LT3431EFE#PBF Linear Technology, LT3431EFE#PBF Datasheet

IC SW REG STEP-DOWN 3A 16TSSOP

LT3431EFE#PBF

Manufacturer Part Number
LT3431EFE#PBF
Description
IC SW REG STEP-DOWN 3A 16TSSOP
Manufacturer
Linear Technology
Type
Step-Down (Buck)r
Datasheet

Specifications of LT3431EFE#PBF

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
1.2 ~ 48 V
Current - Output
3A
Frequency - Switching
500kHz
Voltage - Input
5.5 ~ 60 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
Primary Input Voltage
60V
No. Of Outputs
1
Output Voltage
48V
Output Current
6.5A
No. Of Pins
16
Operating Temperature Range
-40°C To +125°C
Msl
MSL 1 - Unlimited
Rohs Compliant
Yes
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LT3431EFE#PBFLT3431EFE
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Company:
Part Number:
LT3431EFE#PBF
Manufacturer:
LT/凌特
Quantity:
20 000
Company:
Part Number:
LT3431EFE#PBFLT3431EFE#TRPBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
FEATURES
APPLICATIO S
TYPICAL APPLICATIO
(TRANSIENTS
Industrial and Automotive Power Supplies
Portable Computers
Battery Chargers
Distributed Power Systems
Wide Input Range: 5.5V to 60V
3A Peak Switch Current
Small Thermally Enhanced 16-Pin TSSOP Package
Constant 500kHz Switching Frequency
Saturating Switch Design: 0.1
Peak Switch Current Maintained Over
Full Duty Cycle Range
Effective Supply Current: 2.5mA
Shutdown Current: 30 A
1.2V Feedback Reference Voltage
Easily Synchronizable
Cycle-by-Cycle Current Limiting
TO 60V)
12V
V
IN
**
INCREASE INDUCTOR VALUE FOR LOAD CURRENTS ABOVE 2A
(SEE APPLICATIONS INFORMATION—MAXIMUM OUTPUT LOAD CURRENT)
UNITED CHEMI-CON THCS50EZA225ZT
2.2 F
100V
CERAMIC
U
1, 8, 9, 16
3, 4
15
14
5V, 2A Buck Converter
V
SHDN
SYNC
GND
IN
15nF
1.5k
BOOST
LT3431
6
U
BIAS
V
SW
C
FB
11
220pF
2, 5
10
12
30BQ060
0.22 F
10 H**
MMSD914TI
15.4k
4.99k
DESCRIPTIO
The LT
lator that accepts input voltages up to 60V. A high efficiency
3A, 0.1 switch is included on the die along with all the nec-
essary oscillator, control and logic circuitry. A current mode
architecture provides fast transient response and good loop
stability.
Special design techniques and a new high voltage process
achieve high efficiency over a wide input range. Efficiency
is maintained over a wide output current range by using the
output to bias the circuitry and by utilizing a supply boost
capacitor to saturate the power switch. Patented circuitry
maintains peak switch current over the full duty cycle range.
A shutdown pin reduces supply current to 30 A and the de-
vice can be externally synchronized from 580kHz to 700kHz
with logic level inputs.
The LT3431 is available in a thermally enhanced 16-pin
TSSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
47 F
CERAMIC
V
5V
2A
OUT
®
3431 TA01
3431 is a 500kHz monolithic buck switching regu-
Switching Regulator
500kHz Step-Down
U
High Voltage, 3A,
100
60
90
80
70
50
0
V
L = 15 H
IN
Efficiency vs Load Current
= 12V
0.5
LOAD CURRENT (A)
1.0
V
V
OUT
OUT
1.5
= 3.3V
= 5V
LT3431
sn3431 3431fs
2.0
3431 TA02
1
2.5

Related parts for LT3431EFE#PBF

LT3431EFE#PBF Summary of contents

Page 1

... A shutdown pin reduces supply current and the de- vice can be externally synchronized from 580kHz to 700kHz with logic level inputs. The LT3431 is available in a thermally enhanced 16-pin TSSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. MMSD914TI 0. H ...

Page 2

LT3431 ABSOLUTE AXI U RATI GS (Note 1) Input Voltage (V ) ................................................. 60V IN BOOST Pin Above SW ............................................ 35V BOOST Pin Voltage ................................................. 68V SYNC Voltage ........................................................... 7V SHDN Voltage ........................................................... 6V BIAS Pin Voltage ...

Page 3

ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating temperature range, otherwise specifications are 15V 1.5V, SHDN = 1V, BOOST open circuit, SW open circuit, unless otherwise noted PARAMETER Minimum ...

Page 4

LT3431 W U TYPICAL PERFOR A CE CHARACTERISTICS Switch Peak Current Limit TYPICAL 4 GUARANTEED MINIMUM 100 DUTY CYCLE (%) 3431 G01 Lockout and Shutdown Thresholds ...

Page 5

W U TYPICAL PERFOR A CE CHARACTERISTICS Switching Frequency 575 550 525 500 475 450 425 –50 – 100 125 JUNCTION TEMPERATURE ( C) 3431 G10 V Pin Shutdown Threshold C 2.1 1.9 1.7 1.5 1.3 ...

Page 6

LT3431 CTIO S GND (Pins 16): The GND pin connections act as the reference for the regulated output, so load regulation will suffer if the “ground” end of the load is not ...

Page 7

W BLOCK DIAGRA The LT3431 is a constant frequency, current mode buck converter. This means that there is an internal clock and two feedback loops that control the duty cycle of the power switch. In addition to the normal error ...

Page 8

LT3431 U U APPLICATIO S I FOR ATIO FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT3431 is used to set output voltage and provide several overload protection features. The first part of this section deals with selecting resistors ...

Page 9

U U APPLICATIO S I FOR ATIO LT3431 AMPLIFIER Q2 V GND C will increase and the protection accorded by frequency and current foldback will decrease. CHOOSING THE INDUCTOR For most applications, the output inductor will fall into the range ...

Page 10

LT3431 U U APPLICATIO S I FOR ATIO importance, the subsequent suggestions in Peak Induc- tor and Fault Current and EMI will additionally help in the selection of the inductor value. Peak-to-peak output ripple voltage is the sum of a ...

Page 11

... Additional Considerations After making an initial choice, consider additional factors such as core losses and second sourcing, etc. Use the experts in Linear Technology’s Applications department if you feel uncertain about the final choice. They have experience with a wide range of inductor types and can tell you about the latest developments in low profile, surface mounting, etc ...

Page 12

LT3431 U U APPLICATIO S I FOR ATIO To calculate actual peak switch current with a given set of conditions, use OUT SW PEAK OUT F I OUT ...

Page 13

U U APPLICATIO S I FOR ATIO time involved in both the current comparator and turnoff of the output switch. These result in a minimum on time t . When combined with the large ratio of V ON(MIN ...

Page 14

LT3431 U U APPLICATIO S I FOR ATIO Many engineers have heard that solid tantalum capacitors are prone to failure if they undergo high surge currents. This is historically true, and type TPS capacitors are specially tested for surge capability, ...

Page 15

U U APPLICATIO S I FOR ATIO If tantalum capacitors are used, values in the 470 F range are generally needed to minimize ESR and meet ripple current and surge ratings. Care should be taken to ensure ...

Page 16

LT3431 U U APPLICATIO S I FOR ATIO INPUT Threshold voltage for lockout is about 2.38V. A 5.5 A bias current flows out of the pin at this threshold. The internally generated current is used ...

Page 17

U U APPLICATIO S I FOR ATIO reduced. This type of subharmonic switching only occurs at input voltages less than twice output voltage. Higher inductor values will tend to eliminate this problem. See Frequency Compensation section for a discussion of ...

Page 18

LT3431 U U APPLICATIO S I FOR ATIO The V and FB components should be kept as far away as C possible from the switch and boost nodes. The LT3431 pinout has been designed to aid in this. The ground ...

Page 19

U U APPLICATIO S I FOR ATIO Switch loss OUT OUT EFF V IN Boost current loss OUT OUT P BOOST V IN Quiescent current loss: P ...

Page 20

LT3431 U U APPLICATIO S I FOR ATIO Note: Some of the internal power dissipation in the IC, due to BOOST pin voltage, can be transferred outside of the IC to reduce junction temperature, by increasing the voltage drop in ...

Page 21

U U APPLICATIO S I FOR ATIO A detailed theoretical basis for estimating internal power dissipation is given in the Thermal Calculations section. This will allow a first pass check of whether an application’s maximum input voltage requirement is suitable ...

Page 22

LT3431 U U APPLICATIO S I FOR ATIO tantalum output capacitor with a ceramic output capacitor because of its very low ESR. The zero provided by the tantalum output capacitor must now be reinserted back into the loop. Alternatively there ...

Page 23

U U APPLICATIO S I FOR ATIO BUCK CONVERTER WITH ADJUSTABLE SOFT-START Large capacitive loads or high input voltages can cause high input currents at start-up. Figure 13 shows a circuit that limits the dv/dt of the output at start-up, ...

Page 24

LT3431 U U APPLICATIO S I FOR ATIO 16V 36V TRANSIENT C3 2.2 F 50V CER † FOR LOAD CURRENT LESS THAN 25mA, A PRELOAD OF 200 SHOULD BE USED TO IMPROVE LOAD REGULATION. * SEE ...

Page 25

U U APPLICATIO S I FOR ATIO POSITIVE-TO-NEGATIVE CONVERTER The circuit in Figure positive-to-negative topology using a grounded inductor. It differs from the standard approach in the way the IC chip derives its feedback signal because the ...

Page 26

LT3431 U U APPLICATIO S I FOR ATIO For a load current of 0.5A, this says that discontinuous mode can be used and the minimum inductor needed is found from ...

Page 27

... DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights Package 16-Lead Plastic TSSOP (4 ...

Page 28

... Synchronous OUT Step-Down DC/DC Converter LT3430 60V, 2.75A (I ), 200kHz, High Efficiency OUT Step-Down DC/DC Converter ThinSOT is a trademark of Linear Technology Corporation. Linear Technology Corporation 28 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 COMMENTS V = 7.3V to 45/64V DD-5/7, TO220-5/7 Packages ...

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