LTC3643 - 2A Bidirectional Power Backup Supply

Features

  • Bidirectional Synchronous Boost Capacitor Charger/Buck Regulator for System Backup
  • Wide Input Voltage Range: 3V to 17V
  • Up to 40V Capacitor Voltage Storage for High Energy Backup
  • 2A Maximum CAP Charge Current
  • Integrated Power N-Channel MOSFETs (150mΩ Top and 75mΩ Bottom)
  • Integrated Power N-Channel MOSFET for Output/CAP Disconnect (50mΩ)
  • Input Current Limit During Charging
  • Fast 1MHz Switching Frequency
  • ±1% Reference Accuracy for System Voltage Regulation
  • Indicator Outputs for Charge Status and Input Power Fail
  • Low Profile 24-lead 3mm × 5mm QFN Package

Typical Application

LTC3643 Typical Application
LTC3643 Typical Application

Description

The LTC®3643 is a bidirectional synchronous step-up charger and step-down converter which efficiently charges a capacitor array up to 40V from an input supply between 3V to 17V. When the input supply falls below the programmable power-fail threshold, the step-up charger operates in reverse as a synchronous step-down regulator to power the system rail from the backup capacitor during this power interuption/failure condition.

When charging the backup capacitor, an external low-value sense resistor may be used to maintain an accurate current limit from the input supply or implement PowerPath™ functionality.

The step-down converter operates at a 1MHz switching frequency, allowing small external components to be used. Low quiescent current during regulation maximizes the energy usage from the backup capacitor.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprint compatible with Mentor Graphics PADS® v9.5 or later, and Cadence ORCAD® v16.5 or later.

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

Part Number Package Code Temp Package
Drawing
RoHS
LTC3643EUDD#PBF 3x5 QFN-24 UDD E 05-08-1833 Yes
LTC3643EUDD#TRPBF 3x5 QFN-24 UDD E 05-08-1833 Yes
LTC3643IUDD#PBF 3x5 QFN-24 UDD I 05-08-1833 Yes
LTC3643IUDD#TRPBF 3x5 QFN-24 UDD I 05-08-1833 Yes


LTC3643 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
LTC3643EUDD#PBF 3x5 QFN-24 E $6.36 $4.45 Yes
LTC3643EUDD#TRPBF 3x5 QFN-24 E $4.51 Yes
LTC3643IUDD#PBF 3x5 QFN-24 I $7.14 $5.00 Yes
LTC3643IUDD#TRPBF 3x5 QFN-24 I $5.06 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
DC2220A LTC3643 Demo Board | 2A, Bidirectional 40V Boost Charger/Buck Back-Up Power Regulator, 3V ≤ VIN ≤ 17V (Boost), Vout = 5V @ 2A/3A/4A (Buck) $200.00
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Click here to view our complete list of demo boards

Applications

  • Backup Capacitor Systems
  • Power Failure Backup Systems
  • Solid-State Drives

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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

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