LTC3858_15 Datasheet, PDF (5/38 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

TYPICAL PERFORMANCE CHARACTERISTICS
LTC3858
Efficiency and Power Loss
vs Output Current
100
FIGURE 12 CIRCUIT
90 _VIN = 12V
80 ^{VOUT = 3.3V}
10000
1000
70
60
100
50
40
30
20
10
0
0.0001
0.001 0.01
Burst Mode
OPERATION 10
PULSE-
SKIPPING
MODE
1
FORCED
CONTINUOUS
MODE
0.1
0.1
1
10
OUTPUT CURRENT (A)
3858 G01
Efficiency vs Output Current
100
90
V_IN = 5V
80
70
V_IN = 12V
60
50
40
30
20
10
0
0.0001
V_OUT = 3.3V
FIGURE 12 CIRCUIT
0.001 0.01 0.1
1
10
OUTPUT CURRENT (A)
3858 G02
Efficiency vs Input Voltage
98
FIGURE 12 CIRCUIT
96
V_OUT = 3.3V
I_OUT = 4A
94
92
Load Step (Burst Mode Operation)
Load Step
(Forced Continuous Mode)
V_OUT
100mV/DIV
AC-
COUPLED
V_OUT
100mV/DIV
AC-
COUPLED
90
88
86
I_L
2A/DIV
I_L
2A/DIV
84
82
80
0 5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
3858 G03
V_OUT = 3.3V
20μs/DIV
FIGURE 12 CIRCUIT
3858 G04
V_OUT = 3.3V
20μs/DIV
FIGURE 12 CIRCUIT
3858 G05
Load Step (Pulse-Skipping Mode)
Inductor Current at Light Load
Soft-Start
V_OUT
100mV/DIV
AC-
COUPLED
I_L
2A/DIV
V_OUT = 3.3V
20μs/DIV
FIGURE 12 CIRCUIT
FORCED
CONTINUOUS
MODE
Burst Mode
OPERATION
2A/DIV
3858 G06
PULSE-
SKIPPING
MODE
V_OUT = 3.3V
2μs/DIV
I_LOAD = 200μA
FIGURE 12 CIRCUIT
V_OUT2
2V/DIV
V_OUT1
2V/DIV
3858 G07
20ms/DIV
FIGURE 12 CIRCUIT
3858 G08
3858fc
5