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HV823
HV823 High Voltage EL Lamp Driver
Ordering Information
Package Options Device HV823 Input Voltage 2.0V to 9.5V 8-Lead SO HV823LG Die HV823X
Features
Processed with HVCMOS(R) technology 2.0V to 9.5V operating supply voltage DC to AC conversion 180V peak-to-peak typical output voltage Large output load capability typically 50nF Permits the use of high-resistance elastomeric lamp components Adjustable output lamp frequency to control lamp color, lamp life, and power consumption Adjustable converter frequency to eliminate harmonics and optimize power consumption Enable/disable function Low current draw under no load condition
General Description
The Supertex HV823 is a high-voltage driver designed for driving EL lamps of up to 50nF. EL lamps greater than 50nF can be driven for applications not requiring high brightness. The input supply voltage range is from 2.0 to 9.5V. The device uses a single inductor and a minimum number of passive components. The nominal regulated output voltage that is applied to the EL lamp is 90V. The chip can be enabled by connecting the resistors on RSW-osc and REL-osc to VDD and disabled when connected to GND. The HV823 has two internal oscillators, a switching MOSFET, and a high-voltage EL lamp driver. The frequency for the switching converter MOSFET 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 0.01F to 0.1F capacitor is connected between CS and GND. The EL lamp is connected between VA and VB. The switching MOSFET charges the external inductor and discharges it into the Cs capacitor. The voltage at Cs will start to increase. Once the voltage at Cs reaches a nominal value of 90V, the switching MOSFET is turned OFF to conserve power. The outputs VA and VB are configured as an H-bridge and are switched in opposite states to achieve 180V peak-to-peak across the EL lamp.
Applications
Handheld personal computers Electronic personal organizers GPS units Pagers Cellular phones Portable instrumentation
Pin Configuration
VDD RSW-osc Cs Lx
1 2 3 4
8 7 6 5
Absolute Maximum Ratings*
Supply Voltage, VDD Output Voltage, VCs Operating Temperature Range Storage Temperature Range Power Dissipation
Note: *All voltages are referenced to GND. 11/12/01
REL-osc VA VB GND
-0.5V to +10V -0.5V to +120V -25C to +85C -65C to +150C 400mW
SO-8
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.
HV823
Electrical Characteristics
DC Characteristics (VIN = 3.0V, RSW = 750K, REL = 2.0M, TA = 25C unless otherwise specified)
Symbol RDS(on) VCS VA - VB IDDQ IDD Parameter On-resistance of switching transistor Output voltage VCS Regulation Output peak to peak voltage Quiescent VDD supply current, disabled Input current going into the VDD pin 80 160 Min Typ 2 90 180 30 150 Max 6 100 200 100 200 300 500 IIN VCS fEL fSW D Input current including inductor current Output voltage on VCS VA-B output drive frequency Switching transistor frequency Switching transistor duty cycle 60 330 50 25 70 380 60 88 33 85 450 70 Units V V nA A A A mA V Hz KHz % I = 100mA VIN = 2.0 to 9.5V VIN = 2.0V to 9.5V RSW-osc = Low VIN = 3.0V. See Figure 1. VIN = 5.0V. See Figure 2. VIN = 9.0V. See Figure 3. VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1. VIN = 3.0V. See Figure 1. Conditions
Recommended Operating Conditions
Symbol VDD TA Supply voltage Operating temperature Parameter Min 2.0 -25 Typ Max 9.5 +85 Units V C Conditions
Enable/Disable Table
RSW resistor VDD 0V
(See Figure 4)
HV823 Enable Disable
2
HV823
Block Diagram
Lx VDD Cs RSW-osc Enable * Switch Osc
Q
GND Disable
VA + C _
Q
Vref Output Osc
Q
VB REL-osc
Q
* Enable is available in die form only.
Figure 1: Test Circuit, VIN = 3.0V
ON = VDD OFF = 0V
(Low input current with moderate output brightness).
2M
1
750K 560H
1
VDD
REL-osc VA VB GND
8
2.0K
2 3
1N4148
RSW-osc Cs Lx
7
10nF
VDD = VIN = 3.0V
6 5
4
0.1F
2
Equivalent to 3 square inch lamp.
0.1F 100V
HV823
Typical Performance
Lamp Size 3.0
Notes: 1. Murata part # LQH4N561K04 (DC resistance < 14.5) 2. Larger values may be required depending upon supply impedance.
VIN 3.0v
IIN 25mA
VCS 65v
fEL 385Hz
Brightness 6.5ft-lm
in2
For additional information, see Application Notes AN-H33 and AN-H34.
3
HV823
Typical Performance Curves for Figure 1 using 3in2 EL Lamp.
VCS vs. VIN
90 80 70 60 50 40
30 25 20 15 10 5 0
IIN vs. VIN
1
2
3
4
5
VIN (V)
6
7
8
9
IIN (mA)
Vcs (V)
1
2
3
4
5 VIN (V)
6
7
8
9
Brightness vs. VIN
12 10 8 6 4 2 0 30 25 20 15 10 5 0
IIN vs. VCS (V)
Brightness (ft-Im)
IIN (mA)
1
2
3
4
5 VIN (V)
6
7
8
9
40
50
60 VCS (V)
70
80
90
IIN, VCS, Brightness vs. Inductor Value 90 80 70
VCS(V)
9.0 8.0 7.0 6.0 5.0
Brightness (ft-lm)
60
Brightness (ft-Im)
IIN (mA), VCS (V)
50 40 30 20
IIN(mA)
4.0 3.0 2.0 1.0 0
10 0
100
250
400
550
Inductor Value (H)
700
850
1000
4
HV823
Figure 2: Typical 5.0V Application
ON = VDD OFF = 0V 2M
1
750K 560H
1
VDD
REL-osc VA VB GND
8
3.1K
2 3
1N4148
RSW-osc Cs Lx
7
20nF
VDD = VIN = 5.0V
6 5
Equivalent to 6 square inch lamp
4
0.1F
2
0.01F 100V
1nF 16v
HV823
Typical Performance
Lamp Size 6.0
Notes: 1. Murata part # LQH4N561K04 (DC resistance < 14.5) 2. Larger values may be required depending upon supply impedance.
VIN 5.0v
IIN 25mA
VCS 75v
fEL 380Hz
Brightness 6.5ft-lm
in2
For additional information, see Application Notes AN-H33 and AN-H34.
Typical Performance Curves for Figure 2
VCS vs. VIN
90 85 75 70 65
IIN vs. VIN
IIN (mA)
VCS (V)
80
40 38 36 34 32 30 4 5 6
VIN (V)
4
5
6 VIN (V)
7
8
7
8
Brightness vs. VIN 8 7.5 7 6.5 6 5.5
IIN vs. VCS (V)
4
5
6 VIN (V)
7
8
40 38 36 34 32 30 70
Brightness (ft-Im)
IIN (mA)
75
80
VCS (V)
85
90
5
HV823
Figure 3: Typical 9.0V Application*
2M
1
330K 560H1 VDD = VIN = 9.0V 1N4148 0.1F2 0.01F 100V
VDD RSW-osc Cs Lx
REL-osc VA VB GND
8
4.9K
2 3 4
7
42nF
6 5
Equivalent to 12 square inch lamp
1nF 16v
HV823
Typical Performance
Lamp Size 12.0 in2
Notes: 1. Murata part # LQH4N561K04 (DC resistance < 14.5) 2. Larger values may be required depending upon supply impedance.
VIN 9.0v
IIN 30mA
VCS 75v
fEL 380Hz
Brightness 8.5ft-lm
For additional information, see Application Notes AN-H33 and AN-H34.
Typical Performance Curves for Figure 3
VCS vs. VIN 85 80 75 70 65 IIN vs. VIN
40 38 36 34 32 30 4 5 6
VIN (V)
IIN (mA)
VCS (V)
4
5
6 VIN (V)
7
8
7
8
Brightness vs. VIN
IIN vs. VCS (V)
Brightness (ft-Im)
8 7.5 7 6.5 6 5.5
4
5
6
VIN (V)
7
8
40 38 36 34 32 30 70
IIN (mA)
75
80
VCS (V)
85
90
6
HV823
External Component Description
External Component Diode Cs Capacitor REL-osc Selection Guide Line Fast reverse recovery diode, 1N4148 or equivalent. 0.01F to 0.1F, 100V capacitor to GND is used to store the energy transferred from the inductor. The EL lamp frequency is controlled via an external REL resistor connected between REL-osc and VDD of the device. The lamp frequency increases as REL decreases. As the EL lamp frequency increases, the amount of current drawn from the battery will increase and the output voltage VCS will decrease. The color of the EL lamp is dependent upon its frequency. A 2M resistor would provide lamp frequency of 330 to 450Hz. Decreasing the REL-osc by a factor of 2 will increase the lamp frequency by a factor of 2. RSW-osc The switching frequency of the converter is controlled via an external resistor, RSW between RSW-osc and VDD of the device. The switching frequency increases as RSW decreases. With a given inductor, as the switching frequency increases, the amount of current drawn from the battery will decrease and the output voltage, VCS, will also decrease. A 1nF capacitor is recommended on RSW-osc to GND when a 0.01F CS capacitor is used. This capacitor is used to shunt any switching noise that may couple into the RSW-osc pin. The CSW capacitor may also be needed when driving large EL lamp due to increase in switching noise. The inductor Lx is used to boost the low input voltage by inductive flyback. When the internal switch is on, the inductor is being charged. When the internal switch is off, the charge stored 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 EL 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) should be increased to avoid saturation. 560H Murata inductors with 14.5 series DC resistance is typically recommended. For inductors with the same inductance value but with lower series DC resistance, lower RSW value is needed to prevent high current draw and inductor saturation. Lamp As the EL lamp size increases, more current will be drawn from the battery to maintain high voltage across the EL lamp. The input power, (VIN x IIN), will also increase. If the input power is greater than the power dissipation of the package (400mW), an external resistor in series with one side of the lamp is recommended to help reduce the package power dissipation.
CSW Capacitor
Lx Inductor
Enable/Disable Configuration
The HV823 can be easily enabled and disabled via a logic control signal on the RSW and REL resistors as shown in Figure 4 below. The control signal can be from a microprocessor. RSW and REL are typically very high values. Therefore, only 10's of microamperes will be drawn from the logic signal when it is at a logic high (enable) state. When the microprocessor signal is high the device is enabled and when the signal is low, it is disabled.
Figure 4: Enable/Disable Configuration
ON =VDD OFF = 0V Remote Enable REL
1
RSW Lx + VIN = VDD 4.7F 15V
VDD RSW-osc Cs Lx
REL-osc VA VB GND
8 7
EL Lamp
2 3
1N4148
6 5
4
CS 100V
HV823LG
1nF
7
HV823
Split Supply Configuration Using a Single Cell (1.5V) Battery
The HV823 can also be used for handheld devices operating from a single cell 1.5V battery where a regulated voltage is available. This is shown in Figure 5. The regulated voltage can be used to run the internal logic of the HV823. The amount of current necessary to run the internal logic is typically 100A at a VDD of 3.0V. Therefore, the regulated voltage could easily provide the current without being loaded down. The HV823 used in this configuration can also be enabled/disabled via logic control signal on the RSW and REL resistors as shown in Figure 4.
Split Supply Configuration for Battery Voltages of Higher than 9.5V
Figure 5 can also be used with high battery voltages such as 12V as long as the input voltage, VDD, to the HV823 device is within its specifications of 2.0V to 9.5V.
Figure 5: Split Supply Configuration
ON =VDD OFF = 0 VDD = Regulated Voltage RSW Lx + VIN = Battery Voltage Remote Enable
REL
1 2 3
0.1F* CS 100V 1N4148
VDD RSW-osc Cs Lx
REL-osc VA VB GND
8 7
EL Lamp
6 5
4
HV823LG
*Larger values may be required depending upon supply impedance.
For additional information, see Application Notes AN-H33 and AN-H34.
11/12/01
(c)2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
8
1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 744-0100 * FAX: (408) 222-4895 www.supertex.com

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