Datasheet

LTC3827
31
3827ff
TYPICAL APPLICATION
Figure 13. High Effi ciency Dual 8.5V/3.3V Step-Down Converter
C
IN1
10µF
C
INT2
1µF
D2
D1
C1
1nF
R
B1
215k
3827 TA02
C
SS1
0.01µF
C
ITH1
1200pF
R
ITH1
9.53k
R
A1
68.1k
C
ITH1A
150pF
C2
1nF
R
B2
215k
C
SS2
0.01µF
C
ITH2
560pF
R
ITH2
35.7k
R
A2
22.1k
C
ITH2A
100pF
C
B2
0.47µF
100k
C
INT1
4.7µF
C
OUT2
150µF
C
B1
0.47µF
MTOP2
MBOT2
MTOP1
MBOT1
L2
7.2µH
R
SNS2
12mΩ
V
OUT1
3.3V
5A
V
IN
12V
V
OUT2
8.5V
3.5A
L1
3.3µH
R
SNS1
12mΩ
C
IN2
10µF
C
OUT1
150µF
39pF
39pF
MTOP1, MTOP2, MBOT1, MBOT2: Si7848DP
L1: CDEP105-3R2M
L2: CDEP105-7R2M
C
OUT1
, C
OUT2
: SANYO 10TPD150M
I
TH1
V
FB1
SENSE1
+
SENSE1
–
PLLLPF
PHASMD
CLKOUT
PLLIN/MODE
SGND
RUN1
RUN2
SENSE2
–
SENSE2
+
V
FB2
I
TH2
TRACK/SS2
TRACK/SS1
PGOOD2
PGOOD1
TG1
SW1
BOOST1
BG1
V
IN
PGND
EXTV
CC
INTV
CC
BG2
BOOST2
SW2
TG2
FOLDDIS
LTC3827
+
100k
0
20
40
60
80
100
10
30
50
70
90
LOAD CURRENT (mA)
EFFICIENCY (%)
0.01 0.1 1 10 100 1000 10000
3827 F13
0.001
V
OUT
= 3.3V
V
OUT
= 8.5V
20ms/DIV
3827 F14
V
OUT2
2V/DIV
V
OUT1
2V/DIV
1µs/DIV
3827 F15
SW1
5V/DIV
SW2
5V/DIV
Effi ciency vs Load Current Start-Up SW Node Waveform