Patent ID: 6844709

Claim:
A programmable voltage supervisory circuit, comprising: a voltage select circuit connected with a voltage select signal being one of a high, low and floating states for generating a setting voltage being one of a first to third levels in response to said voltage select signal, said voltage select circuit including: a status determine circuit for generating a pair of state signals representative of said voltage select signal being said high, low or floating states, and a voltage generator for generating said setting voltage in reference to said pair of state signals, said voltage generator including: a latch for latching said pair of state signals, a buffer for buffering said latched pair of state signals, a resistor network, a switch assembly for configuring said resistor network to thereby determine an equivalent resistance by said buffered pair of state signals, and an operational amplifier circuit for generating said setting voltage by amplifying a reference voltage with a gain being a ratio of a summation of a reference resistance from a reference resistor and said equivalent resistance to said equivalent resistance; a sample/hold circuit for generating a threshold voltage by sampling and holding said setting voltage; and a real time comparator for generating a monitoring signal by comparing said supply voltage with said threshold voltage.