LTC3838-1 - Dual, Fast, Accurate Step-Down DC/DC Controller with Dual Differential Output Sensing

Features

  • Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
  • Two Independent Channels: Dual/Single Output
  • Output Voltage Regulation Accuracy: ±0.67% (VOUT1) and ±0.75% (VOUT2) Over Temperature
  • Differential Remote Output Sensing: Up to ±500mV (VOUT1) and ±200mV (VOUT2) Ground Deviations
  • Controlled On-Time, Valley Current Mode Control
  • Fast Load Transient Response Without Clock Delay
  • Detect Transient Release (DTR) Reduces VOUT Overshoot
  • Frequency Programmable from 200kHz to 2MHz, Synchronizable to External Clock
  • tON(MIN) = 30ns, tOFF(MIN) = 90ns
  • RSENSE or Inductor DCR Current Sensing
  • Overvoltage Protection and Current Limit Foldback
  • Power Good Output Voltage Monitor
  • Output Voltage Tracking and Adjustable Soft Start-Up
  • Thermally Enhanced 38-Pin (5mm × 7mm) QFN Package

Typical Application

LTC3838-1 Typical Application
LTC3838-1 Typical Application

Description

The LTC®3838-1 is a dual-channel, PolyPhase® synchronous step-down DC/DC switching regulator controller. Two independent channels drive all N-channel power MOSFETs. The controlled on-time, valley current mode control architecture allows for not only fast response to transients without clock delay, but also constant frequency switching at steady load condition. Its proprietary loadrelease transient detection feature (DTR) significantly reduces overshoot at low output voltages.

A precision internal reference enables accurate differential output regulation. The dual channels can either provide two independent output voltages, or be combined into multiphase single-output configuration.

The switching frequency can be programmed from 200kHz to 2MHz with an external resistor and can be synchronized to an external clock. Very low tON and tOFF times allow for near 0% and near 100% duty cycles, respectively. Voltage tracking soft start-up and multiple safety features are provided.

See Table 1 for a comparison of LTC3838, LTC3838-1 and LTC3838-2.

Part NumberDescription
LTC3838 ±0.67% Differential Output Voltage Accuracy Over Temperature on Channel 1, ±1% Output Regulation on Channel 2, Separate Per Channel 30mV to 100mV Current Sense Range Controls
LTC3838-1 ±0.67% Differential Output Voltage Accuracy Over Temperature on Both Channel 1 and Channel 2, Single Pin 30mV/60mV Current Sense Range Controls
LTC3838-2 ±0.67% Differential Output Voltage Accuracy With Internal Reference on Channel 1, ±4mV Differential with External Reference Voltage on Channel 2, Fixed 30mV Current Sense Range

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
LTC3838EUHF-1#PBF 5x7 QFN-38 UHF E 05-08-1701 Yes
LTC3838EUHF-1#TRPBF 5x7 QFN-38 UHF E 05-08-1701 Yes
LTC3838IUHF-1#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC3838IUHF-1#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes


LTC3838-1 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
LTC3838EUHF-1#PBF 5x7 QFN-38 E $4.54 $3.18 Yes
LTC3838EUHF-1#TRPBF 5x7 QFN-38 E $3.24 Yes
LTC3838IUHF-1#PBF 5x7 QFN-38 I $5.13 $3.59 Yes
LTC3838IUHF-1#TRPBF 5x7 QFN-38 I $3.65 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
DC1997A-A LTC3838EUHF-1 Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT1 = 1.5V @ 20A, VOUT2 = 1.2V @ 20A $150.00
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Click here to view our complete list of demo boards

Applications

  • Distributed Power Systems; Power Supply for ASIC
  • Computing, Data Storage, Communication Systems
  • Low Voltage, High Current, and/or High Step-Down Ratio Converters That Demand Tight Load Transient Regulation

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LTC3838
LTC3838-1
LTC3838-2

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:
LTC3838
LTC3838 Parallel
LTC3838-1
LTC3838-2

Technical Support