Overview
Features and Benefits
- Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- OPTI-LOOP® Compensation Minimizes COUT
- ±1% Output Voltage Accuracy
- Power Good Output Voltage Indicator
- Phase-Lockable Fixed Frequency 250kHz to 550kHz
- Dual N-Channel MOSFET Synchronous Drive
- Wide VIN 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 IQ : 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
Product Details
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 VOUT 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
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (3)
Documentation & Resources
-
R384 Reliability Data3/26/2018
-
DC542A - Demo Manual9/24/2009
-
DC447A - Demo Manual9/24/2009
-
DC392A - Demo Manual9/24/2009
Tools & Simulations
LTspice
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LTC3728
LTC3728L
Product Recommendations
LTC3728 Companion Parts
Design Resources
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 Number | Material Declaration | Reliability Data | Pin/Package Drawing | CAD Symbols, Footprints & 3D Models |
|---|---|---|---|---|
| LTC3728EG#PBF | Material Declaration | Reliability Data | 28-Lead SSOP | |
| LTC3728EG#TRPBF | Material Declaration | Reliability Data | 28-Lead SSOP | |
| LTC3728EUH#PBF | Material Declaration | Reliability Data | 32-Lead QFN (5mm x 5mm x 0.75mm w/ EP) | |
| LTC3728EUH#TRPBF | Material Declaration | Reliability Data | 32-Lead QFN (5mm x 5mm x 0.75mm w/ EP) | |
| LTC3728IG#PBF | Material Declaration | Reliability Data | 28-Lead SSOP | |
| LTC3728IG#TRPBF | Material Declaration | Reliability Data | 28-Lead SSOP | |
| LTC3728IUH#PBF | Material Declaration | Reliability Data | 32-Lead QFN (5mm x 5mm x 0.75mm w/ EP) | |
| LTC3728IUH#TRPBF | Material Declaration | Reliability Data | 32-Lead QFN (5mm x 5mm x 0.75mm w/ EP) | |
| Wafer Fabrication Data | R384 Reliability Data |
PCN-PDN Information
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Support & Discussions
LTC3728 Discussions
Sample & Buy
Ordering FAQs
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Buy Now Pricing
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List Pricing
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Lead Times
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Sampling
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Evaluation Boards
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Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.