HV850
________________________________________________________________________________
Initial Release
High Voltage Low Noise Inductorless EL Lamp Driver
Features
No external components required when using an
external EL clock frequency
EL frequency can be set by an external resistor
Low Noise
DC to AC converter
2
Drives up to 4.5nF load (approx. 2.0 inches)
Output voltage regulation
Enable function
General Description
Supertex HV850 is a high voltage electroluminescent
(EL) Lamp Driver IC. It is designed to drive EL lamps
of up to 2.0in
2
, with capacitive values up to 4.5nF.
HV850 converts a low voltage DC input to a high
voltage AC output across an EL lamp. It uses a
charge pump scheme to boost the input voltage
eliminating the need for an external inductor, diode,
and high voltage capacitor commonly found in
conventional topologies.
The charge pump circuit discharges its energy into
an EL lamp through a high voltage H-bridge. Once
the voltage reaches its regulated limit, it is turned off
to conserve power. The EL lamp is then discharged
to ground and the H-bridge changes state to allow
the charge pump to charge the EL lamp in the
opposite direction.
The EL lamp frequency can be set either by an
external resistor R
EL
or by applying an external clock
where the clock frequency is divided by 128 to set
the EL lamp frequency.
Applications
Cell phone keypads and displays
Transceivers
MP3 Players
Watches
Pagers
Measuring instruments/gauges
Typical Application Circuits
V
DD
=ON
V
DD
=ON
GND=OFF
+
GND=OFF
+
V
DD
C
DD
R
EL
EN
Clk-in
V
A
V
B
GND
Clk-en
V
DD
C
DD
R
EL
V
DD
R
EL
EN
Clk-in
V
A
V
B
GND
Clk-en
EL
Lamp
V
DD
-
EL
Lamp
-
V
DD
GND
V
DD
HV850MG
HV850MG
EL lamp frequency set by an external clock
EL lamp frequency set by R
EL
Supertex, Inc.
1
1/21/04
HV850
________________________________________________________________________________
Ordering Information
Device
HV850
Package
MSOP-8
HV850MG*
Die
HV850X
Pin Configuration
V
DD
R
EL
EN
Clk-in
MSOP
(top View)
V
A
V
B
GND
Clk-en
*Product supplied on 2500 piece Carrier Tape Reels.
Absolute Maximum Ratings*
Vdd, Supply Voltage
Operating Temperature
Storage Temperature
Power Dissipation MSOP-8
-0.5V to 4.5V
-25°C to +85°C
-65°C to +150°C
300mW
*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.
Electrical Characteristics
(
unless otherwise specified:
Symbol
I
DDQ
V
A
or V
B
V
A
-V
B
f
EL
I
DD
V
A
or V
B
V
A
-V
B
f
EL
t
rout
Parameter
Quiescent current
Peak output voltage
Peak to Peak output voltage
EL lamp frequency
Operating current
Peak output voltage
Peak to Peak output voltage
EL lamp frequency
Output voltage rise time
Min
63
126
225
54
110
250
1.5
T
A
= 25
°
C, V
DD
= 3.5V)
Typ
Max
Units
Conditions
150
nA
EN=0V
70
77
V
No load.
140
154
V
R
EL
=1.65MΩ or
250
275
Hz
CLK=32KHz
16
mA
See Figure 1, V
DD
=3.5V,
61
68.5
V
R
EL
=1.5MΩ,
122
134
V
Load=3.3nF+1KΩ
294
338
Hz
f
EL
=250Hz, 1in
2
lamp, 0V to
ms
90% of final value
Logic Inputs
Symbol
V
IL
V
IH
I
IL
I
IH
EN
rise
EN
fall
C
in
Parameter
Input logic low voltage
Input logic high voltage
Input logic low current
Input logic high current
Enable input rise time (for delay turn off)
Enable input fall time (for delay turn off)
Logic input capacitance
Min
0
2.0
Typ
Max
0.5
V
DD
1.0
1.0
10
5
10
Units
V
V
µA
µA
ms
s
pF
Conditions
0.01
10µ
Using external R-C
circuit, see Figure 2.
Recommended Operating Conditions
Symbol
V
DD
f
req
C
load
T
A
Parameter
Input voltage
EL lamp frequency
EL lamp capacitance
Operating Temperature
Min
3.0
50
0
-25
Typ
Max
4.2
500
3.5
+85
Units
V
Hz
nF
°C
Conditions
Supertex, Inc.
2
1/21/04
HV850
________________________________________________________________________________
Typical Output Waveform
Vdd=3.5V, Fel=250.0Hz; Load=3.3nF+1 kohm; Idd=9.19mA, CH1 20V/div, 1mS/div
Block Diagram
Vdd
EN
Vdd
Capacitor
Charge Pum p
Circuit
Va
Vsense
High
Voltage
Level
Trans-
lators
Feedback
Clk-in
Clk-en
Rel
GND
Vdd
EL
Oscillator
Vb
MOS FET
Full Bridge
Supertex, Inc.
3
1/21/04
HV850
________________________________________________________________________________
Pin Description
Pin #
1
2
3
4
5
6
7
8
Pad
V
DD
R
EL
EN
Clk-in
Clk-en
Gnd
V
B
V
A
Description
Input supply voltage pin.
An external resistor to V
DD
will set the EL lamp frequency.
Enable input pin. Logic high will turn the device on. An external R-C circuit can be added for a
delayed turn off.
Logic input pin. An external logic clock applied to this pad can be used to set the EL lamp
frequency (see Figure 3). This is useful for applications requiring the EL lamp to be
synchronized to a system clock. Connect to ground when no in use.
Logic input pin. Logic high will cause the EL lamp frequency to be set by the Clk-in input. Logic
low will cause the EL lamp frequency to be set by the external Rel resistor.
IC ground pin.
EL lamp driver output pin. The EL lamp is connected across V
A
and V
B
terminals.
EL lamp driver output pin. The EL lamp is connected across V
A
and V
B
terminals.
Figure 1: Typical Applications
VDD=ON
GND=OFF
+
V
DD
Cdd
Rel
V
DD
R
EL
V
A
V
B
GND
EL
Lamp
EN
Clk-in
-
Clk-en
HV850MG
Note: C
dd
=2.2µF, 6.3V low ESR
Load
3.3nF+1KΩ
R
EL
1.5MΩ
V
DD
3.0V
3.5V
4.0V
I
DD
8.9mA
10.2mA
10.4mA
Peak V
A
53V
61V
66V
f
EL
294Hz
Additional Examples
Lamp Size
1.0in
2
0.5in
2
1.0in
2
0.5in
2
1.0in
2
R
EL
1.65MΩ
2.0MΩ
3.3MΩ
3.3MΩ
4.7MΩ
V
DD
3.0V
3.5V
4.0V
3.0V
3.5V
4.0V
3.0V
3.5V
4.0V
3.0V
3.5V
4.0V
3.0V
3.5V
4.0V
I
DD
8.4mA
9.4mA
9.9mA
5.5mA
5.3mA
4.9mA
5.6mA
5.4mA
5.0mA
4.6mA
4.1mA
3.8mA
4.8mA
4.4mA
5.0mA
Peak V
A
53V
62V
66V
62V
68V
68V
62V
67V
68V
64V
68V
68V
64V
68V
68V
f
EL
250Hz
210Hz
128Hz
128Hz
89Hz
Brightness
7.31cd/m
2
10.35cd/m
2
12.62cd/m
2
11.54cd/m
2
14.33cd/m
2
14.90cd/m
2
8.55cd/m
2
10.29cd/m
2
10.94cd/m
2
8.25cd/m
2
9.62cd/m
2
9.95cd/m
2
6.02cd/m
2
7.50cd/m
2
10.94cd/m
2
Supertex, Inc.
4
1/21/04
HV850
________________________________________________________________________________
Figure 2: Push Button Turn on with Delay Turn off
+
V
DD
Cdd
Push button
turn on
Rel
V
DD
R
EL
EN
V
A
V
B
GND
Clk-en
EL
Lamp
-
C
R
Clk-in
HV 850MG
RC time constant
will set Turn off
Delay time
Figure 3: Independent Programmable Output Frequency (f
EL
)
V DD=ON
GND=OFF
+
V
DD
V
DD
Cdd
V
A
V
B
GND
Clk-en
R
EL
EN
Clk-in
EL
Lamp
-
VDD
GND
HV850MG
Supertex, Inc.
5
1/21/04
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