LTC3868 Datasheet, PDF (5/38 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

Typical Performance Characteristics
LTC3868
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
10
30
20
10
0
0.0001
0.001 0.01
Burst Mode
OPERATION
PULSE-
1
SKIPPING
FCM
0.1
0.1
1
10
OUTPUT CURRENT (A)
3868 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)
3868 G02
Efficiency vs Input Voltage
98
FIGURE 12 CIRCUIT
96
V_OUT = 3.3V
I_OUT = 4A
94
92
Load Step (Burst Mode Operation)
V_OUT
100mV/DIV
AC-
COUPLED
90
88
86
I_L
2A/DIV
84
82
80
0
5
10 15 20 25 28
INPUT VOLTAGE (V)
3868 G03
V_OUT = 3.3V
20µs/DIV
FIGURE 12 CIRCUIT
3868 G04
Load Step
(Forced Continuous Mode)
V_OUT
100mV/DIV
AC-
COUPLED
I_L
2A/DIV
V_OUT = 3.3V
20µs/DIV
FIGURE 12 CIRCUIT
3868 G05
Load Step (Pulse-Skipping Mode)
Inductor Current at Light Load
Soft Start-Up
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
3868 G06
PULSE-
SKIPPING
MODE
V_OUT = 3.3V
2µs/DIV
I_LOAD = 200µA
FIGURE 12 CIRCUIT
V_OUT2
2V/DIV
V_OUT1
2V/DIV
3868 G07
20ms/DIV
FIGURE 12 CIRCUIT
3868 G08
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