LTC1556IGN#PBF

Translators, Level Shifters Overview

The LTC1556IGN#PBF is a SIM power supply and level translator in a 16-lead narrow SSOP package. It features a step-up/step-down charge pump DC/DC converter with an input voltage range of 2.7V to 10V, delivering up to 20mA at VCC when VIN ≥ 3V. The device provides 3V or 5V programmable output levels for SIM interfacing. An auxiliary 4.3V LDO regulator is included for powering external circuitry like frequency synthesizers. Operating current is 60μA, with shutdown current below 1μA.

Translators, Level Shifters Feature Summary

• Integrated step-up/step-down charge pump generates regulated 5V or 3V output for SIM cards
• Includes level translators for bidirectional data transfer between controller and SIM
• Auxiliary 4.3V LDO regulator available on the LTC1556 variant for low-power peripherals
• Features soft start capability to limit inrush current during turn-on

Translators, Level Shifters Applications

• GSM cellular telephone SIM interface
• Smart card readers
• Low-power embedded systems requiring SIM communication

Translators, Level Shifters Procurement Notes

Verify the specific suffix IGN#PBF corresponds to the industrial temperature grade (-40°C to 85°C) and lead-free packaging. Confirm that the 16-lead narrow SSOP package matches your PCB footprint requirements. Ensure the design accounts for the auxiliary LDO functionality unique to the LTC1556 model compared to the LTC1555.

Translators, Level Shifters Selection Notes

Select this component when interfacing 3V controllers with 3V or 5V SIMs. The LTC1556 is preferred over the LTC1555 if an auxiliary power source for a frequency synthesizer or similar low-power load is required. Consider the 60μA operating current for battery life optimization. Ensure the input voltage range of 2.7V to 10V aligns with the system battery specifications.

Translators, Level Shifters Part Context

This part belongs to the LTC1555/LTC1556 family of SIM power supplies. It is designed specifically for GSM applications where a 3V microcontroller must communicate with a SIM card. The family includes variants with different pin counts and auxiliary features, such as the LTC1555 which lacks the LDO found in the LTC1556.

Translators, Level Shifters Replacement Considerations

LTC1555IGN#PBF (lacks auxiliary LDO)

Translators, Level Shifters FAQ

What is the function of the EN and FB pins on the LTC1556?

The EN pin enables the auxiliary LDO output, and the FB pin sets the feedback for the LDO. Connecting FB to the LDO pin regulates the output to 4.3V.

How does the soft start feature work?

Tying the SS pin to GND enables soft start, limiting inrush current to approximately 25mA. Tying it to DVCC disables soft start for faster turn-on.