LTC3890-3 Datasheet, PDF (33/40 Pages) Linear Technology – 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller

Typical Applications
LTC3890-3
R_A1
31.6k
R_B1
100k
C_ITH1A 100pF
C_ITH1 1000pF
R_ITH1
34.8k
C_SS1 0.01µF
SENSE1⁺
C1
1nF
SENSE1^–
PGOOD1
V_FB1
BG1
SW1
ITH1
BOOST1
LTC3890-3
TRACK/SS1
TG1
R_FREQ
41.2k
V_OUT2
C_SS2 0.01µF
C_ITH2 470pF
R_ITH2
34.8k
V_IN
PLLIN/MODE INTV_CC
SGND
EXTV_CC
RUN1
RUN2
FREQ
PGND
TG2
TRACK/SS2 BOOST2
SW2
ITH2
R_A2
10.5k
R_B2
100k
V_FB2
BG2
SENSE2^–
C2
1nF
SENSE2⁺
INTV_CC
100k
C_B1
0.1µF
D1
C_INT
4.7µF
D2
C_B2 0.1µF
MBOT1 _RSENSE1
8mΩ
L1
4.7µH
C_OUT1
470µF
MTOP1
+ _CIN
100µF
MTOP2
L2
8µH
R_SENSE2
10mΩ
MBOT2
V_OUT1
3.3V
5A
V_IN
9V TO 60V
2.2µF
×3
V_OUT2
8.5V
3A
C_OUT2
330µF
38903 TA02a
MTOP1, MTOP2, MBOT1, MBOT2: RJK0651DPB
L1: COILCRAFT SER1360-472KL
L2: COILCRAFT SER1360-802KL
C_OUT1: SANYO 6TPE470M
C_OUT2: SANYO 10TPE330M
D1, D2: DFLS1100
Figure 13. High Efficiency Dual 8.5V/3.3V Step-Down Converter
Efficiency and Power Loss
vs Output Current
100
V_IN = 12V
90 VOUT = 3.3V
80
BURST EFFICIENCY
10000
1000
70
FCM LOSS
60
100
50
PULSE-SKIPPING
40 _LOSS
BURST LOSS
10
30
20
FCM EFFICIENCY
1
10
0
0.0001
PULSE-SKIPPING
EFFICIENCY
0.001 0.01 0.1
1
OUTPUT CURRENT (A)
0.1
10
38903 TA02b
Efficiency vs Load Current
100
90 ^{VOUT = 8.5V}
80
70
V_OUT = 3.3V
60
50
40
30
20
10
0 ^{VIN = 12V}
0.0001 0.001 0.01 0.1
1
10
OUTPUT CURRENT (A)
38903 TA02c
For more information www.linear.com/3890-3
Efficiency vs Input Voltage
100
98
96
V_OUT2 = 8.5V
94
92
90
88
V_OUT1 = 3.3V
86
84
82
80 ^{ILOAD = 2A}
0 5 10 15 20 25 30 35 40 45 50 55 60
INPUT VOLTAGE (V)
38903 TA02d
38903f
33