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
- VIOC Pin Controls Upstream Regulator to Minimize Power Dissipation
- Single Resistor Programs Output Voltage
- 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 3mm × 3mm DFN Packages
The LT3045-1 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 LT3045-1 can be easily paralleled to further reduce noise, increase output current and spread heat on the PCB. In addition to the LT3045 feature set, the LT3045-1 incorporates a VIOC tracking function to control an upstream switching converter to maintain a constant voltage across the LT3045-1 and hence minimize power dissipation.
The device supplies 500mA at a typical 260mV dropout voltage. Operating quiescent current is nominally 2.3mA and drops to <<1μA in shutdown. The LT3045-1’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 LT3045-1 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 LT3045-1 is available in thermally enhanced 12-Lead MSOP and 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
- 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 (2)
Demonstration circuit 2593A features the LT3045EDD-1, a 500mA, ultralow noise, and ultrahigh power supply rejection ratio (PSRR) low dropout (LDO) regulator with programmable current limit. DC2593A operates over an input range of 3.8V to 20V and has a 3.3V output. The LT3045-1 incorporates a VIOC tracking function to control an upstream switching converter to maintain a constant voltage across the LT3045-1 and hence minimize power dissipation.
Demo circuit 2637A features four LT3045EDD-1s in parallel, generating an ultralow noise, ultrahigh power supply rejection ratio (PSRR) low dropout (LDO) regulator with programmable current limit. DC2637A operates over an input range of 3.8V to 20V, and is capable of delivering up to 2A output current by paralleling four LT3045EDD-1s with only 20mΩ ballast resistors.
The VIOC tracking function of the LT3045EDD-1 controls an upstream switching converter to maintain a constant voltage across the regulator and hence minimize power dissipation. In the parallel configuration, connect the VIOC pin of only one IC to the switching converter, while the VIOC pins of the other ICs are left floating. The power good feedback (PGFB) pin is used to set a programmable power good threshold, and also activates the fast start-up circuitry. The PGFB is set on only one IC when they are paralleled. LT3045-1 also offers programmable current limit functionality by connecting a resistor from ILIM to GND on each device. Current monitoring is also achieved by sensing the ILIM pin voltage.
Built-in protection includes reverse battery protection, reverse current protection, internal current limit with fold-back, and thermal limit with hysteresis.
The LT3045-1 data sheet gives a complete description of the device, operation and applications information. The data sheet must be read in conjunction with this demo manual for demonstration circuit 2637A. The LT3045EDD-1 is assembled in a 12-lead (3mm × 3mm) plastic DFN package with an exposed pad on the bottom-side of the IC. Proper board layout is essential for maximum thermal performance.
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:
LT3045-1 Companion Parts
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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.