| 摘要 |
A body implantable cardiac pacemaker having a Hall effect switch (210) which may be activated by a magnetic field in order to alter one or more pacemaker characteristics. The Hall effect element is part of an integrated circuit and is oriented in a plane parallel to the broad plane of the pacemaker. The pacemaker includes a circuit for generating strobe timing signals of duration shorter than the interval between the signals. For example, the strobe signals may be of duration 200 mu s or less and the intervals between the signals may equal the intervals between stimulating pulses, i.e. about 1 second. The strobe signals are used to control subcircuits in the pacemaker so the subcircuits are only on for the duration of the strobe signals, resulting in reduced current drain. Transistor (216) supplies a short current pulse and in the presence of a magnetic field a voltage appears across element (210) turning on one of comparators (233, 234) and supplying a control output (230) via OR gate (236), transistors (245, 256) and flip-flop (265). |
