LT1945
W W
U W
U
W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
ORDER PART
NUMBER
TOP VIEW
VIN, SHDN1, SHDN2 Voltage ................................... 15V
SW1, SW2 Voltage .................................................. 36V
NFB1 Voltage ........................................................... –3V
FB2 Voltage ...............................................................VIN
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
NFB1
SHDN1
GND
SHDN2
FB2
1
2
3
4
5
10 SW1
9
8
7
6
PGND
LT1945EMS
V
IN
PGND
SW2
MS PACKAGE
10-LEAD PLASTIC MSOP
MS PART MARKING
LTTS
TJMAX = 125°C, θJA = 160°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The ● denotes the specifications which apply over the full operating
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum Input Voltage
Quiescent Current, (per Converter)
1.2
V
Not Switching
20
30
1
µA
µA
V
= 0V
SHDN
NFB1 Comparator Trip Point
●
●
–1.205
1.205
–1.23
1.23
8
–1.255
1.255
V
V
FB2 Comparator Trip Point
FB Comparator Hysteresis
mV
%/V
µA
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)
1.2V < V < 12V
0.05
2
0.1
2.9
80
IN
V
V
= –1.23V
●
●
1.3
NFB1
= 1.23V
30
nA
FB2
400
ns
V
V
> 1V
< 0.6V
400
1.5
ns
µs
FB2
FB2
Switch V
I
= 300mA
SW
250
350
350
400
mV
mA
CESAT
Switch Current Limit
SHDN Pin Current
250
0.9
V
V
= 1.2V
= 5V
2
8
3
12
µA
µA
SHDN
SHDN
SHDN Input Voltage High
SHDN Input Voltage Low
Switch Leakage Current
V
V
0.25
5
Switch Off, V = 5V
0.01
µA
SW
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
temperature range are assured by design, characterization and correlation
with statistical process controls.
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
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.
1945f
2
Linear [ Linear ]
