Datasheet

LT1074/LT1076
3
1074fd
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. T
j
= 25°C, V
IN
= 25V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch “On” Voltage (Note 2) LT1074 I
SW
= 1A, T
j
≥ 0°C 1.85 V
I
SW
= 1A, T
j
< 0°C 2.1 V
I
SW
= 5A, T
j
≥ 0°C 2.3 V
I
SW
= 5A, T
j
< 0°C 2.5 V
LT1076 I
SW
= 0.5A ● 1.2 V
I
SW
= 2A ● 1.7 V
Switch “Off” Leakage LT1074 V
IN
≤ 25V, V
SW
= 0 5 300 µA
V
IN
= V
MAX,
V
SW
= 0 (Note 8) 10 500 µA
LT1076 V
IN
= 25V, V
SW
= 0 150 µA
V
IN
= V
MAX,
V
SW
= 0 (Note 8) 250 µA
Supply Current (Note 3) V
FB
= 2.5V, V
IN
≤ 40V ● 8.5 11 mA
40V < V
IN
< 60V ● 912 mA
V
SHUT
= 0.1V (Device Shutdown) (Note 9) ● 140 300 µA
Minimum Supply Voltage Normal Mode ● 7.3 8 V
Startup Mode (Note 4)
● 3.5 4.8 V
Switch Current Limit (Note 5) LT1074 I
LIM
Open ● 5.5 6.5 8.5 A
R
LIM
= 10k (Note 6) 4.5 A
R
LIM
= 7k (Note 6) 3 A
LT1076 I
LIM
Open ● 2 2.6 3.2 A
R
LIM
= 10k (Note 6) 1.8 A
R
LIM
= 7k (Note 6) 1.2 A
Maximum Duty Cycle ● 85 90 %
Switching Frequency 90 100 110 kHz
T
j
≤ 125°C ● 85 120 kHz
T
j
> 125°C ● 85 125 kHz
V
FB
= 0V through 2kΩ (Note 5) 20 kHz
Switching Frequency Line Regulation 8V ≤ V
IN
≤ V
MAX
(Note 8) ● 0.03 0.1 %/V
Error Amplifier Voltage Gain (Note 7) 1V ≤ V
C
≤ 4V 2000 V/V
Error Amplifier Transconductance 3700 5000 8000 µmho
Error Amplifier Source and Sink Current Source (V
FB
= 2V) 100 140 225 µA
Sink (V
FB
= 2.5V) 0.7 1 1.6 mA
Feedback Pin Bias Current V
FB
= V
REF
● 0.5 2 µA
Reference Voltage V
C
= 2V ● 2.155 2.21 2.265 V
Reference Voltage Tolerance V
REF
(Nominal) = 2.21V ±0.5 ±1.5 %
All Conditions of Input Voltage, Output
● ±1 ±2.5 %
Voltage, Temperature and Load Current
Reference Voltage Line Regulation 8V ≤ V
IN
≤ V
MAX
(Note 8) ● 0.005 0.02 %/V
V
C
Voltage at 0% Duty Cycle 1.5 V
Over Temperature
● –4 mV/°C
Multiplier Reference Voltage 24 V
Shutdown Pin Current V
SH
= 5V ● 51020 µA
V
SH
≤ V
THRESHOLD
(≅2.5V) ● 50 µA
Shutdown Thresholds Switch Duty Cycle = 0 ● 2.2 2.45 2.7 V
Fully Shut Down
● 0.1 0.3 0.6 V
Thermal Resistance Junction to Case LT1074 2.5 °C/W
LT1076 4.0 °C/W
ELECTRICAL CHARACTERISTICS