LT1945
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
NFB1
SHDN1
GND
SHDN2
FB2
1
2
3
4
5
10
9
8
7
6
SW1
PGND
V
IN
PGND
SW2
V
IN
, SHDN1, SHDN2 Voltage ................................... 15V
SW1, SW2 Voltage .................................................. 36V
NFB1 Voltage ........................................................... –3V
FB2 Voltage ...............................................................V
IN
Current into NFB1 Pin ........................................... –1mA
Current into FB2 Pin .............................................. 1mA
Junction Temperature ........................................... 125°C
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT1945EMS
MS PART MARKING
LTTS
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 160°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Minimum Input Voltage
Quiescent Current, (per Converter)
NFB1 Comparator Trip Point
FB2 Comparator Trip Point
FB Comparator Hysteresis
NFB1, FB2 Voltage Line Regulation
NFB1 Pin Bias Current (Note 3)
FB2 Pin Bias Current (Note 4)
Switch Off Time, Switcher 1 (Note 5)
Switch Off Time, Switcher 2 (Note 5)
Switch V
CESAT
Switch Current Limit
SHDN Pin Current
SHDN Input Voltage High
SHDN Input Voltage Low
Switch Leakage Current
Switch Off, V
SW
= 5V
V
SHDN
= 1.2V
V
SHDN
= 5V
V
FB2
> 1V
V
FB2
< 0.6V
I
SW
= 300mA
1.2V < V
IN
< 12V
V
NFB1
= –1.23V
V
FB2
= 1.23V
Not Switching
V
SHDN
= 0V
CONDITIONS
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 1.2V, V
SHDN
= 1.2V unless otherwise noted.
MIN
TYP
20
q
q
MAX
1.2
30
1
–1.255
1.255
0.1
2.9
80
UNITS
V
µA
µA
V
V
mV
%/V
µA
nA
ns
ns
µs
–1.205
1.205
–1.23
1.23
8
0.05
q
q
1.3
2
30
400
400
1.5
250
350
400
3
12
0.25
250
350
2
8
0.9
0.01
5
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LT1945 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Bias current flows out of the NFB1 pin.
Note 4:
Bias current flows into the FB2 pin.
Note 5:
See Figure 1 for Switcher 1 and Switcher 2 locations.
2
U
mV
mA
µA
µA
V
V
µA
1945f
W
U
U
W W
W
LINER [ LINEAR TECHNOLOGY ]
