LTC3855 LINER [Linear Technology], LTC3855 Datasheet - Page 6

• Manufacturer Part Number: LTC3855
• Description: Dual, Fast, Accurate Step-Down DC/DC Controller
• Manufacturer: LINER [Linear Technology]

LTC3838
TYPICAL PERFORMANCE CHARACTERISTICS
AC-COUPLED
AC-COUPLED
6
50mV/DIV
50mV/DIV
AC-COUPLED
10A/DIV
10A/DIV
10A/DIV
10A/DIV
I
I
50mV/DIV
V
V
LOAD
LOAD
OUT
OUT
10A/DIV
3V/DIV
1V/DIV
I
I
L
L
V
LOAD TRANSIENT = 0A TO 15A TO 0A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
LOAD TRANSIENT = 500mA TO 15A TO 500mA
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
OUT
Transient Response
(Forced Continuous Mode)
Transient Response
(Discontinuous Mode)
SW
ITH
IN
OUT
IN
OUT
I
L
= 12V
= 12V
Load Release with Detect Transient (DTR)
Feature Enabled
LOAD RELEASE = 15A TO 5A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1 MODIFIED:
R
FROM DTR1 PIN: R
= 1.2V
= 1.2V
IN
OUT
FB2
= 5V
= 0.6V
= 0Ω, V
RNG2
50μs/DIV
50μs/DIV
= SGND, C
ITH1
= 46.4k TO SGND, R
5μs/DIV
ITH1
RNG1
RNG1
= 120pF , C
= SGND
= SGND
3838 G01
3838 G04
AC-COUPLED
AC-COUPLED
ITH2
ITH2
50mV/DIV
50mV/DIV
10A/DIV
10A/DIV
10A/DIV
10A/DIV
= 0pF ,
= 42.2k TO INTV
I
I
V
V
LOAD
LOAD
OUT
OUT
I
I
L
L
LOAD STEP = 0A TO 15A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
LOAD STEP = 500mA TO 15A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
Load Step
(Forced Continuous Mode)
Load Step
(Discontinuous Mode)
3838 G07
IN
OUT
IN
OUT
= 12V
= 12V
= 1.2V
= 1.2V
CC
AC-COUPLED
5μs/DIV
5μs/DIV
50mV/DIV
10A/DIV
3V/DIV
1V/DIV
V
OUT
SW
ITH
I
L
Load Release with Detect Transient (DTR)
Feature Disabled
LOAD RELEASE = 15A TO 5A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1 MODIFIED:
R
R
CONNECTION FROM R
DTR1 PIN TIED TO INTV
IN
OUT
FB2
ITH1/2
RNG1
RNG1
= 5V
= 0.6V
= 0Ω, V
= SGND
= SGND
= 46.4k TO SGND//42.2k TO INTV
3838 G02
3838 G05
RNG2
AC-COUPLED
AC-COUPLED
50mV/DIV
50mV/DIV
= SGND, C
10A/DIV
10A/DIV
10A/DIV
10A/DIV
I
I
ITH1/2
LOAD
V
LOAD
V
CC
OUT
OUT
I
I
L
L
5μs/DIV
AND C
LOAD RELEASE = 15A TO 0A
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
LOAD RELEASE = 15A TO 500mA
V
V
FIGURE 17 CIRCUIT, CHANNEL 1, V
ITH1
Load Release
(Forced Continuous Mode)
Load Release
(Discontinuous Mode)
IN
OUT
IN
OUT
= 12V
= 12V
= 120pF , C
= 1.2V
= 1.2V
ITH1
TO DTR1 PIN REMOVED.
CC
,
ITH2
= 0pF ,
5μs/DIV
5μs/DIV
3838 G08
RNG1
RNG1
= SGND
= SGND
3838fa
3838 G03
3838 G06