Parallel to Serial VID Translations on AMD Processors
Created: Sep 03, 2014
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This application note of Microchip that specifically uses PIC16F506 MCU shows the conversion method of traditional Parallel to Serial Voltage IDentification(VID) codes. The output VID codes from the CPU are used to adjust the output voltage that comes from the core of the CPU voltage regulator. To continue the feasibility of the traditional Parallel VID, it requires an excessive number of I/Os. In order to implement power supply voltage changes without having many I/Os, the Serial VID implementation have a two wire interface. This note shows support processors that output PVIDs and SVIDs, PIC16F506 using a SVI CPU core PWM power supply controller is used to translate PVIDs to SVIDs.
The PIC16F506 is the main controller used to translate the PVID codes and transmit the VID using the Serial VID Interface (SVI) to the PWM controller. Some key features of the PIC16F506 include low-cost baseline architecture, up to 8MHz internal oscillator with 500ns instruction cycles, wide 2V-5V operating voltage range, internal flash memory, and 14-pin package with 12 I/O. Refer to the PIC12F510/16F506 Data Sheet (DS41268) for more information. On power-up, the PIC16F506 initializes internal registers, enables the bypass (which routes the SVI I/O around the PIC16F506), and continuously samples CORE_TYPE. If CORE_TYPE indicates a PVID CPU, then the controller turns OFF the bypass, checks the power-up default pre-PWROK metal VID code from the CPU, and outputs the appropriate default state to the SVID PWM controller. After PWROK is asserted, the controller continuously checks for VID code changes. When the controller detects a VID change, the controller converts the PVID to a SVID data pattern and sends the SVID data to the PWM controller.
The PIC12F510/16F506 devices fit in applications ranging from personal care appliances and security systems to low-power remote transmitters/receivers. The flash technology makes customizing application programs (transmitter codes, appliance settings, receiver frequencies, etc.) extremely fast and convenient. This low-cost, low power, high-performance, ease-of-use and I/O flexibility make the PIC12F510/16F506 devices very versatile, even in areas where no microcontroller use has been considered before (e.g., timer functions, logic and PLDs in larger systems and coprocessor applications).