LT3971_15 Datasheet, PDF (6/28 Pages) Linear Technology – 38V, 1.2A, 2MHz Step-Down Regulator with 2.8A Quiescent Current

LT3971/LT3971-3.3/LT3971-5
TYPICAL PERFORMANCE CHARACTERISTICS T_A = 25°C, unless otherwise noted.
Switch V_CESAT
600
500
400
300
200
100
0
0 250 500 750 1000 1250 1500
SWITCH CURRENT (mA)
3971 G14
LT3971-X Frequency Foldback
900
800
700
600
500
400
300
200
100
0
0
20
40
60
80 100
V_OUT (% OF REGULATION VOLTAGE)
3971 G30
Boost Pin Current
30
25
20
15
10
5
0
0 250 500 750 1000 1250 1500
SWITCH CURRENT (mA)
3971 G15
Minimum Switch On-Time/
Switch Off-Time
400
350
300
250
MIN T_OFF 1A LOAD
200
MIN T_OFF 0.5A LOAD
150
100
MIN T_ON
50
0
–55 –25
5 35 65 95
TEMPERATURE (°C)
125 155
3971 G17
Frequency Foldback
900
800
700
600
500
400
300
200
100
0
0 0.2 0.4 0.6 0.8
FB PIN VOLTAGE (V)
1 1.2
3971 G16
Soft-Start
2.5
2.0
1.5
1.0
0.5
0
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
SS PIN VOLTAGE (V)
3971 G18
Minimum Input Voltage
5.0
V_OUT = 3.3V
4.8
4.6
4.4
4.2
TO START
4.0
3.8
TO RUN
3.6
3.4
3.2
3.0
0
200 400 600 800 1000 1200
LOAD CURRENT (mA)
3971 G19
6
Minimum Input Voltage
6.4
V_OUT = 5V
6.2
6.0
TO START
5.8
5.6
5.4
5.2
TO RUN
5.0
0
200 400 600 800 1000 1200
LOAD CURRENT (mA)
3971 G20
EN Threshold
1.05
1.04
1.03
1.02
1.01
RISING THRESHOLD
1.00
0.99
0.98
FALLING THRESHOLD
0.97
0.96
0.95
–55 –25
5 35 65 95
TEMPERATURE (°C)
125 155
3971 G21
3971fd