AAT2512 Datasheet, PDF (16/20 Pages) Advanced Analogic Technologies – Dual 400mA High Frequency Buck Converter

AAT2512
Dual 400mA High Frequency Buck Converter
AAT2512 Losses
The maximum dissipation occurs at dropout where V_IN = 2.7V. All values assume an ambient temperature of
85°C and a junction temperature of 120°C.
P_TOTAL
=
I_O12
·
(R_DSON(HS)
·
V_O1
+
R_DSON(LS)
·
(V_IN
-V_O1)) + I_O22
V_IN
·
(R_DSON(HS)
·
V_O2
+
R_DSON(LS)
·
(V_IN
-V_O2))
+ (t_sw · F · I_O2 + 2 · I_Q) · V_IN
0.4² · (0.725Ω · 2.5V + 0.7Ω · (2.7V - 2.5V)) + 0.4² · (0.725Ω · 1.8V + 0.7Ω · (2.7V - 1.8V))
=
2.7V
+ 5ns · 1.4MHz · 0.4A + 60μA) · 2.7V = 239mW
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 239mW = 97°C
Output 1 Enable
V_IN
123
C5¹
GND
C4¹
R3
see Table 3
R4
59.0k
R1
see Table 3
R2
59.0k
U1
AAT2512
1 _EN1
VIN1 ¹²
2 _FB1
LX1 ¹¹
3 _{SGND1 GND1} 10
4 _EN2
VIN2 ⁹
5 _FB2
LX2 ⁸
6 _{SGND2 GND2} 7
C3
10μF
C8
0.1μF
LX1
L1
see Table 3
LX2
V_O2
L2
see Table 3
C7
0.01μF
C2¹
4.7μF
V_O1
C1¹
4.7μF
C6
0.01μF
GND
321
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