PRODUCT DATASHEET
AAT1161
TM
SwitchReg
13.2V Input, 3A Step-Down Converter
Input Capacitor
Input Ripple VPP = 50mV
1
1
CIN =
=
= 26µF; use 22µF
⎛ VPP
⎝ ILOAD
⎞
⎛ 50mV
⎞
⎠
- ESR · 4 · FOSC
- 5mΩ · 4 · 800kHz
⎠
⎝
3A
ILOAD
IRMS(MAX)
=
= 1.5Arms
2
P = esr · IRMS2 = 5mΩ · (1.5A)2 = 11.25mW
AAT1161 Losses
Total losses can be estimated by calculating at the nominal input voltage (12V). All values assume an 85°C ambient
temperature and a 140°C junction temperature with the TDFN 50°C/W package.
RDS(ON) = 0.18Ω
tSW = 5ms
IQ = 300µA
ILOAD2 · (RDS(ON) · VOUT
)
+ [(tsw · FOSC · ILOAD + IQ) · VIN]
PLOSS
=
VIN
PLOSS = 823mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 0.823W = 126°C
w w w . a n a l o g i c t e c h . c o m
16
1161.2008.03.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
