LTC3879 Linear Technology Corporation, LTC3879 Datasheet - Page 5

• Manufacturer Part Number: LTC3879
• Description: Wide Operating Range No RSENSE Step-Down Controller
• Manufacturer: Linear Technology Corporation

www.datasheet4u.com
TYPICAL PERFORMANCE CHARACTERISTICS
V
TRACK/SS
V
50mV/DIV
50mV/DIV
OUT
OUT
10A/DIV
10A/DIV
10V/DIV
10A/DIV
10A/DIV
5V/DIV
1V/DIV
I
I
LOAD
V
LOAD
(AC)
(AC)
OUT
V
I
IN
I
L
L
Transient Response FCM
(Forced Continuous Mode)
LOAD STEP 1A TO 11A TO 1A
V
V
MODE = INTV
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
Start-Up After Input Undervoltage
V
Transient Response DCM
(Discontinuous Mode)
V
V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
LOAD STEP 0A TO 10A TO 0A
V
V
MODE = 0V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
IN
OUT
IN
OUT
IN
OUT
IN
= 12V
= 12V
= 12V
Cycled Low to High
= 1.2V
= 1.2V
= 1.2V
CC
100ms/DIV
50μs/DIV
50μs/DIV
3879 G04
3879 G07
3879 G01
TRACK/SS
V
50mV/DIV
0.5V/DIV
0.5V/DIV
OUT
20V/DIV
10A/DIV
10A/DIV
5V/DIV
I
V
LOAD
RUN
V
(AC)
OUT
SW
I
L
Transient Response FCM
Positive Load Step
Normal Start-Up, RUN Pin
Released from GND
V
V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
Coincident Rail Tracking 1.2V
V
V
V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
LOAD STEP 0A TO 10A
V
V
MODE = 0V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
IN
OUT
IN
OUT
IN
OUT
OUT
= 12V
= 12V
= 12V
= 1.2V
= 1.2V
= 1.2V
Tracks External 1.8V Supply
20ms/DIV
V
0.5V/DIV
0.5V/DIV
5ms/DIV
5μs/DIV
MASTER
V
OUT
3879 G02
3879 G05
3879 G08
TRACK/SS
V
50mV/DIV
OUT
0.5V/DIV
0.5V/DIV
20V/DIV
10A/DIV
10A/DIV
5A/DIV
100
I
V
LOAD
90
80
70
60
50
40
30
20
10
(AC)
V
OUT
0
SW
0.01
I
I
L
L
Effi ciency vs Load Current
DISCONTINUOUS
Transient Response FCM
Negative Load Step
LOAD STEP 10A TO 0A
V
V
MODE = 0V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
Start-Up Into a Pre-Biased Output
RUN Pin Released from GND
V
V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
IN
OUT
IN
OUT
= 12V
= 12V
MODE
= 1.2V
= 1.2V
0.1
LOAD CURRENT (A)
20ms/DIV
5μs/DIV
LTC3879
CONTINUOUS
MODE
1
V
V
SW FREQ = 400kHz
FIGURE 10 CIRCUIT
IN
OUT
= 12V
= 1.2V
10
3879 G09
5
3879 G03
3879 G06
3879f
100