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HV831 High Voltage Dual EL Lamp Driver
Features
Independent input control for lamp selection Split supply capability Patented output timing One miniature inductor to power both lamps Low shutdown current Wide input voltage range 2.0V to 5.0V Output voltage regulation No SCR output Available in 10 - pin MSOP package
General Description
The Supertex HV831 is a 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 5.0V. 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 80V is applied to the EL lamps. The two EL lamps can be turned on and off by the two logic input control pins, C1 and C2. The device is disabled when both C1 and C2 (pins 1 and 4) are at logic low. The HV831 has an internal oscillator, a switching MOSFET, and two high voltage EL lamp drivers. An external resistor connected between the RSW-OSC and the voltage supply pin VDD sets the frequency for the switching MOSFET. The EL lamp driver frequency is set by dividing the MOSFET switching frequency by 128. An external inductor is connected between the LX and the VDD pins. Depending on the EL lamp size, a 1.0 to 10.0nF, 100V capacitor is connected between CS and Ground. The two EL lamps are connected between EL1 to Com and EL2 to Com. The switching MOSFET charges the external inductor and discharges it into the capacitor at CS. The voltage at CS increases. Once the voltage at CS reaches a nominal value of 80V, the switching MOSFET is turned off to conserve power. The outputs EL1 to Com and EL2 to Com are configured as H bridges and switch in opposite states to achieve 160V across the EL lamp.
Applications
Mobile cellular phones, dual display Keypad and LCD backlighting Portable instrumentation Dual segment lamps Hand held wireless communication devices
Typical Application Circuit
VDD = ON 0 = OFF VDD = ON 0 = OFF
1
EL Lamp 11 C1 VDD EL1 EL2
10 9 8 7 6
+ VDD -
RSW-OSC CDD
2 3 4 5
RSW-OSC Com C2 GND CS LX
EL Lamp 21 D
HV831MG VIN + CIN -
~
LX
CS
1 The bigger sized lamp should be tied to EL1 and the smaller sized lamp to EL2 terminals (pins 10 and 9 respectively)
A081005
1
HV831
Absolute Maximum Ratings*
Supply Voltage, VDD Supply Voltage, VCS Operating Ambient Temperature Range Storage Temperature Range 10-Pin MSOP Power Dissipation -0.5 to +7.5V -0.5 to +120V -40C to +85C -65 to +150C 250mW HV831
Ordering Information
Package Options DEVICE MSOP-101 HV831MG
1 Product supplied on 2500 piece carrier tape reels only
*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, Gnd
Recommended Operating Conditions
Symbol VDD TA Parameter Supply Voltage Operating Temperature Min 2.0 -40 Typ Max 5.0 85 Units V
o
Conditions
C
Function Table
C1 0 0 1 1 C2 0 1 0 1 EL1 Hi Z Hi Z ON ON EL2 Hi Z ON Hi Z ON Com Hi Z ON ON ON IC OFF ON ON ON
Pin Configuration
C1 1
10 EL1 9 EL2 8 Com 7 CS 6 LX
VDD 2
RSW-OSC 3
C2 4 GND 5 HV831MG
Top View: MSOP-10
Note: Package are not drawn to scale.
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Electrical Characteristics
DC Characteristics (Over operating conditions unless otherwise specified, T = 25C)
A
HV831
Min Typ Max
6.0 2.0 72 144 80 160 5.0 88 176 150 150 45 mA 26.5 35 V
Symbol Parameter
RDS(ON) VDD Vcs VDIFF IDDQ IDD On-resistance of switching transistor Input Voltage Range Output regulation voltage Differential output peak to peak voltage (EL1 to Com, EL2 to Com) Quiescent VDD supply current Input current into the VDD pin
Units
V V V nA A
Conditions
I = 100mA
VDD = 2.0V to 5.0V VDD = 2.0V to 5.0V C1 = C2 = 0V VDD = 2.0V to 5.0V VIN = 3.0V, See Figure 1. TA = -40C to +85C VIN = 3.0V, See Figure 1. TA = +25C VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1.
IIN
Input current including inductor current when driving both lamps Output voltage on VCS when driving both lamps Differential output peak to peak voltage across each lamp (EL1 to Com, EL2 to Com) VDIFF output drive frequency Switching transistor frequency Switching Transistor Duty cycle Input logic low current going into the control pin Input logic low current going into the control pin Logic input low voltage Logic input high voltage 0 0.8VDD 214 27.4 85
VCS VDIFF fEL fSW D IIL IIH VEN-L VEN-H
67.8
135.6
V
244 31.2
274 35 89 -0.6 0.6 0.2VDD VDD
Hz kHz % A A V V
VDD = 2.0V to 5.8V VDD = 2.0V to 5.8V
Thermal Resistance
(Mounted on FR4 board, 25mm x 25mm x 1.57mm)
Package
MSOP-10
JA
400 oC/W
3
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Functional Block Diagram
VDD Lx
HV831
C1 C2 R SW-OSC
CS
Control Logic & Switch-Osc VSENSE Output Drivers
Vcs
EL1
+ Vcs
GND
Disable
Logic Control & Divide by 128
Figure 1: Test Circuit
VDD = ON Enable 1 VDD = ON 0 = OFF 0 = OFF Enable 2 470 k 0.1F
3 4
1 2
C1 VDD
+ VDD -
RSW-OSC Com C2 GND CS LX
5
HV831MG VIN + 4.7F
-
1 or any (equivalent or better) > 90V, fast recovery diode 2 Murata LQH32CN561K21 3 The bigger sized lamp should be tied to EL1 and the smaller sized lamp to EL2 terminals (pins 10 and 9 respectively)
Device HV831MG
Lamp EL1 Both EL1 and EL2 ON
VDD 3.0V
VREF
EL1 EL2
10 9 8 7 6
EL2
COM
EL Lamp 1 (1.3 in2)3
EL Lamp 2 (0.93 in2)3 1N9141
~
560H2 3.3 nF, 100V
IDD 17.3mA 26.5mA
VCS 74.8V 67.8V
fEL 244Hz
Brightness 5.9ft-lm 5.5ft-lm
4
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Typical HV831 Performance Curves
(When driving both EL Lamps, EL1 Lamp = 1.3in2, EL2 Lamp = 0.93in2, VDD = 3.0V)
VCS vs VIN IIN vs VIN
HV831
80 75 70 65 60 55 50 2.0 2.5 3.0
VIN (V)
30 28
IIN (mA)
VCS (V)
26 24 22
3.5
4.0
4.5
2.0
2.5
3.0
VIN (V)
3.5
4.0
4.5
Brightness vs Vin
8 7 6 5 4 3 2 2.0 2.5 3.0
VIN (V)
IIN vs VCS
30 28
IIN (mA)
Brightness (ft-lm)
26 24 22 50 55 60 65
VCS (V)
3.5
4.0
4.5
70
75
80
IIN, VCS, Brightness vs Inductor Value
90
VCS
8.0 7.5 7.0
Brightness (measured on EL1 lamp) Brightness (ft-lm)
80 70
lIN (mA), VCS (V)
60 50 40 30 20 10 100 200 300
lIN
6.5 6.0 5.5 5.0 4.5 4.0
400
500
600
Inductor Value (H)
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HV831
Pin Configuration and Description
Pin #
1 2
Name
C1 VDD
Function
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. Input supply voltage pin. External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency. The external resistor should be connected between this pin and the VDD pin. The EL lamp frequency is switching frequency divided by 128.
3
RSW-OSC The switching frequency increases as the value of RSW-OSC decreases. A 470k resistor will provide a switching frequency of 31.2 kHz, and an EL lamp frequency of 244 Hz. To change the frequency to fSW1, the value of the resistor RSW-OSC1 can be determined as RSW-OSC1 = (470 x 244) / fEL1M.
4 5
C2 GND
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. IC Ground Pin. External inductor connection to boost the low input voltage using inductive flyback. Connect an inductor between VIN and this pin. Also connect a high voltage fast recovery diode between this pin and the CS pin. The anode of the diode needs to be connected to the LX pin and the cathode to the CS pin. In general, small valued inductors, which can handle more current, are more suitable for driving large sized lamps. As the inductor value decreases, the switching frequency should be increased to avoid saturation. 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 CS pin.
6
LX
7 8 9 10
CS Com EL2 EL1
Connect a 100V capacitor between this pin and GND. This capacitor stores the energy transferred from the inductor. Common connection for both EL lamps. Connect one end of both the lamps to this pin. EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected to this pin. EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected to this pin.
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Split Supply Configuration
The HV831 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
HV831
of HV831. The amount of current used to drive the internal logic is less than 150A. Therefore, the regulated voltage could easily provide the current without being loaded down.
Figure 2: Split Supply Configuration
VDD = ON Enable 1 VDD = ON 0 = OFF 0 = OFF Enable 2 Regulated Voltage = VDD RSW-OSC
3 4 5
EL Lamp 11
1 2
C1 VDD
EL1 EL2
10 9 8 7 6
RSW-OSC Com C2 GND CS LX
EL Lamp 21 D
Battery Voltage = VIN
HV831MG
~
LX CS
1 The bigger sized lamp should be tied to EL1 and the smaller sized lamp to EL2 terminals (pins 10 and 9 respectively)
Audible Noise Reduction
This section describes a method (patented) developed at Supertex to reduce the audible noise emitted by the EL lamps used in application sensitive to audible noise. The waveform takes the shape of approximately 2RC time constants for rising and 2RC time constants for falling, where C is the capacitance of the EL lamp, and R is the external resistor, RSER connected in series with the EL lamp. Figure 3 shows a general circuit schematic that uses the series resistors, RSER1 and RSER2, for each of the EL lamps. RSER1 and RSER2 are connected in series with the EL lamp. The audible noise can be set a desirable level by selecting the resistances for RSER1 and RSER2. It is important to note that addition of these external resistors will reduce the voltage across the EL lamp, and hence the brightness of the EL lamp.
Figure 3: Typical Application Circuit For Audible Noise Reduction
ON = VDD OFF = 0V ON = VDD OFF = 0V Enable 1 RSER1 EL Lamp 11 Enable 2 RSW-OSC CDD 5 3 4 1 2
C1 VDD
EL1 EL2
10 9 8 7 6
RSER2 EL Lamp 21 D
+ VDD
RSW-OSC Com C2 GND CS LX
HV831MG VIN + CIN -
~
LX
CS
1 The bigger sized lamp should be tied to EL1 and the smaller sized lamp to EL2 terminals (pins 10 and 9 respectively)
7
A081005
HV831
10-Lead MSOP Package Outline (MG)
0.0200.006 (0.5000.152) GATE PLANE = 0.1930.004 (4.9000.100) 0.1180.004 (3.0000.100) 0- 6 0.0210.005 (0.5500.150) 0.010 (0.250)
*
Full Circle or Half Circle
*
0.1180.004 (3.0000.100)
DETAIL A
0.0370.005 (0.950.015)
0.0330.004 (0.8500.100)
0.0070.002 (0.1800.050)
SEE DETAIL A
0.0130.003 (0.3250.075)
0.0040.002 (0.1000.050)
Doc.# DSFP-HV831 B081005
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