AAT2315_07 Datasheet, PDF (18/22 Pages) Advanced Analogic Technologies – Dual 600mA Step-Down Converter with Synchronization

AAT2513
Dual 600mA Step-Down
Converter with Synchronization
AAT2513 Losses
The maximum dissipation occurs at dropout where V_IN = 2.7V. All values assume an 85°C ambient and a 120°C
junction temperature.
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
0.6² · (0.725Ω · 2.5V + 0.7Ω · (2.7V - 2.5V)) + 0.6² · (0.725Ω · 1.8V + 0.7Ω · (2.7V - 1.8V))
=
2.7V
+ (5ns · 1.7MHz · 0.6A + 60µA) · 2.7V = 533mW
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 533mW = 111°C
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (28°C/W) · 533mW = 100°C
Phase Shift
3
2
1
C4
100pF
V_IN
C5
100pF
R3
88.7k
V_IN
R1
187k
C10
120μF
GND
R2
59.0k
R4
59.0k
C9
10μF
L1, L2 CDRH2D11
C1, C2 4.7μF 10V 0805 X5R
U1
AAT2513
6
N/C
15
N/C
16
VIN2
14
LX2
1
PS
13
PGND2
2
12
AGND MODE/SYNC
3
FB2
11
VCC
4
FB1
10
EN1
5
VIN1
9
EN2
7
LX1
8
PGND1
LX2
V_O2
V_IN
L2
Sync
C7
1
1μF
2
C2
3
V_CC
LX1
C8
0.1μF
L1
C3
C1
10μF
V_O1
C6
1μF
GND
GND
GND
R5
10
VCC
321
Enable 2
V_IN
321
Enable 1
GND
Figure 2: AAT2513 Evaluation Board Schematic¹.
1. For enhanced transient configuration C5, C4 = 100pF and C1, C2 = 10µF.
18
2513.2007.04.1.1