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Rarely Asked QuestionsCurrent Noise in FET Input Amps
Features and Benefits
- Ultralow RMS Noise: 0.8µVRMS (10Hz to 100kHz)
- Ultralow Spot Noise: 2nV/√Hz at 10kHz
- Ultrahigh PSRR: 76dB at 1MHz
- Output Current: 500mA
- Wide Input Voltage Range: 1.8V to 20V
- Single Capacitor Improves Noise and PSRR
- 100µA SET Pin Current: ±1% Initial Accuracy
- Single Resistor Programs Output Voltage
- High Bandwidth: 1MHz
- Programmable Current Limit
- Low Dropout Voltage: 260mV
- Output Voltage Range: 0V to 15V
- Programmable Power Good
- Fast Start-Up Capability
- Precision Enable/UVLO
- Parallelable for Lower Noise and Higher Current
- Internal Current Limit with Foldback
- Minimum Output Capacitor: 10µF Ceramic
- Reverse-Battery and Reverse-Current Protection
- 12-Lead MSOP and 10-Lead 3mm × 3mm DFN Packages
The LT3045 is a high performance low dropout linear regulator featuring LTC’s ultralow noise and ultrahigh PSRR architecture for powering noise sensitive applications. Designed as a precision current reference followed by a high performance voltage buffer, the LT3045 can be easily paralleled to further reduce noise, increase output current and spread heat on the PCB.
The device supplies 500mA at a typical 260mV dropout voltage. Operating quiescent current is nominally 2.2mA and drops to <<1µA in shutdown. The LT3045’s wide output voltage range (0V to 15V) while maintaining unity-gain operation provides virtually constant output noise, PSRR, bandwidth and load regulation, independent of the programmed output voltage. Additionally, the regulator features programmable current limit, fast start-up capability and programmable power good to indicate output voltage regulation.
The LT3045 is stable with a minimum 10µF ceramic output capacitor. Built-in protection includes reverse-battery protection, reverse-current protection, internal current limit with foldback and thermal limit with hysteresis. The LT3045 is available in thermally enhanced 12-Lead MSOP and 10-Lead 3mm × 3mm DFN packages.
- RF Power Supplies: PLLs, VCOs, Mixers, LNAs, PAs
- Very Low Noise Instrumentation
- High Speed/High Precision Data Converters
- Medical Applications: Imaging, Diagnostics
- Precision Power Supplies
- Post-Regulator for Switching Supplies
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demo circuit DC2491A features the LT3045EDD, a 500mA, ultralow noise and ultrahigh power supply rejection ratio (PSRR) low dropout (LDO) regulator with programmable current limit. DC2491A operates over an input voltage range of 3.8V to 20V. The LT3045 delivers a maximum output current of 500mA, but at this current level, thermal performance limits the maximum input voltage to 8.3V without a larger copper area or forced-air cooling.
In addition to featuring ultralow noise and ultrahigh PSRR, the regulator offers programmable power good functionality as well as programmable current limit. Current monitoring is also achieved by sensing the ILIM pin 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:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
Design tools for the following parts are available in LTpowerCAD:
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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.
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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.