Granted Patent B1

US 9,275,927 · App. 13/719,883 · Granted Mar 1, 2016

Abstract

Claims (31)

1. A method for heating an integrated circuit (IC) including a first drive circuit configured to drive a spindle motor and a second drive circuit configured to drive a voice coil motor (VCM) coil, the method comprising:

selectively operating the first drive circuit to drive the spindle motor;

selectively operating the second drive circuit to drive the VCM coil; and

selectively operating the first and second drive circuits to heat the IC to a target temperature.

2. The method of claim 1 , wherein the integrated circuit further includes a third drive circuit configured to drive a voltage regulator, and wherein the method further comprises:

selectively operating the third drive circuit to drive the voltage regulator; and

selectively operating the third drive circuit to heat the IC to the target temperature.

3. The method of claim 1 , further comprising:

measuring a temperature of the IC; and

computing a difference between the target temperature and the measured temperature,

wherein selectively operating the first and second drive circuits to heat the IC is based on the difference between the target temperature and the measured temperature.

4. The method of claim 3 , further comprising:

measuring a current in a drive circuit of the first and second drive circuits;

determining a current command based on the difference between the target temperature and the measured temperature; and

computing a difference between the current command and the measured current,

wherein selectively operating the drive circuit to heat the IC comprises adjusting the current in the drive circuit based on the difference between the current command and the measured current.

5. The method of claim 1 , wherein a drive circuit of the first and second drive circuits comprises a first transistor and a second transistor in series and selectively operating the drive circuit to heat the IC comprises operating both the first and second transistors in a linear region to run a current through both the first and second transistors to heat the IC.

6. The method of claim 1 , further comprising:

selectively operating both the first and second drive circuits to heat the IC simultaneously.

7. The method of claim 1 , wherein

the first drive circuit comprises a first bridge circuit configured to drive the spindle motor, the first bridge circuit comprising a first transistor and a second transistor in series; and

the second drive circuit comprises a second bridge circuit configured to drive the VCM coil, the second bridge circuit comprising a third transistor and a fourth transistor in series.

8. The method of claim 4 , wherein the determined current command is proportional to the difference between the target temperature and the measured temperature.

9. The method of claim 4 , wherein the current command is determined based on a proportional-integral-derivative (PID) control of the difference between the target temperature and the measured temperature.

10. The method of claim 4 , wherein the current command is determined by using the difference between the target temperature and the measured temperature to determine a corresponding temperature difference range in a lookup table comprising a plurality of temperature difference ranges including current commands for the plurality of temperature difference ranges.

11. The method of claim 1 , wherein a drive circuit of the first and second drive circuits includes a first transistor and a second transistor in series and selectively operating the drive circuit to drive the spindle motor or the VCM coil comprises alternately turning on the first transistor and the second transistor so that only one of the first transistor and the second transistor is turned on at a time.

12. The method of claim 1 , wherein the IC is coupled to a test computer, and wherein the method further comprises:

receiving an enable signal from the test computer; and

in response to receiving the enable signal, selectively operating the first and second drive circuits to heat the IC to the target temperature.

13. The method of claim 1 , wherein the IC is coupled to a test computer and the IC further comprises a first controller for controlling the first drive circuit and a second controller for controlling the second drive circuit, and wherein the method further comprises enabling one of the first drive circuit or the second drive circuit to heat the IC by sending an enable signal from the test computer to one of the first controller or the second controller.

14. The method of claim 1 , further comprising setting the target temperature to one of a plurality of different reference temperatures.

Assignments (8)