Reference Manual for Toshiba 12-bit Analog to Digital Converter (ADC-G)

Quick guide from the manual

This document provides technical specifications and operational instructions for the Toshiba 12-bit Analog to Digital Converter (ADC-G). It covers the configuration of the ADC, including clock supply, start-up factors, and monitor functions. Users should refer to this manual for register settings, conversion timing calculations, and integration with peripheral functions like the Programmable Motor Control Circuit (PMD).

ADC Configuration and Signals

The ADC unit converts multiple analog inputs (AINx00 to AINx24) to digital values. Key components include:

• Conversion Control: Manages start-up factors and conversion programs.
• PMD Trigger Control: Synchronizes ADC conversion with motor drive timing.
• General Purpose Start-up: Supports software-triggered single or continuous conversions.
• AD Monitor Function: Allows monitoring of conversion results against set values to trigger interrupts or protection signals.

Operation Modes

The ADC supports several conversion modes:

• General Purpose Start-up: Triggered by software or general purpose timer inputs. Supports single and continuous conversion modes.
• PMD Trigger Conversion: Triggered by PMD signals, allowing synchronized conversion for motor control applications (e.g., 3-shunt or 1-shunt configurations).

Conversion Timing and Settings

Conversion time is calculated as the sum of sampling time and comparison time. Users must configure the following based on power supply voltage (AVDD5) and SCLK frequency:

• Sampling Time: Configurable via [ADxCLK] and [ADxMOD1] registers.
• Conversion Time: Varies depending on the SCLK frequency (20MHz or 30MHz) and voltage range (2.7V to 5.5V).

AD Monitor Function

The monitor function compares conversion results against a reference value. It supports:

• Determination Conditions: Larger or smaller than the comparison register.
• Count Conditions: Continuous count or accumulated count to trigger an interrupt (INTADxCP0/1).

Register Overview

The ADC is controlled via memory-mapped registers. Key registers include:

• [ADxCR0] / [ADxCR1]: Control registers for enabling ADC, starting conversions, and configuring DMA requests.
• [ADxST]: Status register to check conversion progress.
• [ADxTSETn]: General purpose start-up factor program registers.
• [ADxPSETn]: PMD trigger program registers.
• [ADxREGn]: Conversion result storage registers.

Usage Examples

The manual provides specific sequences for:

• Single Conversion: Setting up interrupts, configuring DAC, and initiating conversion via software.
• PMD Trigger Conversion: Configuring trigger assignments and program registers for synchronized motor control (3-shunt and 1-shunt examples).

Precautions

To ensure accuracy, avoid changing output pin data during conversion. Use bypass capacitors between AVDD5/AVSS and VREFHx/VREFLx pins to minimize digital noise.