Datasheet
MT8870D/MT8870D-1 Data Sheet
2
Zarlink Semiconductor Inc.
External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and
latched three-state bus interface.
Figure 2 - Pin Connections
Pin Description
Pin #
Name Description
18 20
11 IN+Non-Inverting Op-Amp (Input).
22 IN- Inverting Op-Amp (Input).
33 GSGain Select. Gives access to output of front end differential amplifier for connection of
feedback resistor.
44 V
Ref
Reference Voltage (Output). Nominally V
DD
/2 is used to bias inputs at mid-rail (see Fig. 6
and Fig. 10).
55 INHInhibit (Input). Logic high inhibits the detection of tones representing characters A, B, C
and D. This pin input is internally pulled down.
66PWDNPower Down (Input). Active high. Powers down the device and inhibits the oscillator. This
pin input is internally pulled down.
78 OSC1Clock (Input).
89 OSC2Clock (Output). A 3.579545 MHz crystal connected between pins OSC1 and OSC2
completes the internal oscillator circuit.
910 V
SS
Ground (Input). 0 V typical.
10 11 TOE Three State Output Enable (Input). Logic high enables the outputs Q1-Q4. This pin is
pulled up internally.
11-
14
12-
15
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.
15 17 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
.
16 18 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.
1
2
3
4
5
6
7
8
9
10
18
17
16
15
14
13
12
11
IN+
IN-
GS
VRef
INH
PWDN
OSC1
OSC2
VSS
VDD
St/GT
ESt
StD
Q4
Q3
Q2
Q1
TOE
18 PIN PLASTIC DIP/SOIC
1
2
3
4
5
6
7
8
9
10
11
12
20
19
18
17
16
15
14
13
IN+
IN-
GS
VRef
INH
PWDN
NC
OSC1
OSC2
VSS
20 PIN SSOP
VDD
St/GT
ESt
StD
Q4
Q3
Q2
Q1
TOE
NC