ltc3851-1 Linear Technology Corporation, ltc3851-1 Datasheet - Page 5

• Manufacturer Part Number: ltc3851-1
• Description: Synchronous Step-down Switching Regulator Controller
• Manufacturer: Linear Technology Corporation

TYPICAL PERFORMANCE CHARACTERISTICS
Coincident Tracking with Master
Supply
AC COUPLED
0.2A TO 7.5A
100
100mV/DIV
90
85
80
70
95
75
4
Effi ciency and Power Loss vs
Input Voltage
5A/DIV
5A/DIV
I
V
LOAD
OUT
POWER LOSS,
EFFICIENCY,
I
I
L
OUT
8
I
OUT
Load Step
(Pulse skip Mode)
V
V
FIGURE 11 CIRCUIT
V
0.5V/DIV
OUT
IN
MASTER
= 0.5A
= 5A
12
= 12V
10ms/DIV
INPUT VOLTAGE (V)
= 1.5V
16
2A LOAD
0.5V/DIV
20
V
V
FIGURE 11 CIRCUIT
V
100μs/DIV
IN
OUT
POWER LOSS,
OUT
= 12V
EFFICIENCY,
I
I
OUT
OUT
= 3.3V
24
38511 G10
= 5A
= 0.5A
28
38511 G04
32
10000
1000
100
3851 G07
V
0.5V/DIV
2A LOAD
0.5V/DIV
MASTER
AC COUPLED
V
0.2A TO 7.5A
CONTINOUS
PULSE SKIP
OPERATION
OUT
100mV/DIV
Burst Mode
FORCED
5A/DIV
5A/DIV
Ratiometric Tracking with Master
Supply
5A/DIV
5A/DIV
5A/DIV
I
MODE
MODE
LOAD
V
OUT
I
L
V
V
FIGURE 11 CIRCUIT
Load Step
(Burst Mode Operation)
Inductor Current at Light Load
OUT
IN
V
V
I
FIGURE 11 CIRCUIT
LOAD
OUT
IN
= 12V
= 12V
= 1.5V
= 1.5V
= 1mA
10ms/DIV
100μs/DIV
1μs/DIV
38511 G11
38511 G05
38511 G08
AC COUPLED
0.2A TO 7.5A
100mV/DIV
0.5V/DIV
2V/DIV
5A/DIV
5A/DIV
I
3.0
2.5
2.0
1.5
1.0
0.5
V
V
LOAD
OUT
OUT
V
0
FB
I
L
4
Input DC Supply Current vs Input
Voltage
Load Step
(Forced Continuous Mode)
V
V
FIGURE 11 CIRCUIT
Start-Up with Prebiased Output
at 2V
OUT
IN
8
= 12V
= 1.5V
12
INPUT VOLTAGE (V)
16
LTC3851-1
20
100μs/DIV
20ms/DIV
24
28
0.5V/DIV
32
TK/SS
36
38511 G12
38511f
38511 G06
38511 G09
5
40