Datasheet

LT8640/LT8640-1
7
Rev.C
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TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
Switching Frequency
Burst Frequency
Frequency Foldback
Minimum Load to Full Frequency
(Pulse-Skipping Mode)
Soft-Start Tracking
Soft-Start Current
PG High Thresholds
PG Low Thresholds
LOAD CURRENT (A)
0
DROPOUT VOLTAGE (mV)
400
54.54
8640 G19
200
0
1
2
3
0.5
1.5
2.5
3.5
600
300
500
100
V
IN
= 5V
V
OUT
SET TO REGULATE AT 5V
L = IHLP3232DZ-01, 1µH
TEMPERATURE (°C)
–50
SWITCHING FREQUENCY (kHz)
730
25
8640 G20
700
680
–25 0 50
670
660
740
R
T
= 60.4k
720
710
690
75 100 150125
FB VOLTAGE (V)
0
SWITCHING FREQUENCY (kHz)
300
400
500
0.6
1
8640 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
TR/SS VOLTAGE (V)
0
FB VOLTAGE (V)
0.8
1.0
1.2
0.6 1.0
8640 G24
0.6
0.4
0.2 0.4
0.8 1.2 1.4
0.2
0
TEMPERATURE (°C)
–50
SS PIN CURRENT (µA)
1.8
2.0
150
8640 G25
1.6
1.4
0
50
100
–25
25
75
125
2.2
1.7
1.9
1.5
2.1
V
SS
= 0.5V
TEMPERATURE (°C)
–50
6.0
PG THRESHOLD OFFSET FROM V
REF
(%)
6.5
7.5
8.0
8.5
10.0
9.5
0
50
75 100
8640 G26
7.0
9.0
–25
25
150125
FB FALLING
FB RISING
TEMPERATURE (°C)
–50
–10.0
PG THRESHOLD OFFSET FROM V
REF
(%)
–9.5
–8.5
–8.0
–6.0
–7.5
0
50
75 100 125
8640 G27
–9.0
–7.0
–6.5
–25
25
150
FB FALLING
FB RISING
LOAD CURRENT (mA)
0
0
SWITCHING FREQUENCY (kHz)
200
400
600
800
1000
1200
100 200 300 400
8640 G21
FRONT PAGE APPLICATION
V
IN
= 12V
V
OUT
= 5V
INPUT VOLTAGE (V)
5
LOAD CURRENT (mA)
60
80
100
20 30 45
8640 G22
40
20
0
10 15
25
35 40
FRONT PAGE APPLICATION
V
OUT
= 5V
f
SW
= 1MHz
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