LTC3859_15 Datasheet, PDF (7/42 Pages) Linear Technology – Low IQ, Triple Output, Buck/Buck/Boost Synchronous Controller

TYPICAL PERFORMANCE CHARACTERISTICS
LTC3859
Efficiency and Power Loss
vs Output Current (Buck)
100
10000
90
80
1000
70
60
100
50
40
30
20
10
0
0.0001 0.001 0.01
CCM EFFICIENCY 10
PULSE-SKIPPING
EFFICIENCY
BURST LOSS
BURST EFFICIENCY 1
CCM LOSS
PULSE-SKIPPING
LOSS
0.1
0.1
1
10
OUTPUT CURRENT (A)
FIGURE 12 CIRCUIT
V_IN = 10V, V_OUT = 5V
3859 G01
Load Step (Buck)
Burst Mode Operation
Efficiency
vs Output Current (Buck)
100
90
V_IN = 10V
80
V_IN = 20V
70
60
50
40
30
20
10
FIGURE 12 CIRCUIT
0
0.0001 0.001 0.01 0.1
1
OUTPUT CURRENT (A)
10
3859 G02
Efficiency vs Input Voltage (Buck)
100
FIGURE 12 CIRCUIT
99 ^{VOUT = 5V}
I_LOAD = 4A
98
97
96
95
94
93
92
0 5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
3859 G03
Load Step (Buck)
Pulse-Skipping Mode
Load Step (Buck)
Forced Continuous Mode
V_OUT
100mV/DIV
AC-COUPLED
V_OUT
100mV/DIV
AC-COUPLED
V_OUT
100mV/DIV
AC-COUPLED
I_L
2A//DIV
50μs/DIV
V_IN = 12V
V_OUT = 5V
FIGURE 12 CIRCUIT
3859 G04
I_L
2A//DIV
50μs/DIV
V_IN = 12V
V_OUT = 5V
FIGURE 12 CIRCUIT
3859 G05
I_L
2A//DIV
50μs/DIV
V_IN = 12V
V_OUT = 5V
FIGURE 12 CIRCUIT
3859 G06
Inductor Current at Light Load
(Buck)
Soft Start-Up
FORCED
CONTINUOUS
MODE
Burst Mode
OPERATION
1A/DIV
PULSE-
SKIPPING
MODE
2μs/DIV
V_IN = 10V
V_OUT = 5V
I_LOAD = 1mA
FIGURE 12 CIRCUIT
3859 G07
2ms/DIV
FIGURE 12 CIRCUIT
V_OUT2
2V/DIV
V_OUT1
2V/DIV
3859 G08
Buck Regulated Feedback Voltage
vs Temperature
808
806
804
802
800
798
796
794
792
–45 –20
5 30 55 80
TEMPERATURE (°C)
105 130
3859 G09
3859fa
7