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AAT1102_5 Datasheet, PDF (12/18 Pages) Advanced Analog Technology, Inc. – ADVANCED PWM DC-DC CONVERTER WITH INTERNAL SWITCH AND SOFT-START
Advanced Analog Technology, Inc.
Rc
= Vo
VFB
2πf ci CRcs
kg m
(RL + 2rc )
⎢⎣⎡(1 −
D)RL
−
r⎤
(1 − D)⎥⎦
VFB is equal to reference voltage,VREF .
VREF =1.24V, k is the correct factor, and
k = (6 − 8)
AAT1102 (BIN2)
5. The output filter capacitor is chosen so C .
RL pole cancels Rc . Cc zero
Rc C c
=
(1
C
−
3)
⎜⎛
⎝
RL
2
+
rc
⎟⎞
⎠
,
and
Cc
=
C
(1 − 3)Rc
⎜⎛ RL
⎝2
+
rc
⎟⎞
⎠
Example:
VIN =5V, VO =9.6V, IO =250mA, f s =600 kHz,
VFB =1.25V, L = 6.8uH , gm = 105uS , Rcs = 0.275
V/A,
rL
= 0.1Ω , rDS
= 0.23Ω , r
C
= 50mΩ ,
k =7
RF = 1.4Ω , fci = 21.4 kHz, Cc =1.3nF, Rc = 27k
Ω, C =4.7uF
Fig.5. Bode diagram using Matlab simulation
Fig.4. CH1: PWM waveform, CH2, v p− p
for Vo
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– Advanced Analog Technology, Inc. –
Page 12 of 18
V5.0