900,000+ datasheet pdf search and download

Datasheet4U offers most rated semiconductors data sheet pdf




Linear Technology Electronic Components Datasheet

LT1945 Datasheet

Dual Micropower DC/DC Converter

No Preview Available !

FEATURES
n Generates Well-Regulated Positive and
Negative Outputs
n Low Quiescent Current:
20μA in Active Mode (per Converter)
<1μA in Shutdown Mode
n Operates with VIN as Low as 1.2V
n Low VCESAT Switch: 250mV at 300mA
n Uses Small Surface Mount Components
n High Output Voltage: Up to ±34V
n Tiny 10-Pin MSOP Package
APPLICATIONS
n Small TFT LCD Panels
n Handheld Computers
n Battery Backup
n Digital Cameras
LT1945
Dual Micropower DC/DC
Converter with Positive and
Negative Outputs
DESCRIPTION
The LT®1945 is a dual micropower DC/DC converter in a
10-pin MSOP package. Each converter is designed with
a 350mA current limit and an input voltage range of 1.2V
to 15V, making the LT1945 ideal for a wide variety of ap-
plications. Both converters feature a quiescent current of
only 20μA at no load, which further reduces to 0.5μA in
shutdown. A current limited, fixed off-time control scheme
conserves operating current, resulting in high efficiency
over a broad range of load current. The 36V switch allows
high voltage outputs up to ±34V to be easily generated
without the use of costly transformers. The LT1945’s
low off-time of 400ns permits the use of tiny, low profile
inductors and capacitors to minimize footprint and cost
in space-conscious portable applications.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Dual Output (+12V, –20V) Converter
VIN
2.7V
TO 5V
C1
4.7μF
L1
10μH
C4
0.1μF
D1
8 10
VIN
2
SHDN1
SW1
1
NFB1
LT1945
4
SHDN2
5
FB2
GND PGND PGND SW2
37 96
D2
100pF 365k
24.9k
–20V
10mA
C2
1μF
L2
10μH
C1: TAIYO YUDEN JMK212BJ475
C2, C3: TAIYO YUDEN TMK316BJ105
C4: TAIYO YUDEN EMK107BJ104
D1, D2, D3: ZETEX ZHCS400
L1, L2: MURATA LQH3C100
4.7pF
D3
115k
1M
C3
1μF
12V
20mA
1945 TA01
90
85
80
75
70
65
60
55
50
0.1
Efficiency at VIN = 3.6V
+12V OUTPUT
–20V OUTPUT
1 10
LOAD CURRENT (mA)
100
1945 TA01a
1945fa
1


Linear Technology Electronic Components Datasheet

LT1945 Datasheet

Dual Micropower DC/DC Converter

No Preview Available !

LT1945
ABSOLUTE MAXIMUM RATINGS
(Note 1)
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
PIN CONFIGURATION
NFB1 1
SHDN1 2
GND 3
SHDN2 4
FB2 5
TOP VIEW
10 SW1
9 PGND
8 VIN
7 PGND
6 SW2
MS PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 160°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1945EMS#PBF
LT1945EMS#TRPBF
LTTS
10-Lead Plastic MSOP
–40°C to 85°C
LT1945IMS#PBF
LT1945IMS#TRPBF
LTTS
10-Lead Plastic MSOP
–40°C to 125°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1945EMS
LT1945EMS#TR
LTTS
10-Lead Plastic MSOP
–40°C to 85°C
LT1945IMS
LT1945IMS#TR
LTTS
10-Lead Plastic MSOP
–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/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
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
1.2 V
Quiescent Current, (per Converter)
NFB1 Comparator Trip Point
FB2 Comparator Trip Point
FB Comparator Hysteresis
Not Switching
VSHDN = 0V
–40°C < TJ < 85°C
–40°C < TJ < 125°C
–40°C < TJ < 85°C
–40°C < TJ < 125°C
–1.205
–1.195
1.205
1.195
20
–1.23
1.23
8
30
1
–1.255
1.255
1.255
1.255
μA
μA
V
V
V
V
mV
NFB1, FB2 Voltage Line Regulation
NFB1 Pin Bias Current (Note 3)
FB2 Pin Bias Current (Note 4)
Switch Off Time, Switcher 1 (Note 5)
1.2V < VIN < 12V
VNFB1= –1.23V
–40°C < TJ < 85°C
–40°C < TJ < 125°C
0.05 0.1
l 1.3 2 2.9
30 80
300
400
%/V
μA
nA
nA
ns
Switch Off Time, Switcher 2 (Note 5)
Switch VCESAT
Switch Current Limit
VFB2 > 1V
VFB2 < 0.6V
ISW = 300mA
400
1.5
250 350
250 350 400
ns
μs
mV
mA
1945fa
2


Part Number LT1945
Description Dual Micropower DC/DC Converter
Maker Linear Technology
PDF Download

LT1945 Datasheet PDF





Similar Datasheet

1 LT1940 1.1MHz Step-Down Switching Regulator
Linear Technology
2 LT1940L 1.1MHz Step-Down Switching Regulator
Linear
3 LT1941 Triple Monolithic Switching Regulator
Linear Technology
4 LT1942 Quad DC/DC Converter
Linear
5 LT1943 High Current Quad Output Regulator
Linear
6 LT1944-1 Dual Micropower Step-Up DC/DC Converter
Linear
7 LT1945 Dual Micropower DC/DC Converter
Linear Technology
8 LT1946 1.2MHz Boost DC/DC Converter
Linear Technology
9 LT1946A 2.7MHz Boost DC/DC Converter
Linear Technology





Part Number Start With

0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O    P    Q    R    S    T    U    V    W    X    Y    Z

Site map

Webmaste! click here

Contact us

Buy Components

Privacy Policy