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LT1961EMS8E#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
1
LT1961
1961fa
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
1.5A, 1.25MHz Step-Up
Switching Regulator
■
1.5A Switch in a Small MSOP Package
■
Constant 1.25MHz Switching Frequency
■
Wide Operating Voltage Range: 3V to 25V
■
High Efficiency 0.2Ω Switch
■
1.2V Feedback Reference Voltage
■
±2% Overall Output Voltage Tolerance
■
Uses Low Profile Surface Mount External
Components
■
Low Shutdown Current: 6μA
■
Synchronizable from 1.5MHz to 2MHz
■
Current-Mode Loop Control
■
Constant Maximum Switch Current Rating at All Duty
Cycles*
■
Thermally Enhanced Exposed Pad 8-Lead Plastic
MSOP Package
The LT
®
1961 is a 1.25MHz monolithic boost switching
regulator. A high efficiency 1.5A, 0.2Ω switch is included
on the die together with all the control circuitry required to
complete a high frequency, current-mode switching regu-
lator. Current-mode control provides fast transient re-
sponse and excellent loop stability.
New design techniques achieve high efficiency at high
switching frequencies over a wide operating voltage range.
A low dropout internal regulator maintains consistent
performance over a wide range of inputs from 24V sys-
tems to Li-Ion batteries. An operating supply current of
1mA maintains high efficiency, especially at lower output
currents. Shutdown reduces quiescent current to 6μA.
Maximum switch current remains constant at all duty
cycles. Synchronization allows an external logic level
signal to increase the internal oscillator from 1.5MHz to
2MHz.
The LT1961 is available in an exposed pad, 8-pin MSOP
package. Full cycle-by-cycle switch current limit protec-
tion and thermal shutdown are provided. High frequency
operation allows the reduction of input and output filtering
components and permits the use of chip inductors.
■
DSL Modems
■
Portable Computers
■
Battery-Powered Systems
■
Distributed Power
Efficiency vs Load Current
5V to 12V Boost Converter
LT1961
V
IN
V
OUT
12V
0.5A*
V
IN
5V
1961 TA01
6800pF
100pF
6.8k
10k
1%
90.9k
UPS120
10μF
CERAMIC
2.2μF
CERAMIC
V
SW
FB
SHDN
OPEN
OR
HIGH
= ON
GND
V
C
SYNC
*MAXIMUM OUTPUT CURRENT IS SUBJECT TO THERMAL DERATING.
6.8μH
2
6
73,48
5
1
LOAD CURRENT (mA)
0
EFFICIENCY (%)
90
85
80
75
70
65
60
100 200 300 400
1961 TA01a
500
V
IN
= 5V
V
OUT
= 12V
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. *Patent Pending
2
LT1961
1961fa
ABSOLUTE MAXIMUM RATINGS
W
WW
U
Input Voltage .......................................................... 25V
Switch Voltage ......................................................... 35V
SHDN Pin ............................................................... 25V
FB Pin Current ....................................................... 1mA
SYNC Pin Current .................................................. 1mA
Operating Junction Temperature Range (Note 2)
LT1961E, LT1961I ........................... – 40°C to 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
(Note 1)
T
JMAX
= 125°C, θ
JA
= 50°C/W
GROUND PAD CONNECTED
TO LARGE COPPER AREA
1
2
3
4
V
IN
SW
GND
GND
8
7
6
5
SYNC
V
C
FB
SHDN
TOP VIEW
MS8E PACKAGE
8-LEAD PLASTIC MSOP
PI CO FIGURATIO
UUU
PARAMETER CONDITION MIN TYP MAX UNITS
Recommended Operating Voltage ● 325V
Maximum Switch Current Limit ● 1.5 2 3 A
Oscillator Frequency 3.3V < V
IN
< 25V ● 1 1.5 MHz
Switch On Voltage Drop I
SW
= 1.5A ● 310 500 mV
V
IN
Undervoltage Lockout (Note 3) ● 2.47 2.6 2.73 V
V
IN
Supply Current I
SW
= 0A ● 0.9 1.3 mA
V
IN
Supply Current/I
SW
I
SW
= 1.5A 27 mA/A
Shutdown Supply Current V
SHDN
= 0V, V
IN
= 25V, V
SW
= 25V 6 20 μA
● 45 μA
Feedback Voltage 3V < V
IN
< 25V, 0.4V < V
C
< 0.9V 1.182 1.2 1.218 V
● 1.176 1.224 V
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
C
= 0.8V, SHDN, SYNC and switch open unless otherwise noted.
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1961EMS8E#PBF LT1961EMS8E#TRPBF LTQY 8-Lead Plastic MSOP –40°C to 125°C
LT1961IMS8E#PBF LT1961IMS8E#TRPBF LTQY 8-Lead Plastic MSOP –40°C to 125°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1961EMS8E LT1961EMS8E#TR LTQY 8-Lead Plastic MSOP –40°C to 125°C
LT1961IMS8E LT1961IMS8E#TR LTQY 8-Lead Plastic MSOP –40°C to 125°C
ORDER I FOR ATIO
UUW
Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are 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/
3
LT1961
1961fa
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITION MIN TYP MAX UNITS
FB Input Current ● 0 –0.2 – 0.4 μA
FB to V
C
Voltage Gain 0.4V < V
C
< 0.9V 150 350
FB to V
C
Transconductance ΔI
VC
= ±10μA ● 500 850 1300 μMho
V
C
Pin Source Current V
FB
= 1V ● – 85 – 120 –165 μA
V
C
Pin Sink Current V
FB
= 1.4V ● 70 110 165 μA
V
C
Pin to Switch Current Transconductance 2.4 A/V
V
C
Pin Minimum Switching Threshold Duty Cycle = 0% 0.3 V
V
C
Pin 1.5A I
SW
Threshold 0.9 V
Maximum Switch Duty Cycle V
C
= 1.2V, I
SW
= 100mA ● 80 90 %
V
C
= 1.2V, I
SW
= 1A, 25°C ≤ T
A
≤ 125°C7580%
V
C
= 1.2V, I
SW
= 1A, T
A
≤ 25°C7075%
SHDN Threshold Voltage ● 1.28 1.35 1.42 V
SHDN Input Current (Shutting Down) SHDN = 60mV Above Threshold ● –7 –10 –13 μA
SHDN Threshold Current Hysteresis SHDN = 100mV Below Threshold 4 7 10 μA
SYNC Threshold Voltage 1.5 2.2 V
SYNC Input Frequency 1.5 2 MHz
SYNC Pin Resistance I
SYNC
= 1mA 20 kΩ
The ● denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
C
= 0.8V, SHDN, SYNC and switch open unless otherwise noted.
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1961E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT1961I is guaranteed over the – 40ºC to 125ºC operating junction
temperature range.
Note 3: Minimum input voltage is defined as the voltage where the
internal regulator enters lockout. Actual minimum input voltage to
maintain a regulated output will depend on output voltage and load
current. See Applications Information.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LT1961EMS8E#PBF

Mfr. #:
Buy LT1961EMS8E#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 1.5A, 1.25MHz Boost Sw Reg
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
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