LTC3890
Typical perForMance characTerisTics
Efficiency and Power Loss
vs Output Current
Efficiency vs Output Current
Efficiency vs Input Voltage
100
98
96
94
92
90
88
86
84
100
90
80
70
60
50
40
30
20
10000
1000
100
100
90
80
70
60
50
40
30
20
V
V
= 12V
IN
OUT
BURST EFFICIENCY
V
= 8.5V
OUT
= 3.3V
V
= 3.3V
OUT
V
= 8.5V
OUT2
CCM LOSS
BURST LOSS
PULSE-SKIPPING
LOSS
V
= 3.3V
10
OUT1
CCM EFFICIENCY
1
Burst Mode OPERATION
PULSE-SKIPPING
EFFICIENCY
82
80
10
0
10
0
I
= 2A
V
IN
= 12V
LOAD
5
0.1
10
0.0001 0.001
0.01
0.1
1
0
10 15 20 25 30 35 40 45 50 55 60
0.0001 0.001
0.01
0.1
1
10
OUTPUT CURRENT (A)
INPUT VOLTAGE (V)
OUTPUT CURRENT (A)
3890 G01
3890 G03
3890 G02
FIGURE 13 CIRCUIT
FIGURE 13 CIRCUIT
FIGURE 13 CIRCUIT
Load Step
Burst Mode Operation
Load Step
Pulse-Skipping Mode
Load Step
Forced Continuous Mode
V
V
V
OUT
OUT
OUT
100mV/DIV
100mV/DIV
100mV/DIV
AC-
AC-
AC-
COUPLED
COUPLED
COUPLED
I
I
I
L
L
L
2A/DIV
2A/DIV
2A/DIV
3890 G04
3890 G06
3890 G05
50µs/DIV
50µs/DIV
50µs/DIV
V
V
= 12V
V
V
= 12V
V
V
= 12V
IN
OUT
IN
OUT
IN
OUT
= 3.3V
= 3.3V
= 3.3V
FIGURE 13 CIRCUIT
FIGURE 13 CIRCUIT
FIGURE 13 CIRCUIT
Soft Start-Up
Tracking Start-Up
Inductor Current at Light Load
FORCED
CONTINUOUS
MODE
V
OUT2
V
OUT2
2V/DIV
2V/DIV
Burst Mode
OPERATION
1A/DIV
V
V
OUT1
OUT1
2V/DIV
2V/DIV
PULSE-SKIPPING
MODE
3890 G08
3890 G07
3890 G09
2ms/DIV
FIGURE 13 CIRCUIT
5µs/DIV
2ms/DIV
FIGURE 13 CIRCUIT
V
V
LOAD
= 12V
IN
= 3.3V
OUT
I
= 200µA
3890fb
5
Linear Systems [ Linear Systems ]
