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HV839 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 5.8V Output voltage regulation No SCR output Available in small packages (10-lead MSOP and 10-lead DFN/MLP)
General Description
The Supertex HV839 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 5.8V. 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, C1 and C2. The device is disabled when both C1 and C2 (pins 1 and 4) are at logic low. The HV839 has an internal oscillator, a switching MOSFET, and two high voltage EL lamp drivers. An external resistor connected between the RSW-OSC pin 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 90V, 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 180V 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
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Ordering Information
Device HV839 Package Options MSOP-102 DFN/MLP-101 HV839K6-G HV839MG-G
Absolute Maximum Ratings*
Supply Voltage, VDD Output Voltage, VCS Operating Temperature Range Storage temperature -0.5V to 7.5V -0.5V to 120V -40C to 85C -65C to 150C
1 Product supplied on 3000 piece carrier tape reels only 2 Product supplied on 2500 piece carrier tape reels only -G indicates package is RoHS compliant - "Green"
*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 5.8 85 Units V C Conditions
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
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Electrical Characteristics DC Characteristics (Over recommended operating conditions unless otherwise specified, TA= 25C)
Symbol RDS(ON) VDD Vcs VDIFF IDDQ IDD IIN Parameter 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 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 frequency drift 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 1.5 85 440 56.3 2.0 80 160 90 180 Min Typ Max 6.0 5.8 100 200 150 500 190 60 mA 45 76.2 152.4 500 64.0 560 71.7 5.0 89 -0.6 0.6 0.3 VDD 53 V V Hz kHz kHz % A A V V VDD = 2.0V to 5.8V VDD = 2.0V to 5.8V Units V V V nA nA A VDD = 2.0V to 5.8V VDD = 2.0V to 5.8V C1 = C2 = 0 to 0.1V C1 = C2 = 0.1 to 0.3V VDD = 2.0V to 5.8V 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. TA = -40C to +85C Conditions I = 100mA
VCS VDIFF fEL fSW fSW Drift D IIL IIH VEN-L VEN-H
Thermal Resistance
(Mounted on FR4 board, 25mm x 25mm x 1.57mm)
Package MSOP-10 DFN/MLP-10
ja
400 C/W 60 C/W
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Functional Block Diagram
VDD Lx
C1 C2 RSW-OSC
CS Control Logic & Switch Osc Vsense Output Drivers
Vcs
EL1
+
Vcs
GND
Disable
Logic Control & Divide by 128
Figure 1: Test Circuit
Device HV839MG-G or HV839K6-G EL1
Lamp
VIN = VDD 3.0V
Both EL1 and EL2 ON
-
Vref
EL2
COM
IIN 29.6mA 45.0mA
VCS 85.8 76.2
fEL 500Hz
Brightness 13.68ft-lm 12.66ft-lm
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Typical HV839 Performance Curves
(EL1 Lamp = 1.3in2, EL2 = Lamp = 0.93in2, VDD = 3.0V)
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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 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 220k resistor will provide a switching frequency of 64.0 kHz, and an EL lamp frequency of 500 Hz. To change the frequency to fEL1, the value of the resistor RSW-OSC1 can be determined as RSW-OSC1 = (220 x 500) / fEL1 k. Enable input signal for EL lamp 2. Logic high will turn ON the EL lamp 2 and logic low will turn it OFF. Refer 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. 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.
4 5
C2 GND
6
LX
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Split Supply Configuration
The HV839 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 HV839. The amount of current used to drive the internal logic is less than 190A. Therefore, the regulated voltage could easily provide the current without being loaded down.
Figure 2: Split Supply Configuration
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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
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Doc.# DSFP-HV839 A033106
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