Datasheet
LT3971A/LT3971A-5
3
3971af
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3971AI is guaranteed over the full –40°C to 125°C operating
junction temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
Note 3: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the switch.
Note 4: Minimum input voltage depends on application circuit.
V
OUT
Pin Current V
OUT
= 5V
V
OUT
= 5V
l
–0.65
–0.90
–0.5
–0.5
–0.38
–0.32
A
A
V
OUT
Pin Clamp Voltage I
VOUT
= –2mA 9 11 13 V
Feedback Voltage
l
1.176
1.173
1.192
1.19
1.204
1.207
V
V
LT3971A-5 Output Voltage
l
4.94
4.93
5.01
5
5.06
5.07
V
V
FB Voltage Line Regulation 4.3V < V
IN
< 38V (Note 4) 0.0002 0.01 %/V
Switching Frequency R
T
= 11k
R
T
= 35.7k
R
T
= 255k
1.8
0.8
160
2.2
1
200
2.6
1.2
240
MHz
MHz
kHz
Minimum Switch On Time 80 ns
Minimum Switch Off Time 110 150 ns
Switch Current Limit 2.0 2.5 3.2 A
Switch V
CESAT
I
SW
= 1A 330 mV
Switch Leakage Current 0.02 1 A
Boost Schottky Forward Voltage I
SH
= 100mA 770 mV
Boost Schottky Reverse Leakage V
REVERSE
= 12V 0.02 1 A
Minimum Boost Voltage (Note 3) V
IN
= 5V
l
1.4 1.8 V
BOOST Pin Current I
SW
= 1A, V
BOOST
= 15V 20 28 mA
EN Voltage Threshold EN Rising
l
0.95 1.01 1.07 V
EN Voltage Hysteresis 30 mV
EN Pin Current 0.2 20 nA
LT3971A PG Threshold Offset from V
FB
V
FB
Rising 60 100 140 mV
LT3971A PG Hysteresis 20 mV
LT3971A-5 PG Threshold Offset from V
OUT
V
OUT
Rising 5.5 9 12.5 %
LT3971A-5 PG Hysteresis 1.3 %
PG Leakage V
PG
= 3V 0.02 1 µA
PG Sink Current V
PG
= 0.4V
l
300 570 A
SYNC Threshold 0.6 0.8 1.0 V
SYNC Pin Current 0.1 nA
SS Source Current V
SS
= 1V 0.6 1 1.6 A
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
EN
= 12V, V
BD
= 3.3V unless otherwise noted. (Note 2)