A8483 Datasheet, PDF (1/9 Pages) Allegro MicroSystems – 1.2 MHz Step-up Converter for Display Bias Supply

Package EK:
MLP/TDFN, 3 × 3 mm
0.75 mm Nominal Height
A8483
1.2 MHz Step-up Converter
for Display Bias Supply
Approximate Scale 1:1
FEATURES
„ 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
„ 1 μA shutdown current
„ Low-noise PWM/analog dimming
L1
5
10 µH ₁
VIN
SW
VSUPPLY C1
1 µF
Li-ion
2.5 V to
5.5 V
A8483
EN GND FB
423
Enable
VOUT
D1
R1
820 kΩ
R2
39 kΩ
C2
1 µF
Figure 1. OLED Bias Supply. Use for cell phones, MP3
players, DSCs, and PDAs.
L1
5
10 µH ₁
VIN
SW
VOUT
D1
32 V, 18 mA
25 V, 25 mA
VSUPPLY C1
1 µF
5V
A8483
EN GND FB
423
R1
768 kΩ for
VOUT = 32 V
604 kΩ for
VOUT = 25 V
C2
1 µF / 50 V
Enable
R2
15 kΩ
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
components and integrated 36 V switch reduce component
count and footprint for a variety of applications.
APPLICATIONS
„ OLED bias supply / WLED backlight
„ Portable battery-powered equipment
„ Cellular phones
„ PDAs (Personal Digital Assistant)
„ Camcorders, personal stereos, MP3 players, cameras
„ Mobile GPS systems
L1
5
10 µH ₁
VIN
SW
VSUPPLY _C1
1 µF
Li-ion
2.5 V to
5.5 V
A8483
EN GND FB
423
Enable
D1
R1
732 kΩ
R2
39 kΩ
C2
0.47 µF
IOUT1 + IOUT2 = 15 mA
VOUT1
+12 V
C3
0.47 µF
VOUT2
D2
–12 V
C4
0.47 µF
Figure 2. Small LCD Bias Supply. Li+ battery to ±12 V.
Connect either VZ or VBIAS
V_Z
7.5 V
L1
22 µH ₁
SW
VSUPPLY
12 V
C1
1 µF
VBIAS
VIN
5
A8483
EN GND FB
423
5V
Enable
C3
0.1 µF
VOUT
D1
32 V, 40 mA
25 V, 80 mA
R1
768 kΩ for
VOUT = 32 V
604 kΩ for
VOUT = 25 V
C2
1 µF / 50 V
R2
15 kΩ
Figure 3. LCD TV, Plasma TV Bias, FED Display,
Varactor Diode Bias. Using 5 V input.
L1
5
10 µH
1
VIN
SW
VSUPPLY C1
1 µF
Li-ion
2.5 V to
5.5 V
A8483
EN GND FB
423
Enable
Cf
0.01 µF
VOUT
D1
R3
24 kΩ
R2
5 kΩ
R1
47 Ω
C2
0.22 µF
VC
Analog Voltage or
PWM
Figure 5. WLED Backlighting.
A8483-DS, Rev. 1
Figure 4. LCD TV, Plasma TV Bias, FED Display,
Varactor Diode Bias. Using 12 V input.
VSUPPLY
Li-ion
2.5 V to
5.5 V
C1
1 µF
L1
5
10 µH ₁
VIN
SW
A8483
EN GND FB
423
Enable
R3
160 kΩ
VOUT
D1
R1
560 kΩ
R2
47 kΩ
C2
1 µF
Cf
1 nF
Analog Voltage or
Cf for PWM dimming only
PWM 10 kHz
VC
Figure 6. OLED Bias Supply. Use for low-noise PWM
dimming, or with analog voltage through the FB pin.