Datasheet

LT8641
6
Rev B
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TYPICAL PERFORMANCE CHARACTERISTICS
Switching Frequency
Frequency Foldback
Soft-Start Current
PG High Thresholds
PG Low Thresholds
FB VOLTAGE (V)
0
SWITCHING FREQUENCY (kHz)
300
400
500
0.6
1
8641 G23
200
100
0
0.2 0.4 0.8
600
700
800
V
OUT
= 3.3V
V
IN
= 12V
V
SYNC
= 0V
R
T
= 60.4k
V
IN
= 5V
V
OUT
SET TO REGULATE AT 5V
L = WE–LHMI7050, 1µH
LOAD CURRENT (A)
0
0.5
1
1.5
2
2.5
3
3.5
0
100
200
300
400
500
600
DROPOUT VOLTAGE (mV)
Dropout Voltage
8641 G19
FRONT PAGE APPLICATION
V
IN
= 12V
V
OUT
= 5V
LOAD CURRENT (mA)
0
200
400
600
800
0
200
400
600
800
1000
1200
SWITCHING FREQUENCY (kHz)
Burst Frequency
8641 G21
FRONT PAGE APPLICATION
V
OUT
= 5V
f
SW
= 1MHz
INPUT VOLTAGE (V)
5
15
25
35
45
55
65
0
20
40
60
80
100
120
140
LOAD CURRENT (mA)
(Pulse-Skipping Mode)
Minimum Load to Full Frequency
8641 G22
TR/SS VOLTAGE (V)
0
0.2
0.4
0.6
0.8
1.0
1.2
0
0.2
0.4
0.6
0.8
1.0
FB VOLTAGE (V)
Soft-Start Tracking
8641 G24
R
T
= 60.4k
TEMPERATURE (°C)
–50
–25
0
25
50
75
100
125
150
660
670
680
690
700
710
720
730
740
SWITCHING FREQUENCY (kHz)
Switching Frequency
8641 G20
V
SS
= 0.5V
TEMPERATURE (°C)
–50
–25
0
25
50
75
100
125
150
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
SS PIN CURRENT (µA)
Soft–Start Current
8641 G25
FB RISING
FB FALLING
TEMPERATURE (°C)
–50
–25
0
25
50
75
100
125
150
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
PG THRESHOLD OFFSET FROM V
REF
(%)
PG High Thresholds
8641 G26
FB RISING
FB FALLING
TEMPERATURE (°C)
–50
–25
0
25
50
75
100
125
150
–10.0
–9.5
–9.0
–8.5
–8.0
–7.5
–7.0
–6.5
–6.0
PG THRESHOLD OFFSET FROM V
REF
(%)
PG Low Thresholds
8641 G27
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