Datasheet

3
LT1961
1961fa
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITION MIN TYP MAX UNITS
FB Input Current ● 0 –0.2 – 0.4 μA
FB to V
C
Voltage Gain 0.4V < V
C
< 0.9V 150 350
FB to V
C
Transconductance ΔI
VC
= ±10μA ● 500 850 1300 μMho
V
C
Pin Source Current V
FB
= 1V ● – 85 – 120 –165 μA
V
C
Pin Sink Current V
FB
= 1.4V ● 70 110 165 μA
V
C
Pin to Switch Current Transconductance 2.4 A/V
V
C
Pin Minimum Switching Threshold Duty Cycle = 0% 0.3 V
V
C
Pin 1.5A I
SW
Threshold 0.9 V
Maximum Switch Duty Cycle V
C
= 1.2V, I
SW
= 100mA ● 80 90 %
V
C
= 1.2V, I
SW
= 1A, 25°C ≤ T
A
≤ 125°C7580%
V
C
= 1.2V, I
SW
= 1A, T
A
≤ 25°C7075%
SHDN Threshold Voltage ● 1.28 1.35 1.42 V
SHDN Input Current (Shutting Down) SHDN = 60mV Above Threshold ● –7 –10 –13 μA
SHDN Threshold Current Hysteresis SHDN = 100mV Below Threshold 4 7 10 μA
SYNC Threshold Voltage 1.5 2.2 V
SYNC Input Frequency 1.5 2 MHz
SYNC Pin Resistance I
SYNC
= 1mA 20 kΩ
The ● denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
C
= 0.8V, SHDN, SYNC and switch open unless otherwise noted.
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 LT1961E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT1961I is guaranteed over the – 40ºC to 125ºC operating junction
temperature range.
Note 3: Minimum input voltage is defined as the voltage where the
internal regulator enters lockout. Actual minimum input voltage to
maintain a regulated output will depend on output voltage and load
current. See Applications Information.