NEC uPD7002 4-channel A/D converter pinout

DIP-28. Four-channel integrating A/D converter, 8 or 10-bit, with a microprocessor bus interface.

An 8 or 10-bit integrating converter (the BBC reads a 12-bit field; trust 10 bits at most). Reference is about 1.8 V from three diodes. End of conversion interrupts through system VIA CB1. It sits straight on the analog port with no protection: any input above 5.5 V or below -0.5 V can kill it. On the BBC: registers at &FEC0-&FEC2; XI (pin 2) takes 1 MHz (Master SM 7.5.1); the integrating capacitor (C25 / C49) sits on pins 4 and 6; VREF (pin 8) should be a quiet 1.8 V to pin 9; CH0-CH3 (pins 13-10) go to analog port pins 15, 7, 12, 4; /CS (pin 23) comes from the Master I/O controller IC15 pin 35; /EOC (pin 28) goes to system VIA CB1.

Open the interactive 7002 pinout

Pins

Pin	Name	Type	Signal
1	X0	clock	External clock input (the data sheet lists X0 and X1 together as the clock input). Not connected on the BBC boards, which feed the clock to pin 2.
2	XI	clock	External clock input.
3	VSS	ground	TTL ground.
4	CI	io	Integrating capacitor.
5	GD	io	Guard.
6	CI	io	Integrating capacitor, other end.
7	GD	io	Guard.
8	VREF	power	Reference voltage input (to analog ground, pin 9).
9	GND	ground	Analog ground.
10	CH3	io	Analog input channel 3.
11	CH2	io	Analog input channel 2.
12	CH1	io	Analog input channel 1.
13	CH0	io	Analog input channel 0.
14	VDD	power	+5 V.
15	D7	data	Data bus bit 7.
16	D6	data	Data bus bit 6.
17	D5	data	Data bus bit 5.
18	D4	data	Data bus bit 4.
19	D3	data	Data bus bit 3.
20	D2	data	Data bus bit 2.
21	D1	data	Data bus bit 1.
22	D0	data	Data bus bit 0.
23	/CS	ctrl	Chip select.
24	/WR	ctrl	Write strobe.
25	/RD	ctrl	Read strobe.
26	A0	addr	Register address bit 0.
27	A1	addr	Register address bit 1.
28	/EOC	ctrl	End of conversion, low when done.

Fitted in

BBC Micro Model B IC73
BBC Master 128 IC49

NEC uPD7002 4-channel A/D converter pinout

Pins

Fitted in

Sources