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Número de pieza | HV861 | |
Descripción | Dual EL Lamp Driver | |
Fabricantes | Supertex | |
Logotipo | ||
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HV861
Dimmable, Low Noise, Dual EL Lamp Driver
Features
► Adjustable output regulation for dimming
► Lamp fade-in/fade-out capability
► Low audible noise
► 180VPP output voltage for higher brightness
► 1.5V enable input logic high
► Single cell lithium ion compatible
► One miniature inductor to power both lamps
► Separately adjustable lamp and converter frequencies
► Split supply capability
► 16-Lead QFN package
Applications
► Dual display cellular phones
► Keypad and LCD backlighting
► PDAs
► Handheld wireless communication products
► Global Positioning Systems (GPS)
General Description
The Supertex HV861 is a low noise, dimmable, high
voltage, dual EL Lamp driver designed for driving two
electroluminescent (EL) Lamps with a combined area of 5.0
square inches. The input supply voltage range is from 2.5V
to 4.5V. Enable input logic high can go as low as 1.5V, which
allows logic interface operating from typical 1.8V supplies.
The device is designed to minimize audible noise emitted by
the EL Lamps.
The device uses a single inductor and a minimum number of
passive components. Using the internal reference voltage,
the regulated output voltage is at a nominal value of 90V.
The EL Lamps will therefore see ±90V. The two EL Lamps
can be turned ON and OFF using two CMOS logic inputs,
EN1 and EN2. The driver is disabled when both EN1 and
EN2 are at logic low.
The HV861 has two internal oscillators, a switching MOSFET,
and two high voltage EL Lamp driver H-bridges. Each driver
has its own half bridge common output, COM1 and COM2,
which significantly minimizes the DC offset seen by the EL
Lamp. The frequency for the switching 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 the REL-Osc pin
and the VDD pin. An external inductor is connected between
the LX and VDD pins or VIN for split supply applications.
Depending upon the EL Lamp sizes, a 1.0nF to 10.0nF
capacitor is connected between the CS and ground.
As the switching MOSFET charges the external inductor
and discharges it into the capacitor at CS, 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.
EL Lamp dimming can be accomplished by applying a PWM
logic signal to the PWM pin. The EL Lamp brightness will be
inversely proportional to the PWM duty cycle. The HV861
can also slowly turn the EL Lamp ON/OFF giving a fade ON/
OFF appearance.
Typical Application Circuit
VIN = 3.2 to 4.2V
4.7µF
100µH Coilcraft
LPS4012
3.3MΩ
1N4148
VDD = 3.0V
0.1µF
Input Logic Control:
ON = 1.5 to VDD
OFF = 0 to 0.2V
15 14 7
8
VREG VOUT LX
CS
3
2.0MΩ 1
12
VDD HV861K7-G EL1
REL-Osc
COM1 11
2 RSW-Osc
9
825kΩ
EL2
4 EN1
5 EN2
COM2 10
VREF PWM
GND
16 13
6
2.2µF
3.3nF
100V NPO
EL1
EL2
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com
1 page HV861
Figure 3: Typical Waveform EL1, COM1 and Differential Waveform EL1 – COM1
EL1
COM1
EL1 - COM1
Split Supply Configuration
The HV861 can also be used for handheld devices operating
from a battery where a regulated voltage is available. This
is shown in Figure 4. The regulated voltage can be used to
run the internal logic of the HV861. The amount of current
necessary to run the internal logic is 250µA max. Therefore,
the regulated voltage could easily provide the current with-
out being loaded down.
Enable/Disable Configuration
EL1 and EL2 outputs can be enabled and disabled via a
logic control signal on the EN1 and EN2 pins respectively.
When EN1 is high/low, the Lamp1 (EL1) will be ON/OFF.
When EN2 is high/low, the Lamp2 (EL2) will be ON/OFF.
The control signal can be from a microprocessor.
Figure 4: Split Supply and Enable/Disable Configuration
+
Battery Voltage = VIN _ CIN
Regulated Voltage = VDD
+
_ CDD
Input Logic Control:
Input Logic Control:
LX
RREG
D
15 14 7
8
VREG VOUT LX
CS
3
REL 1
2
RSW 4
5
VDD HV861
REL-Osc
RSW-Osc
EN1
EN2
EL1 12
COM1 11
EL2 9
10
COM2
VREF PWM GND
CREF 16 13 6
CS
EL1
EL2
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com
5
5 Page |
Páginas | Total 7 Páginas | |
PDF Descargar | [ Datasheet HV861.PDF ] |
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