Datasheet
LT3956
2
3956f
absoluTe MaxiMuM raTings
V
IN
, ISP, ISN ..............................................................80V
SW ............................................................................84V
EN/UVLO (Note 3) .....................................................80V
INTV
CC
......................................................V
IN
+ 0.3V, 8V
PWMOUT ..................................................INTV
CC
+ 0.3V
CTRL, PWM, VMODE ................................................12V
FB ...............................................................................8V
V
C
, V
REF
, SS ................................................................3V
RT ............................................................................1.5V
PGND to GND .........................................................±0.5V
Operating Junction Temperature Range
(Note 2) ............................................. –40°C to 125°C
Maximum Junction Temperature........................... 125°C
Storage Temperature Range ................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
(Note 1)
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3956EUHE#PBF LT3956EUHE#TRPBF 3956
36-Lead (5mm × 6mm) Plastic QFN
–40°C to 125°C
LT3956IUHE#PBF LT3956IUHE#TRPBF 3956
36-Lead (5mm × 6mm) Plastic QFN
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Minimum Operating Voltage V
IN
Tied to INTV
CC
l
4.5 V
V
IN
Shutdown I
Q
EN/UVLO = 0V
EN/UVLO = 1.15V
0.1 1
5
µA
µA
V
IN
Operating I
Q
(Not Switching) PWM = 0V 1.4 1.7 mA
V
REF
Voltage –100µA ≤ I
VREF
≤ 0µA
l
1.965 2.00 2.045 V
V
REF
Line Regulation 4.5V ≤ V
IN
≤ 80V 0.006 %/V
pin conFiguraTion
12 13 14
TOP VIEW
37
GND
38
SW
UHE PACKAGE
36-LEAD (5mm s 6mm) PLASTIC QFN
15 16 17
36 35 34 33 32 31 30
21
23
24
25
27
28
8
6
4
3
2
1NC
EN/UVLO
INTV
CC
GND
V
IN
SW
SW
NC
ISP
ISN
FB
GND
PWMOUT
SW
SW
RT
SS
VMODE
PWM
V
REF
CTRL
V
C
PGND
PGND
PGND
PGND
PGND
PGND
20
9
10
T
JMAX
= 125°C, θ
JA
= 43°C/W, θ
JC
= 5°C/W
EXPOSED PAD (PIN 37) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 38) IS SW, MUST BE SOLDERED TO PCB
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at T
A
= 25°C. V
IN
= 24V, EN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise noted.