LTC3838

RECOMMENDED FOR NEW DESIGNS

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

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Overview

  • Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
  • ±0.67% Output Voltage Accuracy Over Temperature, Differential Output Voltage Sensing, Allowing Up to ±500mV Line Loss at Remote Ground on Channel 1
  • ±1% Output on the Independent 2nd Channel
  • Controlled On-Time, Valley Current Mode Control
  • Fast Load Transient Response
  • Detect Transient (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 and TSSOP packages

The LTC3838 is a dual, 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 fast transient response and constant frequency switching in steady-state operation, independent of VIN, VOUT and load current. Its load-release transient detection feature significantly reduces overshoot at low output voltages.

Differential output voltage sensing, along with a precision internal reference, offers an accurate ±0.67% output regulation on Channel 1, even if the remote output ground deviates from local ground by ±500mV. The second channel can either provide an independent ±1% output, or together with the first channel of this controller, serve as one of the PolyPhase channels for a single-output voltage.

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 below for a comparison of LTC3838, LTC3838-1 and LTC3838-2.

Part Number Description
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

Applications

  • Distributed Power Systems
  • Point-of-Load Converters
  • Computing Systems
  • Data Communication Systems
LTC3838
Dual, Fast, Accurate Step- Down DC/DC Controller with Differential Output Sensing
1.2V/1.5V, 15A, 350kHz, DCR Sense, Step-Down Converter (Refer to Figure 16 for Full Design) Efficiency/Power Loss Product Package 1 Product Package 2
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 2

Application Note 2

Design Note 1

Technical Articles 3

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Circuit Monitors 1
LTC2960
RECOMMENDED FOR NEW DESIGNS 36V Nano-Current Two-Input Voltage Monitor
Power System Management (PSM) & Sequencers 1
LTC2974
RECOMMENDED FOR NEW DESIGNS 4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
Protection Switches & Controllers 1
LT4363
RECOMMENDED FOR NEW DESIGNS High Voltage Surge Stopper with Current Limit
Switching Regulators & Controllers 1
LTC3880
RECOMMENDED FOR NEW DESIGNS Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
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Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

  • LTC3838
  • LTC3838-1
  • LTC3838-2

LTpowerCAD 4

Design tools for the following parts are available in LTpowerCAD:

  • LTC3838
  • LTC3838DC1626A-ADCRSENSE
  • LTC3838DC1626A-BRSENSE
  • LTC3838DC1801A-BDEMOBOARDRSENSE
LTspice

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.

LTpowerCAD

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.

Evaluation Kits

eval board
schematic 1
schematic 2
schematic 3
schematic 4
schematic 5
DC1626A-B

LTC3838EFE Demo Board (RSENSE) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A

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Product Details

Demonstration circuit 1626A is a dual output 1.5V/15A and 1.2V/15A synchronous buck converter operating with a switching frequency of 300kHz over an input voltage range of 4.5V to 26V. The demo board comes in two versions. The -A version uses inductor DCR current sensing with an iron powder inductor for high efficiency. The -B version uses a 2.5mΩ sense resistor for accurate current sensing with a low DCR ferrite inductor.



eval board
schematic 6
DC1626A-A

LTC3838EFE Demo Board (DCR Sense) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A

Buy Now View Details

Product Details

Demonstration circuit 1626A is a dual output 1.5V/15A and 1.2V/15A synchronous buck converter operating with a switching frequency of 300kHz over an input voltage range of 4.5V to 26V. The demo board comes in two versions. The -A version uses inductor DCR current sensing with an iron powder inductor for high efficiency. The -B version uses a 2.5mΩ sense resistor for accurate current sensing with a low DCR ferrite inductor.



eval board
schematic 7
DC1801A-B

LTC3838EUHF Demo Board (RSENSE) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A

Buy Now View Details

Product Details

Demonstration circuit 1801A is a dual output 1.5V/20A and 1.2V/20A synchronous buck converter operating with a switching frequency of 300kHz over an input voltage range of 4.5V to 14V. The demo board comes in two versions. The A version uses inductor DCR current sensing for high efficiency. The B version uses 2mΩ sense resistor for accurate current sensing with a low DCR ferrite inductor. The fixed on-time valley current mode topology of the LTC3838 allows for a fast load step response.

eval board
schematic 8
DC1801A-A

LTC3838EUHF Demo Board (DCR Sense) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A

Buy Now View Details

Product Details

Demonstration circuit 1801A is a dual output 1.5V/20A and 1.2V/20A synchronous buck converter operating with a switching frequency of 300kHz over an input voltage range of 4.5V to 14V. The demo board comes in two versions. The A version uses inductor DCR current sensing for high efficiency. The B version uses 2mΩ sense resistor for accurate current sensing with a low DCR ferrite inductor. The fixed on-time valley current mode topology of the LTC3838 allows for a fast load step response.
DC1626A-B
LTC3838EFE Demo Board (RSENSE) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A
DC1626A-B Demo Board DC1626A-B Demo Board DC1626A-B Demo Board DC1626A-B Demo Board DC1626A-A - Schematic
DC1626A-A
LTC3838EFE Demo Board (DCR Sense) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A
DC1626A-A - Schematic
DC1801A-B
LTC3838EUHF Demo Board (RSENSE) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A
DC1801A-A - Schematic
DC1801A-A
LTC3838EUHF Demo Board (DCR Sense) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A
DC1801A-A - Schematic

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