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LT1765EFE#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
LT1765/LT1765-1.8/LT1765-2.5/
LT1765-3.3/LT1765-5
1
1765fd
TYPICAL APPLICATION
DESCRIPTION
Monolithic 3A, 1.25MHz
Step-Down Switching Regulator
The LT
®
1765 is a 1.25MHz monolithic buck switching
regulator. A high effi ciency 3A, 0.09Ω switch is included
on the die together with all the control circuitry required
to construct a high frequency, current mode switching
regulator. Current mode control provides fast transient
response and excellent loop stability.
New design techniques achieve high effi ciency at high
switching frequencies over a wide operating voltage
range. A low dropout internal regulator maintains con-
sistent performance over a wide range of inputs from
24V systems to Li-Ion batteries. An operating supply
current of 1mA improves effi ciency, especially at lower
output currents. Shutdown reduces quiescent current to
15μA. Maximum switch current remains constant at all
duty cycles. Synchronization allows an external logic level
signal to increase the internal oscillator into the range of
1.6MHz to 2MHz.
Full cycle-by-cycle current control and thermal shutdown
are provided. High frequency operation allows the reduc-
tion of input and output fi ltering components and permits
the use of chip inductors.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
*Patent Pending
5V to 3.3V Step-Down Converter
FEATURES
APPLICATIONS
n
DSL Modems
n
Portable Computers
n
Regulated Wall Adapters
n
Battery-Powered Systems
n
Distributed Power
n
3A Switch in a Thermally Enhanced 16-Lead
TSSOP or 8-Lead SO Package
n
Constant 1.25MHz Switching Frequency
n
Wide Operating Voltage Range: 3V to 25V
n
High Effi ciency 0.09Ω Switch
n
1.2V Feedback Reference Voltage
n
Uses Low Profi le Surface Mount Components
n
Low Shutdown Current: 15μA
n
Synchronizable to 2MHz
n
Current Mode Loop Control
n
Constant Maximum Switch Current Rating at
All Duty Cycles*
n
Available in 8-Lead SO and 16-Lead Thermally
Enhanced TSSOP Packages
BOOST
LT1765-3.3
V
IN
OUTPUT
3.3V
2.5A
INPUT
5V
1765 TA01
0.18μF
2.2nF
UPS120
4.7μF
CERAMIC
2.2μF
CERAMIC
CMDSH-3
1.5μH
V
SW
FBSHDN
ONOFF
GND
V
C
SYNC
Effi ciency vs Load Current
SWITCH CURRENT (A)
0
EFFICIENCY (%)
80
85
2.0
1765 • TAO1a
75
70
0.5
1.0
1.5
90
V
IN
= 10V
V
OUT
= 5V
LT1765/LT1765-1.8/LT1765-2.5/
LT1765-3.3/LT1765-5
2
1765fd
ABSOLUTE MAXIMUM RATINGS
Input Voltage ........................................................... 25V
BOOST Pin Above SW ............................................. 20V
Max BOOST Pin Voltage ............................................35V
SHDN Pin ................................................................. 25V
FB Pin Current ......................................................... 1mA
(Note 1)
FE PACKAGE
16-LEAD PLASTIC TSSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
GND
BOOST
V
IN
V
IN
SW
SW
NC
GND
GND
NC
SYNC
V
C
FB
SHDN
NC
GND
17
θ
JA
= 45°C/W, θ
JC(PAD)
= 10°C/W
EXPOSED PAD (PIN 17) SOLDERED TO LARGE COPPER PLANE
TOP VIEW
SYNC
V
C
FB
SHDN
BOOST
V
IN
SW
GND
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
T
JMAX
= 125°C, θ
JA
= 90°C/W, θ
JC(PIN 4)
= 30°C/W
GROUND PIN CONNECTED TO LARGE COPPER AREA
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1765EFE#PBF LT1765EFE#TRPBF 1765EFE 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-1.8#PBF LT1765EFE-1.8#TRPBF 1765EFE-1.8 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-2.5#PBF LT1765EFE-2.5#TRPBF 1765EFE-2.5 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-3.3#PBF LT1765EFE-3.3#TRPBF 1765EFE-3.3 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-5#PBF LT1765EFE-5#TRPBF 1765EFE-5 16-Lead Plastic TSSOP –40°C to 125°C
LT1765ES8#PBF LT1765ES8#TRPBF 1765 8-Lead Plastic SO –40°C to 125°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1765EFE LT1765EFE#TR 1765EFE 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-1.8 LT1765EFE-1.8#TR 1765EFE-1.8 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-2.5 LT1765EFE-2.5#TR 1765EFE-2.5 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-3.3 LT1765EFE-3.3#TR 1765EFE-3.3 16-Lead Plastic TSSOP –40°C to 125°C
LT1765EFE-5 LT1765EFE-5#TR 1765EFE-5 16-Lead Plastic TSSOP –40°C to 125°C
LT1765ES8 LT1765ES8#TR 1765 8-Lead Plastic SO –40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to:
http://www.linear.com/tapeandreel/
SYNC Pin Current ................................................... 1mA
Operating Junction Temperature Range
(Note 2) ................................................. –40°C to 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................ 300°C
LT1765/LT1765-1.8/LT1765-2.5/
LT1765-3.3/LT1765-5
3
1765fd
ELECTRICAL CHARACTERISTICS
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 LT1765E is guaranteed to meet performance specifi cations
from 0°C to 125°C. Specifi cations over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Maximum Switch Current Limit 346 A
Oscillator Frequency 3.3V < V
IN
< 25V
l
1.1 1.25 1.6 MHz
Switch On Voltage Drop I = 3A
l
270 430 mV
V
IN
Undervoltage Lockout (Note 3)
l
2.47 2.6 2.73 V
V
IN
Supply Current
l
1 1.3 mA
Shutdown Supply Current V
SHDN
= 0V, V
IN
= 25V, V
SW
= 0V
l
15 35
55
μA
μA
Feedback Voltage 3V < V
IN
< 25V, 0.4V < V
C
< 0.9V
(Note 3)
LT1765 (Adj)
l
1.182
1.176
1.2 1.218
1.224
V
V
LT1765-1.8
l
1.764 1.8 1.836 V
LT1765-2.5
l
2.45 2.5 2.55 V
LT1765-3.3
l
3.234 3.3 3.366 V
LT1765-5
l
4.9 5 5.1 V
FB Input Current LT1765 (Adj)
l
–0.25 –0.5 μA
FB Input Resistance LT1765-1.8
LT1765-2.5
LT1765-3.3
LT1765-5
l
l
l
l
10.5
14.7
19
29
15
21
27.5
42
21
30
39
60
kΩ
kΩ
kΩ
kΩ
FB Error Amp Voltage Gain 0.4V < V
C
< 0.9V 150 350
FB Error Amp Transconductance
ΔI
VC
= ±10μA
l
500 850 1300 μMho
V
C
Pin Source Current V
FB
= V
NOM
– 17%
l
80 120 160 μA
V
C
Pin Sink Current V
FB
= V
NOM
+ 17%
l
70 110 180 μA
V
C
Pin to Switch Current Transconductance 5A/V
V
C
Pin Minimum Switching Threshold Duty Cycle = 0% 0.4 V
V
C
Pin 3A ISW Threshold 0.9 V
Maximum Switch Duty Cycle V
C
= 1.2V, I
SW
= 800mA, V
IN
= 6V
l
85
80
90 %
%
Minimum Boost Voltage Above Switch I
SW
= 3A
l
1.8 2.7 V
Boost Current I
SW
= 1A (Note 4)
I
SW
= 3A (Note 4)
l
l
20
70
30
140
mA
mA
SHDN Threshold Voltage
l
1.27 1.33 1.40 V
SHDN Threshold Current Hysteresis
l
4710 μA
SHDN Input Current (Shutting Down) SHDN = 60mV Above Threshold
l
–7 –10 –13 μA
SYNC Threshold Voltage 1.5 2.2 V
SYNC Input Frequency 1.6 2 MHz
SYNC Pin Resistance I
SYNC
= 1mA 20 kΩ
The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T
A
= 25°C.
V
IN
= 15V, V
C
= 0.8V, Boost = V
IN
+ 5V, SHDN, SYNC and switch open unless otherwise noted.
Note 3: Minimum input voltage is defi ned 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.
Note 4: Current fl ows into the BOOST pin only during the on period of the
switch cycle.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LT1765EFE#PBF

Mfr. #:
Buy LT1765EFE#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Mono 3A, 1.25MHz Buck Sw Regs
Lifecycle:
New from this manufacturer.
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