LTC1556CGN

Translators, Level Shifters Overview

The LTC1556CGN is a power conversion and level translator IC designed for GSM cellular telephone SIM interfaces. It features a step-up/step-down charge pump DC/DC converter generating a regulated VCC output of 3V or 5V from an input voltage range of 2.7V to 10V. The device provides 3V to 5V signal level translators for controller-to-SIM communication. Key electrical parameters include a switching frequency of 650kHz, operating current of 60μA, and shutdown current under 1μA. An auxiliary 4.3V LDO/power switch is included exclusively on the LTC1556 variant.

Translators, Level Shifters Feature Summary

• Integrated step-up/step-down charge pump DC/DC converter for SIM power supply
• Bidirectional and unidirectional signal level translators between controller and SIM
• Auxiliary low-dropout regulator (LDO) and power switch for external circuitry
• Soft start capability to limit inrush current during turn-on

Translators, Level Shifters Applications

• GSM Cellular Telephone SIM Interface
• Smart Card Readers
• Low Power DC/DC Converter Systems

Translators, Level Shifters Procurement Notes

Verify the specific suffix 'CGN' corresponds to the commercial temperature range (0°C to 70°C). Confirm package type is 16-lead narrow SSOP. Ensure compatibility with system DVCC levels (1.8V to 5.5V) and required VCC output settings via M0/M1 pins. Check for RoHS compliance status if required by assembly specifications.

Translators, Level Shifters Selection Notes

Select the LTC1556 over the LTC1555 when an auxiliary power source is needed for components like frequency synthesizers. Evaluate the need for soft-start functionality based on the capabilities of the upstream VIN supply. Consider the 16-lead narrow SSOP package constraints for board space. Verify that the controller interface supports open-drain configurations if using bidirectional data transfer.

Translators, Level Shifters Part Context

The LTC1556 is part of the LTC1555/LTC1556 family of SIM interface controllers manufactured by Analog Devices (formerly Linear Technology). These devices are specifically engineered to bridge the gap between 3V microcontrollers and 3V/5V Subscriber Identity Modules. The CGN designation indicates the commercial grade version housed in a plastic SSOP package.

Translators, Level Shifters Replacement Considerations

LTC1555CGN: Identical function but lacks the auxiliary LDO/power switch found in the LTC1556.

Translators, Level Shifters FAQ

What is the purpose of the auxiliary LDO on the LTC1556?

The auxiliary LDO provides a regulated 4.3V output or acts as a low-resistance power switch to supply low-power external circuitry, such as frequency synthesizers, when VCC is set to 5V.

How is the VCC output voltage determined?

The VCC output voltage is programmed via the M0 and M1 mode control pins. Configuring these pins allows selection of 3V, 5V, or direct connection to the VIN pin.