Features and Benefits
- 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
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.
- High Peak Power Battery/USB Powered Equipment
- Industrial PDAs
- Portable Instruments/Monitoring Equipment
- Power Meters, SuperCap Backup Circuits
- PC Card/USB Modems
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.