1
HV845
Initial Release
Low Noise Dual EL Lamp Driver
Features
Low audible noise
Independent input control for lamp selection
180V
PP
output voltage
Split supply capability
Patented output timing
One miniature inductor to power both lamps
Low shutdown current
Wide input voltage range 2.0V to 5.8V
Output voltage regulation
No SCR output
Available in 12-Lead QFN/MLP package
Applications
Dual display cellular phones
Keypad and LCD backlighting
Portable instrumentation
Dual segment lamps
Hand held wireless communication devices
General Description
The Supertex HV845 is a low noise, high voltage driver
designed for driving two EL lamps with a combined area of 3.5
square inches. The input supply voltage range is from 2.0V to
5.8V. The device is designed to reduce the amount of audible
noise emitted by the lamp. This device uses a single inductor
and minimum number of passive components to drive two EL
lamps. The nominal regulated output voltage of 90V is applied
to the EL lamps. The two EL lamps can be turned ON and OFF
by the two logic input control pins, C
1
and C
2
. The device is
disabled when both C
1
and C
2
(pins 12 and 3) are at logic low.
The HV845 has an internal oscillator, a switching MOSFET, and
two high voltage EL lamp drivers. Each driver has its own half
bridge common output COM1 and COM2, which signifi cantly
minimizes the DC offset seen by the EL lamp. An external
resistor connected between the R
SW-OSC
pin and the voltage
supply pin, V
DD
, sets the frequency for the switching MOSFET.
The EL lamp driver frequency is set by dividing the MOSFET
switching frequency by 512. An external inductor is connected
between the L
X
and the V
DD
pins. Depending on the EL lamp size,
a 1.0 to 10.0nF, 100V capacitor is connected between C
S
and
Ground. The switching MOSFET charges the external inductor
and discharges it into the capacitor at C
S
. The voltage at C
S
increases. Once the voltage at C
S
reaches a nominal value of
90V, the switching MOSFET is turned OFF to conserve power.
Typical Application Circuit
HV845K7-G
+
-
+
-
6
4
7
10
9
1
2
3
12
8
5
V
DD
R
SW-OSC
COM2
C
1
EL
2
L
X
C
S
GND
C
2
EL
1
COM1
D
1.0F
1.5V
0
1.5V
0
V
DD
V
IN
C
IN
4.7F
C
DD
0.1F
845k
3.3M
3.3M
EL Lamp 1
EL Lamp 2
1.0F
330
H
C
S
3.3nF, 100V
L
X
2
HV845
Ordering Information
Device
Package Options
QFN/MLP - 12
HV845
HV845K7-G
-G indicates package is RoHS compliant (`Green')
Absolute Maximum Ratings
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Electrical Characteristics
(Over recommended operating conditions unless otherwise specifi ed - V
IN
= V
DD
= 3.3V, T
A
=25C)
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.
Parameter
Value
Supply Voltage, V
DD
-0.5V to 7.5V
Output Voltage, V
CS
-0.5V to 120V
Operating Temperature Range
-40C to 85C
Storage temperature
-65C to 150C
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Recommended Operating Conditions
V
DD
Supply voltage
2.0
-
5.8
V
---
T
A
Operating temperature
-40
-
+85
o
C
---
Pin Confi guration
Thermal Resistance
Package
ja
QFN/MLP - 12
60
o
C/W
Note: Mounted on FR4 board, 25mm x 25mm x 1.57mm
R
DS(ON)
On-resistance of switching
transistor
-
-
10
I = 100mA
V
DD
Input voltage range
2.0
-
5.8
V
---
V
CS
Output regulation voltage
80
90
100
V
V
DD
= 2.0V to 5.8V
V
DIFF
Differential output peak to peak
voltage
(EL
1
to COM1, EL
2
to COM2)
160
180
200
V
V
DD
= 2.0V to 5.8V
I
DDQ
Quiescent V
DD
supply current
-
-
150
nA
C
1
= C
2
= 0.1V
-
-
250
nA
C
1
= C
2
= 0.3V
I
DD
Input current into the V
DD
pin
-
-
250
A
V
DD
= 5.8V
I
IN
Average input current including
inductor current when driving both
lamps
-
20
30
mA
V
IN
= 5.5V (See Figure 1)
V
CS
Output voltage on V
CS
when driving
both lamps
-
87
-
V
V
IN
= 5.5V (See Figure 1)
Note: Pads are on the bottom of the package.
Back-side heat slug is at ground potential.
HV845K7-G
Top View
C
1
V
DD
R
SW-OSC
C
2
GND
EL
2
EL
1
COM2
C
S
L
X
COM1
NC
1
12 11 10
9
8
7
6
5
4
3
2
3
HV845
Functional Block Diagram
V
DIF
Differential output peak to peak volt-
age across each lamp
(EL
1
to COM1, EL
2
to COM2)
160
180
200
V
V
IN
= 5.5V (See Figure 1)
f
EL
V
DIFF
output drive frequency
170
200
230
Hz
R
SW
= 845k
f
SW
Switching transistor frequency
87
102
118
kHz
R
SW
= 845k
f
SW temp
Switching transistor frequency
tempco
-
15
-
%
T
A
= -40C to +85C
D
Switching transistor duty cycle
-
85
-
%
T
A
= -40C to +85C
I
IL
Input logic low current
-
-
1.0
A
V
DD
= 2.0V to 5.8V
I
IH
Input logic low current
-
-
1.0
A
V
DD
= 2.0V to 5.8V
V
IL
Logic input low voltage
0
-
0.3
V
---
V
IH
Logic input high voltage
1.5
-
V
DD
V
---
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Electrical Characteristics (cont.)
V
CS
Output
Drivers
V
SENSE
-
+
V
REF
Control logic
and switch
oscillator
Disable
Logic control and
divide by 512
EL
1
EL
2
R
SW-OSC
C
S
L
X
V
DD
C
1
C
2
GND
C
COM1
V
DD
V
CS
V
CS
COM2
Function Table
Logic Inputs
Outputs
Device
C
1
C
2
EL
1
EL
2
COM1
COM2
0
0
Hi Z
Hi Z
Hi Z
Hi Z
OFF
0
1
Hi Z
ON
Hi Z
ON
ON
1
0
ON
Hi Z
ON
Hi Z
ON
1
1
ON
ON
ON
ON
ON
4
HV845
Figure 1 - Test Circuit
C
S
3.3nF, 100V
HV845K7-G
+
-
1N4148*
+
-
6
4
7
10
9
1
2
3
12
8
5
* or any (equivalent or better) > 90V, fast recovery diode
** Cooper LPO6610-334MLB
*** The bigger sized lamp should be tied to EL
1
and the
smaller sized lamp to EL
2
(pins 10 and 9 respectively)
V
DD
R
SW-OSC
COM2
C
1
EL
2
L
X
C
S
GND
C
2
EL
1
COM1
620
620
11nF
13nF
1.8in
2
EL Lamp 2***
2.1in
2
EL Lamp 1***
330H**
845k
C
DD
0.1F
C
IN
4.7F
V
DD
V
IN
L
X
V
IH
= ON
0 = OFF
V
IH
= ON
0 = OFF
Typical Performance
Lamp
V
DD
(V)
V
IN
(V)
I
IN
(mA)
V
CS
(V
PEAK
)
f
EL
(Hz)
Lamp Brightness (cd/in
2
)
EL
1
EL
2
EL
1
ON
3.0V
5.2V
7.96
88
195
13.89
-
EL
2
ON
6.91
-
12.89
Both EL
1
and EL
2
ON
13.93
13.02
11.24
EL
1
ON
5.5V
7.47
13.93
-
EL
2
ON
6.42
-
13.22
Both EL
1
and EL
2
ON
13.42
13.30
12.05
EL
1
ON
5.8V
7.04
14.03
-
EL
2
ON
6.01
-
13.30
Both EL
1
and EL
2
ON
12.94
13.55
12.51
5
HV845
Pin Confi guration and Description
Pin # Function
Description
1
V
DD
Input voltage supply pin.
2
R
SW-OSC
External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency.
The external resistor should be connected between V
DD
and this pin. The EL lamp frequency is the
switching frequency divided by 512. The switching frequency is inversely proportional to the resis-
tor value. A 845k resistor will provide a nominal switching frequency of 102kHz and an EL lamp
frequency of 200Hz. To change the frequency to f
EL1
, the value of the resistor R
SW-OSC1
can be deter-
mined as R
SW-OSC1
= (845 x 200) / f
EL1
k.
3
C
2
Enable input signal for EL Lamp 2. Logic high will turn ON the EL lamp 2 and logic low will turn it OFF.
Refer to the function table.
4
GND
Device ground.
5
L
X
Drain of internal switching MOSFET. Connection for an external inductor. When the switching
MOSFET is turned ON, the inductor is being charged. When the MOSFET is turned OFF, the energy
stored in the inductor is transferred to the high voltage capacitor connected at the C
S
pin.
6
C
S
Connect a 100V capacitor between this pin and GND. This capacitor stores the energy transferred
from the inductor.
7
COM2
Common lamp connection for EL
2
.
8
COM1
Common lamp connection for EL
1
.
9
EL
2
EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected
to this pin.
10
EL
1
EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected
to this pin.
11
NC
No connect.
12
C
1
Enable input signal for EL Lamp 1. Logic high will turn ON the EL lamp 1 and logic low will turn it OFF.
Refer to the function table.
Figure 2 - Split Supply Confi guration
HV845K7-G
4
7
10
9
1
2
3
12
8
5
V
DD
R
SW-OSC
COM2
C
1
EL
2
L
X
C
S
GND
6
C
2
EL
1
COM1
D
C
S
L
X
C
IN
C
DD
V
IH
= ON
0 = OFF
V
IH
= ON
0 = OFF
Regulated Voltage = V
DD
Battery Voltage = V
IN
R
SW-OSC
EL Lamp 1
EL Lamp 2
Split Supply Confi guration
The HV845 can be used in applications operating from a
battery where a regulated voltage is available. This is shown
in Figure 2. The regulated voltage can be used to drive the
internal logic of HV845. The amount of current used to drive
the internal logic is less than 200A. Therefore, the regu-
lated voltage could easily provide the current without being
loaded down.
6
Doc.# DSFP - HV845
062306
HV845
Top View
Side View
3.00 0.15
0.40 0.10
1.25 - 1.65
0.50 BSC
0.20
0.25 + 0.05
- 0.07
0 - 14
O
1.25 - 1.65
Note:
1. All dimensions are in millimeters; all angles in degrees
2. Corner shape may differ from drawing
0.75 0.05
0.0 - 0.05
Pin #1 Index
3.00 0.15
Note 2
12-Lead QFN/MLP (3x3) Package (K7)
(The package drawing(s) in this data sheet may not refl ect the most current specifi cations. For the latest package outline
information go to
http://www.supertex.com/packaging.html
.)
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