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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 | |||
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Advanced Analog Technology, Inc.
Rc
= Vo
VFB
2Ïf ci CRcs
kg m
(RL + 2rc )
â¢â£â¡(1 â
D)RL
â
râ¤
(1 â D)â¥â¦
VFB is equal to reference voltage,VREF .
VREF =1.24V, k is the correct factor, and
k = (6 â 8)
AAT1102 (BIN2)
5. The output filter capacitor is chosen so C .
RL pole cancels Rc . Cc zero
Rc C c
=
(1
C
â
3)
ââ
â
RL
2
+
rc
ââ
â
,
and
Cc
=
C
(1 â 3)Rc
ââ RL
â2
+
rc
ââ
â
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 pâ p
for Vo
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â Advanced Analog Technology, Inc. â
Page 12 of 18
V5.0
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