AAT1150
1MHz 1A Step-Down DC/DC Converter
Power and Signal Source
Current Limit and Over-Temperature
Protection
Separate small signal ground and power supply
pins isolate the internal control circuitry from the
noise associated with the output MOSFET switch-
ing. The low pass filter R1 and C3 in schematic
Figures 1 and 2 filters the noise associated with the
power switching.
For overload conditions, the peak input current is lim-
ited. Figure 3 displays the VI current limit character-
istics. As load impedance decreases and the output
voltage falls closer to zero, more power is dissipated
internally, raising the device temperature. Thermal
protection completely disables switching when inter-
nal dissipation becomes excessive, protecting the
device from damage. The junction over-temperature
threshold is 140°C with 15°C of hysteresis.
1.5V Efficiency vs. IOUT
2.7V-5.5V
AAT1150-1.5
100
VOUT 1.5V 1A
VP
FB
LX
LX
2.7V
R1 100
80
VCC
EN
L1
4.1µH
R2
100k
C3
C2, C4
2x 22µF
60
4.2V
C1
10µF
SGND PGND
40
3.6V
0.1µF
20
0
RTN
C1 Murata 10µF 6.3V X5R GRM42-6X 5R106K6.3
C2, C4 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 X5R
L1 Sumida CDRH5D18-4R 1µH
10
100
1000
IOUT (mA)
Figure 1: Lithium-Ion to 1.5V Converter.
3.3 Volt Efficiency vs. IOUT
3.5V-5.5V
VOUT 3.3V 1A
AAT1150-3.3
100
90
80
70
60
50
40
30
20
10
0
VP
FB
LX
LX
VIN = 5.0V
R1 100
VCC
EN
L1
4.1µH
R2
C2, C4
2x 22µF
100k
C1
10µF
SGND PGND
C3
0.1µF
RTN
C1 Murata 10µF 6.3V X5R GRM42-6X 5R106K6.3
C2, C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805
L1 Sumida CDRH5D18-4R 1µH
10
100
1000
IOUT (mA)
Figure 2: 5V Input to 3.3V Output Converter.
10
1150.2005.03.1.2
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
