LTC3890
Typical applicaTions
+
–
SENSE1
SENSE1
INTV
C1
1nF
CC
R
B1
100k
100k
100k
R
PGOOD1
PGOOD2
BG1
A1
31.6k
V
FB1
C
100pF
R
ITH1A
MBOT1
R
SENSE1
8mΩ
V
3.3V
5A
OUT1
C
1000pF
ITH1
SW1
ITH1
34.8k
L1
BOOST1
ITH1
4.7µH
C
OUT1
470µF
C
LTC3890
TRACK/SS1
C
SS1
0.01µF
B1
0.1µF
TG1
MTOP1
D1
I
LIM
V
IN
PHSMD
CLKOUT
PLLIN/MODE
V
IN
9V TO 60V
C
IN
220µF
INTV
CC
C
INT
4.7µF
SGND
EXTV
PGND
V
OUT2
CC
RUN1
RUN2
FREQ
R
FREQ
41.2k
D2
TG2
MTOP2
C
SS2
0.01µF
C
0.1µF
B2
L2
8µH
R
TRACK/SS2
ITH2
BOOST2
SW2
SENSE2
10mΩ
R
ITH2
34.8k
C
470pF
V
8.5V
3A
ITH2
R
OUT2
C
OUT2
A2
10.5k
330µF
MBOT2
V
BG2
FB2
R
B2
100k
–
SENSE2
C2
1nF
+
SENSE2
3890 TA02a
MTOP1, MTOP2, MBOT1, MBOT2: RJK0651DPB
L1: COILCRAFT SER1360-472KL
L2: COILCRAFT SER1360-802KL
C
C
: SANYO 6TPE470M
: SANYO 10TPE330M
OUT1
OUT2
D1, D2: DFLS1100
Figure 13. High Efficiency Dual 8.5V/3.3V Step-Down Converter
Efficiency and Power Loss
vs Output Current
Efficiency vs Load Current
Efficiency vs Input Voltage
10000
1000
100
100
90
80
70
60
50
40
30
20
100
98
96
94
92
90
88
86
84
100
90
80
70
60
50
40
30
20
V
V
= 12V
IN
OUT
V
= 8.5V
BURST EFFICIENCY
OUT
= 3.3V
V
OUT
= 3.3V
V
= 8.5V
OUT2
CCM LOSS
BURST LOSS
PULSE-SKIPPING
LOSS
10
V
OUT1
= 3.3V
CCM EFFICIENCY
1
PULSE-SKIPPING
EFFICIENCY
10
0
82
80
10
0
V
IN
= 12V
I
= 2A
LOAD
5
0.1
10
0.0001 0.001
0.01
0.1
1
10
0
10 15 20 25 30 35 40 45 50 55 60
INPUT VOLTAGE (V)
0.0001 0.001
0.01
0.1
1
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
3890 TA02c
3890 TA02d
3890 TA02b
3890fb
32
Linear Systems [ Linear Systems ]
