Diagnostic system for a power supply

A diagnostic system for a power supply having first and second output terminals that output first and second reference voltages, respectively, is provided. The diagnostic system includes a microcontroller having an analog-to-digital converter with first and second banks of channels. The microcontroller samples the first reference voltage at a first sampling rate utilizing a first common channel in the first bank of channels to obtain a first predetermined number of voltage samples. The microcontroller determines a first number of voltage samples in the first predetermined number of voltage samples in which the first reference voltage was outside of a predetermined voltage range. The microcontroller sets a first power supply diagnostic flag equal to a first fault value if the first number of voltage samples is greater than a first threshold number of voltage samples.

BACKGROUND

The inventors herein have recognized a need for an improved diagnostic system. The diagnostic system for a power supply provides a technical effect of obtaining diagnostic diversity by sampling a reference voltage from the power supply using a common channel in a first bank of channels of an analog-to-digital converter, and then sampling the reference voltage using the common channel in a second bank of channels of the analog-to-digital converter to determine fault conditions associated with the power supply.

SUMMARY

A diagnostic system for a power supply in accordance with an exemplary embodiment is provided. The power supply has first and second output terminals outputting first and second reference voltages, respectively. The diagnostic system includes a microcontroller having an analog-to-digital converter. The analog-to-digital converter has a first bank of channels and a second bank of channels. The first bank of channels includes first and second common channels and at least first and second non-common channels. The second bank of channels includes the first and second common channels and at least third and fourth non-common channels. The first common channel is electrically coupled to the first output terminal of the power supply for receiving the first reference voltage. The second common channel is electrically coupled to the second output terminal of the power supply for receiving the first reference voltage. The microcontroller is programmed to sample the first reference voltage at a first sampling rate utilizing the first common channel in the first bank of channels to obtain a first predetermined number of voltage samples. The microcontroller is further programmed to determine a first number of voltage samples in the first predetermined number of voltage samples in which the first reference voltage was outside of a predetermined voltage range. The microcontroller is further programmed to set a first power supply diagnostic flag equal to a first fault value if the first number of voltage samples is greater than a first threshold number of voltage samples. The microcontroller is further programmed to sample the first reference voltage at the first sampling rate utilizing the first common channel in the second bank of channels to obtain a second predetermined number of voltage samples. The microcontroller is further programmed to determine a second number of voltage samples in the second predetermined number of voltage samples in which the first reference voltage was outside of the predetermined voltage range. The microcontroller is further programmed to set a second power supply diagnostic flag equal to a second fault value if the second number of voltage samples is greater than a second threshold number of voltage samples.

DETAILED DESCRIPTION

Referring toFIG. 1, a vehicle10includes a power supply20, a diagnostic system30for the power supply20in accordance with an exemplary embodiment, and a control circuit40. An advantage of the diagnostic system30is that the system30obtains diagnostic diversity by sampling a reference voltage from the power supply20using a common channel in a first bank of channels of an analog-to-digital converter74, and then sampling the reference voltage using the common channel in a second bank of channels of the analog-to-digital converter74to robustly determine fault conditions associated with the power supply20.

The power supply20includes an output terminal50and an output terminal52. The output terminal50outputs a first reference voltage (e.g., 3.3 Vdc), and the output terminal52outputs a second reference voltage (e.g., 5.0 Vdc). The first reference voltage is utilized as an operational voltage for enabling operation of a microprocessor70in the microcontroller60. The second reference voltage is utilized as an operational voltage for enabling operation of the analog-to-digital converter74in the microcontroller60.

The diagnostic system30is provided to perform diagnostic tests on the power supply20, which will be described in greater detail below. The diagnostic system30includes the microcontroller60and electrical sense lines62,64.

The microcontroller60includes the microprocessor70, a memory72, and the analog-to-digital converter74. The microcontroller60is programmed to perform diagnostic steps described herein utilizing the microprocessor70which executes software instructions stored in the memory72. The microprocessor70operably communicates with the analog-to-digital converter74and the memory72.

Referring toFIGS. 1 and 2, the analog-to-digital converter74includes a first bank of channels76(also referred to as ADC1herein) and a second bank of channels78(also referred to as ADC2herein). The first bank of channels76includes common channels90(shown inFIG. 2) and non-common channels92, which collectively comprise twelve channels in an exemplary embodiment. The common channels90include common channel94and common channel95. The second bank of channels78includes the common channels90and non-common channels100, which collectively comprise twelve channels in an exemplary embodiment. Thus, both the first and second bank of channels76,78share the common channels90including the common channel94and the common channel95.

The electrical sense line62is electrically coupled to and between the output terminal50of the power supply20and the common channel94of the analog-to-digital converter74. Further, the electrical sense line64is electrically coupled to and between the output terminal52of the power supply20and the common channel95of the analog-to-digital converter74.

The common channels94,95of the analog to digital converter74of the microcontroller60are utilized to sample the first and second reference voltages, respectively, of the power supply20for performing diagnostic tests on the power supply20, as will be described in greater detail below.

Referring toFIG. 1, the control circuit40is utilized to control operation of the contactor154and the DC-DC voltage converter160. The control circuit40includes the microcontroller60, a low side driver circuit150, a high side driver circuit152, the contactor154, a battery module156, a DC-DC voltage converter160, a battery162, and electrical lines170,172,174,176,178,180,182,184,186.

The low side driver circuit150and the high side driver circuit152are provided to energize and de-energize a coil280of the contactor154.

The low side driver circuit150includes an input node250and output node252. The input node250is electrically coupled to the microcontroller60utilizing the electrical line170. The output node252is electrically coupled to a first end of the contactor coil280via the electrical line174.

The high side driver circuit152includes an input node260and output node262. The input node260is electrically coupled to the microcontroller60utilizing the electrical line172. The output node262is electrically coupled to a second end of the contactor coil280via the electrical line176.

The contactor154is electrically coupled in series between a positive terminal300of the battery module156and a first node360of a high voltage bi-directional MOSFET switch340in the DC-DC voltage converter160. The contactor154includes a contactor coil280, a contact282, and a housing284. A first end of the contactor coil280is electrically coupled to the output node252of the low side driver circuit150utilizing the electrical line174. A second end of the contactor coil280is electrically coupled to the output node262of the high side driver circuit152via the electrical line176. Further, a first end of the contact282is selectively electrically coupled to the positive terminal300of the battery module156utilizing the electrical line178. Further, a second end of the contact282is selectively electrically coupled to a first node360of the high voltage bi-directional MOSFET switch340. When the microcontroller60generates first and second control signals that are received by the low side driver circuit150and the high side driver circuit152, respectively, the driver circuits150,152, energize the contactor coil280, which moves the contact282to a closed operational position. Alternately, when the microcontroller60stops generating the first and second control signals, the driver circuits150,152de-energize the contactor coil280, which moves the contact282to an open operational position.

The battery module156includes a positive terminal300and a negative terminal302. In an exemplary embodiment, the battery module156generates 48 Vdc between the positive terminal300and the negative terminal302.

The DC-DC voltage converter160is provided to receive a first voltage level (e.g., 48 Vdc) from the battery module156and to output a second voltage level (e.g., 12 Vdc) to the battery162. Alternately, the DC-DC voltage converter160can receive the second voltage level from the battery162and output a first voltage level to other devices electrically coupled to the electrical line180, when the contactor154has an open operational position. The DC-DC voltage converter160includes the high voltage bi-directional MOSFET switch340, a DC-DC control circuit342, and a low voltage bi-directional MOSFET switch344.

Referring toFIGS. 1 and 3, the high voltage bi-directional MOSFET switch340includes a first node360and a second node362. The first node360is electrically coupled to a first end of the contact282utilizing the electrical line180. The second node362is electrically coupled to a first node370of the DC-DC control circuit342. In an exemplary embodiment, the high voltage bi-directional MOSFET switch340includes MOSFETs400,402and diodes404,406as illustrated inFIG. 3. Of course, in an alternative embodiment, the high voltage bi-directional MOSFET switch340could be replaced with another type of bi-directional switch having desired voltage and current capabilities. When the microcontroller60generates a third control signal that is received by the high voltage bi-directional MOSFET switch340via the electrical line184, the switch340transitions to a closed operational state. When the microcontroller60stops generating the third control signal, the switch340transitions to an open operational state.

The DC-DC control circuit342has a first node370and a second node372. The first node370is electrically coupled to the second node362of the high voltage bi-directional MOSFET switch340. The second node372is electrically coupled to the first node380of the low voltage bi-directional MOSFET switch344.

The low voltage bi-directional MOSFET switch344includes a first node380and a second node382. The first node380is electrically coupled to the second node372of the DC-DC control circuit342. The second node382is electrically coupled to the battery162utilizing the electrical line182. In an exemplary embodiment, the low voltage bi-directional MOSFET switch344has an identical structure as the high voltage bi-directional MOSFET switch340illustrated inFIG. 3. Of course, in an alternative embodiment, the high voltage bi-directional MOSFET switch340could be replaced with another type of bi-directional switch having desired voltage and current capabilities. When the microcontroller60generates a fourth control signal that is received by the low voltage bi-directional MOSFET switch344via the electrical line186, the switch344transitions to a closed operational state. When the microcontroller60stops generating the third control signal, the switch344transitions to an open operational state.

The battery162includes a positive terminal410and a negative terminal412. In an exemplary embodiment, the battery162generates 12 Vdc between the positive terminal410and the negative terminal412.

Referring toFIGS. 1, 2 and 4-16, a flowchart of a method for performing diagnostic tests on the power supply20and for implementing control steps based on the results of the diagnostic tests, will now be explained.

The microcontroller60executes a main routine580(shown inFIG. 4) which calls functions of other subroutines for performing the diagnostic tests and for implementing the control steps based on the results of the diagnostic tests. The main routine580will now be described.

At step596, the microcontroller60initializes the following flags:

First reference voltage slow diagnostic flag=first initialization value

First reference voltage fast diagnostic flag=second initialization value

Second reference voltage slow diagnostic flag=third initialization value

Second reference voltage fast diagnostic flag=fourth initialization value. After step596, the method advances to step598.

At step598, the microcontroller60generates first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to energize the contactor coil280to transition the contact282of the contactor154to a closed operational position. After step598, the method advances to step600.

At step600, the microcontroller60generates third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to each transition to a closed operational state. After step600, the method advances to step602.

At step602, the microcontroller60executes a first diagnostic function628(shown inFIG. 5) of a first subroutine. After step602, the method advances to step604.

At step604, the microcontroller60executes a first diagnostic function648(shown inFIG. 6) of a second subroutine. After step604, the method advances to step606.

At step606, the microcontroller60executes a first diagnostic function668(shown inFIG. 7) of a third subroutine. After step606, the method advances to step608.

At step608, the microcontroller60executes a first diagnostic function688(shown inFIG. 8) of a fourth subroutine. After step608, the method advances to step610.

At step610, the microcontroller60executes a second diagnostic function708(shown inFIGS. 9 and 10) of the second subroutine. After step610, the method advances to step612.

At step612, the microcontroller60executes a second diagnostic function738(shown inFIGS. 11 and 12) of the first subroutine. After step612, the method advances to step614.

At step614, the microcontroller60executes a second diagnostic function768(shown inFIGS. 13 and 14) of the fourth subroutine. After step614, the method advances to step616.

At step616, the microcontroller60executes a second diagnostic function808(shown inFIGS. 15 and 16) of the third subroutine.

Referring toFIG. 5, the first diagnostic function628of the first subroutine will now be explained.

At step630, the microcontroller60samples the first reference voltage (3.3V) at a first sampling rate utilizing a first common channel94(shown inFIG. 2) in the first bank of channels76(ADC1) to obtain a first predetermined number of voltage samples. After step630, the method advances to step632.

At step632, the microcontroller60determines a first number of voltage samples in the first predetermined number of voltage samples in which the first reference voltage is outside of a first predetermined voltage range. After step632, the method advances to step634.

At step634, the microcontroller60makes a determination as to whether the first number of voltage samples is greater than a first threshold number of samples. If the value of step634equals “yes”, the method advances to step636. Otherwise, the method advances to step638.

At step636, the microcontroller60sets the first reference voltage slow diagnostic flag equal to a first fault value. After step636, the method advances to step640.

Referring again to step634, if the value of step634equals “no”, the method advances to step638. At step638, the microcontroller60sets the first reference voltage slow diagnostic flag equal to a first pass value. After step638, the method advances to step640.

At step640, the microcontroller60sends the first reference voltage slow diagnostic flag from the first diagnostic function628of the first subroutine to the second diagnostic function708(shown inFIGS. 9 and 10) of the second subroutine. After step640, the method returns to the main routine580(shown inFIG. 4).

Referring toFIG. 6, the first diagnostic function628of the second subroutine will now be explained.

At step650, the microcontroller60samples the first reference voltage (3.3) at a second sampling rate utilizing the first common channel94(shown inFIG. 2) in the second bank of channels78(ADC2) to obtain a second predetermined number of voltage samples. The second sampling rate is faster than the first sampling rate. After step650, the method advances to step652.

At step652, the microcontroller60determines a second number of voltage samples in the second predetermined number of voltage samples in which the first reference voltage is outside of a second predetermined voltage range. After step652, the method advances to step654.

At step654, the microcontroller60makes a determination as to whether the second number of voltage samples is greater than a third threshold number of samples. If the value of step654equals “yes”, the method advances to step656. Otherwise, the method advances to step658.

At step656, the microcontroller60sets the first reference voltage fast diagnostic flag equal to a second fault value. After step656, the method advances to step660.

Referring again to step654, if the value of step654equals “no”, the method advances to step658. At step658, the microcontroller60sets the first reference voltage fast diagnostic flag equal to a second pass value. After step658, the method advances to step660.

At step660, the microcontroller60sends the first reference voltage fast diagnostic flag from the first diagnostic function648of the second subroutine to the second diagnostic function738(shown inFIGS. 11 and 12) of the first subroutine. After step660, the method returns to the main routine580(shown inFIG. 4).

Referring toFIG. 7, the first diagnostic function668of the third subroutine will now be explained.

At step670, the microcontroller60samples the second reference voltage (5.0) at the first sampling rate utilizing a second common channel95(shown inFIG. 2) in the first bank of channels76(ADC1) to obtain a third predetermined number of voltage samples. After step670, the method advances to step672.

At step672, the microcontroller60determines a third number of voltage samples in the third predetermined number of voltage samples in which the second reference voltage is outside of a third predetermined voltage range. After step672, the method advances to step674.

At step674, the microcontroller60makes a determination as to whether the third number of voltage samples is greater than a first threshold number of samples. If the value of step674equals “yes”, the method advances to step676. Otherwise, the method advances to step678.

At step676, the microcontroller60sets the second reference voltage slow diagnostic flag equal to a third fault value. After step676, the method advances to step680.

Referring again to step674, if the value of step674equals “no”, the method advances to step678. At step678, the microcontroller60sets the second reference voltage slow diagnostic flag equal to a third pass value. After step678, the method advances to step680.

At step680, the microcontroller60sends the second reference voltage slow diagnostic flag from the first diagnostic function668of the third subroutine to the second diagnostic function678(shown inFIGS. 13 and 14) of the fourth subroutine. After step680, the method returns to the main routine580(shown inFIG. 4).

Referring toFIG. 8, the first diagnostic function688of the fourth subroutine will now be explained.

At step690, the microcontroller60samples the second reference voltage (5.0) at the second sampling rate utilizing the second common channel95(shown inFIG. 2) in the second bank of channels78(ADC2) to obtain a fourth predetermined number of voltage samples. After step690, the method advances to step692.

At step692, the microcontroller60determines a fourth number of voltage samples in the fourth predetermined number of voltage samples in which the second reference voltage is outside of a fourth predetermined voltage range. After step692, the method advances to step694.

At step694, the microcontroller60makes a determination as to whether the fourth number of voltage samples is greater than a third threshold number of samples. If the value of step694equals “yes”, the method advances to step696. Otherwise, the method advances to step698.

At step696, the microcontroller60sets the second reference voltage fast diagnostic flag equal to a fourth fault value. After step696, the method advances to step700.

Referring again to step694, if the value of step694equals “no”, the method advances to step698. At step698, the microcontroller60sets the second reference voltage fast diagnostic flag equal to a fourth pass value. After step698, the method advances to step700.

At step700, the microcontroller60sends the second reference voltage fast diagnostic flag from the first diagnostic function688of the fourth subroutine to the second diagnostic function808(shown inFIGS. 15 and 16) of the third subroutine. After step700, method returns to the main routine580(shown inFIG. 4).

Referring toFIGS. 9 and 10, the second diagnostic function708of the second subroutine will now be explained.

At step710, the microcontroller60makes a determination as to whether the first reference voltage slow diagnostic flag is equal to the first initialization value. If the value of step710and equals “yes”, the method advances to step712. Otherwise, the method advances to step716.

At step712, the microcontroller60stops generating first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step712, the method advances to step714.

At step714, the microcontroller60stops generating third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step714, the method advances to step716.

At step716, the microcontroller60makes a determination as to whether the first reference voltage slow diagnostic flag is equal to the first pass value. If the value of step716equals “yes”, the method advances to step718. Otherwise, the method advances to step722.

At step718, the microcontroller60continues generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to continue energizing the contactor coil280to maintain closure of the contact282of the contactor154. After step718, the method advances to step720.

At step720, the microcontroller60continues generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to maintain a closed operational state. After step720, the method advances to step722.

At step722, the microcontroller60makes a determination as to whether the first reference voltage slow diagnostic flag is equal to the first fault value. If the value of step722equals “yes”, the method advances to step724. Otherwise, the method advances to step728.

At step724, the microcontroller60stops generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step724, the method advances to step726.

At step726, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step726, the method advances to step728.

At step728, the microcontroller60makes a determination as to whether the first reference voltage slow diagnostic flag is not equal to the first initialization value, and whether the first reference voltage slow diagnostic flag is not equal to the first pass value, and whether the first reference voltage slow diagnostic flag is not equal to the first fault value. If the value of step728equals “yes”, the method advances to step730. Otherwise, the method returns to the main routine580(shown inFIG. 4).

At step730, the microcontroller60stops generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step730, the method advances to step732.

At step732, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step732, the method returns to the main routine580(shown inFIG. 4).

Referring toFIGS. 11 and 12, the second diagnostic function738of the first subroutine will now be explained.

At step740, the microcontroller60makes a determination as to whether the first reference voltage fast diagnostic flag is equal to the second initialization value. If the value of step740equals “yes”, the method advances to step742. Otherwise, the method advances to step744.

At step742, the microcontroller60stops generating third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step742, the method advances to step744.

At step744, the microcontroller60makes a determination as to whether the first reference voltage fast diagnostic flag is equal to the second pass value. If the value of step744equals “yes”, the method advances to step746. Otherwise, the method advances to step750.

At step746, the microcontroller60continues generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to continue energizing the contactor coil280to maintain closure of the contact282of the contactor154. After step746, the method advances to step748.

At step748, the microcontroller60continues generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to maintain a closed operational state. After step748, the method advances to step750.

At step750, the microcontroller60makes a determination as to whether the first reference voltage fast diagnostic flag is equal to the second fault value. If the value of step750equals “yes”, the method advances to step752. Otherwise, the method advances to step754.

At step752, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step752, the method returns to the main routine580(shown inFIG. 4).

At step754, the microcontroller60makes a determination as to whether the first reference voltage fast diagnostic flag is not equal to the second initialization value, and whether the first reference voltage fast diagnostic flag is not equal to the second pass value, and whether the first reference voltage fast diagnostic flag is not equal to the second fault value. If the value of step754equals “yes”, the method advances to step756. Otherwise, the method returns to the main routine580(shown inFIG. 4).

At step756, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step756, the method returns to the main routine580(shown inFIG. 4).

Referring toFIGS. 13 and 14, the second diagnostic function768of the fourth subroutine will now be explained.

At step770, the microcontroller60makes a determination as to whether the second reference voltage slow diagnostic flag is equal to the third initialization value. If the value of step770equals “yes”, the method advances to step772. Otherwise, the method advances to step776.

At step772, the microcontroller60stops generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step772, the method advances774.

At step774, the microcontroller60stops generating third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step774, the method advances to step776.

At step776, the microcontroller60makes a determination as to whether the second reference voltage slow diagnostic flag is equal to the third pass value. If the value of step776equals “yes”, the method advances to step778. Otherwise, the method advances to step782.

At step778, the microcontroller60continues generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to continue energizing the contactor coil280to maintain closure of the contact282of the contactor154. After step778, the method advances to step780.

At step780, the microcontroller60continues generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to maintain a closed operational state. After step780, the method advances to step782.

At step782, the microcontroller60makes a determination as to whether the second reference voltage slow diagnostic flag is equal to the third fault value. If the value of step782equals “yes”, the method advances to step784. Otherwise, the method advances to step788.

At step784, the microcontroller60stops generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step784, the method advances to step786.

At step786, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step786, the method advances to step788.

At step788, the microcontroller60makes a determination as to whether the second reference voltage slow diagnostic flag is not equal to the third initialization value, and whether the second reference voltage slow diagnostic flag is not equal to the third pass value, and whether the second reference voltage slow diagnostic flag is not equal to the third fault value. If the value of step788equals “yes”, method advances to step790. Otherwise, the method returns to the main routine580(shown inFIG. 4).

At step790, the microcontroller60stops generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to de-energize the contactor coil280to open the contact282of the contactor154. After step790, the method advances to step792.

At step792, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step792, the method returns to the main routine580(shown inFIG. 4).

Referring toFIGS. 15 and 16, the second diagnostic function808of the third subroutine will now be explained.

At step810, the microcontroller60makes a determination as to whether the second reference voltage fast diagnostic flag is equal to the fourth initialization value. If the value of step810equals “yes”, the method advances to step812. Otherwise, the method advances to step814.

At step812, the microcontroller60stops generating third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step812, the method advances to step814.

At step814, the microcontroller60makes a determination as to whether the second reference voltage fast diagnostic flag is equal to the fourth pass value. If the value of step814equals “yes”, the method advances to step816. Otherwise, the method advances to step820.

At step816, the microcontroller60continues generating the first and second control signals to induce the low side driver circuit150and the high side driver circuit152, respectively, to continue energizing the contactor coil280to maintain closure of the contact282of the contactor154. After step816, the method advances to step818.

At step818, the microcontroller60continues generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to maintain a closed operational state. After step818, the method advances to step820.

At step820, the microcontroller60makes a determination as to whether the second reference voltage fast diagnostic flag is equal to the fourth fault value. If the value of step820equals “yes”, the method advances to step822. Otherwise, the method advances to step824.

At step822, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step822, the method advances to step824.

At step824, the microcontroller60makes a determination as to whether the second reference voltage fast diagnostic flag is not equal to the fourth initialization value, and whether the second reference voltage fast diagnostic flag is not equal to the fourth pass value, and whether the second reference voltage fast diagnostic flag is not equal to the fourth fault value. If the value of step824equals “yes”, the method advances to step826. Otherwise, the method returns to the main routine580(shown inFIG. 4).

At step826, the microcontroller60stops generating the third and fourth control signals to induce the high voltage bi-directional MOSFET switch340and the low voltage bi-directional MOSFET switch344, respectively, to transition to an open operational state. After step826, the method returns to the main routine580(shown inFIG. 4).

The diagnostic system for a power supply described herein provides a substantial advantage over other systems and methods. In particular, the diagnostic system for a power supply provides a technical effect of obtaining diagnostic diversity by sampling a reference voltage from the power supply using a common channel in a first bank of channels of an analog-to-digital converter, and then sampling the reference voltage using the common channel in a second bank of channels of the analog-to-digital converter to determine fault conditions associated with the power supply.