1
HV825
Absolute Maximum Ratings*
Supply voltage, V
DD
-0.5V to +2.5V
Operating Temperature Range
-25
C to +85C
Storage Temperature Range
-65
C to +150C
MSOP-8 Power Dissipation
300mW
SO-8 Power Dissipation
400mW
Note:
*All voltages are referenced to GND.
High Voltage EL Lamp Driver
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
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 V
DD
/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
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. A 0.01 to 0.1
F, 100V
capacitor is connected between C
S
and ground. The EL lamp is
connected between V
A
and V
B
.
The switching BJT charges the external inductor and discharges
it into the 0.01 to 0.1
F, 100V capacitor at C
S
. The voltage at C
S
will start to increase. The outputs V
A
and V
B
are configured as
an H-bridge and are switching in opposite states to achieve a
peak-to-peak voltage of two times the V
CS
voltage across the EL
lamp.
Pin Configuration
Applications
Pagers
Portable Transceiver
Cellular phones
Remote control units
Calculators
1
2
3
4
8
7
6
5
V
DD
R
EL-osc
R
SW-osc
V
A
C
s
V
B
L
x
GND
top view
SO-8/MSOP-8
For detailed circuit and application information, please refer
to application notes AN-H33 and AN-H34.
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.
Ordering Information
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.
2
HV825
Symbol
Parameter
Min
Typ
Max
Units
Conditions
R
DS(ON)
On-resistance of switching transistor
15
I=50mA
I
IN
V
DD
supply current (including inductor current)
30
38
mA
V
DD
=1.5V. See test circuit.
I
DDQ
Quiescent V
DD
supply current
1.0
A
R
SW-osc
=GND
V
CS
Output voltage on V
CS
52
56
62
V
V
DD
=1.5V. See test circuit.
V
A-B
Differential output voltage across lamp
104
112
124
V
V
DD
=1.5V. See test circuit.
f
EL
V
A-B
output drive frequency
400
Hz
V
DD
=1.5V. See test circuit.
f
SW
Switching transistor frequency
30
KHz
V
DD
=1.5V. See test circuit.
D
Switching transistor duty cycle
88
%
Electrical Characteristics
DC Characteristics
(Over recommended operating conditions unless otherwise specified, T
A
=25
C)
Symbol
Parameter
Min
Typ
Max
Units
Conditions
V
DD
Supply voltage
1.0
1.6
V
C
L
Load Capacitance
0
6.0
nF
T
A
Operating temperature
-25
+85
C
Recommended Operating Conditions
Symbol
Parameter
Min
Typ
Max
Units
Conditions
V
IL
Low level input voltage to R
SW-osc
resistor
0
0.2
V
V
DD
=1.0V-1.6V.
V
IH
High level input voltage to R
SW-osc
resistor
V
DD
-0.5
V
DD
V
V
DD
=1.0V-1.6V.
Enable/Disable Table
4
HV825
External Component Description
External Component
Selection Guide Line
Diode
Fast reverse recovery, 1N4148 or equivalent.
C
S
Capacitor
0.01 to 0.1
F, 100V capacitor to GND is used to store the energy transferred from the inductor.
R
EL-osc
Resistor
The lamp frequency is controlled via the R
EL-osc
. The lamp frequency increases as the R
EL-osc
decreases.
As the lamp frequency increases, the amount of current drawn from the battery will increase and the output
voltage V
CS
will decrease. This is because the lamp will draw more current from V
CS
when driven at higher
frequencies.
In general, as the lamp size increases, larger R
EL-osc
is recommended to provide higher V
CS
. However, the
color of the lamp is dependent upon its frequency and the shade of the color will change slightly with different
frequencies.
R
SW-osc
Resistor
The switching frequency of the inductor is controlled via the R
SW-osc
. The switching frequency increases as
the R
SW-osc
decreases. As the switching frequency increases, the amount of current drawn from the battery
will decrease and the output voltage V
CS
will also decrease.
L
X
Inductor
The inductor L
X
is used to boost up the low input voltage. When the internal switch is on, the inductor is being
charged. When the internal switch is off, the charge 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
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-osc
)
should be increased to avoid saturation.
The test circuit uses a Murata (LQH4N561) 560
H inductor. Using different inductor values or inductors from
different manufacturers will affect the performance.
As the inductor value decreases, smaller R
SW-osc
value shall be used. This will prevent inductor saturation.
Inductor with the same inductance value (560
H) but lower series resistance will charge faster. The
R
SW-osc
resistor value needs to be decreased to prevent inductor saturation and high current consumption.
C
SW
Capacitor
A 1nF capacitor is recommended from R
SW-OSC
to GND. This capacitor is used to shunt any switching noise
that may couple into the R
SW-OSC
pin.
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 FAX: (408) 222-4895
www.supertex.com
11/12/01
2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
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