AAT2512
Dual 400mA High Frequency Buck Converter
AAT2512 Losses
The maximum dissipation occurs at dropout where VIN = 2.7V. All values assume an ambient temperature of
85°C and a junction temperature of 120°C.
IO12 · (RDSON(HS) · VO1 + RDSON(LS) · (VIN -VO1)) + IO22 · (RDSON(HS) · VO2 + RDSON(LS) · (VIN -VO2))
PTOTAL
=
VIN
+ (tsw · F · IO2 + 2 · IQ) · VIN
0.42 · (0.725
Ω
·
2.5V + 0.7Ω
·
(2.7V - 2.5V)) + 0.42 · (0.725
2.7V
Ω
·
1.8V + 0.7Ω
·
(2.7V - 1.8V))
=
+ 5ns · 1.4MHz · 0.4A + 60μA) · 2.7V = 239mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 239mW = 97°C
Output 1 Enable
VIN
1
2 3
U1
C41
R1
see Table 3
AAT2512
LX1
1
2
3
4
5
6
12
11
10
9
L1
EN1
FB1
VIN1
LX1
see Table 3
VO1
C3
SGND1 GND1
C51
LX2
VO2
R3
10μF
see Table 3
L2
EN2
FB2
VIN2
LX2
see Table 3
8
C11
4.7μF
C6
0.01μF
7
SGND2 GND2
C21
4.7μF
R4
59.0k
R2
59.0k
C7
0.01μF
C8
0.1μF
GND
GND
3
2 1
Output 2 Enable
Figure 3: AAT2512 Evaluation Board Schematic.
1. For enhanced transient configuration C5, C4 = 100pF and C1, C2 = 10µF.
16
2512.2006.06.1.4
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
