Browse Prior Art Database

LOW COST TEMPERATURE CUT OFF FOR A RADIO TRANSMISSION SYSTEM

IP.com Disclosure Number: IPCOM000007339D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-18
Document File: 1 page(s) / 52K

Publishing Venue

Motorola

Related People

John Wetters: AUTHOR [+2]

Abstract

Modems used in consumer grade electronics need a signal to alert the user that the temperature range of the product has been exceeded. This invention uses the circuitry already in use for the temperature compensation circuit of the reference oscillator used in an existing synthesizer IC to also provide a tem- perature indication signal at low and high tempera- ture extremes.

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MOTOROLA Technical Developments Volume 24 March 1995

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LOW COST TEMPERATURE CUT OFF FOR A RADIO TRANSMISSION SYSTEM

by John Wetters and Mike Crafl

  Modems used in consumer grade electronics need a signal to alert the user that the temperature range of the product has been exceeded. This invention uses the circuitry already in use for the temperature compensation circuit of the reference oscillator used in an existing synthesizer IC to also provide a tem- perature indication signal at low and high tempera- ture extremes.

  Two comparators (C4,C5) were added to the existing temperature compensation circuit with a resistor string (R5,R6,R7) to set the high and low

temperature cut off points. Combinational logic is used to acquire a "TX ON" signal. Assuming that the It's programmable register bit "SRL" is pro- grammed to a high and either the unit is out of temperature range or out of lock, the output at "TX ON" will be low. This will disable the transmitter. If "SRL" is low, only the "LOCK DETECT" state will determine the state of "TX ON? Using this circuit we have maintained backwards compatibility to the existing lock detector output and have added an "out of temperature range" feature for new modem con- sumer applications.

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TX CUT OFF HOT c4

TX CUT OFF cm0 c5 1 TX ON implies either lock detect tot backwards compatibility

0, lock oetect l~"CK DETECT and ix is VAhh Lcmperature range.

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