AAT1152 Datasheet, PDF (10/18 Pages) Advanced Analogic Technologies – 850kHz 1A Synchronous Buck DC/DC Converter

AAT1152
850kHz 1A Synchronous Buck DC/DC Converter
Enable
2V/div
V_OUT
1V/div
I_L
0.5A/div
V_IN=3.6V
V_OUT=1.5V
I_L=1A
200µsec/div
Figure 1: Inrush Limit
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 fig-
ures 3 and 4 filters the noise associated with the
power switching.
Current Limit and Over-temperature
protection
For overload conditions the peak input current is
limited. Figure 2 displays the VI current limit char-
acteristics. As load impedance decreases and the
output voltage falls closer to zero, more power is
dissipated internally, raising the device tempera-
ture. Thermal protection completely disables
switching when internal dissipation becomes
excessive, protecting the device from damage. The
junction over-temperature threshold is 140°C with
15°C of hysteresis.
Current Limit Characteristic
3.5
3
V_CC =V_P = 5.0V
2.5
V_O = 3.3V
Figure 4 schematic
2
1.5
1
V_CC =V_P =3.6V
V_O = 1.5V
0.5
Figure 3 schematic
0
0
0.5
1
1.5
2
2.5
I_OUT (A)
Figure 2.
10
1152.2003.01.0.9