AAT1150 Advanced Analogic Technologies, AAT1150 Datasheet - Page 10

• Manufacturer Part Number: AAT1150
• Description: 1MHz 1A Step-Down DC/DC Converter
• Manufacturer: Advanced Analogic Technologies

Power and Signal Source
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.
10
10µF
10µF
C1
C1
2.7V-5.5V
3.5V-5.5V
C1 Murata 10µF 6.3V X5R GRM42-6X 5R106K6.3
C2, C4 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 X5R
L1 Sumida CDRH5D18-4R 1µH
C1 Murata 10µF 6.3V X5R GRM42-6X 5R106K6.3
C2, C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805
L1 Sumida CDRH5D18-4R 1µH
R2
100k
0.1µF
100k
R2
R1 100
0.1µF
R1 100
C3
C3
VP
VCC
EN
SGND
SGND
VP
VCC
EN
AAT1150-1.5
AAT1150-3.3
RTN
RTN
PGND
PGND
Figure 2: 5V Input to 3.3V Output Converter.
FB
LX
LX
FB
LX
LX
Figure 1: Lithium-Ion to 1.5V Converter.
4.1µH
4.1µH
L1
L1
V
V
OUT
OUT
3.3V 1A
1.5V 1A
C2, C4
C2, C4
2x 22µF
2x 22µF
1MHz 1A Step-Down DC/DC Converter
Current Limit and Over-Temperature
Protection
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.
100
100
90
80
70
60
50
40
30
20
10
80
60
40
20
0
0
10
10
V
IN
= 5.0V
2.7V
3.3 Volt Efficiency vs. I
3.6V
1.5V Efficiency vs. I
4.2V
I
OUT
I
OUT
100
100
(mA)
(mA)
AAT1150
OUT
OUT
1150.2005.03.1.2
1000
1000