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In current days, the variety of digital management models (ECUs) within the automotive continues to extend, on the identical time there’s a necessity to scale back the sleep present to enhance the effectivity of the battery. In fuel powered automobiles this has grow to be obligatory.
Wow the engineering world along with your distinctive design: Design Concepts Submission Information
Limitations on controlling sleep state present
These days, a number of ECUs are mixed and powered from a single fuse/E-fuse to avoid wasting on design prices, however this has the downside of controlling the ECUs independently. If we wish unbiased ON/OFF management, then the design price will enhance considerably.
To beat the fee subject, every ECU comes with a further I/O known as “IGNITION” from the principle ECU. Upon receiving the IGNITION enter, the slave ECUs will get up from the sleep state. This conventional structure has its personal limitations, as an example, it wants a further communication interface like LIN, CAN, or Ethernet to speak energy modes akin to sleep, lively, and different standing info. This will increase the system price additional.
IGNITION is a unidirectional sign that will likely be asserted by the principle ECU, for the slave ECU, this will likely be solely an enter. As a way to detect this IGNITION enter, the microcontroller within the slave ECU have to be get up supply enabled. Regardless that the ECU is in a low energy state, it consumes some energy to maintain the microcontroller in sleep state as properly the DC-DC controller.
In lots of car architectures the CAN or LIN interface is used for each communication in addition to for Wake functions (wake over CAN) the place there isn’t any want for an Ignition enter. Nonetheless, this consumes extra sleep energy than the earlier situation.
Determine 1 The standard car structure the place a number of ECUs are mixed and powered from a single fuse to avoid wasting on design prices. This causes limitations on controlling present within the sleep state.
Proposed Answer
Within the proposed structure, the IGNITION I/O will likely be changed with {Hardware} Wake I/O (HW_WAKE). A primary block diagram of the proposed structure with {Hardware} Wake I/O is proven in Determine 2.
Determine 2 The proposed structure utilizing {Hardware} Wake I/O (HW_WAKE).
The inner circuit of a {Hardware} Wake I/O is proven in Determine 3.
Determine 3 The {Hardware} Wake bi-directional circuit with two transistors for controlling the output, a resistor divider for studying the identical I/O, and diodes for reverse safety.
It consists of two transistors Q1 twin package deal (one NPN & one PNP) for controlling the output performance in addition to a easy resistor divider (R2, R3 & R4) for receiving or studying the identical I/O. As well as, there are diodes (D1, D2) for reverse safety.
It is a bidirectional I/O, the place we are able to obtain alerts like wake, reset, and sleep in addition to ship alerts akin to suggestions and error standing. The voltage ranges of HW_WAKE I/O observe the battery voltage, with a managed present of 13.5 mA within the proposed design. The person can determine their present by altering the resistor R1.
This circuit has quick circuit safety and doesn’t require any fancy or protocol transceiver. The HW_WAKE sign will be linked “n” variety of ECUs. As a way to keep away from I/O contamination, the person can learn the “HW_WAKE_RX_TO_MCU” I/O standing earlier than asserting “HW_WAKE_TX_FROM_MCU_GPIO”.
Benefits of the HW_WAKE sign
Since this HW_WAKE is a bidirectional I/O, any ECU can act as a grasp, that is helpful in situations the place a number of wake sources are wanted (e.g., if one ECU wakes and sends wake alerts to all of the others). The default state of the HW_WAKE I/O is open (0 V), it is going to be asserted (VBAT) solely when required. Each management and standing info are transmitted over this single wire interface by sampling, sending the timing-based alerts.
Whereas utilizing HW_WAKE I/O, we are able to keep away from utilizing the LIN or CAN protocol medium, which saves lot of design and implementation price. The person can implement their very own timings for all of the alerts. We will utterly energy down the ECU throughout a sleep state, this fashion we are able to obtain an ultra-low energy of just about 0 mA. This may be achieved by additionally connecting the “HW_WAKE_RX_TO_MCU” to the allow pin of DC-DC converter, enabling the ability provide. This will even allow the microcontroller, as soon as microcontroller is up, then it’s going to maintain the allow for DC-DC converter.
When a sleep/energy down sign is obtained, the microcontroller will disable the allow for the ability provide. This turns off the availability utterly (like self-killing) attaining ultra-low (0 mA) energy dissipation.
Timing examples
Management and standing info and timing examples will be seen in Determine 4.
Determine 4 Management and standing timing examples for WAKE_IN, ACK, ERROR, and POWER DOWN/SLEEP.
- WAKE_IN: This sign is triggered by the principle ECU by merely asserting the HW_WAKE. All different ECUs will get up primarily based on this sign. The everyday excessive time of the sign is 100 ms (low time N/A).
- ACK: The slave ECUs ship an acknowledgement sign again to the grasp by merely asserting the HW_WAKE. Typical excessive time of the sign is 20 ms (low time N/A).
- ERROR: Slave ECUs ship a sample sign high-low-high-low-high, to speak the error standing. The everyday excessive time of the sign is 20 ms whereas typical low time is 10 ms.
- POWER DOWN/SLEEP: The ability down or sleep sign will likely be communicated from the grasp to all slave ECUs by asserting the HW_WAKE for 200 ms.
Rajesh Subramanyam (Senior Member, IEEE) obtained his bachelor’s diploma in electrical and electronics engineering from Anna College, Chennai, India. He presently works as a senior {hardware} design engineer at an EV firm in California, USA with a core experience in automotive infotainment controller {hardware} design. Rajesh can be a member of the editorial assessment board for the SAE worldwide journal.
Selvakumar Sonai (Senior Member, IEEE) obtained his grasp’s diploma in microelectronics from BITS Pilani, India. He presently works as a senior {hardware} design engineer at an EV firm in California, USA with a core experience in automotive infotainment controller {hardware} design. Sonai is a member of IEEE Transactions on Circuits and Methods in addition to the editorial assessment board for the SAE inner journal.
Logesh Sekar (Senior Member, IEEE) obtained his bachelor’s diploma in electrical and electronics engineering from Anna College, Chennai, India He presently works as a senior {hardware} design engineer at an EV firm in California, USA with a core experience in automotive infotainment controller {hardware} design. Sekar can be a member of the editorial assessment board for the SAE worldwide journal.
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