Torex launches a single cell step-up synchronous PFM DC/DC converter

Integrating a 0.6O N-ch driver transistor and a 0.8O synchronous P-ch switching transistor the XC9140 from Torex Semiconductor has been designed to offer high levels of efficiency and performance for battery powered applications. The IC is designed to allow the use of ceramic capacitors and achieves a very low supply current due to the combination of PFM control and CMOS structure. The 1.2MHz nominal switching frequency, makes it possible to use a small multilayer coil and together with two ceramic capacitors the PCB mounting area is approximately 74% smaller than that of the previous product.

Able to start operation from Input Voltages as low as 0.9V the XC9140 is suitable for use with single alkaline or nickel metal hydride cells. Like all step-up DC/DCs, the output current that the XC9140 can supply will depend on the (VIN, VOUT) conditions, but up to 100mA of output current can be supplied with VIN=1.8V and VOUT=3.3V and with a VIN=0.9V, more than 50mA is possible.

The output voltage is set internally between 1.8V~5.0V (±2%) in 0.1V increments and with a quiescent current of only 6.3µA (typ), reducing to 0.1µA (typ) during standby, the XC9140 helps to further maximise battery life in portable applications.

The XC9140 series also features a soft-start circuit, an enable pin to turn the IC on and off, and a load disconnect function that prevents the battery charge from leaking to the output while the IC is not operating (XC9140A). An optional CL discharge function can quickly discharge the output capacitor when the IC is turned off and an Input by-pass mode function type is also available to keep the connection between the input and output side during shutdown (XC9140C).

An optional UVLO function can also be used to reduce the leakage of potassium hydroxide from small batteries by stopping IC operation while battery voltage is declining. The standard release voltage of UVLO is 2.15V (±3.0%) and selectable voltages range from 1.65V~2.2V.

The XC9140 is available in the USP-6EL package for applications that require both a small form factor or in the industry standard SOT-25 package.


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