AAT2510
Dual 400mA, 1MHz Step-Down DC-DC Converter
V
IN
= 2.7 - 5.5V
C3
10µF
12
1
V
IN
U1
AAT2510
9
C8
0.1µF
C3
10µF
12
U1
AAT2510
VIN1
EN1
LX1
FB1
SGND1
GND1
VIN2
EN2
LX2
FB2
SGND2
GND2
9
1
4
8
5
6
7
C8
0.1µF
2.5V
L2
10µH
C5
100pF
R3
187k
C2
10µF
VIN1
VIN2
4
1.8V
8
2.5V at 400mA
L1
4.7µH
EN1
11
EN2
LX2
5
L2
4.7µH
1.8V at 400mA
L1
C4
100pF
4.7µH
LX1
2
11
2
3
10
FB1
3
FB2
6
SGND1 SGND2
C1
4.7µF
10
7
GND1
GND2
C2
4.7µF
C1
10µF
R1
118k
R2
59.0k
R4
59.0k
L1, L2 Sumida CDRH3D16-4R7 C1, C2 Murata GRM219R61A475KE19
C3 Murata GRM21BR60J106KE19
Figure 1: AAT2510 Fixed Output.
Figure 2: AAT2510 Adjustable Output with
Enhanced Transient Response.
Soft Start
The AAT2510 soft-start control prevents output
voltage overshoot and limits inrush current when
either the input power or the enable input is
applied. When pulled low, the enable input forces
the converter into a low-power, non-switching state
with a bias current of less than 1µA.
MOSFET is turned on continuously for 100% duty
cycle. At 100% duty cycle, the output voltage tracks
the input voltage minus the I*R drop of the high
side P-channel MOSFET R
DS(ON)
.
Low Supply
The under-voltage lockout (UVLO) feature guaran-
tees sufficient V
IN
bias and proper operation of all
internal circuitry prior to activation.
Low Dropout Operation
For conditions where the input voltage drops to the
output voltage level, the converter duty cycle
increases to 100%. As 100% duty cycle is
approached, the minimum off-time initially forces
the high side on-time to exceed the 1MHz clock
cycle and reduce the effective switching frequency.
Once the input drops below the level where the out-
put can be regulated, the high side P-channel
Fault Protection
For overload conditions, the peak inductor current is
limited. Thermal protection disables switching when
the internal dissipation or ambient temperature
becomes excessive. The junction over-temperature
threshold is 140°C with 15°C of hysteresis.
2510.2005.08.1.5
9
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
