Features and Benefits
- High Efficiency (No Sense Resistor Required)
- Wide Input Voltage Range: 2.5V to 36V
- Current Mode Control Provides Excellent Transient Response
- High Maximum Duty Cycle (92% Typ)
- ±2% RUN Pin Threshold with 100mV Hysteresis
- ±1% Internal Voltage Reference
- Micropower Shutdown: IQ = 10μA
- Programmable Operating Frequency (50kHz to 1MHz) with One External Resistor
- Synchronizable to an External Clock Up to 1.3 × fOSC
- User-Controlled Pulse Skip or Burst Mode® Operation
- Internal 5.2V Low Dropout Voltage Regulator
- Output Overvoltage Protection
- Capable of Operating with a Sense Resistor for High Output Voltage Applications
- Small 10-Lead MSOP Package
The LTC1871 is a wide input range, current mode, boost, flyback or SEPIC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to medium power applications, it eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maximizing efficiency.
The IC’s operating frequency can be set with an external resistor over a 50kHz to 1MHz range, and can be synchronized to an external clock using the MODE/SYNC pin. Burst Mode operation at light loads, a low minimum operating supply voltage of 2.5V and a low shutdown quiescent current of 10μA make the LTC1871 ideally suited for battery-operated systems.
For applications requiring constant frequency operation, Burst Mode operation can be defeated using the MODE/ SYNC pin. Higher output voltage boost, SEPIC and flyback applications are possible with the LTC1871 by connecting the SENSE pin to a resistor in the source of the power MOSFET.
The LTC1871 is available in the 10-lead MSOP package.
|LTC1871||2.5V to 36V||5.2V||-|
|LTC1871-1||2.5V to 36V||5.2V||Lower Burst Mode Threshold (0.195V vs. 0.3V)|
|LTC1871-7||6V to 36V||7V||Drives 6V Gate N-Channel MOSFETs|
|LTC1871X||2.5V to 36V||5.2V||175°C Junction Temp, 100% Tested at 175°C|
- Telecom Power Supplies
- Portable Electronic Equipment
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 (2)
Demonstration circuit DC414 is a step-up (Boost) DC-DC converter featuring the LTC1871 controller. The circuit is capable of providing an output voltage of 5V at 7A (10A peak) from an input supply of 3.3V. External frequency synchronization is provided, as are two modes of operation at light load conditions: Burst mode™ operation to reduce switching losses and maintain high operating efficiency, and continuous mode to provide constant operating frequency with low quiescent current. The LTC1871 is a No RSENSE™ current mode step-up controller. It eliminates the need for a current sense resistor and maximizes the efficiency of the demo circuit —up to 95%. The LTC1871 can operate up to a frequency of 1MHz, allowing for the use of small inductors and capacitors. The low shutdown quiescent current of 10μA makes the LTC1871 ideally suited for battery-operated systems. Applications include telecom power supplies, cellular phones, PDAs and portable electronic equipment.
Demonstration circuit 415 is a SEPIC (step-up or step-down) DC/DC converter featuring the LTC1871 controller. The circuit is capable of providing an output voltage of 12V at 2A from an input voltage of 5V to 15V. External frequency synchronization is provided, as are two modes of operation at light load conditions: Burst Mode® operation reduces switching losses and maintains high efficiency operation; and continuous mode which provides constant operating frequency with low quiescent current.
Tools & Simulations
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:
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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.