The UCD8220 analog pulse-width modulator (PWM) device isused in digitally managed power supplies using a microcontroller or the TMS320 DSP family.
The UCD8220 device is a double-ended PWM controllerconfigured with push-pull drive logic.
Systems using the UCD8220 device close the PWM feedbackloop with traditional analog methods, but the UCD8220 controllerincludes circuitry to interpret a time-domain digital pulse train. The pulse train contains theoperating frequency and maximum duty cycle limit which are used to control the power supplyoperation. The device circuitry eases implementation of a converter with high level controlfeatures without the added complexity or possible PWM resolution limitations of closing the controlloop in the discrete time domain.
The UCD8220 device can be configured for either peakcurrent mode or voltage mode control. The device provides a programmable current-limit function anda digital output current-limit flag which can be monitored by the host controller to set thecurrent limit operation. For fast switching speeds, the output stage uses the TrueDrive outputcircuit architecture, which delivers rated current of ±4-A into the gate of a MOSFET. Finally thedevice also includes a 3.3-V, 10-mA linear regulator to provide power to the digital controller oract as a reference in the system.
The UCD8220 controller is compatible with the standard3.3-V I/O ports of UCD9K digital power controllers, DSPs, microcontrollers, or ASICs and is offeredin the PowerPAD™ integrated circuit package HTSSOP.