Electrostatic discharge protection of a power efficient stylus for an electronic device
Systems, methods, and computer-readable media for enabling a power efficient stylus for an electronic device are provided. Various components may be provided for providing electrostatic discharge protection of such a stylus.
1. An accessory for use with an electronic device that comprises an input component with an input surface, the accessory comprising:
an enclosure; and
accessory circuitry at least partially positioned within the enclosure, wherein:
the accessory circuitry comprises:
body circuitry;
a tip interface component; and
tip circuitry positioned between and electrically coupled to each one of the body circuitry and the tip interface component;
the tip circuitry comprises:
first circuitry that is operative to provide an asymmetric load between the body circuitry and the tip interface component when the accessory is stimulated by an external stimulation; and
second circuitry that is operative to provide electrostatic discharge (“ESD”) protection to the first circuitry; and
the second circuitry comprises:
ESD path circuitry electrically coupled in parallel to the first circuitry; and
ESD resistance circuitry electrically coupled in series with the first circuitry.
2. The accessory of claim 1 , wherein the second circuitry comprises the ESD path circuitry electrically coupled in parallel to the first circuitry, and the ESD resistance circuitry electrically coupled in series with the first circuitry.
3. The accessory of claim 2 , wherein the ESD resistance circuitry is electrically coupled in series with the first circuitry and in parallel to the ESD path circuitry.
4. The accessory of claim 1 , wherein:
the second circuitry comprises ESD resistance circuitry electrically coupled in series with the first circuitry;
the second circuitry further comprises ESD path circuitry electrically coupled in parallel to the first circuitry;
the accessory further comprises signaling resistance circuitry;
the signaling resistance circuitry is electrically coupled in series with the ESD resistance circuitry and in parallel to the first circuitry; and
the signaling resistance circuitry comprises a plurality of resistors in series.
5. The accessory of claim 1 , wherein the ESD path circuitry comprises at least one transient voltage suppression (“TVS”) diode.
6. The accessory of claim 1 , wherein the ESD path circuitry comprises at least two diodes electrically coupled to one another in series.
7. The accessory of claim 1 , wherein the ESD resistance circuitry is operative to limit an amount of current able to pass through the first circuitry.
8. The accessory of claim 1 , wherein the ESD resistance circuitry comprises at least one current limiting resistor.
9. The accessory of claim 1 , wherein the ESD resistance circuitry comprises at least two resistors electrically coupled to one another in series.
10. The accessory of claim 1 , further comprising a circuit board, wherein:
the first circuitry is mounted on a first surface of the circuit board;
at least a portion of the ESD resistance circuitry is mounted on the first surface of the circuit board; and
the ESD path circuitry is mounted on a second surface of the circuit board that is opposite the first surface of the circuit board.
11. The accessory of claim 10 , wherein:
a first portion of the ESD resistance circuitry is mounted on the first surface of the circuit board; and
a second portion of the ESD resistance circuitry is mounted on the second surface of the circuit board.
12. The accessory of claim 11 , wherein:
the first portion of the ESD resistance circuitry comprises a plurality of resistors in series; and
the second portion of the ESD resistance circuitry comprises at least one resistor.
13. The accessory of claim 10 , further comprising signaling resistance circuitry, wherein:
the signaling resistance circuitry is electrically coupled in series with the ESD resistance circuitry and in parallel to the first circuitry; and
the signaling resistance circuitry is mounted on the second surface of the circuit board.
14. The accessory of claim 1 , further comprising signaling resistance circuitry, wherein:
the signaling resistance circuitry is electrically coupled in series with the ESD resistance circuitry and in parallel to the first circuitry; and
the signaling resistance circuitry comprises a plurality of resistors in series.
15. The accessory of claim 1 , wherein the asymmetric load is operative to provide an accessory electric field that is detectable by the electronic device when the tip interface component of the accessory is positioned adjacent the input surface of the input component of the electronic device.
16. The accessory of claim 1 , wherein the first circuitry comprises at least one of the following:
a plurality of diodes; or
at least one Schottky diode.
17. The accessory of claim 1 , wherein:
the enclosure comprises:
a first enclosure;
a second enclosure that is removably coupled to the first enclosure; and
a cover provided over an opening of the first enclosure;
wherein:
the tip circuitry is at least partially positioned within a tip housing space defined by first enclosure;
prior to the first enclosure being coupled to the second enclosure, the cover is operative to prevent an ESD event within the tip housing space; and
when the first enclosure is coupled to the second enclosure, a portion of the body circuitry passes through the cover and into the tip housing space.
18. The accessory of claim 17 , further comprising a conductive pad that is at least partially positioned within the tip housing space, wherein, when the first enclosure is coupled to the second enclosure, the portion of the body circuitry passes through the cover presses into the conductive pad.
19. The accessory of claim 18 , further comprising a spring, wherein, when the first enclosure is coupled to the second enclosure, the spring electrically couples the conductive pad to the tip circuitry.
20. The accessory of claim 17 , wherein the cover is an ESD protective film.