Datasheet

LT3972
3
3972fa
PARAMETER CONDITIONS MIN TYP MAX UNITS
Quiescent Current from BD V
RUN/SS
= 0.2V 0.01 0.5 μA
V
BD
= 3V, Not Switching
●
90 130 μA
V
BD
= 0, Not Switching 15 μA
Minimum Bias Voltage (BD Pin) 2.7 3 V
Feedback Voltage
●
780
775
790
790
800
805
mV
mV
FB Pin Bias Current (Note 3) V
FB
= 0.8V, V
C
= 1.2V
●
10 40 nA
FB Voltage Line Regulation 4V < V
IN
< 33V 0.002 0.01 %/V
Error Amp g
m
500 μmho
Error Amp Gain 2000
V
C
Source Current 60 μA
V
C
Sink Current 60 μA
V
C
Pin to Switch Current Gain 5.3 A/V
V
C
Clamp Voltage 2V
Switching Frequency R
T
= 8.66k
R
T
= 29.4k
R
T
= 187k
2.2
1.0
200
2.45
1.1
230
2.7
1.25
260
MHz
MHz
kHz
Minimum Switch Off-Time
●
60 150 ns
Switch Current Limit Duty Cycle = 5% 4.6 5.4 6.2 A
Switch V
CESAT
I
SW
= 3.5A 335 mV
Boost Schottky Reverse Leakage V
BD
= 0V 0.02 2 μA
Minimum Boost Voltage (Note 4)
●
1.5 2 V
BOOST Pin Current I
SW
= 1A 35 50 mA
RUN/SS Pin Current V
RUN/SS
= 2.5V 5 8 μA
RUN/SS Input Voltage High 2.5 V
RUN/SS Input Voltage Low 0.2 V
PG Threshold Offset from Feedback Voltage V
FB
Rising 65 mV
PG Hysteresis 10 mV
PG Leakage
V
PG
= 5V 0.1 1 μA
PG Sink Current V
PG
= 0.4V
●
200 800 μA
SYNC Low Threshold 0.5 V
SYNC High Threshold 0.7 V
SYNC Pin Bias Current V
SYNC
= 0V 0.1 μA
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 LT3972E is guaranteed to meet performance specifi cations
from 0°C to 125°C. Specifi cations over the –40°C to 125°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LT3972I specifi cations are
guaranteed over the –40°C to 125°C temperature range. The LT3972H
specifi cations are guaranteed over the –40°C to 150°C operating
temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
Note 3: Bias current fl ows out of the FB pin.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the switch.
Note 5: Absolute Maximum at V
IN
and RUN/SS pins is 62V for non-
repetitive 1 minute transients, and 40V for continuous operation.
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 10V, V
RUN/SS
= 10V, V
BOOST
= 15V, V
BD
= 3.3V unless otherwise
noted. (Note 2)
ELECTRICAL CHARACTERISTICS