Single Cell Micropower 600kHz PWM DC/DC Converters

The LT1307/LT1307B are micropower, fixed frequency DC/DC converters that operate from an input voltage as low as 1V. First in the industry to achieve true current mode PWM performance from a single cell supply, the LT1307 features automatic shifting to power saving Burst Mode operation at light loads. High efficiency is maintained over a broad 100uA to 100mA load range. The LT1307B does not shift into Burst Mode operation at light loads, eliminating low frequency output ripple at the expense of light load efficiency. The devices contain a low-battery detector with a 200mV reference and shut down to less than 5µA. No load quiescent current of the LT1307 is 50µA and the internal NPN power switch handles a 500mA current with a voltage drop of just 295mV.

Unlike competitive devices, large electrolytic capacitors are not required with the LT1307/LT1307B in single cell applications. The high frequency (600kHz) switching allows the use of tiny surface mount multilayer ceramic (MLC) capacitors along with small surface mount inductors. The devices work with just 10µF of output capacitance and require only 1µF of input bypassing.

The LT1307/LT1307B are available in 8-lead MSOP, PDIP and SO packages.

Applications

* Pagers

* Cordless Telephones

* GPS Receivers

* Battery Backup

* Portable Electronic Equipment

* Glucose Meters

* Diagnostic Medical Instrumentation

* Uses Small Ceramic Capacitors

* 50µA Quiescent Current (LT1307)

* 1mA Quiescent Current (LT1307B)

* Operates with VIN as Low as 1V

* 600kHz Fixed Frequency Operation

* Starts into Full Load

* Low Shutdown Current: 3µA

* Low-Battery Detector

* 3.3V at 75mA from a Single Cell

* Automatic Burst Mode® Operation at Light Load (LT1307)

* Continuous Switching at Light Load (LT1307B)

* Low VCESAT Switch: 295mV at 500mA