A watchdog circuit for a mobile phone battery charging system

A watchdog circuit ensures that that the charging control circuit of a mobile phone is set to a safe state in the event of a fault occurring. An alternating output (S) from the CPU of the phone causes periodic discharge of a capacitor (C185) through a current sink (TR28-B) and maintains a low voltag...

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Bibliographische Detailangaben
1. Verfasser:	ANTHONY PAUL BANKS
Format:	Patent
Sprache:	eng
Schlagworte:	BASIC ELECTRIC ELEMENTS BASIC ELECTRONIC CIRCUITRY CALCULATING CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER COMPUTING CONVERSION OR DISTRIBUTION OF ELECTRIC POWER COUNTING CURRENT COLLECTORS ELECTRIC COMMUNICATION TECHNIQUE ELECTRIC DIGITAL DATA PROCESSING ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR ELECTRICITY EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS GENERATION LINE CONNECTORS MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS PHYSICS PRINTED CIRCUITS PULSE TECHNIQUE SYSTEMS FOR STORING ELECTRIC ENERGY TRANSMISSION
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Beschreibung
Zusammenfassung:	A watchdog circuit ensures that that the charging control circuit of a mobile phone is set to a safe state in the event of a fault occurring. An alternating output (S) from the CPU of the phone causes periodic discharge of a capacitor (C185) through a current sink (TR28-B) and maintains a low voltage on the emitter of a transistor (TR28A). With the low voltage maintained at its emitter the transistor remains switched on and charging continues. Loss of the alternating voltage (S) removes the periodic current sink from the capacitor (C185) which charges to a high voltage and by switching off the transistor (TR28A) terminates charging of the phone.