MT8889C/MT8889C-1

4-108

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

20

24

11

IN+

Non-inverting op-amp input.

22

IN-

Inverting op-amp input.

33

GS

Gain Select. Gives access to output of front end differential amplifier for connection of

feedback resistor.

44

55

Ground (0V).

66

OSC1

Oscillator input. This pin can also be driven directly by an external clock.

77

OSC2

Oscillator output. A 3.579545 MHz crystal connected between OSC1 and OSC2 completes

the internal oscillator circuit. Leave open circuit when OSC1 is driven externally.

8

10

TONE

Output from internal DTMF transmitter.

911

R/W

(WR)

(Motorola) Read/Write or (Intel) Write microprocessor input. TTL compatible.

10

12

CS

Chip Select input. This signal must be qualified externally by either address strobe (AS),

valid memory address (VMA) or address latch enable (ALE) signal, see Figure 12.

11

13

RS0

Register Select input. Refer to Table 3 for bit interpretation. TTL compatible.

12

14

DS (RD) (Motorola) Data Strobe or (Intel) Read microprocessor input. Activity on this input is only

required when the device is being accessed. TTL compatible.

13

15

IRQ/CP Interrupt Request/Call Progress (open drain) output. In interrupt mode, this output goes

low when a valid DTMF tone burst has been transmitted or received. In call progress mode,

this pin will output a rectangular signal representative of the input signal applied at the input

op-amp. The input signal must be within the bandwidth limits of the call progress filter, see

Figure 8.

14-

17

18-

21

D0-D3

Microprocessor data bus. High impedance when CS = 1 or DS =0 (Motorola) or RD = 1

(Intel). TTL compatible.

18

22

ESt

Early Steering output. Presents a logic high once the digital algorithm has detected a valid

tone pair (signal condition). Any momentary loss of signal condition will cause ESt to return

to a logic low.

19

23

St/GT

St causes the device to register the detected tone pair and update the output latch. A

reset the external steering time-constant; its state is a function of ESt and the voltage on St.

20

24

Positive power supply (5V typ.).

8,9

16,

17

NC

No Connection.

1

2

3

4

5

6

7

8

9

10

11

12

20

19

18

17

16

15

14

13

IN+

IN-

GS

VRef

VSS

OSC1

OSC2

TONE

R/W/WR

CS

VDD

St/GT

ESt

D3

D2

D1

D0

IRQ/CP

DS/RD

RS0

NC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

24

23

22

21

20

19

18

17

IN+

IN-

GS

VRef

VSS

OSC1

OSC2

NC

TONE

R/W/WR

CS

VDD

St/GT

ESt

D3

D2

D1

D0

NC

NC

IRQ/CP

DS/RD

RS0

24 PIN SSOP

20 PIN CERDIP/PLASTIC DIP/SOIC