The μPD7002 is a high performance, low power monolithic CMOS A/D converter designed for microprocessor applications. The Analogue input voltage is applied to one of the 4 analog inputs.
By loading the input register with the multiplexer channel & the desired resolution of 8 or 12 bits, the integrating A/D conversion sequence is started.
At the end of the conversion the EOC signal goes low and if connected to the interrupt line of a microprocessor will cause an interrupt. At this point the digital data can be read in two bytes from the output registers.
The μPD7002 also features a status register that can be read at any time.
The μPD7002 is the A/D converter used by the BBC Microcomputer.
| Pin | I/O | Description | |
|---|---|---|---|
| No | Name | ||
| 1, 2 | X0…1 | I | External Clock Input |
| 3 | VSS | TTL Ground | |
| 4, 6 | CI | Integrating Capacitor | |
| 5, 7 | GD | Guard | |
| 8 | VREF | I | Reference Voltage Input |
| 9 | GND | Analogue Ground | |
| 10…13 | CH0…3 | I | Analog Channel 0…3 |
| 14 | VDD | I | TTL Voltage +5V |
| 15…22 | D0…7 | I/O | Data Bus |
| 23 | CS | I | Chip Select |
| 24 | WR | I | Control Bus |
| 25 | RD | I | Control Bus |
| 26…27 | A0…1 | I | Address Bus |
| 28 | EOC | O | End of Conversion Interrupt |
Note: Be careful as this chip has 2 grounds which are independent of each other:
- VSS which is TTL Ground
- GND which is Analogue ground