AAT1145_08 Datasheet, PDF (16/17 Pages) Advanced Analogic Technologies – 1.5A Step-Down Converter

SwitchReg^TM
Input Capacitor
Input ripple V_PP = 50mV
1
1
C_IN(MIN) = _{⎛ VPP}
⎝ I_O
- ESR^⎞⎠ · 4 · f_S
=
= 8.9µF; use 10µF
⎛
⎝
0.05
1.5
-
0.01^⎞⎠
· 4 · 1.2 · 10⁶
I_RMS =
I_O
2
= ^1.5 = 750mArms
2
P_CIN = ESR · I_RMS2 = 0.01 · 0.75² = 5.6mW
PRODUCT DATASHEET
AAT1145
1.5A Step-Down Converter
AAT1145 Losses
P_TOTAL = I_O2 · R_DS(ON)P · D + I_O2 · R_DS(ON)N · (1 - D) + (tSW · f_S · I_O) · V_IN
1.8
= 1.5² · 0.135 ·
4.2
+ 1.5² · 0.095 · ^⎛⎝1 -
1.8_⎞
4.2⎠
+
(5
·
10^-9
·
1.2
·
10⁶
·
1.5)
·
4.2
=
290mW
16
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1145.2008.01.1.2