Datasheet

LTC3857-1
5
38571fc
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency and Power Loss
vs Output Current
Efficiency vs Output Current
Load Step (Burst Mode Operation)
Load Step
(Forced Continuous Mode)
Load Step
(Pulse-Skipping Mode)
Inductor Current at Light Load Soft Start-Up Tracking Start-Up
Efficiency vs Input Voltage
OUTPUT CURRENT (A)
0.00001 0.0001
40
EFFICIENCY (%)
POWER LOSS (mW)
50
60
70
80
0.001 0.01 0.1 1 10
38571 G01
30
20
10
0
90
100
10
100
1000
1
0.1
10000
BURST EFFICIENCY
PULSE-SKIPPING
EFFICIENCY
CCM EFFICIENCY
BURST LOSS
PULSE-SKIPPING
LOSS
CCM LOSS
V
IN
= 12V
V
OUT
= 3.3V
FIGURE 13 CIRCUIT
OUTPUT CURRENT (A)
0.00001 0.0001
40
EFFICIENCY (%)
50
60
70
80
0.001 0.01 0.1 1 10
38571 G02
30
20
10
0
90
100
V
OUT
= 3.3V
FIGURE 13 CIRCUIT
V
IN
= 5V
V
IN
= 12V
INPUT VOLTAGE (V)
1
EFFICIENCY (%)
90
92
94
40
38571 G03
88
86
80
10
20
30
5
15
25
35
82
84
98
96
V
OUT
= 3.3V
I
LOAD
= 5A
V
OUT
100mV/DIV
INDUCTOR
CURRENT
2A/DIV
V
IN
= 12V
V
OUT
= 3.3V
FIGURE 13 CIRCUIT
20µs/DIV
38571 G04
V
OUT
100mV/DIV
INDUCTOR
CURRENT
2A/DIV
V
IN
= 12V
V
OUT
= 3.3V
FIGURE 13 CIRCUIT
20µs/DIV
38571 G05
V
OUT
100mV/DIV
INDUCTOR
CURRENT
2A/DIV
V
IN
= 12V
V
OUT
= 3.3V
FIGURE 13 CIRCUIT
20µs/DIV
38571 G06
FORCED
CONTINUOUS
MODE
PULSE-
SKIPPING
MODE
Burst Mode
OPERATION
1A/DIV
V
IN
= 12V
V
OUT
= 3.3V
I
LOAD
= 200µA
FIGURE 13 CIRCUIT
5µs/DIV
38571 G07
FIGURE 13 CIRCUIT
20ms/DIV
V
OUT2
2V/DIV
V
OUT1
2V/DIV
38571 G08
FIGURE 13 CIRCUIT
20ms/DIV
V
OUT2
2V/DIV
V
OUT1
2V/DIV
38571 G09