Alternative Parts
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 (LTC3728LC)
- Power Good Output Voltage Indicator
- Phase-Lockable Fixed Frequency 250kHz to 550kHz
- Dual N-Channel MOSFET Synchronous Drive
- Wide VIN Range: 4.5V to 28V 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
- Low Shutdown IQ: 20µA
- 5V and 3.3V Standby Regulators
- 3 Selectable Operating Modes: Constant-Frequency, Burst Mode® Operation and PWM
- 5mm × 5mm QFN and 28-Lead Narrow SSOP Packages
Product Details
The LTC3728L/LTC3728LX are dual high performance step-down switching regulator controllers that drive 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 4.5V to 28V (30V maximum) input supply range encompasses all battery chemistries.
A RUN/SS pin for each controller provides both soft-start 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 LTC3728L/LTC3728LX include 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 (4)
Documentation
Reliability Data (1)
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.
Models for the following parts are available in LTspice:
Design Resources
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Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.