MT88L70
IN+
IN-
GS
VRef
INH
PWDN
OSC1
OSC2
VSS
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
VDD
St/GT
ESt
StD
Q4
Q3
Q2
Q1
TOE
IN+
IN-
GS
VRef
INH
PWDN
NC
OSC1
OSC2
VSS
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VDD
St/GT
ESt
StD
NC
Q4
Q3
Q2
Q1
TOE
18 PIN CERDIP/PDIP/SOIC
20 PIN SSOP/TSSOP
Figure 2 - Pin Connections
Pin Description
Pin #
Name
18
1
2
3
4
5
6
7
8
9
10
20
1
2
3
4
5
6
8
9
10
11
IN+
IN-
GS
V
Ref
INH
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).
Nominally V
DD
/2 is used to bias inputs at mid-rail (see Figure
5 and Figure 6).
Inhibit (Input).
Logic high inhibits the detection of tones representing characters A, B, C
and D. This pin input is internally pulled down.
Description
PWDN
Power Down (Input).
Active high. Powers down the device and inhibits the oscillator. This
pin input is internally pulled down.
OSC1
OSC2
V
SS
TOE
Clock (Input).
Clock (Output).
A 3.579545 MHz crystal connected between pins OSC1 and OSC2
completes the internal oscillator circuit.
Ground (Input).
0V typical.
Three State Output Enable (Input).
Logic high enables the outputs Q1-Q4. This pin is
pulled up internally.
11- 12-
14 15
15
17
Q1-Q4
Three State Data (Output).
When enabled by TOE, provide the code corresponding to the
last valid tone-pair received (see Table 1). When TOE is logic low, the data outputs are high
impedance.
StD
Delayed Steering (Output).Presents
a logic high when a received tone-pair has been
registered and the output latch updated; returns to logic low when the voltage on St/GT falls
below V
TSt
.
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.
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.
Positive power supply (Input).
+3V typical.
No Connection.
16
18
ESt
17
19
St/GT
18
20
7,
16
V
DD
NC
4-24
MITEL [ MITEL NETWORKS CORPORATION ]
