LTC7821

RECOMMENDED FOR NEW DESIGNS

Hybrid Step-Down Synchronous Controller

Data Sheet (Rev. B) Product Selection Table
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Overview

  • Wide VIN Range: 10V to 72V (80V ABS Max)
  • Soft Switching for Low Noise Operation
  • Phase-Lockable Fixed Frequency 200kHz to 1.5MHz
  • ±1% Output Voltage Accuracy
  • RSENSE or DCR Current Sensing
  • Programmable CCM, DCM, or Burst Mode® Operation
  • CLKOUT Pin for Multiphase Operation
  • Short Circuit Protected
  • EXTVCC Input for Improved Efficiency
  • Monotonic Output Voltage Start-Up
  • Optional External Reference
  • 32-Pin (5mm × 5mm) QFN
LTC7821
Hybrid Step-Down Synchronous Controller
LTC7821 Application Circuit LTC7821 Pin Configuration LTC7821 Performance Graph EDN HOT 100
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Documentation

Data Sheet 1

User Guide 3

Design Note 1

Technical Articles 3

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Hot Swap Controllers 1
LTC4260
RECOMMENDED FOR NEW DESIGNS Positive High Voltage Hot Swap Controller with I2C Compatible Monitoring
Power System Management (PSM) & Sequencers 1
LTC2975
RECOMMENDED FOR NEW DESIGNS 4-Channel PMBus Power System Manager Featuring Accurate Input Current and Energy Measurement
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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC7821
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.

Evaluation Kits

eval board
schematic 1
schematic 2
schematic 3
DC2513B

LTC7821 Demo Board | 12V, 20A Hybrid Step-Down Synchronous Converter

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Product Details

Demonstration circuit 2513B is a high efficiency, high power density hybrid converter. It can deliver 12V/20A with an input voltage from 36V to 72V. This demo board features the LTC7821, which uses an architecture that merges soft-switching switched-capacitor topology with a traditional step-down converter to provide superior efficiency compared to the traditional switching architectures. It offers a high efficiency/high density and cost effective solution for nonisolated intermediate bus applications in power distribution, datacom and telecom as well as emerging 48V automotive systems.

External MOSFETs switch at a 500kHz fixed frequency for this demo board and can be programmed from 200kHz to 1.5MHz. The LTC7821’s powerful 1Ω N-channel MOSFET gate drivers maximize efficiency and can drive multiple MOSFETs in parallel for higher power applications. Due to its current mode control architecture, multiple LTC7821s can be operated in a parallel, multiphase configuration with excellent current sharing and low output voltage ripple to enable much higher power applications. Other benefits include low EMI emissions due to a soft-switched front end and reduced MOSFET stress.

The LTC7821 design eliminates the inrush current typically associated with switched capacitor circuits by prebalancing the capacitors on start-up. The LTC7821 also monitors system voltage, current and temperature for faults, and uses a sense resistor for overcurrent protection. It stops switching and pulls the FAULT pin low when a fault condition occurs. An onboard timer can be set for appropriate restart/retry times.

Additional features include ±1% output voltage accuracy over temperature, a clock output for multiphase operation, a power good output signal, short-circuit protection, monotonic output voltage start-up, optional external reference, undervoltage lockout and internal charge balance circuitry.

The LTC7821 data sheet must be used in conjunction with this demo board manual.

eval board
schematic 4
schematic 5
schematic 6
DC2787A

LTC7821 Demo Board | 40V ≥ VIN ≥ 60V, VOUT = 12V @ 100A

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Product Details

Demonstration circuit 2787A is a high efficiency, 4 phase, hybrid converter. It can deliver 12V/100A with the input voltage from 40V to 60V. The demo board features the LTC7821, which uses an architecture that merges a soft-switching switched-capacitor topology with a traditional step-down converter to provide superior efficiency compared to the traditional switching architectures. It offers a high efficiency/high density and cost effective solution for nonisolated intermediate bus applications in power distribution, datacom and telecom as well as emerging 48V automotive systems. 

External MOSFETs switch at a 400kHz fixed frequency for this demo board and can be programmed from 200kHz to 1.5MHz. The LTC7821’s powerful 1Ω N-channel MOSFET gate drivers maximize efficiency and can drive multiple MOSFETs in parallel for higher power applications. Due to its current mode control architecture, multiple LTC7821 devices can be operated in a parallel, multiphase configuration with excellent current sharing and low output voltage ripple to enable much higher power applications. Other benefits include low EMI emissions due to a soft-switched front end and reduced MOSFET stress.

The LTC7821 design eliminates the inrush current typically associated with switched capacitor circuits by prebalancing the capacitors on start-up. The LTC7821 also monitors system voltage, current and temperature for faults, and uses a sense resistor for overcurrent protection. It stops switching and pulls the FAULT pin low when a fault condition occurs. An onboard timer can be set for appropriate restart/retry times. Additional features include ±1% output voltage accuracy over temperature, a clock output for multiphase operation, a power good output signal, short-circuit protection, monotonic output voltage start-up, optional external reference, undervoltage lockout and internal charge balance circuitry. The LTC7821 data sheet must be used in conjunction with this demo board manual.

eval board
schematic 7
DC2513A

OBSOLETE: LTC7821EUH Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V at 20A, 97.5% Efficiency/500kHz

Buy Now View Details

Product Details

This evaluation board is obsolete and no longer recommended.  The replacement board is the DC2513B.

Demonstration circuit 2513A is a high efficiency, high power density hybrid converter. It can deliver 12V/20A with an input voltage from 36V to 72V. This demo board features the LTC7821, which uses an architecture that merges soft-switching switched-capacitor topology with a traditional step-down converter to provide superior efficiency compared to the traditional switching architectures. It offers a high efficiency/high density and cost effective solution for non isolated intermediate bus applications in power distribution, datacom and telecom as well as emerging 48V automotive systems.
DC2513B
LTC7821 Demo Board | 12V, 20A Hybrid Step-Down Synchronous Converter
DC2513B Evaluation Board DC2513B Evaluation Board DC2513B Diagram
DC2787A
LTC7821 Demo Board | 40V ≥ VIN ≥ 60V, VOUT = 12V @ 100A
DC2787A Evaluation Board DC2787A Evaluation Board - Top View DC2787A Evaluation Board - Bottom View
DC2513A
OBSOLETE: LTC7821EUH Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V at 20A, 97.5% Efficiency/500kHz
DC2513A

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