Datasheet

LT3685
3
3685fb
PARAMETER CONDITIONS MIN TYP MAX UNITS
Quiescent Current from BD V
RUN/SS
= 0.2V
V
BD
= 3V, Not Switching
V
BD
= 0, Not Switching
●
0.01
0.9
1
0.5
1.3
5
μA
mA
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
C
= 1.2V
●
730 nA
FB Voltage Line Regulation 4V < V
IN
< 36V 0.002 0.01 %/V
Error Amp g
m
500 μMho
Error Amp Gain 1000
V
C
Source Current 45 μA
V
C
Sink Current 45 μA
V
C
Pin to Switch Current Gain 3.5 A/V
V
C
Clamp Voltage 2V
Switching Frequency R
T
= 8.66k
R
T
= 29.4k
R
T
= 187k
2.1
0.9
160
2.4
1
200
2.7
1.15
240
MHz
MHz
kHz
Minimum Switch Off-Time
●
60 150 nS
Switch Current Limit Duty Cycle = 5% 3.2 3.7 4.2 A
Switch V
CESAT
I
SW
= 2A 500 mV
Boost Schottky Reverse Leakage V
SW
= 10V, V
BD
= 0V 0.02 2 μA
Minimum Boost Voltage (Note 4)
●
1.5 2.1 V
BOOST Pin Current I
SW
= 1A 22 35 mA
RUN/SS Pin Current V
RUN/SS
= 2.5V 5 10 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 90 mV
PG Hysteresis 12 mV
PG Leakage V
PG
= 5V 0.1 1 μA
PG Sink Current V
PG
= 0.4V
●
100 600 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 LT3685E 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 LT3685I specifi cations are
guaranteed over the –40°C to 125°C temperature range.
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 Voltage at V
IN
and RUN/SS pins is 60V for
nonrepetitive 1 second 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