MT8888C/MT8888C-1
IN+
IN-
GS
VRef
VSS
OSC1
OSC2
TONE
R/W
CS
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VDD
St/GT
ESt
D3
D2
D1
D0
IRQ/CP
RD
RS0
IN+
IN-
GS
VRef
VSS
OSC1
OSC2
NC
NC
TONE
R/W
CS
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VDD
St/GT
ESt
D3
D2
D1
D0
NC
NC
IRQ/CP
RD
RS0
20 PIN CERDIP/PLASTIC DIP/SOIC
24 PIN SSOP
Figure 2 - Pin Connections
Pin Description
Pin #
20
1
2
3
4
5
6
7
8
9
10
11
12
13
24
1
2
3
4
5
6
7
10
11
12
13
14
15
Name
IN+
IN-
GS
V
Ref
V
SS
Non-inverting
op-amp input.
Inverting
op-amp input.
Gain Select.
Gives access to output of front end differential amplifier for connection of
feedback resistor.
Reference Voltage
output (V
DD
/2).
Ground (0V).
Description
OSC1
Oscillator
input. This pin can also be driven directly by an external clock.
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.
TONE Output from internal DTMF transmitter.
WR
CS
RS0
RD
IRQ/
CP
Write
microprocessor input. TTL compatible.
Chip Select
input. Active Low. This signal must be qualified externally by address latch
enable (ALE) signal, see Figure 12.
Register Select
input. Refer to Table 3 for bit interpretation. TTL compatible.
Read
microprocessor input. TTL compatible.
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
18-
21
22
D0-D3 Microprocessor Data Bus. High impedance when CS = 1 or RD = 1.
TTL compatible.
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
Steering Input/Guard Time
output (bidirectional). A voltage greater than V
TSt
detected at St
causes the device to register the detected tone pair and update the output latch. A voltage
less than V
TSt
frees the device to accept a new tone pair. The GT output acts to reset the
external steering time-constant; its state is a function of ESt and the voltage on St.
V
DD
NC
Positive power supply (5V typ.).
No Connection.
20
24
8,9
16,17
4-92
MITEL [ MITEL NETWORKS CORPORATION ]
