Supertex inc.
HV857L
Low Noise, High Voltage
EL Lamp Driver IC
Features
General Description
Applications
The HV857L 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 RSWOsc pin and the supply pin, VDD. The EL lamp driver frequency
is set by an external resistor connected between the REL-Osc
and VDD pins. 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 the VA and VB pins.
►► Audible noise reduction
►► 190 VPP output voltage for higher brightness
►► 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
►► Available in 8-Lead DFN and 8-Lead MSOPpackages
►►
►►
►►
►►
►►
►►
Mobile cellular phones
Keypad backlighting
LCD backlighting
PDAs
Handheld wireless communication products
Global Positioning Systems (GPS)
The Supertex HV857L is a low noise, high voltage driver designed
for driving Electroluminescent (EL) lamps of up to five square
inches. It is the low noise version of the EL lamp driver HV857. 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 ±95V. The chip can be enabled/disabled by connecting the
resistor on RSW-Osc to VDD/ground.
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 configured as an H bridge, and are
switching in opposite states to achieve ±95V across the EL lamp.
Typical Application Circuit
ON = VDD
OFF = 0
+
V
_
DD
Enable Signal
1
CDD
RSW
2
3
+
_
VIN
Doc.# DSFP-HV857L
A062013
CIN
REL
4
VDD
HV857L
VA
RSW-Osc
VB
REL-Osc
CS
GND
LX
8
EL Lamp
7
6
5
D
LX
CS
Supertex inc.
www.supertex.com
HV857L
Pin Configurations
Ordering Information
Part Number
Package
Packing
HV857LK7-G
8-Lead DFN
3000/Reel
HV857LMG-G
8-Lead MSOP
2500/Reel
1
8
VA
RSW-Osc
2
7
VB
CS
REL-Osc
3
6
CS
LX
GND
4
5
LX
1
8
VA
RSW-Osc
2
7
VB
REL-Osc
3
6
GND
4
5
-G denotes a lead (Pb)-free / RoHS compliant package
8-Lead MSOP
8-Lead DFN
Absolute Maximum Ratings
Parameter
VDD
VDD
(top view)
(top view)
Pads are at the bottom of the package.
Exposed center pad is at ground potential.
Value
-0.5V to 6.5V
Supply voltage, VDD
Operating temperature
-40°C to +85°C
Storage temperature
Product Marking
-65°C to +150°C
8-Lead DFN power dissipation
8-Lead MSOP power dissipation
Output voltage, VCS
1.6W
857L
YWLL
300mW
-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
implied. Continuous operation of the device at the absolute rating level
may affect device reliability. All voltages are referenced to device ground.
Package may or may not include the following marks: Si or
8-Lead DFN
Typical Thermal Resistance
Package
θja
8-Lead DFN
37OC/W
8-Lead MSOP
171OC/W
Y = Last Digit of Year Sealed
W = Code for Week Sealed
L = Lot Number
= “Green” Packaging
Top Marking
857L
LLLL
Mounted on FR4 board, 25mm x 25mm x 1.57mm
Bottom Marking
YYWW
L = Lot Number
YY = Year Sealed
WW = Week Sealed
= “Green” Packaging
Package may or may not include the following marks: Si or
8-Lead MSOP
Recommended Operating Conditions
Sym
Parameter
Min
Typ
Max
Units
VDD
Supply voltage
1.8
-
5.0
V
---
fEL
Operating drive frequency
-
-
1
kHz
---
TA
Operating temperature
-40
-
+85
C
---
Doc.# DSFP-HV857L
A062013
2
O
Conditions
Supertex inc.
www.supertex.com
HV857L
Electrical Characteristics
DC Characteristics (Over recommended operating conditions unless otherwise specified, T
A
Sym
Min
Typ
Max
Units
-
-
6.0
Ω
I = 100mA
Max. output regulation voltage
85
95
105
V
VDD = 1.8 to 5.0V
VA – VB
Peak 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 Fig. 1
IIN
Input current including inductor current
-
25
40
mA
See Fig. 1*
VCS
Output voltage on VCS
-
92
-
V
See Fig. 1
fEL
EL lamp frequency
175
205
235
Hz
See Fig. 1
fSW
Switching transistor frequency
65
77
89
kHz
See Fig. 1
D
Switching transistor duty cycle
-
88
-
%
See Fig. 1
RDS(ON)
VCS
Parameter
= 25°C)
On-resistance of switching transistor
Conditions
* The inductor used is a 220µH Murata inductor, max DC resistance of 8.4Ω, part # LQH32CN221K21.
Enable/Disable Function Table
Sym
Parameter
Min
Typ
Max
Units
EN-L
EN-H
Conditions
Logic input low voltage
0
-
0.2
V
VDD = 1.8 to 5.0V
Logic input high voltage
VDD - 0.2
-
VDD
V
VDD = 1.8 to 5.0V
Block Diagram
LX
CS
VDD
RSW-Osc
Switch
Osc
Q
GND
Disable
C
+
Q
VREF
_
High
Voltage
Level
Translator
VDD
REL-Osc
VA
VSENSE
Q
EL
Osc
VB
Q
Doc.# DSFP-HV857L
A062013
3
Supertex inc.
www.supertex.com
HV857L
Fig. 1: Typical Application/ Test Circuit
ON = VDD
Enable Signal
OFF = 0V
+
VDD
-
1
560kΩ
0.1µF
2
3
2.0MΩ
+
VIN
-
4
4.7µF
VDD
VA
RSW-Osc
VB
REL-Osc
CS
GND
LX
HV857L
8
3.0in2 EL lamp
7
6
BAS21
5
3.3nF
100V
220µH*
* Murata Inductor LQH32CN221K21
Typical Performance
Device
Lamp Size
VDD = VIN
IIN
VCS
fEL
Brightness
HV857LMG-G
3.0in2
3.3V
25.40mA
92V
205Hz
5.70ft-lm
Typical Performance Curves for Fig. 1 (EL Lamp = 3.0in , V
2
VCS vs VIN
105
IIN (mA)
VCS (V)
85
75
65
2.5
3.5
= 3.0V)
IIN vs VIN
33
95
55
1.5
DD
4.5
28
23
18
13
1.5
5.5
2.5
3.5
Brightness vs VIN
7
6
5
4
3
2
1
1.5
2.5
3.5
IIN vs VCS
34
4.5
29
24
19
14
5.5
5.5
6.5
7.5
8.5
9.5
10.5
VCS (V)
VIN (V)
Doc.# DSFP-HV857L
A062013
5.5
VIN (V)
IIN (mA)
Brightness (ft-lm)
VIN (V)
4.5
4
Supertex inc.
www.supertex.com
HV857L
Typical Waveform on VA, VB and Differential Waveform VA - VB
Fig. 2: Split Supply and Enable/Disable Configuration
ON = VDD
Enable Signal
OFF = 0V
Regulated Voltage = VDD
1
CDD
RSW
2
3
Battery Voltage = VIN
REL
4
CIN
VDD
HV857L
VA
RSW-Osc
VB
REL-Osc
CS
GND
LX
8
7
EL Lamp
6
D
5
CS
LX
Split Supply Configuration
cessor, 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.
The HV857L can also be used for handheld devices operating from a battery where a regulated voltage is available.
This is shown in Fig. 2. The regulated voltage can be used
to run the internal logic of the HV857L. The amount of current necessary to run the internal logic is 150µA maximum at
a VDD of 5.0V. Therefore, the regulated voltage could easily
provide the current without being loaded down.
Audible Noise Reduction
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 HV857L employs a circuit designed to
help minimize the EL lamp’s audible noise by slowing down
the rise and fall times seen by the EL lamp.
Enable/Disable Configuration
The HV857L can be easily enabled and disabled via a logic
control signal on the RSW and REL resistors as shown in Fig.
2 below. The control signal, which can be from a micropro-
Doc.# DSFP-HV857L
A062013
5
Supertex inc.
www.supertex.com
HV857L
External
Component
Diode
CS Capacitor
Description
Fast reverse recovery diode, BAS21 diode or equivalent.
0.003µF to 0.1µF, 100V capacitor to GND is used to store the energy transferred from the inductor.
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.
REL Resistor
A 2MΩ resistor would provide lamp frequency of 205Hz. Decreasing the REL resistor by a factor of 2 will
increase the lamp frequency by a factor of 2.
fEL =
RSW Resistor
REL
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 =
LX Inductor
(2MΩ)(205Hz)
(560kΩ)(77Hz)
RSW
The inductor LX is used to boost the low input voltage by inductive flyback. 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 switching 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, a lower RSW resistor
value is needed to prevent high current draw and inductor saturation.
Lamp
Doc.# DSFP-HV857L
A062013
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 recommended to help reduce the package power dissipation.
6
Supertex inc.
www.supertex.com
HV857L
8-Lead DFN Package Outline (K7)
3.00x3.00mm body, 0.80mm height (max), 0.65mm pitch
D2
D
8
8
E
E2
Note 1
(Index Area
D/2 x E/2)
Note 1
(Index Area
D/2 x E/2)
Top View
1
e
b
1
Bottom View
View B
Note 3
θ
A
L
Seating
Plane
A3
A1
L1
Note 2
Side View
View B
Notes:
1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; 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.
Symbol
Dimension
(mm)
A
A1
MIN
0.70
0.00
NOM
0.75
0.02
MAX
0.80
0.05
A3
0.20
REF
b
D
D2
E
E2
0.25
2.85*
1.60
2.85*
1.35
0.30
3.00
-
3.00
-
0.35
3.15*
2.50
3.15*
1.75
e
0.65
BSC
L
L1
θ
0.30
0.00*
0O
0.40
-
-
0.50
0.15
14O
JEDEC Registration MO-229, Variation WEEC-2, Issue C, Aug. 2003.
* This dimension is not specified in the JEDEC drawing.
Drawings not to scale.
Supertex Doc. #: DSPD-8DFNK73X3P065, Version C081109.
Doc.# DSFP-HV857L
A062013
7
Supertex inc.
www.supertex.com
HV857L
8-Lead MSOP Package Outline (MG)
3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch
D
θ1
8
Note 1
(Index Area
D/2 x E1/2)
E1
E
L2
L
θ
L1
1
Gauge
Plane
Seating
Plane
View B
Top View
View B
A
A A2
Seating
Plane
A1
e
b
Side View
View A-A
A
Note:
1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or
a printed indicator.
Symbol
Dimension
(mm)
A
A1
A2
b
D
E
E1
MIN
0.75*
0.00
0.75
0.22
2.80*
4.65*
2.80*
NOM
-
-
0.85
-
3.00
4.90
3.00
MAX
1.10
0.15
0.95
0.38
3.20*
5.15*
3.20*
e
0.65
BSC
L
0.40
0.60
0.80
L1
L2
θ
θ1
0
5O
-
-
8
15O
O
0.95
REF
0.25
BSC
O
JEDEC Registration MO-187, Variation AA, Issue E, Dec. 2004.
* This dimension is not specified in the JEDEC drawing.
Drawings are not to scale.
Supertex Doc. #: DSPD-8MSOPMG, Version H041309.
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information go to http://www.supertex.com/packaging.html.)
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)
Supertex inc.
©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited.
Doc.# DSFP-HV857L
A062013
8
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: 408-222-8888
www.supertex.com
