DESCRIPTION
●The LTC® 1986 is a micropower charge pump DC/DC converter that provides power for either 3V or 5V GSM SIM cards. It operates in one of three modes: VOUT= 5V (5V mode), V
●OUT= VIN (3V mode) or shutdown. The input voltage range is 2.6V to 4.4V and the part can provide 10mA of output current. The LTC1986 allows VINto drop as low as 2.6V by providing a boost feature in 3V mode. In 3V mode, VOUTis connected directly to VINthrough a 2.5Ω
●switch until VINdrops below 2.85V. When VINis below 2.85V, the part automatically boosts VOUT to maintain a regulated 2.9V output, thereby ensuring VOUT stays within
●the 3V SIM VCC specification.
●FEATURES
●■ VINRange: 2.6V to 4.4V
●■ Step-Up Charge Pump Generates 5V
●■ Output Current: 10mA
●■ VINto VOUTDirect Connection for 3V SIMs
●■ Ultralow Power Operating Current: 14µA Shutdown Current: <1µA
●■ No Inductors
●■ Short-Circuit/Thermal Protected
●■ Switching Frequency: 900kHz
●■ Soft-Start Limits Inrush Current at Turn-On
●■ Output Driven to Ground During Shutdown
●■ Ultrasmall Application Circuit (< 0.045in2)
●■ 6-Lead SOT-23 Package
●APPLICATIONS
●■ GSM Cellular Telephones
●■ PCS/DCS Cellular Telephones
●■ Portable POS Terminals
●U
