW Resistor
The switching frequency of the converter is controlled via an external resistor, RSW between RSW-Osc
and VDD of the device. The switching frequency increases as RSW decreases. With a given inductor, as
the switching frequency increases, the amount of current drawn from the battery will decrease and the
output voltage, VCS, will also decrease.
fSW = (560kΩ)(80Hz)
RSW
LX Inductor
The inductor LX is used to boost the low input voltage by inductive 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 CS. 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 switch-
ing frequency of the inductor (controlled by RSW) should be increased to avoid saturation.
A 220µH Murata (LQH32CN221) inductor with 8.4Ω series DC resistance is typically recommended. For
inductors with the same inductance value, but with lower series DC resistance, lower RSW 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, (VIN x IIN), 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 recom-
mended to help reduce the package power dissipation.
6
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
Split Supply Conguration
The HV857 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 HV857. The amount of current
necessary to run the internal logic is 150µA Max at a VDD of
3.0V. Therefore, the regulated voltage could easily provide
the current without being loaded down.
The HV857 can be easily enabled and disabled via a logic
control signal on the RSW and REL resistors as shown in Fig-
ure 2 below. The control signal can be from a microproces-
sor. The control signal has to track the VDD supply. RSW and
REL 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.
Enable/Disable Conguration
Figure 2: Split Supply and Enable/Disable Conguration
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,
RSER, connected in series with the EL lamp.
EL Lamp
ON = VDD
OFF = 0V
Enable Signal
LX
C
S
Regulated Voltage = V
DD
CIN
D
REL
RSW
CDD
VIN
+
-
1
2
3
4
8
7
6
5
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
HV857
Figure 3: Typical Application Circuit for Audible Noise Reduction
1
2
3
4
8
7
6
5
HV857
EL Lamp
ON = VDD
OFF = 0V
Enable
L
X
C
S
+
-
V
IN
C
IN
D
R
EL
R
SW
+
-
V
DD
C
DD
R
SER
VDD
RSW-Osc
REL-Osc
GND
VA
VB
CS
LX
7
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
Minimization of 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 wave-
form 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 capaci-
tance of the EL lamp, and R is the external resistor, RSER,
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 per-
formance 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.
Effect of Series Resistor on EL Lamp
Audible Noise and Brightness
As EL lamp ages, its brightness is reduced and its capaci-
tance 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).
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.
8
Supertex inc.
www.supertex.com
Doc.# DSFP-HV857
A062013
HV857
8-Lead DFN Package Outline (K7)
3.00x3.00mm body, 0.80mm height (max), 0.65mm pitch
Symbol A A1 A3 b D D2 E E2 e L L1 θ
Dimension
(mm)
MIN 0.70 0.00
0.20
REF
0.25 2.85* 1.60 2.85* 1.35
0.65
BSC
0.30 0.00* 0O
NOM 0.75 0.02 0.30 3.00 -3.00 - 0.40 - -
MAX 0.80 0.05 0.35 3.15* 2.50 3.15* 1.75 0.50 0.15 14O
JEDEC Registration MO-229, Variation WEEC-2, Issue C, Aug. 2003.
* This dimension is not specied in the JEDEC drawing.
Drawings not to scale.
Supertex Doc. #: DSPD-8DFNK73X3P065, Version C081109.
Seating
Plane
θ
Top View Bottom View
A
A1
D
E
D2
E2
A3
L
L1
View B
Note 1
(Index Area
D/2 x E/2)
Note 3
Note 2
Note 1
(Index Area
D/2 x E/2)
1
1
88
e
b
Side View View B
Notes:
1. A Pin 1 identier must be located in the index area indicated. The Pin 1 identier can be: a molded mark/identier; an embedded metal marker; or
a printed indicator.
2. Depending on the method of manufacturing, a maximum of 0.15mm pullback (L1) may be present.
3. The inner tip of the lead may be either rounded or square.
Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives
an adequate “product liability indemnification insurance agreement.” Supertex inc. 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 and inaccuracies. Circuitry and
specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com)
©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Supertex inc.
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: 408-222-8888
www.supertex.com
9
HV857
(The package drawing(s) in this data sheet may not reect the most current specications. For the latest package outline
information go to http://www.supertex.com/packaging.html.)
Doc.# DSFP-HV857
A062013
8-Lead MSOP Package Outline (MG)
3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch
View B
View A-A
Seating
Plane
Gauge
Plane
L
L1
L2
View B
θ1
θ
1
8
EE1
D
eb
AA2
A1
Seating
Plane
A
A
Top View
Side View
Note 1
(Index Area
D/2 x E1/2)
Symbol A A1 A2 b D E E1 e L L1 L2 θ θ1
Dimension
(mm)
MIN 0.75* 0.00 0.75 0.22 2.80* 4.65* 2.80*
0.65
BSC
0.40
0.95
REF
0.25
BSC
0O5O
NOM - - 0.85 - 3.00 4.90 3.00 0.60 - -
MAX 1.10 0.15 0.95 0.38 3.20* 5.15* 3.20* 0.80 8O15O
JEDEC Registration MO-187, Variation AA, Issue E, Dec. 2004.
* This dimension is not specied in the JEDEC drawing.
Drawings are not to scale.
Supertex Doc. #: DSPD-8MSOPMG, Version H041309.
Note:
1. A Pin 1 identier must be located in the index area indicated. The Pin 1 identier can be: a molded mark/identier; an embedded metal marker; or
a printed indicator.
