Datasheet

LTC3891
7
3891fa
TYPICAL PERFORMANCE CHARACTERISTICS
V
ITH
(V)
0
CURRENT SENSE THESHOLD (mV)
40
60
80
0.6 1.0
3891 G13
20
0
0.2 0.4
0.8 1.2 1.4
–20
–40
Burst Mode
OPERATION
PULSE-SKIPPING MODE
5% DUTY CYCLE
FORCED CONTINUOUS MODE
I
LIM
= FLOAT
I
LIM
= INTV
CC
I
LIM
= GND
V
SENSE
COMMON MODE VOLTAGE (V)
0
SENSE
–
CURRENT (µA)
20
3891 G14
400
300
10 155 25
800
700
600
500
200
100
0
–100
DUTY CYCLE (%)
0
MAXIMUM CURRENT SENSE VOLTAGE (mV)
50
40
60
70
80
3891 G15
30
20
20
40
50
100
80
60
10
30
90
70
I
LIM
= FLOAT
I
LIM
= INTV
CC
I
LIM
= GND
FEEDBACK VOLTAGE (MV)
0
MAXIMUM CURRENT SENSE VOLTAGE (mV)
40
60
800
3891 G16
20
0
200
400
500
80
30
50
10
70
600
100
300
700
I
LIM
= FLOAT
I
LIM
= INTV
CC
I
LIM
= GND
TEMPERATURE (°C)
–75
QUIESCENT CURRENT (µA)
75
50250
3891 G17
60
50
–50 –25 75
45
30
40
35
80
70
65
55
100 125 150
V
IN
= 12V
Maximum Current Sense Voltage
vs I
TH
Voltage
SENSE
–
Pin Input Bias Current
Maximum Current Sense
Threshold vs Duty Cycle
Foldback Current Limit
Quiescent Current vs Temperature INTV
CC
vs Load Current
TEMPERATURE (°C)
–75
REGULATED FEEDBACK VOLTAGE (mV)
806
0 25 50
3891 G21
800
796
–50 –25 75
794
792
808
804
802
798
100 125 150
TRACK/SS Pull-Up Current
vs Temperature
Shutdown (RUN) Threshold
vs Temperature
Regulated Feedback Voltage
vs Temperature
LOAD CURRENT (mA)
0
INTV
CC
VOLTAGE (V)
5.25
40
3891 G18
4.50
20 60
4.00
5.50
5.00
4.75
4.25
80 100
EXTV
CC
= 5V
EXTV
CC
= 8.5V
EXTV
CC
= 0V
V
IN
= 12V
TEMPERATURE (°C)
–75
TRACK/SS CURRENT (µA)
11.5
5025
3891 G19
10.0
–25 0–50 75
12.0
11.0
10.5
9.5
9.0
8.5
8.0
125100 150
TEMPERATURE (°C)
–75
RUN PIN VOLTAGE (V)
500 25
3891 G20
1.20
–25–50 75
1.30
1.25
1.15
1.10
125100 150
RUN RISING
RUN FALLING