LTC1555 - SIM Power Supplyand Level Translator


  • Step-Up/Step-Down Charge Pump Generates 5V
  • Input Voltage Range: 2.7V to 10V
  • Output Current: 10mA (VIN >/= 2.7V) 20mA (VIN >/=3V)
  • 3V to 5V Signal Level Translators
  • >10kV ESD on All SIM Contact Pins
  • Short-Circuit and Overtemperature Protected
  • Very Low Operating Current: 60µA
  • Very Low Shutdown Current: <1µA
  • Soft Start Limits Inrush Current at Turn-On
  • Programmable 3V or 5V Output Voltage
  • 650kHz Switching Frequency
  • Auxiliary 4.3V LDO/Power Switch (LTC1556 Only)
  • Available in a 16- and 20-Pin Narrow SSOP

Typical Application

LTC1555 Typical Application


The LTC1555/LTC1556 provide power conversion and level shifting needed for 3V GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). These parts contain a charge pump DC/DC converter that delivers a regulated 5V to the SIM card. Input voltage may range from 2.7V to 10V, allowing direct connection to the battery. Output voltage may be programmed to 3V, 5V or direct connection to the VIN pin.

A soft start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low power DC/DC converter. The LTC1556 also includes an auxiliary LDO regulator/power switch that may be used to power the frequency synthesizer or other low power circuitry.

Battery life is maximized by 60µA operating current and 1µA shutdown current. Board area is minimized by miniature 16- and 20-pin narrow SSOP packages and the need for only three small external capacitors.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC1555CGN#PBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LTC1555CGN#TRPBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LTC1555IGN#PBF SSOP-16 GN I 05-08-1641 (GN16) Yes
LTC1555IGN#TRPBF SSOP-16 GN I 05-08-1641 (GN16) Yes

LTC1555 Package Drawing
LTC1555 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC1555CGN#PBF SSOP-16 C $3.60 $2.85 Yes
LTC1555CGN#TRPBF SSOP-16 C $2.91 Yes
LTC1555IGN#PBF SSOP-16 I $4.30 $3.45 Yes
LTC1555IGN#TRPBF SSOP-16 I $3.51 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Click here to view our complete list of demo boards


  • SIM Interface in GSM Cellular Telephones
  • Smart Card Readers

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