A8483
1.2 MHz Step-up Converter
for Display Bias Supply
Package EK:
MLP/TDFN, 3 × 3 mm
0.75 mm Nominal Height
The A8483 is a current mode step-up dc-to-dc converter,
available in a 5-pin 3 mm × 3 mm thermally enhanced
MLP/TDFN lead (Pb) free package. Smaller external
componentsandintegrated36Vswitchreducecomponent
count and footprint for a variety of applications.
Approximate Scale 1:1
FEATURES
APPLICATIONS
Output voltage up to 35 V
2.5 to 10 V input
0.9 to 18 V input with separate bias supply
Delivers 15 V at 15 mA with 2.7 V input
Constant 1.2 MHz switching frequency provides low noise
350 mA switch current limit
OLED bias supply/WLED backlight
Portable battery-powered equipment
Cellular phones
PDAs (Personal Digital Assistant)
Camcorders, personal stereos, MP3 players, cameras
Mobile GPS systems
1 μA shutdown current
Low-noise PWM/analog dimming
I
+ I = 15 mA
OUT2
OUT1
V
OUT
L1
10 µH
L1
10 µH
V
OUT1
+12 V
D1
R1
D1
5
VIN
1
SW
5
VIN
1
SW
C3
0.47 µF
C2
0.47 µF
V
SUPPLY
732 kΩ
R1
820 kΩ
C1
1 µF
A8483
V
C1
1 µF
A8483
SUPPLY
C2
1 µF
EN GND FB
EN GND FB
4
2
3
Li-ion
2.5 V to
5.5 V
4
2
3
Li-ion
2.5 V to
5.5 V
V
OUT2
–12 V
Enable
Enable
D2
R2
39 kΩ
R2
39 kΩ
C4
0.47 µF
Figure 2. Small LCD Bias Supply. Li+ battery to ±12 V.
Figure 1. OLED Bias Supply. Use for cell phones, MP3
players, DSCs, and PDAs.
32 V, 18 mA
25 V, 25 mA
32 V, 40 mA
25 V, 80 mA
Connect either V or V
Z
V
OUT
BIAS
V
OUT
L1
10 µH
L1
22 µH
D1
D1
5
VIN
1
SW
1
SW
VZ
7.5 V
R1
768 kΩ for
R1
768 kΩ for
VIN
V
V
C1
1 µF
A8483
A8483
SUPPLY
C2
1 µF / 50 V
SUPPLY
C2
1 µF / 50 V
5
V
OUT = 32 V
VOUT = 32 V
C1
1 µF
EN GND FB
EN GND FB
V
BIAS
604 kΩ for
OUT = 25 V
604 kΩ for
VOUT = 25 V
12 V
5 V
4
2
3
V
4
2
3
Enable
Enable
5 V
R2
15 kΩ
R2
15 kΩ
C3
0.1 µF
Figure 3. LCD TV, Plasma TV Bias, FED Display,
Varactor Diode Bias. Using 5 V input.
Figure 4. LCD TV, Plasma TV Bias, FED Display,
Varactor Diode Bias. Using 12 V input.
V
OUT
V
OUT
L1
10 µH
L1
10 µH
D1
D1
5
VIN
1
SW
5
VIN
1
SW
R1
560 kΩ
C2
0.22 µF
C2
1 µF
V
V
C1
1 µF
A8483
A8483
C1
1 µF
SUPPLY
SUPPLY
R3
24 kΩ
EN GND FB
EN GND FB
V
C
Li-ion
2.5 V to
5.5 V
4
2
3
4
2
3
Li-ion
2.5 V to
5.5 V
Analog Voltage or
PWM
Cf
1 nF
Enable
Enable
R2
5 kΩ
R1
47 Ω
R3
160 kΩ
R2
47 kΩ
Cf
0.01 µF
Analog Voltage or
PWM 10 kHz
Cf for PWM dimming only
V
C
Figure 5. WLED Backlighting.
Figure 6. OLED Bias Supply. Use for low-noise PWM
dimming, or with analog voltage through the FB pin.
A8483-DS, Rev. 1