LTC4123 Low Power Wireless Charger for Hearing Aids FeaTuresDescripTion n Complete Low Power Wireless NiMH Charger The LTC®4123 is a low power wireless receiver and a n Low Minimum Input Voltage: 2.2V constant-current/constant-voltage linear charger for NiMH n Small Total Solution Volume batteries. An external programming resistor sets the charge n 1.5V, 25mA Linear Single-Cell NiMH Charger current up to 25mA. The temperature compensated charge n Temperature Compensated Charge Voltage voltage feature protects the NiMH battery and prevents n Integrated Rectifier with Overvoltage Limit overcharging. n Zinc-Air Battery Detection Wireless charging with the LTC4123 allows products to n Reverse Polarity Protection be charged while sealed within enclosures and eliminates n Thermally Enhanced 6-Lead (2mm × 2mm) bulky connectors in space constrained environments. The DFN package LTC4123 also makes it possible to charge NiMH batteries used in moving or rotating equipment. applicaTions The LTC4123 prevents charging of Zinc-Air batteries as well as batteries inserted with reverse polarity. The LTC4123 n Hearing Aids pauses charging if its temperature is too hot or too cold. n Smart Cards An internal timer provides time-based charging termination. n Fitness Devices n Moving and/or Rotating Equipment The 2mm × 2mm DFN package and low external compo- nent count make the LTC4123 well-suited for hearing aid applications or other low power portable devices where small solution size is mandatory. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical applicaTion25mA NiMH Wireless Battery ChargerComplete Wireless Charging Solution for a Hearing Aid AIR GAP T ACIN x COIL ICHARGE = 25mA MAX L TRANSMITTER RX BAT 13µH CIRCUIT VCC V + IN LED LTC4123 – CRX 1.5V 33nF + NiMH CHRG BATTERY CIN GND PROG 4.7µF RPROG 953Ω 4123 TA01 4123fa For more information www.linear.com/LTC4123 1
