Features and Benefits
- Outputs May be Paralleled for Higher Current and Heat Spreading
- Output Current: 500mA
- Single Resistor Programs Output Voltage
- 1% Initial Accuracy of SET Pin Current
- Output Adjustable to 0V
- Current Limit Constant with Temperature
- Low Output Noise: 40μVRMS (10Hz to 100kHz)
- Wide Input Voltage Range: 1.2V to 36V
- Low Dropout Voltage: 275mV
- < 1mV Load Regulation
- < 0.001%/V Line Regulation
- Minimum Load Current: 0.5mA
- Stable with Minimum 2.2μF Ceramic Capacitor
- Current Limit with Foldback and Overtemperature Protected
- 8-Lead MSOP, and 6-Lead 2mm × 3mm DFN Packages
The LT3085 is a 500mA low dropout linear regulator that can be paralleled to increase output current or spread heat on surface mounted boards. Designed as a precision current source and voltage follower, this new regulator finds use in many applications requiring high current, adjustability to zero, and no heat sink. The device also brings out the collector of the pass transistor to allow low dropout operation—down to 275mV—when used with a second supply.
A key feature of the LT3085 is the capability to supply a wide output voltage range. By using a reference current through a single resistor, the output voltage is programmed to any level between zero and 36V. The LT3085 is stable with 2.2μF of capacitance on the output, and the IC uses small ceramic capacitors that do not require additional ESR as is common with other regulators.
Internal protection circuitry includes current limiting and thermal limiting. The LT3085 is offered in the 8-lead MSOP and a low profile (0.75mm) 6-lead 2mm × 3mm DFN package (both with an Exposed Pad for better thermal characteristics).
- High Current All Surface Mount Supply
- High Efficiency Linear Regulator
- Post Regulator for Switching Supplies
- Low Parts Count Variable Voltage Supply
- Low Output Voltage Power Supplies
Markets & Technology
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 (1)
Demonstration circuit 1401A is an adjustable 500mA linear regulator featuring the LT3085. Architected as a precision current source and voltage follower, the LT3085 can be used in many applications requiring up to 500mA output current, adjustability down to 0V at the output and no heat sink. The device brings out the collector of the pass transistor to allow low dropout operation when used with multiple supplies. The demo board operates with an input voltage range from 1.7V to 25V (the maximum output voltage is limited by the output capacitor's voltage rating) and provides a jumper-selectable output voltage of 1.2V, 1.8V, 2.5V, 3.3V, 5V or a user-defined value.
For the LT3085 to regulate properly, the voltage on the control pin (VCONTROL) must be more than approximately 1.2V greater than the output voltage.
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:
LT Journal (1)
Product Selector Card (1)
Product Selection Guide (1)
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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.