Datasheet

LT3975
6
3975f
TYPICAL PERFORMANCE CHARACTERISTICS
Internal Undervoltage Lockout
(UVLO) EN Thresholds PG Thresholds
Minimum Input Voltage,
V
OUT
= 5V
Minimum Input Voltage,
V
OUT
= 3.3V
Burst Frequency
Switching Frequency
R
T
Programmed Switching
Frequency Frequency Foldback
T
A
= 25°C, unless otherwise noted.
TEMPERATURE (°C)
–55
SWITCHING FREQUENCY (kHz)
660
720
780
35 95
3975 G19
600
540
–25 5
65 125 155
480
420
SWITCHING FREQUENCY (MHz)
0.2
0
R
T
RESISTOR (kΩ)
50
150
200
250
350
0.4
1.2
1.6
3975 G20
100
300
1
2
2.2
0.6
0.8
1.4 1.8
FB PIN VOLTAGE (V)
0
700
600
500
400
300
200
100
0
0.6 1
3975 G21
0.2 0.4
0.8 1.2
SWITCHING FREQUENCY (kHz)
TEMPERATURE (°C)
–55
INPUT VOLTAGE (V)
4
5
6
35 95
3975 G22
3
2
–25 5
65 125 155
1
0
TEMPERATURE (°C)
–55
EN THRESHOLD (V)
1.08
35
3975 G23
1.05
1.03
–25 5 65
1.02
1.01
1.09
1.07
1.06
1.04
95 125 155
EN RISING
EN FALLING
TEMPERATURE (°C)
–55
PG THRESHOLD (V)
1.11
35
3975 G24
1.08
1.06
–25 5 65
1.05
1.04
1.12
1.10
1.09
1.07
95 125 155
FB RISING
FB FALLING
LOAD CURRENT (A)
0
INPUT VOLTAGE (V)
5.5
6.0
6.5
2
3975 G25
5.0
4.5
4.0
0.5
1
1.5
2.5
V
OUT
= 5V
f
SW
= 800kHz
TO RUN/TO START
LOAD CURRENT (A)
0
INPUT VOLTAGE (V)
4.0
4.5
5.0
2
3975 G26
3.5
3.0
2.5
0.5
1
1.5
2.5
V
OUT
= 3.3V
FRONT PAGE APPLICATION
TO RUN/TO START
LOAD CURRENT (mA)
0
SWITCHING FREQUENCY (kHz)
500
600
700
160
3975 G27
400
300
0
40
80
120
20
60
100
140
200
100
900
800
V
OUT
= 5V
f
SW
= 800kHz
V
OUT
= 3.3V
f
SW
= 600kHz