Toshiba GD-1210, GD-1260, GD-1250, GD-1270, GD-1160 CI detection circuit, NA/TW models, IC26

4.2.5CI detection circuit

NA/TW models

NCU board

	+12V	RLY2
		CML relay
	1	12
4 Lb	9	1

Q51

3

FAX board

3 CML1 21

IC29

Line

		0	10
CN10			ZD1 ZD3 C1	R2
	3 La	1
		4
		0	3

D52

AG 5VPS

R79

17

14

PC2

23

SG

CN9

CN501

17 CI1 4

[IC26]

ASIC

Fig. 4-11

The CI detection circuit consists of the photocoupler (PC2), ASIC (IC29 [IC26]) on the FAX board and the other peripheral devices to detect a ring signal input from the telephone line.

The ASIC makes the CML1 signal become LOW to connect the CI detection circuit to the telephone line.

When a ring signal is input from the telephone line, the photocoupler is repeatedly turned ON/OFF. This allows the CI1 signal to become a pulse signal and input to the ASIC on the FAX board, thereby detect- ing the ring signal.

Signal Name	Type	Active	Description	Destination
CI1	I	-	Line 1 CI Detect Signal	IC29 [IC26]

*Values in [ ] are for GD-1250/1270 in case that the descriptions vary between GD-1210 and GD- 1250/1270.

4

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