Datasheet

LTC3878
4
3878fa
Typical perForMance characTerisTics
Transient Response FCM
(Forced Continuous Mode)
Transient Response FCM
Positive Load Step
Transient Response FCM
Negative Load Step
Transient Response DCM
(Discontinuous Mode)
Normal Start-Up, RUN/SS
Release from Zero
Start-Up V
IN
Cycled Low and High
Efficiency vs Load Current Efficiency vs Input Voltage Frequency vs Input Voltage
V
IN
(V)
4
50
EFFICIENCY (%)
60
70
80
8
12
16 20
3878 G08
24
90
100
55
65
75
85
95
28
1A CCM
15A CCM
1A DCM
V
OUT
= 1.2V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
V
IN
(V)
4
300
FREQUENCY (kHz)
320
340
360
380
420
8
12 16 20
3878 G09
24 28
0A
15A
400
310
330
350
370
410
390
V
OUT
= 1.2V
FIGURE 7 CIRCUIT
V
OUT
(AC)
50mV/DIV
I
L
10A/DIV
I
LOAD
10A/DIV
50µs/DIV
LOAD STEP 0A TO 10A TO 0A
V
IN
= 12V
V
OUT
= 1.2V
FCB = 0V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G01
V
OUT
(AC)
50mV/DIV
V
SW
20V/DIV
I
L
10A/DIV
I
LOAD
10A/DIV
5µs/DIV
LOAD STEP 0A TO 10A
V
IN
= 12V
V
OUT
= 1.2V
FCB = 0V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G02
V
OUT
(AC)
50mV/DIV
V
SW
20V/DIV
I
L
10A/DIV
I
LOAD
10A/DIV
5µs/DIV
LOAD STEP 10A TO 0A
V
IN
= 12V
V
OUT
= 1.2V
FCB = 0V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G03
V
OUT
(AC)
50mV/DIV
I
L
10A/DIV
I
LOAD
10A/DIV
50µs/DIV
LOAD STEP 1A TO 11A TO 1A
V
IN
= 12V
V
OUT
= 1.2V
FCB = INTV
CC
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G04
V
OUT
500mV/DIV
I
L
10A/DIV
RUN/SS
2V/DIV
50ms/DIV
V
IN
= 12V
V
OUT
= 1.2V
FCB = 0V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G05
V
OUT
1V/DIV
V
IN
10V/DIV
I
L
10A/DIV
RUN/SS
5V/DIV
100ms/DIV
V
IN
= 12V
V
OUT
= 1.2V
FCB = 0V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT
3878 G06
LOAD CURRENT (A)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.01 1 10 100
3878 G07
0
0.1
CONTINUOUS
MODE
DISCONTINUOUS
MODE
V
IN
= 12V
V
OUT
= 1.2V
SW FREQ = 400kHz
FIGURE 7 CIRCUIT