L6611D

The L6611 is a control and housekeeping IC developed in BCD technology; it is intended for acting at the secondary side of desktop PC's or server's switching power supplies, in presence of standard voltage rails (+3.3V, +5V, ±12V) generated by a main converter and of a supply line generated by an auxiliary converter. The typical application circuit is showed on the front page.

The Housekeeping's main function is to control and monitor the voltages generated by both the main and the auxiliary converter: it senses those voltages, sends feedback signals to the primary controllers for regulation and, upon detection of an undervoltage (UV), or overvoltage (OV) condition, reports such fault and takes proper action to protect the system.

However, the peculiar feature of this IC is its digital programming capability that enables an accurate trimming of the output voltage rails during production test via software, without any use of external discrete trimming components or need for manual intervention on the PSU. It is also possible to program some of the monitoring functions and select how UV and OC conditions are handled in the main converter: whether latched-mode (the information is latched and released only by forcing the restart of the IC) or bouncing-mode (an attempt is made to automatically restart the converter after 1 second wait).

A key feature of this IC is its contribution to a very low external component count. Besides the extensive use of onboard programmable switches, which prevents the need for external trimming components, the IC embeds reference voltages, error amplifiers and most of the housekeeping circuitry normally required.