Datasheet

LT3581
3
3581fa
For more information www.linear.com/LT3581
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage
l
2.3 2.5 V
V
IN
Overvoltage Lockout 22.1 23.5 25 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
81 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 270 µmhos
Error Amp Voltage Gain 70 V/V
Quiescent Current Not Switching 1.9 2.3 mA
Quiescent Current in Shutdown V
SHDN
= 0V 0 1 µA
Reference Line Regulation 2.5V ≤ V
IN
≤ 20V 0.01 0.05 %/V
Switching Frequency, f
OSC
R
T
= 34k
l
2.25 2.5 2.75 MHz
R
T
= 432k
l
180 200 220 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 Synchronization
l
1.3 V
SYNC Low Level for Synchronization
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
l
1.9 2.4 3 A
Current Sharing (SW2/SW1) 78 %
SW1 + SW2 Current Limit At All Duty Cycles, SW2/SW1 = 78% (Note 3)
l
3.3 4.3 5.4 A
Switch V
CESAT
SW1 & SW2 Tied Together, I
SW1
+ I
SW2
= 2.75A 250 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).