Low Input Voltage Current Mode Step-Down DC/DC Controller

The LTC1622 is a constant frequency current mode step-down DC/DC controller providing excellent AC and DC load and line regulation. The device incorporates an accurate undervoltage feature that shuts the LTC1622 down when the input voltage falls below 2V.

The LTC1622 boasts a ±1.9% output voltage accuracy and consumes only 350µA of quiescent current. For applications where efficiency is a prime consideration and the load current varies from light to heavy, the LTC1622 can be configured for Burst Mode™ operation. Burst Mode operation enhances low current efficiency and extends battery run time. Burst Mode operation is inhibited during synchronization or when the SYNC/MODE pin is pulled low to reduce noise and possible RF interference.

High constant operating frequency of 550kHz allows the use of a small inductor. The device can also be synchronized up to 750kHz for special applications. The high frequency operation and the available 8-lead MSOP package create a high performance solution in an extremely small amount of PCB area.

To further maximize the life of the battery source, the P-channel MOSFET is turned on continuously in dropout (100% duty cycle). In shutdown, the device draws a mere 15µA.

Applications

* 1- or 2-Cell Li-Ion Powered Applications

* Cellular Telephones

* Wireless Modems

* Portable Computers

* Distributed 3.3V, 2.5V or 1.8V Power Systems

* Scanners

* Battery-Powered Equipment

* High Efficiency

* Constant Frequency 550kHz Operation

* VIN Range: 2V to 10V

* Multiampere Output Currents

* OPTI-LOOP™ Compensation Minimizes COUT

* Selectable, Burst Mode Operation

* Low Dropout Operation: 100% Duty Cycle

* Synchronizable up to 750kHz

* Current Mode Operation for Excellent Line and Load Transient Response

* Low Quiescent Current: 350µA

* Shutdown Mode Draws Only 15µA Supply Current

* ±1.9% Reference Accuracy

* Available in 8-Lead MSOP