Features and Benefits
- Wide Input Voltage Range: 4.5V to 40V
- Wide Output Voltage Range: 0.8V to 40V
- Low Operating IQ
- 14μA (14V to 3.3V, Channel 1 On)
- PassThru™/100% Duty Cycle Capable
- Spread Spectrum Operation
- RSENSE or DCR Current Sensing
- Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- Programmable Fixed Frequency (100kHz to 3MHz)
- Phase-Lockable Frequency (100kHz to 3MHz)
- Selectable Continuous, Pulse-Skipping, or Low Ripple, Burst Mode® Operation at Light Loads
- Power Good Output Voltage Monitors
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- Low Shutdown IQ: 1.5μA
- Side Wettable 28-Lead 4mm × 5mm QFN Package
- AEC-Q100 Automotive Qualification in Process
The LTC7805 is a high performance dual step-down synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 3MHz. The LTC7805 operates from a wide 4.5V to 40V input supply range. Power loss and supply noise are minimized by operating the two controller output stages out-of-phase.
The very low no-load quiescent current extends operating runtime in battery powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC7805 features a precision 0.8V reference and power good output indicators. The MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.
The LTC7805 additionally features spread spectrum operation which significantly reduces the peak radiated and conducted noise on both the input and output supplies, making it easier to comply with electromagnetic interference (EMI) standards.
- Automotive and Transportation
- Military / Avionics
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)
Demonstration circuit 3138A is a dual output step-down DC/DC converter that operates over a 12V to 36V input voltage range. It provides two outputs of 5V at 15A and 12V at 10A, and features the LTC7805 dual output synchronous step-down controller.
Key features of this board include:
- FREQUENCY jumper for spread spectrum or external clock
- EXTVCC jumper to use VOUT2, EXTVCC, or other derived VCC
- MODE jumper that allows the converter to run in FCM, pulse-skipping, or Burst Mode® operation
- PGOOD signals for each output
The two channels can be paralleled for higher output current. See the data sheet for more information on setting up the board for paralleling the two outputs.
The LTC7805 data sheet gives a complete description of the device, its operation and application information. The data sheet must be read in conjunction with the demo manual prior to working on or modifying demo circuit 3138A.
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.
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.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
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.
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.