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High Voltage EL Lamp Driver
Ordering Information
Package Options
Device Input Voltage 8-Lead SO MSOP-8 Die
HV825 1.0 to 1.6V HV825LG HV825MG* HV825X
* Product supplied on 2500 piece carrier tape reels.
HV825
Features
❏ Processed with HVCMOS® technology
❏ 1.0V to 1.6V operating supply voltage
❏ DC to AC conversion
❏ Output load of typically up to 6nF
❏ Adjustable output lamp frequency
❏ Adjustable converter frequency
❏ Enable function
Applications
❏ Pagers
❏ Portable Transceiver
❏ Cellular phones
❏ Remote control units
❏ Calculators
Absolute Maximum Ratings*
Supply voltage, V
DD
Operating Temperature Range -25°C to +85°C
Storage Temperature Range -65°C to +150°C
-0.5V to +2.5V
General Description
The Supertex HV825 is a high voltage driver designed for driving
EL lamps typically up to 6nF. The input supply voltage range is
from 1.0V to 1.6V. The device uses a single inductor and a
minimum number of passive components. Typical output
voltage that can be applied to the EL lamp is ±56V.
The HV825 can be enabled/disabled by connecting the R
SW-osc
resistor to VDD/ground.
The HV825 has two internal oscillators, a switching bipolar
junction transistor (BJT), and a high voltage EL lamp driver. The
frequency for the switching BJT is set by an external resistor
connected between the R
pin and the supply pin VDD. The
SW-osc
EL lamp driver frequency is set by an external resistor connected
between R
connected between the L
capacitor is connected between C
connected between V
pin and the VDD pin. An external inductor is
EL-osc
and VDD pins. A 0.01 to 0.1µF, 100V
X
and VB.
A
and ground. The EL lamp is
S
The switching BJT charges the external inductor and discharges
it into the 0.01 to 0.1µF, 100V capacitor at C
. The voltage at C
S
will start to increase. The outputs VA and VB are configured as
an H-bridge and are switching in opposite states to achieve a
peak-to-peak voltage of two times the V
voltage across the EL
CS
lamp.
Pin Configuration
S
MSOP-8 Power Dissipation 300mW
1
V
SO-8 Power Dissipation 400mW
Note:
*All voltages are referenced to GND.
For detailed circuit and application information, please refer
to application notes AN-H33 and AN-H34.
11/12/01
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 "products liability
indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be 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. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
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R
SW-osc
DD
C
L
2
3
s
4
x
top view
SO-8/MSOP-8
8
R
EL-osc
7
V
A
6
V
B
5
GND
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Electrical Characteristics
DC Characteristics (Over recommended operating conditions unless otherwise specified, T
Symbol Parameter Min Typ Max Units Conditions
R
DS(ON)
I
IN
I
DDQ
V
CS
V
A-B
f
EL
f
SW
D Switching transistor duty cycle 88 %
On-resistance of switching transistor 15 Ω I=50mA
VDD supply current (including inductor current) 30 38 mA VDD=1.5V. See test circuit.
Quiescent VDD supply current 1.0 µAR
Output voltage on V
CS
52 56 62 V VDD=1.5V. See test circuit.
Differential output voltage across lamp 104 112 124 V VDD=1.5V. See test circuit.
V
output drive frequency 400 Hz VDD=1.5V. See test circuit.
A-B
Switching transistor frequency 30 KHz VDD=1.5V. See test circuit.
=25°C)
A
SW-osc
=GND
Recommended Operating Conditions
Symbol Parameter Min Typ Max Units Conditions
HV825
V
DD
C
L
T
A
Supply voltage 1.0 1.6 V
Load Capacitance 0 6.0 nF
Operating temperature -25 +85 °C
Enable/Disable Table
Symbol Parameter Min Typ Max Units Conditions
V
IL
V
IH
Low level input voltage to R
High level input voltage to R
resistor 0 0.2 V VDD=1.0V-1.6V.
SW-osc
resistor VDD-0.5 V
SW-osc
DD
VVDD=1.0V-1.6V.
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Block Diagram
5
6V
D
µ
00V
0.1
560
µ
8
825LG
D
osc
osc
s
V
DD
R
SW-osc
GND
R
EL-osc
Switch
Osc
Output
Osc
HV825
L
x
C
s
Q
V
A
Q
Q
V
B
Q
Test Circuit
VIN= VDD = 1.0V to 1.
Typical Performance
Lamp Size V
2
1.5 in
ON = V
FF = GN
DD
1MΩ
-
W-
1N414
N
µF
Enable
0.1
1
HV825MG or
HV
*560µH Murata inductor (LQH4N561K04), max DC resistance of 14.5Ω.
DD
I
DD
V
CS
f
EL
Brightness
1.5v 30mA 56v 450Hz 3.65ft-lm
2.2K
4.7nF
Equivalent to a 1.5
square inch lamp.
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External Component Description
External Component Selection Guide Line
Diode Fast reverse recovery, 1N4148 or equivalent.
CS Capacitor 0.01 to 0.1µF, 100V capacitor to GND is used to store the energy transferred from the inductor.
R
Resistor The lamp frequency is controlled via the R
EL-osc
As the lamp frequency increases, the amount of current drawn from the battery will increase and the output
voltage VCS will decrease. This is because the lamp will draw more current from VCS when driven at higher
frequencies.
In general, as the lamp size increases, larger R
color of the lamp is dependent upon its frequency and the shade of the color will change slightly with different
frequencies.
R
Resistor The switching frequency of the inductor is controlled via the R
SW-osc
the R
decreases. As the switching frequency increases, the amount of current drawn from the battery
SW-osc
will decrease and the output voltage VCS will also decrease.
Inductor The inductor LX is used to boost up the low input voltage. When the internal switch is on, the inductor is being
L
X
charged. When the internal switch is off, the charge in the inductor will be transferred to the high voltage
capacitor C
. The energy stored in the capacitor is connected to the internal H-bridge and therefore to the
S
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
should be increased to avoid saturation.
The test circuit uses a Murata (LQH4N561) 560µH inductor. Using different inductor values or inductors from
different manufacturers will affect the performance.
As the inductor value decreases, smaller R
Inductor with the same inductance value (560µH) but lower series resistance will charge faster. The
R
resistor value needs to be decreased to prevent inductor saturation and high current consumption.
SW-osc
CSW Capacitor A 1nF capacitor is recommended from R
that may couple into the R
SW-OSC
SW-OSC
pin.
. The lamp frequency increases as the R
EL-osc
is recommended to provide higher VCS. However, the
EL-osc
. The switching frequency increases as
SW-osc
value shall be used. This will prevent inductor saturation.
SW-osc
EL-osc
decreases.
to GND. This capacitor is used to shunt any switching noise
HV825
SW-osc
)
©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
11/12/01
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 • FAX: (408) 222-4895
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www.supertex.com
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