Power Management Supercapacitor Chargers

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LTC4425 - Linear SuperCap Charger with Current-Limited Ideal Diode and V/I Monitor

Features

  • 50mΩ Ideal Diode from VIN to VOUT
  • Smart Charge Current Profile Limits Inrush Current
  • Internal Cell Balancer (No External Resistors)
  • Programmable Output Voltage (LDO Mode)
  • Programmable VIN to VOUT Current Limit
  • Continuous Monitoring of VIN to VOUT Current via PROG Pin
  • Low Quiescent Current: 20μA
  • VIN Power Fail, PGOOD Indicator
  • 2.45V/2.7V Cell Protection Shunts
    (4.9V/5.4V SuperCap Max Top-Off Voltage)
  • 3A Peak Current Limit, Thermal Limiting
  • Tiny Application Circuit, 3mm × 3mm × 0.75mm DFN and 12-Lead MSOP Packages

Typical Application

LTC4425 Typical Application
LTC4425 Typical Application

Description

The LTC4425 is a constant-current/constant-voltage linear charger designed to charge a 2-cell supercap stack from either a Li-Ion/Polymer battery, a USB port, or a 2.7V to 5.5V current-limited supply. The part operates as an ideal diode with an extremely low 50mΩ on-resistance making it suitable for high peak-power/low average power applications. The LTC4425 charges the output capacitors to an externally programmed output voltage in LDO mode at a constant charge current, or to VIN in normal mode with a smart charge current profile to limit the inrush current until the VIN to VOUT differential is less than 250mV. In addition the LTC4425 can be set to clamp the output voltage to 4.9V or 5.4V.

Charge current (VOUT current limit) is programmed by connecting a resistor between PROG and GND. The voltage on the PROG pin represents the current fl owing from VIN to VOUT for current monitoring. An internal active balancing circuit maintains equal voltages across each supercapacitor and clamps the peak voltage across each cell to a pin-selectable maximum value. The LTC4425 operates at a very low 20μA quiescent current (shutdown current <3μA) and is available in a low profile 12-pin 3mm × 3mm DFN or a 12-lead MSOP package.

Packaging

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

DFN-12, MS-12

LTC4425 Package Drawing
LTC4425 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC4425EDD#PBF DFN 12 E $3.22 $2.25 View
LTC4425EDD#TRPBF DFN 12 E $2.31 View
LTC4425EMSE#PBF MSOP 12 E $3.36 $2.35 View
LTC4425EMSE#TRPBF MSOP 12 E $2.41 View
LTC4425IDD#PBF DFN 12 I $3.71 $2.60 View
LTC4425IDD#TRPBF DFN 12 I $2.66 View
LTC4425IMSE#PBF MSOP 12 I $3.86 $2.70 View
LTC4425IMSE#TRPBF MSOP 12 I $2.76 View
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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 demo boards are offered free of charge to qualified customers. Contact your local sales office or distributor to request 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
DC1589A LTC4425EDD Demo Board | Linear SuperCap Charger with Current-Limited Ideal Diode and V/I Monitor $100.00
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Click here to view our complete list of demo boards

Applications

  • High Peak Power Battery/USB Powered Equipment
  • Industrial PDAs
  • Portable Instruments/Monitoring Equipment
  • Power Meters, SuperCap Backup Circuits
  • PC Card/USB Modems

Simulate

LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.

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