Convertor and LDO united

Edited by the Electronicstalk editorial team May 5, 2004

The XC9510/XC9511 series is a highly integrated solution combining step-down DC/DC convertor, high-speed, low-noise LDO voltage regulator and an internal comparator for low voltage detection.

The XC9510/XC9511 series is a highly integrated solution combining step-down DC/DC convertor, high-speed, low-noise LDO voltage regulator and an internal comparator for low voltage detection.

The XC9510/XC9511 offers designers a cheaper, smaller and more reliable alternative to current discrete solutions and is supplied in a SOP-8 package.

The XC9510/11 is an ideal partner for the latest DSPs and microcontrollers which require 1.8V for the memory (taken from the DC/DC portion of the IC) and 1.5V for the core (provided by the LDO portion of the IC).

The new device's 0.6ohm P-channel driver transistor and 0.6ohm N-channel switching transistor means that efficiencies over 90% can be achieved without the need for an external Schottky diode.

The XC9510/11 is designed for use with low ESR ceramic capacitors and small chip inductors making it the ideal choice for designs where space is at a premium.

Output current is 800mA (DC/DC convertor), 400mA (voltage regulator).

Operating voltage range is 2.4 to 6.0V.

DC/DC output voltage is factory set in 0.1V steps between 0.9 and 4.0V (XC9511) and between 1.6 and 4.0V (XC9510).

Voltage regulator output range is between 0.9 and 4.0V and voltage detector range is 0.9 to 5.0V, again in 0.1V steps.

Three switching frequencies are available: 300kHz, 600kHz or 1.2MHz.

A choice of switching control method is provided: either synchronous-rectified PWM switching control, or synchronous PWM/PFM auto switching, selectable via the XC9510/11's mode pin.

This gives the designer fast response, low ripple output and high efficiency over a broad range of output loads.

The voltage regulator's dropout voltage is 80mV at 100mA (typical) and ripple rejection is 60dB at 1kHz (2.8V output).

Other features include a built-in current limit, an internal soft-start (set to 10ms) and an under voltage lockout circuit.