LTC3869-2_15 Datasheet, PDF (31/42 Pages) Linear Technology – Dual, 2-Phase Synchronous Step-Down DC/DC Controllers

LTC3869/LTC3869-2
Applications Information
L1
0.56µH
3.09k
1%
2.2Ω
1µF
4.7µF
M1
0.1µF
M2
0.1µF
D3 _{VIN PGOOD EXTVCC INTVCC}
TG1
TG2
BOOST1
SW1
BG1
LTC3869
BOOST2
SW2
BG2
MODE/PLLIN
I_LIM
PGND
FREQ
SENSE1⁺
SENSE2⁺
SENSE1^–
SENSE2^–
D4
0.1µF
0.1µF
+
10µF
25V
×2
82µF
25V
V_IN
4.5V TO
20V
M3
L2
0.56µH
M4
3.09k
1%
V_OUT1
1.8V
15A
40.2k
1%
+ _COUT1
330µF
×2
20k
1%
1nF
12.1k
1%
L1, L2: VISHAY IHLP4040DZ-01, 0.56µH
M1, M3: RENESAS RJK0305DPB
M2, M4: RENESAS RJK0330DPB
RUN2
RUN1
V_FB1
I_TH1
150pF ^TK/SS1
0.1µF
SGND
V_FB2
I_TH2
TK/SS2
0.1µF
1nF
100k 4.99k
1%
1%
20k
1%
150pF
+
20k
1%
3869 F13
V_OUT2
1.2V
15A
C_OUT2
330µF
×2
Figure 13. High Efficiency Dual 400kHz 1.8V/1.2V Step-Down Converter
95
V_IN = 12V
MODE = CCM
90
5
1.8V R_SENSE
1.8V DCR SENSE
4
EFFICIENCY
85
3
80
2
POWER LOSS
75
1
1.2V R_SENSE
1.2V DCR SENSE
70
0
0 2 4 6 8 10 12 14 16
LOAD CURRENT (A)
DCR SENSE APP: SEE FIGURE 16
R_SENSE APP: SEE FIGURE 19
3869 F14
Figure 14. DCR Sense Efficiency vs R_SENSE Efficiency
For more information www.linear.com/LTC3869
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