15-9
15
General Description
The Supertex HV8051 and HV8053 are high-voltage drivers
designed for driving EL lamps of typically 4nF and 12nF for a 1V
and 3V operation. The input supply voltage range is from 1.0V to
1.6V for HV8051 and 2.4V to 3.5V for HV8053. 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 50V
for HV8051 and 70V for HV8053.
The HV8051/HV8053 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 0.1F
capacitor is connected between C
s
and GND pins. The EL lamp
is connected between V
A
and V
B
pins.
The switching BJT charges the external inductor and discharges
it into the 0.1F 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.
HV8051
HV8053
High-Voltage EL Lamp Driver
Ordering Information
Absolute Maximum Ratings*
Supply voltage, V
DD
-0.5V to +4.5V
Operating temperature range
-25C to +85C
Storage temperature range
-65C to +150C
SO-8 power dissipation
400mW
Note:
*All voltages are referenced to GND.
Features
Processed with HVCMOS
technology
1.0V to 3.5V operating supply voltage
DC to AC conversion
Adjustable output lamp frequency to control lamp color,
lamp life, and power consumption
Adjustable converter frequency to eliminate harmonics and
optimize power consumption
Applications
Pagers
Portable transceiver
Cellular phones
Remote control units
Calculators
Package Options
Device
Input Voltage
8-Lead SO
Die
HV8051
1.0V to 1.6V
HV8051LG
HV8051X
HV8053
2.4V to 3.5V
HV8053LG
HV8053X
Pin Configuration
SO-8
1
2
3
4
8
7
6
5
top view
V
DD
R
EL-osc
R
SW-osc
V
A
C
s
V
B
L
x
GND
OBSOLETE
15-10
HV8051/HV8053
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
HV8051
8.0
15
mA
V
DD
= 1.0V to 1.6V. See Figure 1.
inductor current)
HV8053
40
65
V
DD
= 2.4V to 3.5V. See Figure 2.
V
CS
Output voltage on V
CS
HV8051
41
V
DD
= 1.0V to 1.3V. See Figure 1.
52
V
V
DD
= 1.3V to 1.6V. See Figure 1.
HV8053
43
V
DD
= 2.4V to 3.0V. See Figure 2.
52
V
DD
= 3.0V to 3.5V. See Figure 2.
f
EL
V
A-B
output drive frequency
HV8051
60
160
V
DD
= 1.0V. See Figure 1.
70
220
Hz
V
DD
= 1.6V. See Figure 1.
HV8053
200
350
V
DD
= 2.4V to 3.5V. See Figure 2.
f
sw
Switching transistor frequency
HV8051
50
KHz
V
DD
= 1.0V to 1.6V. See Figure 1.
HV8053
50
V
DD
= 2.4V to 3.5V. See Figure 2.
D
Switching transistor duty cycle
85
%
See Figures 1 and 2.
Electrical Characteristics
DC Characteristics
(Over recommended operating conditions unless otherwise specified, T
A
= 25C)
Symbol
Parameter
Min
Typ
Max
Units
Conditions
V
DD
Supply voltage
HV8051
1.0
1.6
V
@ V
DD
= 1.0V to 1.6V
HV8053
2.4
3.5
V
@ V
DD
= 2.4V to 3.5V.
C
L
Load capacitance*
HV8051
0
4.0
nF
@ V
DD
= 1.0V to 1.6V
HV8053
0
12
nF
@ V
DD
= 2.4V to 3.5V
T
A
Operating temperature
-25
85
C
*Larger panels can be driven with HV8051/HV8053. See application note AN-H33.
Recommended Operating Conditions
Block Diagram
Switch
Osc
Output
Osc
GND
V
DD
R
sw-osc
R
EL-osc
Q
Q
V
A
C
s
L
x
V
B
Q
Q
OBSOLETE
15-12
HV8051/HV8053
External Component Description
External Component
Selection Guide Line
Diode
Fast reverse recovery diode, 1N4148 or equivalent.
Cs Capacitor
0.01F to 0.1F, 100V capacitor to GND is used to store the energy transferred from the inductor.
R
EL-osc
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.
R
SW-osc
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.
C
SW
Capacitor
A 1nF capacitor is typically recommended on R
SW-osc
to GND for HV8053. As the input voltage of the device
increases, a faster switching converter frequency is required to avoid saturating the inductor. With the
higher switching frequency, more noise will be introduced. This capacitor is used to shunt any switching
noise that may couple into the R
SW-osc
pin.
C
Lx
Capacitor
In order to drive the HV8053 more efficiently when high brightness is required, a 47pF, 100V C
Lx
capacitor
needs to be used at the L
x
pin to GND. This capacitor reduces the total amount of current drawn by the
circuit by reducing the dv/dt voltage on the internal switch.
Lx Inductor
The inductor L
x
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 C
S
. The energy stored in the capacitor is then available 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 size decreases, the switching
frequency of the inductor (controlled by R
SW
) should be increased to avoid saturation.
560H Murata inductors with 14.5 series DC resistance is typically recommended. For inductors with the
same inductance value but with lower series DC resistance, lower R
SW
value is needed to prevent high
current draw and inductor saturation.
Lamp Size
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 (350mW), an external resistor in series with one side of the lamp is recom-
mended to help reduce the package power dissipation.
Application Hints
Start with a high conversion frequency to avoid inductor satura-
tion. Adjust converter frequency (via R
SW-osc
) and inductor value
to obtain desired lamp drive voltage and supply current. Make
sure that inductor current does not approach saturation as
specified on the inductor data sheet. Higher V
IN
's and smaller
inductors require a higher conversion frequency to avoid satura-
tion.
Adjust the lamp drive frequency via R
EL-osc
to obtain desired
lamp brightness and hue.
If the desired V
CS
cannot be obtained, try decreasing lamp drive
frequency slightly.
If V
CS
is above 80 volts, insert a 2k resistor in series with the
lamp.
Monitor overall power consumption. If above 350mW, insert a
resistor in series with the lamp to decrease device power
dissipation.
In keeping with good circuit design practice, the supply voltage
should be bypassed with a capacitor located close to the lamp
driver. Values can range from 0.1F to 1F depending on supply
impedance. A supply bypass capacitor elsewhere in the host
circuit is sufficient if located close to the driver.
For lower power consumption, set a low lamp drive frequency,
use a 1mH inductor, and adjust power conversion frequency for
minimum current draw.
For high brightness, set lamp drive frequency for desired hue,
use a 330H inductor and adjust power conversion frequency
until desired brightness is obtained.
For longer lamp life, use as low a lamp drive frequency as is
acceptable. Adjust converter frequency and inductor value to
obtain acceptable brightness.
For high lamp drive frequencies, employ a FET follower on the
output. See application note AN-H33.
OBSOLETE
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