LTC7851 - Quad Output, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing

Features

  • 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

Typical Application

LTC7851 Typical Application

Description

The LTC®7851/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.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC7851EUHH-1#PBF 5x9 QFN-58 UHH E 05-08-1672 Yes
LTC7851EUHH-1#TRPBF 5x9 QFN-58 UHH E 05-08-1672 Yes
LTC7851EUHH#PBF 5x9 QFN-58 UHH E 05-08-1672 Yes
LTC7851EUHH#TRPBF 5x9 QFN-58 UHH E 05-08-1672 Yes
LTC7851IUHH-1#PBF 5x9 QFN-58 UHH I 05-08-1672 Yes
LTC7851IUHH-1#TRPBF 5x9 QFN-58 UHH I 05-08-1672 Yes
LTC7851IUHH#PBF 5x9 QFN-58 UHH I 05-08-1672 Yes
LTC7851IUHH#TRPBF 5x9 QFN-58 UHH I 05-08-1672 Yes


LTC7851 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC7851EUHH-1#PBF 5x9 QFN-58 E $6.10 $4.27 Yes
LTC7851EUHH-1#TRPBF 5x9 QFN-58 E $6.16 $4.33 Yes
LTC7851EUHH#PBF 5x9 QFN-58 E $6.10 $4.27 Yes
LTC7851EUHH#TRPBF 5x9 QFN-58 E $6.16 $4.33 Yes
LTC7851IUHH-1#PBF 5x9 QFN-58 I $6.97 $4.88 Yes
LTC7851IUHH-1#TRPBF 5x9 QFN-58 I $7.03 $4.94 Yes
LTC7851IUHH#PBF 5x9 QFN-58 I $6.97 $4.88 Yes
LTC7851IUHH#TRPBF 5x9 QFN-58 I $7.03 $4.94 Yes
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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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2380A-A LTC7851EUHH Demo Board | 4-Phase Voltage Mode Buck Controller, 7V ≤ VIN ≤ 14V; Vout1 = 1.8V @ 30A, Vout2 = 1.5V @ 30A, Vout3 = 1.2V @ 30A, Vout4 = 1V @ 30A $250.00
DC2380A-B LTC7851EUHH Demo Board | Dual Output, 4-Phase Voltage Mode Buck Controller, 7V ≤ VIN ≤ 14V; Vout1 = 1.8V @ 60A, Vout3 = 1.2V @ 60A $300.00
DC2380A-C LTC7851EUHH Demo Board | Single Output, 4-Phase Voltage Mode Buck Controller, 7V ≤ VIN ≤ 14V; Vout1 = 1.2V @ 120A $400.00
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Click here to view our complete list of demo boards

Applications

  • High Current Distributed Power Systems
  • DSP, FPGA and ASIC Supplies
  • Datacom, Telecom and Computing Systems

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Design Tools

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LTC7851
LTC7851 Parallel
LTC7851-1
LTC7851-1 Parallel

Technical Support