30V, low power consumption step-down DC/DC Controller IC

Paul Boughton

Able to operate from inputs up to 30V, Torex’s new XC9252 is a step-down DC/DC controller IC designed specifically for applications that require high efficiency and low power consumption.

Power consumption is increasingly critical for many applications and the XC9252 requires only 30µA when operating in PFM mode under no load conditions.

To ensure maximum efficiency at higher output loads the designer can select fixed frequency PWM mode using the MODE/SYNC pin or alternatively PFM/PWM automatic switching can be used for improved efficiency during light loads.

With an external P-ch transistor, the XC9252 can generate a stable output from input Voltages as low as 3.0V. With a 0.8V reference voltage source (FB) the Output Voltage can be set freely from 1.5V using external resistors (RFB1, RFB2). There is also an optional Power-Good feature that allows the user to monitor the output state and the PG pin will go LOW if the FB drops below 90 per cent of its nominal voltage.

The internal switching frequency can be externally set-up between 280kHz to 550kHz by connecting a resistor to the ROSC pin and the designers can also opt to synchronize the switching frequency of the DC/DC with an external CLK signal (within ±25 per cent of the nominal frequency).

The XC9252 includes Over Current and short circuit protection.  The current limit threshold can be set externally with RSENSE and the designer can select either a Latch or Auto-restart configuration.  

The XC9252 series will be forced to stop operating by various protection circuits, such as a thermal shutdown circuit when the chip’s temperature reaches 150˚C and a UVLO (Under Voltage Lock Out) circuit when the input voltage decreases below 2.5V. Both of the above functions are implemented using hysteresis, and will allow the XC9252 to resume normal operation when the chip’s temperature drops below 125˚C and when the input voltage increases to 2.73V respectively.

Inexpensive ceramic capacitors can be used for the output load capacitor (CL) and the soft start time can be set as desired by adding an external capacitor to the SS pin.

With an operating temperature range of -40˚C ~+105˚C, the XC9252 is available in the USP-10B package for applications that require both a small form factor and a good amount of power dissipation and the TSSOP-16 package for handling even higher power dissipations.  Additionally, fully populated EVBs can be provided upon request.

For information, visit www.torex-europe.com/products/range/400