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| LTC3890 Datasheet, PDF (31/36 Pages) Linear Technology – 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller | |||
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TYPICAL APPLICATIONS
LTC3890
RA1
31.6k
RB1
100k
CITH1A 100pF
CITH1 1000pF
RITH1
34.8k
CSS1 0.01μF
SENSE1+
C1
1nF
SENSE1â
VFB1
PGOOD1
PGOOD2
BG1
SW1
ITH1
BOOST1
LTC3890
TRACK/SS1
TG1
ILIM
PHSMD
CLKOUT
PLLIN/MODE
VIN
INTVCC
RFREQ
41.2k
VOUT2
CSS2 0.01μF
CITH2 470pF
RITH2
34.8k
SGND
EXTVCC
RUN1
RUN2
FREQ
PGND
TG2
TRACK/SS2 BOOST2
SW2
ITH2
RA2
10.5k
RB2
100k
VFB2
BG2
SENSE2â
C2
1nF
SENSE2+
INTVCC
100k
100k
CB1
0.1μF
D1
CINT
4.7μF
D2
CB2 0.1μF
MBOT1 RSENSE1
8mΩ
L1
4.7μH
COUT1
470μF
MTOP1
CIN
220μF
MTOP2
L2
8μH
RSENSE2
10mΩ
MBOT2
VOUT1
3.3V
5A
VIN
9V TO 60V
VOUT2
8.5V
3A
COUT2
330μF
3890 TA07a
MTOP1, MTOP2, MBOT1, MBOT2: RJK0651DPB
L1: COILCRAFT SER1360-472KL
L2: COILCRAFT SER1360-802KL
COUT1: SANYO 6TPE470M
COUT2: SANYO 10TPE330M
D1, D2: DFLS1100
Figure 13. High Efï¬ciency Dual 8.5V/3.3V Step-Down Converter
Efï¬ciency and Power Loss
vs Output Current
100
VIN = 12V
90 VOUT = 3.3V
80
BURST EFFICIENCY
10000
1000
70
CCM LOSS
60
100
50
PULSE-SKIPPING
40 LOSS
BURST LOSS
10
30
20
CCM EFFICIENCY
1
10
0
0.0001
PULSE-SKIPPING
EFFICIENCY
0.001 0.01 0.1
1
OUTPUT CURRENT (A)
0.1
10
3890 TA07b
Efï¬ciency vs Load Current
100
VOUT = 8.5V
90
80
70
VOUT = 3.3V
60
50
40
30
20
10
VIN = 12V
0
0.0001 0.001 0.01 0.1
1
10
OUTPUT CURRENT (A)
3890 TA07c
Efï¬ciency vs Input Voltage
100
98
96
VOUT2 = 8.5V
94
92
90
88
VOUT1 = 3.3V
86
84
82
80 ILOAD = 2A
0 5 10 15 20 25 30 35 40 45 50 55 60
INPUT VOLTAGE (V)
3890 TA07d
3890f
31
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