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 current limit characteris-
tics. 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.
Efficiency vs. Output Current
(VOUT = 1.5V)
2.7V-5.5V
AAT1150-1.5
VOUT 1.5V 1A
100
VP
FB
LX
LX
R1 100
2.7V
VCC
EN
80
L1
4.1μH
R2
100k
C7
C2, C3, C4
3x 22μF
6.3V
60
C1
10μF
SGND PGND
4.2V
0.1μF
40
3.6V
RTN
20
0
C1 Murata 10μF 6.3V X5R GRM42-6X 5R106K6.3
C2, C3, C4 MuRata 22μF 6.3V GRM21BR60J226ME39L 0805 X5R
L1 Sumida CDRH5D18-4R1μH
10
100
1000
Output Current (mA)
Figure 1: Lithium-Ion to 1.5V Converter.
Efficiency vs. Output Current
(VOUT = 3.3V)
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, C3, C4
3x 22μF
6.3V
100k
C1
10μF
SGND PGND
C7
0.1μF
RTN
C1 Murata 10μF 6.3V X5R GRM42-6X 5R106K6.3
C2, C3, C4 MuRata 22μF 6.3V GRM21BR60J226ME39L X5R 0805
L1 Sumida CDRH5D18-4R1μH
10
100
1000
Output Current (mA)
Figure 2: 5V Input to 3.3V Output Converter.
10
1150.2006.09.1.5
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
