ISL6550A

® ISL6550A, ISL6550B, ISL6550C Data Sheet July 2003 FN9036.2 SAM (Supervisor And Monitor) The ISL6550 is a precision, flexible, VID-code-controlled reference and voltage monitor for high-end microprocessor and memory power supplies. It monitors various input signals, and supervises the system (typically a DC/DC converter) with its output signals. See the Block Diagram for reference. The ISL6550 includes a 5-bit DAC (Digital-to-Analog Converter), which is programmed by the five VID inputs. The voltage range of the BDAC (Buffered DAC output) is determined by the DACHI and DACLO voltage levels, which are externally adjustable through the R1, R2, R3 resistor divider network. VREF5 is a precision-trimmed 5V reference, and is used to set the voltage at the top of the resistor divider. Programmable window comparators monitor Over-Voltage (OV) and Under-Voltage (UV) levels. The OVUVSEN input, usually coming from the associated power converter device is monitored and compared with BDAC; an error band is established via the R4 and R5 resistor setting on the OVUVTH pin. An optional external capacitor on the UVDLY pin gives a programmable delay on the UV. A high gain operational amplifier is available at pins VOPP, VOPM, and VOPOUT; it can be used as a gain stage to permit monitoring voltages that are different from the BDAC levels. The PEN (Power supply ENable) input, driven from an opencollector source, enables (when logic high) the external converter output, via the PGOOD or START o...