Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing
Features and Benefits
- Operates with Power Blocks, DrMOS or External Gate Drivers and MOSFETs
- Voltage Mode Control with Accurate Current Sharing
- ±0.75% 0.6V Voltage Reference
- Quad Differential Output Voltage Sense Amplifiers
- Multiphase Capability
- Phase-Lockable Fixed Frequency 250kHz to 2.25MHz
- Lossless Current Sensing Using Inductor DCR or Precision Current Sensing with Sense Resistor or DrMOS with Integrated Current Sensing
- VCC Range: 3V to 5.5V
- VOUT Range: 0.6V to VCC – 0.5V
- Power Good Output Voltage Monitor
- Output Voltage Tracking Capability with Soft-Start
- Available in 58-Lead 5mm × 9mm QFN Package
The LTC7851/LTC7851-1 are quad output multiphase synchronous step-down switching regulator controllers that employ a constant frequency voltage mode architecture. They maintain excellent current balance between channels when paralleled with their internal current sharing loop. Lossless DCR or a low value RSENSE is used for output current sensing. Multiple LTC7851/LTC7851-1 devices can be used for high phase count operation.
A very low offset, high bandwidth error amplifier, combined with remote output voltage sensing, provides excellent transient response and output regulation. The LTC7851/ LTC7851-1 operates with a VCC supply voltage from 3V to 5.5V and is designed for step-down conversion with VIN from 3V to 27V and produces an output voltage from 0.6V to VCC – 0.5V.
The LTC7851-1 is identical to the LTC7851 except it has a lower current sense amplifier gain, making it ideal for DrMOS devices with internal current sense.
- High Current Distributed Power Systems
- DSP, FPGA and ASIC Supplies
- Datacom, Telecom and Computing Systems
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 (3)
Demonstration circuit DC2380A features the LTC7851, a high performance 4-phase step-down, voltage mode controller. The DC2380A-B operates with a 7V to 14V input supply voltage and provides the follow two high current outputs: 1.8V @ 60A and 1.2V @ 60A. The LTC7851’s integrated current share circuit provides highly accurate current sharing. Since the LTC7851 does not include MOSFET drivers, its PWM outputs drive external DrMOS devices.
Demonstration circuit DC2380A features the LTC7851, a high performance 4-phase step-down, voltage mode controller. The DC2380A-A operates with a 7V to 14V input supply voltage and provides the follow four high current outputs: 1.8V @ 30A, 1.5V @ 30A, 1.2V @ 30A and 1.0V @ 30A. Since the LTC7851 does not include MOSFET drivers, its PWM outputs drive external DrMOS devices.
Demonstration circuit DC2380A features the LTC7851, a high performance 4-phase step-down, voltage mode controller. The DC2380A-C operates with a 7V to 14V input supply voltage and provides a single 1.2V @ 120A output. The LTC7851’s integrated current share circuit provides highly accurate current sharing. Since the LTC7851 does not include MOSFET drivers, its PWM outputs drive external DrMOS devices.
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.
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.
Design tools for the following parts are available in LTpowerCAD:
Solutions Bulletins & Brochures (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.