Datasheet

LT3579/LT3579-1
3
35791fa
For more information www.linear.com/LT3579
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage
l
2.3 2.5 V
V
IN
Overvoltage Lockout 16.2 18.7 21.2 V
Positive Feedback Voltage
l
1.195 1.215 1.230 V
Negative Feedback Voltage
l
3 9 16 mV
Positive FB Pin Bias Current V
FB
=Positive Feedback Voltage, Current into Pin
l
80.5 83.3 85 µA
Negative FB Pin Bias Current V
FB
=Negative Feedback Voltage, Current out of Pin
l
81 83.3 85.5 µA
Error Amp Transconductance
ΔI=10μA
250 µmhos
Error Amp Voltage Gain 70 V/V
Quiescent Current Not Switching 1.9 2.4 mA
Quiescent Current in Shutdown V
SHDN
= 0V 0 1 µA
Reference Line Regulation 2.5V ≤ V
IN
≤ 15V 0.01 0.05 %/V
Switching Frequency, f
OSC
R
T
= 34kΩ
l
2.2 2.5 2.8 MHz
R
T
= 432kΩ
l
175 200 225 kHz
Switching Frequency in Foldback Compared to Normal f
OSC
1/6 ratio
Switching Frequency Range Free-Running or Synchronizing
l
200 2500 kHz
SYNC High Level for Sync
l
1.3 V
SYNC Low Level for Sync
l
0.4 V
SYNC Clock Pulse Duty Cycle V
SYNC
= 0V to 2V 20 80 %
Recommended Minimum SYNC Ratio
f
SYNC
/f
OSC
3/4
Minimum Off-Time 45 nS
Minimum On-Time 55 nS
SW1 Current Limit At All Duty Cycles (Note 3)
l
3.4 4.2 5.1 A
SW Current Sharing, I
SW2
/I
SW1
SW1 and SW2 Tied Together 0.78 A/A
SW1 + SW2 Current Limit I
SW2
/I
SW1
= 0.78, At All Duty Cycles (Note 3)
l
6 7.5 9.4 A
Switch V
CESAT
SW1 and SW2 Tied Together, I
SW1
+ I
SW2
= 5.5A 250 350 mV
SW1 Leakage Current V
SW1
= 5V 0.01 1 µA
SW2 Leakage Current V
SW2
= 5V 0.01 1 µA
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
SHDN
= V
IN,
V
FAULT
= V
IN
unless otherwise noted. (Note 2).