3V to 5V Regulating Charge Pumps for SIM Cards

The MAX1686 provides power for dual-voltage subscriber ID module (SIM) cards in portable applications such as GSM cellular phones. Designed to reside in the portable unit (cellular phone handset), the 1MHz charge pump converts a 2.7V to 4.2V input to regulated 5V output. The MAX1686H has a nominal output voltage of 5.0V, while the MAX1686 is set to 4.75V to reduce SIM card current drain. The charge pump has only 45µA quiescent supply current, which reduces to 3µA when a 3V-capable SIM card is being powered and the charge pump is disabled. An internal input/output shorting switch provides power for 3V SIM cards.

The MAX1686/MAX1686H require only three external capacitors around their space-saving, thin (1mm) 8-pin µMAX® packages.

Applications

* GSM Cellular Phones * PCS Phones * Personal Communicators * Portable POS Terminals

* 2.7V to 4.2V Input Range

* 12mA min Charge-Pump Output Current

* 45µA Quiescent Supply Current

* 0.1µA Supply Current in Shutdown Mode

* 5.0V Regulated Charge-Pump Output (MAX1686H)

* 4.75V Regulated Charge-Pump Output (MAX1686)

* Input-Output Shorting Switch for 3V Cards

* Small External Components (Uses a 0.047µF, 0.1µF, and a 2.2µF Capacitor)

* Output Driven to Ground in Shutdown Mode

* Super-Small 8-Pin µMAX Package

* Soft-Start and Short-Circuit Protection

* Regulated charge pump for SIM cards nominal output voltage of 5.0V (MAX1686H)