PRODUCT DATASHEET
AAT1153
2A Step-Down Converter
Input Capacitor
Input ripple VPP = 25mV
1
1
CIN(MIN)
=
=
= 13.9µF; use 22µF
⎛ VPP
⎝ IO
⎞
⎛0.025
⎞
- ESR · 4 · fS
- 0.01 ·4 · 1.2 · 106
⎠
⎝
2
⎠
IO
2
2
=
IRMS
=
= 1Arms
2
PCIN = ESR · IRMS2 = 0.01 · 12 = 10mW
AAT1153 Losses
PTOTAL = IO2 · RDS(ON)P · D + IO2 · RDS(ON)N · (1 - D) + (tSW · fS · IO) · VIN
1.8
4.2
1.8
4.2
⎛
⎞
⎠
= 22 · 0.135 ·
+ 22 · 0.095 · 1 -
+ (5 · 10-9 · 1.2 · 106 · 2) · 4.2 = 498.9mW
⎝
w w w . a n a l o g i c t e c h . c o m
18
1153.2007.11.1.1