ltc3890 Linear Technology Corporation, ltc3890 Datasheet - Page 5

• Manufacturer Part Number: ltc3890
• Description: 60v Low Iq, Dual, 2-phase Synchronous Step-down Dc/dc Controller
• Manufacturer: Linear Technology Corporation

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