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HV825 High Voltage EL Lamp Driver
Ordering Information
Package Options Device HV825 Input Voltage 1.0 to 1.6V 8-Lead SO HV825LG MSOP-8 HV825MG* Die HV825X
* Product supplied on 2500 piece carrier tape reels.
Features
Processed with HVCMOS(R) technology 1.0V to 1.6V operating supply voltage DC to AC conversion Output load of typically up to 6nF Adjustable output lamp frequency Adjustable converter frequency Enable function
General Description
The Supertex HV825 is a high voltage driver designed for driving EL lamps typically up to 6nF. The input supply voltage range is from 1.0V to 1.6V. 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 56V. The HV825 can be enabled/disabled by connecting the RSW-osc resistor to VDD/ground. The HV825 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 RSW-osc pin and the supply pin VDD. The EL lamp driver frequency is set by an external resistor connected between REL-osc pin and the VDD pin. An external inductor is connected between the LX and VDD pins. A 0.01 to 0.1F, 100V capacitor is connected between CS and ground. The EL lamp is connected between VA and VB. The switching BJT charges the external inductor and discharges it into the 0.01 to 0.1F, 100V capacitor at CS. The voltage at CS will start to increase. The outputs VA and VB are configured as an H-bridge and are switching in opposite states to achieve a peak-to-peak voltage of two times the VCS voltage across the EL lamp.
Applications
Pagers Portable Transceiver Cellular phones Remote control units Calculators
Absolute Maximum Ratings*
Supply voltage, VDD Operating Temperature Range Storage Temperature Range MSOP-8 Power Dissipation SO-8 Power Dissipation
Note: *All voltages are referenced to GND.
-0.5V to +2.5V -25C to +85C -65C to +150C 300mW 400mW VDD RSW-osc Cs Lx
1 2 3 4
8 7 6 5
Pin Configuration
REL-osc VA VB GND
For detailed circuit and application information, please refer to application notes AN-H33 and AN-H34.
top view SO-8/MSOP-8
11/12/01
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the 1 Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
HV825
Electrical Characteristics
DC Characteristics
Symbol RDS(ON) IIN IDDQ VCS VA-B fEL fSW D (Over recommended operating conditions unless otherwise specified, TA=25C) Parameter On-resistance of switching transistor VDD supply current (including inductor current) Quiescent VDD supply current Output voltage on VCS Differential output voltage across lamp VA-B output drive frequency Switching transistor frequency Switching transistor duty cycle 52 104 400 30 88 56 112 30 Min Typ Max 15 38 1.0 62 124 Units mA A V V Hz KHz % I=50mA VDD=1.5V. See test circuit. RSW-osc=GND VDD=1.5V. See test circuit. VDD=1.5V. See test circuit. VDD=1.5V. See test circuit. VDD=1.5V. See test circuit. Conditions
Recommended Operating Conditions
Symbol VDD CL TA Supply voltage Load Capacitance Operating temperature Parameter Min 1.0 0 -25 6.0 +85 Typ Max 1.6 Units V nF C Conditions
Enable/Disable Table
Symbol VIL VIH Parameter Low level input voltage to RSW-osc resistor High level input voltage to RSW-osc resistor Min 0 VDD-0.5 Typ Max 0.2 VDD Units V V Conditions VDD=1.0V-1.6V. VDD=1.0V-1.6V.
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HV825
Block Diagram
Lx VDD Cs RSW-osc Switch Osc
Q
GND
Q
VA
Output Osc
Q
VB REL-osc
Q
Test Circuit
Enable ON = VDD OFF = GND 1M
1
1M 560H* VIN= VDD = 1.0V to 1.6V 0.1F 0.1F 100V
VDD RSW-osc Cs Lx
REL-osc VA VB GND
8
2.2K
2 3
1N4148
7
4.7nF
6 5
Equivalent to a 1.5 square inch lamp.
4
CSW 1nF
HV825MG or HV825LG
*560H Murata inductor (LQH4N561K04), max DC resistance of 14.5.
Typical Performance
Lamp Size 1.5 in2 VDD 1.5v IDD 30mA VCS 56v fEL 450Hz Brightness 3.65ft-lm
3
HV825
External Component Description
External Component Diode CS Capacitor REL-osc Resistor Selection Guide Line Fast reverse recovery, 1N4148 or equivalent. 0.01 to 0.1F, 100V capacitor to GND is used to store the energy transferred from the inductor. The lamp frequency is controlled via the REL-osc. The lamp frequency increases as the REL-osc decreases. As the lamp frequency increases, the amount of current drawn from the battery will increase and the output voltage VCS will decrease. This is because the lamp will draw more current from VCS when driven at higher frequencies. In general, as the lamp size increases, larger REL-osc is recommended to provide higher VCS. However, the color of the lamp is dependent upon its frequency and the shade of the color will change slightly with different frequencies. RSW-osc Resistor The switching frequency of the inductor is controlled via the RSW-osc. The switching frequency increases as the RSW-osc decreases. As the switching frequency increases, the amount of current drawn from the battery will decrease and the output voltage VCS will also decrease. The inductor LX is used to boost up the low input voltage. When the internal switch is on, the inductor is being charged. When the internal switch is off, the charge in the inductor will be transferred to the high voltage capacitor CS. The energy stored in the capacitor is connected to the internal H-bridge and therefore to the lamp. In general smaller value inductors, which can handle more current, are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency of the inductor (controlled by RSW-osc) should be increased to avoid saturation. The test circuit uses a Murata (LQH4N561) 560H inductor. Using different inductor values or inductors from different manufacturers will affect the performance. As the inductor value decreases, smaller RSW-osc value shall be used. This will prevent inductor saturation. Inductor with the same inductance value (560H) but lower series resistance will charge faster. The RSW-osc resistor value needs to be decreased to prevent inductor saturation and high current consumption. CSW Capacitor A 1nF capacitor is recommended from RSW-OSC to GND. This capacitor is used to shunt any switching noise that may couple into the RSW-OSC pin.
LX Inductor
11/12/01
(c)2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
4
1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 744-0100 * FAX: (408) 222-4895 www.supertex.com

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