Micropower Step-Down Regulator Has On-Chip Watchdog Timer

The LT3689 is a 700-mA, 36-V input step-down switching regulator with a power-on reset and watchdog timer. Its Burst Mode operation keeps quiescent current under 85 µA in no-load standby conditions. The regulator’s 3.6-V to 36-V input voltage range, with 60-V transient ride-through, makes it suitable for load-dump and cold-crank conditions commonly found in automotive applications. Its 1.2-A internal switch can deliver up to 700 mA of continuous output current at voltages as low as 0.8 V. The device’s Burst Mode operation provides ultra-low quiescent current, well suited for applications such as automotive or telecom systems, which demand always-on operation and optimum battery life. Switching frequency is user-programmable from 350 kHz to 2.2 MHz, enabling the designer to optimize efficiency while avoiding critical noise-sensitive frequency bands. The LT3689’s 3-mm x 3-mm QFN-14 (or thermally enhanced MSOP-16) package and high switching frequency keeps external inductors and capacitors small. The LT3689EUD and LT3689EMSE start at $3.20 and $3.25 each, respectively. The LT3689IUD and LT3689IMSE withstand a -40ºC to 125ºC operating junction temperature and cost $3.56 and $3.61 each, respectively. Finally, the LT3689HMSE withstand a -40ºC to 150ºC operating junction temperature and costs $3.86 each. All versions are available from stock and all prices are in lots of 1000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900.