LTC3728

PRODUCTION

Dual, 550kHz, 2-Phase Synchronous Step-Down Switching Regulator

Part Models: 8
1ku List Price: Starting From $6.00

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Part Details

Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
OPTI-LOOP^® Compensation Minimizes C_OUT
±1% Output Voltage Accuracy
Power Good Output Voltage Indicator
Phase-Lockable Fixed Frequency 250kHz to 550kHz
Dual N-Channel MOSFET Synchronous Drive
Wide V_IN Range: 3.5V to 36V Operation
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Soft-Start Current Ramping
Foldback Output Current Limiting
Latched Short-Circuit Shutdown with Defeat Option
Output Overvoltage Protection
Remote Output Voltage Sense
Low Shutdown I_Q : 20µA
5V and 3.3V Regulators
3 Selectable Operating Modes: Constant-Frequency, Burst Mode^® Operation and PWM
Available in 32-Pin 5mm x 5mm QFN and 28-Pin SSOP Packages

The LTC3728 is a dual high performance step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant-frequency current mode architecture allows phase-lockable frequency of up to 550kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out of phase.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The precision 0.8V reference and power good output indicator are compatible with future microprocessor generations, and a wide 3.5V to 30V (36V maximum) input supply range encompasses all battery chemistries.

A RUN/SS pin for each controller provides both softstart and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when overcurrent latchoff is disabled. Output overvoltage protection circuitry latches on the bottom MOSFET until V_OUT returns to normal. The FCB mode pin can select among Burst Mode, constant-frequency mode and continuous inductor current mode or regulate a secondary winding. The LTC3728 includes a power good output pin that indicates when both outputs are within 7.5% of their designed set point.


	Vin Range	Vref Accy	Current Limit Latch Off	3.3V LDO Available
LTC3728	3.5V to 36V	+/-1%	Yes
LTC3728L	4.5V to 28V	+/-1%	Yes	Yes
LTC3728LX	4.5V to 28V	+/- 1.5%	Yes	Yes
LTC3728L-1	4.5V to 28V	+/- 1.5%	Foldback only	Yes

Applications

Notebook and Palmtop Computers
Telecom Systems
Portable Instruments
Battery-Operated Digital Devices
DC Power Distribution Systems

Part Models: 8
1ku List Price: Starting From $6.00

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3728EG#PBF	28-Lead SSOP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728EG#TRPBF	28-Lead SSOP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728EUH#PBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728EUH#TRPBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728IG#PBF	28-Lead SSOP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728IG#TRPBF	28-Lead SSOP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728IUH#PBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3728IUH#TRPBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Aug 6, 2022 - 22_0171 Laser Top Mark Conversion for SSOP Packages Assembled in PNG
		PCN22_0171_Form Material_Report Delta Qualification Matrix
LTC3728EG#PBF	PRODUCTION
LTC3728EG#TRPBF	PRODUCTION
LTC3728IG#PBF	PRODUCTION
LTC3728IG#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Hardware Ecosystem

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Multiple Output Buck Regulators 1
LTC3880	RECOMMENDED FOR NEW DESIGNS	Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
Silicon Oscillators 1
LTC6909	PRODUCTION	1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
Surge Stopper, Overvoltage, and Overcurrent Protection 1
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit

Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

LTC3728
LTC3728L

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Evaluation Kits

LTC3728EUH Demo Board | Dual Output, 5V to 24VIN, 5VOUT1 @ 4A, 3.3VOUT2 @ 5A

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Product Details

Demonstration circuit 392 is a dual output, step-down, synchronous buck converter featuring either the 150kHz to 300kHz LTC1628EUH controller (DC392A-A), the 250kHz to 550kHz LTC3728EUH (DC392A-B) or 250kHz to 550kHz LTC3728LUH (DC392A-C). It operates with an input voltage range of 7V to 24V and provides 3.3V @ 5A and 5V @ 4A at its output.

Resources

DC392A - Demo Manual
613.00K

DC392A - Schematic
97.00K

DC392A - Design File
621.00K

LTC3728EUH | 2-Phase Dual Output Power Supply, VIN = 5V - 14V, VOUT1 = 2.5V @ 13A, VOUT2 = 1.8V @ 13A

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Product Details

Demonstration circuit 447 is a step-down converter featuring the LTC3728EUH regulator. The PolyPhase^® dual output controller LTC3728EUH drives two high current synchronous buck converters. Input is 5V–14V, output 1 is 2.5V with loads up to 13A and output 2 is 1.8V with loads up to 13A. For applications with input voltage less than 5V, DC447 includes a circuit footprint on the bottom side to provide a 5V bias power supply.

Resources

DC447A - Design File
2.00M

DC447A - Demo Manual
513.00K

DC447A - Schematic
64.00K

LTC3728EG | Dual 2-Phase, 8V to 24V Input, 5V/3.3V 0A to 12A, 3.3V/2.5V 0A to 12A

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Product Details

Demonstration circuit 542 is a dual output, dual phase synchronous step-down controller, featuring the LTC3728EG. Output #1 can be configured for either 5.0V or 3.3V and output #2 can be configured for either 3.3V or 2.5V. The maximum load for both rails is 12A. The input voltage range of the DC542 is 8V to 24V. The DC542 also contains a footprint for a 5.5V boost converter bias supply whose output is connected to EXTVCC. See the “Optional Bias Supply” section for more details.

Resources

DC542A - Demo Manual
405.00K

DC542A - Schematic
56.00K

DC542A - Design File
1.00M

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Part Details

Documentation

Data Sheet 1

Reliability Data 1

User Guide 3

Design Note 1

Technical Articles 3

Hardware Ecosystem

Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

Evaluation Kits

Product Details

Resources

Product Details

Resources

Product Details

Resources

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