Step-up DC/DC converters suit mobile applications

All series are able to start operation from VIN as low as 0.9V and as high as 5.5V, making them suitable for mobile equipment using a single Alkaline or Nickel metal hydride battery.

However, after the start-up procedure has completed, it is worth noting that these series will carry on operating for input voltages decreasing down to 0.65V, or down to the UVLO (Under Voltage Lock Out) detect value for the XC9135 series.

The output voltage is selectable between 1.8 and 5.0V.

In the case of the XC9135/36 series, this output voltage is set internally and is available in 0.1V increments, whereas the XC9131 series offers the flexibility to adjust the output voltage externally with two resistors.

Like all step-up DC/DCs, the output current that the XC9131 and XC9135/36 series can supply will depend on the (VIN, VOUT) conditions.

For example, up to 500mA of output current can be supplied with VIN=1.8V and VOUT=3.3V.

Both the XC9131 and the XC9135/36 series feature 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.

All series are available with a CL discharge function that quickly discharges the output capacitor when the IC is turned off.

The protection circuits common to the XC9131 and XC9135/36 series comprise a thermal-shutdown circuit and a current-limiting circuit.

In addition to that, it is possible to select the XC9135 with an output voltage drop protection function.

On its input side the XC9135 series includes a UVLO function that reduces the leaking of potassium hydroxide by stopping IC operation when the battery voltage drops below a selectable threshold.

The XC9131 and XC9135/36 series are available in a small 2.9 x 2.6mm USP-10B package.