Circuitry for Charging a Depleted Battery in an Implantable Medical Device Without Passive Trickle Charging

摘要

Charging circuitry is disclosed for receiving a magnetic charging field and using the received field to charge a battery in an Implantable Medical Device (IMD) without passive trickle charging, and even if the battery voltage (Vbat) is severely depleted. The charging circuitry includes a source capable of producing a constant charging current via a current mirror that receives a reference current for setting the charging current. Two reference current generators are provided: a first enabled when Vbat is severely depleted to produce a small non-adjustable reference current; and a second enabled once Vbat is recovered to produce a reference current that can be controlled to adjust the charging current. Because Vbat may be too low, the first generator is powered by a DC voltage produced from the magnetic charging field. A passively-generated undervoltage control signal is used to transition between use of the first and second generators.

主权项

1. Battery charging circuitry for an implantable medical device, comprising:
a rechargeable battery having a battery voltage and configured to receive a battery charging current; front-end circuitry configured to generate a DC voltage upon receipt of a wireless charging field; undervoltage detection circuitry configured to indicate whether the battery voltage is above or below a threshold voltage; and source circuitry configured to produce
a first battery charging current as the battery charging current when the undervoltage detection circuitry indicates that the battery voltage is below the threshold voltage, anda second battery charging current as the battery charging current when the undervoltage detection circuitry indicates that the battery voltage is higher than the threshold voltage.