One-wire device with A-to-D converter

Abstract

A low power integrated circuit having analog to digital conversion circuitry capable of receiving a plurality of analog signals and converting them to a digital value. The digital value is then transmitted, upon request, over a single wire bus. The accuracy of the analog to digital conversion circuitry can be calibrated via trim codes stored in an onboard EPROM.

What is claimed is:  
     
         1 . An integrated circuit for converting an analog signal to a digital signal and providing said digital signal to a host device via a single wire data bus, said integrated circuit comprising: 
 input/output circuitry for connecting to said single wire data bus;    analog to digital conversion circuitry for providing a digital signal to said input/output circuitry;    an analog input for connecting an analog signal source and for providing an analog signal to said analog to digital conversion circuitry; and    an EPROM memory for storing trim codes for calibrating said analog to digital conversion circuitry.    
     
     
         2 . The integrated circuit of    claim 1   , wherein said analog input comprises four analog input connections connected to a four to one multiplexer, said multiplexer providing one of said four analog input connections to said analog to digital conversion circuitry.  
     
     
         3 . The integrated circuit of    claim 1   , wherein said integrated circuit operates parasitically from said single wire data bus.  
     
     
         4 . The integrated circuit of    claim 1   , wherein said analog to digital conversion circuitry is configurable to provide a plurality of conversion resolutions.  
     
     
         5 . The integrated circuit of claim if wherein said integrated circuit uses less than 5 miliwatts of power while active.  
     
     
         6 . The integrated circuit of    claim 1   , wherein said single wire data bus utilizes a One-Wire data protocol.  
     
     
         7 . An analog to digital converter comprising: 
 at least one analog input for receiving an analog signal from an external analog signal producing device;    an analog to digital conversion circuit;    means for connecting said at least one analog input to said digital conversion circuit;    a plurality of registers for storing an output of said analog to digital conversion circuit; and    input/output circuitry for retrieving said output of said analog to digital conversion circuit and providing said output to a single wire bus.    
     
     
         8 . The analog to digital converter of    claim 7   , wherein said means connecting said at least one analog input to said digital conversion circuit comprises a MUX circuit with an input from the at least one analog input and an output to said analog to digital conversion circuit.  
     
     
         9 . The analog to digital converter of    claim 7   , wherein said analog to digital converter is powered parasitically from said single wire bus.  
     
     
         10 . The analog to digital converter of    claim 7   , further comprising EPROM circuitry for storing trim code information, said trim code information comprising information for calibrating said analog to digital conversion circuitry.  
     
     
         11 . The analog to digital converter of    claim 7   , wherein said analog to digital converter can be programmed to convert each one of said at least one analog inputs to a digital signal with a different resolution.  
     
     
         12 . The analog to digital converter of    claim 7   , wherein said plurality of registers can also store alarm conditions indicating that said analog input is above or below a predetermined voltage.