Datasheet

LTC3855
7
3855f
V
ITH
(V)
0
–40
V
SENSE
(mV)
–20
0
20
40
60
80
0.5 1 1.5 2
3855 G10
I
LIM
= GND
I
LIM
= FLOAT
I
LIM
= INTV
CC
V
SENSE
COMMON MODE VOLTAGE (V)
0
CURRENT SENSE THRESHOLD (mV)
30
40
50
12
20
10
0
2 6
8 10
4
60
70
80
3855 G11
I
LIM
= GND
I
LIM
= FLOAT
I
LIM
= INTV
CC
60
80
40
20
50
70
30
10
0
DUTY CYCLE (%)
0
CURRENT SENSE THRESHOLD (mV)
60
100
20 40 80
3855 G12
I
LIM
= GND
I
LIM
= FLOAT
I
LIM
= INTV
CC
Typical perForMance characTerisTics
Current Sense Threshold
vs I
TH
Voltage
Maximum Current Sense
Threshold vs Common Mode
Voltage
Maximum Current Sense
Threshold vs Duty Cycle
Maximum Current Sense Voltage
vs Feedback Voltage (Current
Foldback)
TK/SS Pull-Up Current
vs Temperature
Tracking Up and Down
with External Ramp
Quiescent Current
vs Temperature without EXTV
CC
INTV
CC
Line Regulation
V
IN
= 12V
V
OUT1
= 1.8V, 1.5Ω LOAD
V
OUT2
= 1.2V, 1Ω LOAD
10ms/DIV
3855 G07
TK/SS1
TK/SS2
2V/DIV
V
OUT1
V
OUT2
500mA/DIV
V
OUT1
V
OUT2
QUIESCENT CURRENT (mA)
4.5
4.0
3.0
2.0
1.0
3.5
2.5
1.5
0.5
0
TEMPERATURE (°C)
–50 500 100
3855 G08
12525–25 75
INTV
CC
VOLTAGE (V)
5.5
5.0
4.5
4.0
3.0
3.5
2.5
2.0
INPUT VOLTAGE (V)
0 10 30
3855 G09
4020
FEEDBACK VOLTAGE (V)
0
MAXIMUM CURRENT SENSE THRESHOLD (mV)
30
40
50
0.6
20
10
0
0.1 0.3
0.4 0.5
0.2
60
70
90
80
3855 G13
I
LIM
= GND
I
LIM
= FLOAT
I
LIM
= INTV
CC
TK/SS CURRENT (µA)
1.6
1.2
1.4
1.0
TEMPERATURE (°C)
–50 500 100
3855 G14
12525–25 75