Datasheet

LT3959
3
3959fa
For more information www.linear.com/LT3959
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Operating Voltage
l
1.6 40 V
V
IN
Start-Up Voltage R
T
= 27.4kΩ, FBX = 0
l
2.5 2.65 V
V
IN
Shutdown I
Q
EN/UVLO < 0.4V
EN/UVLO = 1.15V
0.1 1
6
µA
µA
V
IN
Operating I
Q
350 450 µA
DRIVE Shutdown Quiescent Current EN/UVLO < 0.4V
EN/UVLO = 1.15V
0.1
0.1
1
2
µA
µA
DRIVE Quiescent Current (Not Switching) R
T
= 27.4kΩ, DRIVE = 6V 2.0 2.5 mA
SW Pin Current Limit
l
6.0 7.0 8.0 A
SW Pin On Voltage I
SW
= 3A 100 mV
SW Pin Leakage Current SW = 40V 5 µA
Error Amplifier
FBX Regulation Voltage (V
FBX(REG)
) FBX > 0V
FBX < 0V
l
l
1.580
–0.815
1.6
–0.80
1.620
–0.785
V
V
FBX Pin Input Current FBX = 1.6V
FBX = –0.8V
–10
80
130
10
nA
nA
Transconductance g
m
(∆I
VC
/∆V
FBX
) FBX = V
FBX(REG)
240 µs
V
C
Output Impedance 5
FBX Line Regulation [∆V
FBX(REG)
/(∆V
IN
V
FBX(REG)
)] 1.6V < V
IN
< 40V, FBX >0
1.6V < V
IN
< 40V, FBX <0
0.02
0.02
0.05
0.05
%/V
%/V
V
C
Source Current FBX = 0V, V
C
= 1.3V –13 µA
V
C
Sink Current FBX = 1.7V, V
C
= 1.3V
FBX = –0.85V, V
C
= 1.3V
13
10
µA
µA
Oscillator
Switching Frequency R
T
= 27.4k to SGND, V
FBX
= 1.6V
R
T
= 86.6k to SGND, V
FBX
= 1.6V
R
T
= 6.81k to SGND, V
FBX
= 1.6V
l
250 300
100
1000
340 kHz
kHz
kHz
R
T
Voltage FBX = 1.6V, –0.8V 1.13 V
SW Minimum Off-Time 150 200 ns
SW Minimum On-Time 150 200 ns
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 12V, EN/UVLO = 12V, INTV
CC
= 4.75V, unless otherwise noted.
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3959EUHE#PBF LT3959EUHE#TRPBF 3959 36-Lead (5mm × 6mm) Plastic QFN –40°C to 125°C
LT3959IUHE#PBF LT3959IUHE#TRPBF 3959 36-Lead (5mm × 6mm) Plastic QFN –40°C to 125°C
LT3959EFE#PBF LT3959EFE#TRPBF LT3959FE 38-Lead Plastic TSSOP –40°C to 125°C
LT3959IFE#PBF LT3959IFE#TRPBF LT3959FE 38-Lead Plastic TSSOP –40°C to 125°C
Consult LT C Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping
container. Consult LT C Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/