Smallest 1A micro dc-dc with integrated coil

Paul Boughton

Radiated noise or EMI is a constant concern for many electronic design engineers.

The XCL219/XCL220 has been designed to minimise this unwanted noise, making it suitable for sensitive RF applications. When tested and compared with a conventional DC/DC circuit with an external coil, the XCL219/XCL220, with its integrated coil, shows a significant reduction in radiated noise achieved across all frequency bands.

The small size and simple circuit architecture makes the XCL219/XCL220 an ideal replacement for inefficient LDO voltage regulators and by integrating the coil, Torex Semiconductor has simplified the circuit layout for the designer and reduced the number of external components normally needed to implement this type of DC/DC solution. 

The smaller circuit layout also means less PCB tracking, which helps further reduce the radiated noise.

With a nominal 3.0MHz (±15%) switching frequency as standard the output voltage can be fixed internally within a range of 0.8V to 3.6V in 50mV steps (accuracy: ±2.0%). The XCL219 operates with fixed frequency PWM control whereas the XCL220 has automatic PWM/PFM switching control providing fast response, low ripple and high efficiency over the full range of load conditions (from light load to heavy load).

The XCL219/220 series include a 0.25ms (typ.) high speed soft-start function for quick turn-on, a chip enable pin to turn the IC on and off and an optional CL discharge function to quickly discharge the output capacitor when the IC is turned off. A thermal shutdown circuit is also built in which shuts down the IC when the chip’s temperature reaches 150°C and re-starts it when the temperature drops to 120°C (TYP.) or less.

Other features include a built-in UVLO (Under Voltage Lock Out) circuit whose threshold is 1.6V (typ). The XCL219/220 will stop operating when the input voltage decreases below this threshold, and will resume normal operation when the input voltage rises above this threshold.

The XCL219/XCL220 is available in the CL2025  package. Additionally, fully populated EVBs can be provided upon request.