Data storage device capable of overriding a servo command to avoid an overcurrent condition

1. A data storage device comprising:

a disk;

a head;

a first actuator configured to actuate the head over the disk;

a second actuator configured to rotate the disk;

a first control circuit configured to generate a servo command; and

a second control circuit configured to:

receive the servo command from the first control circuit;

control the first actuator or the second actuator using the servo command; and

override the servo command to avoid an overcurrent condition.

2. The data storage device as recited in claim 1 , wherein the second control circuit comprises a digital-to-analog converter (DAC) and the second control circuit is further configured to:

apply the servo command to the DAC to generate an analog control signal;

apply the analog control signal to the first actuator or the second actuator; and

override the servo command by applying an override command to the DAC.

3. The data storage device as recited in claim 1 , further comprising an input configured to receive a supply voltage from a host, wherein when the data storage device nears a current limit of the supply voltage, the second control circuit is configured to override the servo command.

4. The data storage device as recited in claim 3 , wherein the second control circuit is further configured to detect when the data storage device nears the current limit of the supply voltage.

5. The data storage device as recited in claim 4 , wherein the second control circuit is further configured to notify the first control circuit when the servo command has been overridden.

6. The data storage device as recited in claim 1 , wherein the first control circuit is further configured to:

seek the head over the disk during a seek operation; and

abort the seek operation due to the second control circuit overriding the servo command.

7. The data storage device as recited in claim 6 , wherein the first control circuit is further configured to:

receive a notification from the second control circuit when the second control circuit overrides the servo command; and

abort the seek operation in response to the notification.

8. The data storage device as recited in claim 6 , wherein the first control circuit is further configured to:

monitor at least one servo state of the first actuator or the second actuator; and

abort the seek operation based on the monitored servo state.

9. The data storage device as recited in claim 1 , wherein the second control circuit is further configured to:

detect when the first actuator or the second actuator nears a current limit; and

override the servo command to prevent the first actuator or the second actuator from reaching the current limit.

10. Control circuitry comprising a digital-to-analog converter (DAC), wherein the control circuitry is configured to:

receive a servo command from a servo control circuit;

apply the servo command to the DAC to generate an analog control signal;

apply the analog control signal to a first actuator configured to actuate a head over a disk or to a second actuator configured to rotate the disk; and

override the servo command by applying an override command to the DAC to avoid an overcurrent condition.

11. The control circuitry as recited in claim 10 , further comprising an input configured to receive a supply voltage from a host, wherein the control circuitry is further configured to override the servo command in order to avoid a current limit of the supply voltage.

12. The control circuitry as recited in claim 11 , wherein the control circuitry is further configured to detect when the supply voltage is nearing the current limit.

13. The control circuitry as recited in claim 12 , wherein the control circuitry is further configured to notify the servo control circuit when the servo command has been overridden.

14. The control circuitry as recited in claim 10 , wherein the control circuitry is further configured to:

detect when the first actuator or the second actuator nears a current limit; and

override the servo command to prevent the first actuator or the second actuator from reaching the current limit.

15. The control circuitry as recited in claim 10 , wherein the control circuitry is further configured to:

override the servo command for a predetermined interval; and

after the predetermined interval, terminate the override.

16. The control circuitry as recited in claim 10 , wherein the control circuitry is further configured to decrease the override command open-loop over a predetermined interval.

17. The control circuitry as recited in claim 10 , wherein the control circuitry is further configured to adjust the override command using a closed loop control based on least one of a target current or a target voltage of the control circuitry.

18. The control circuitry as recited in claim 10 , wherein the control circuitry is further configured to:

measure at least one of a load current or a load voltage of the control circuitry; and

terminate the override based on at least one of the measured load current or the measured load voltage.

19. The control circuitry as recited in claim 18 , wherein the control circuitry is further configured to terminate the override when at least one of the measured load current rises above a threshold or the measured load voltage falls below a threshold.

20. Control circuitry comprising:

a means for receiving a servo command from a servo control circuit;

a means for generating an analog control signal in response to the servo command;

a means for applying the analog control signal to a first actuator configured to actuate a head over a disk or to a second actuator configured to rotate the disk; and

a means for overriding the servo command to avoid an overcurrent condition.