MT3170B/71B, MT3270B/71B, MT3370B/71B Data Sheet
2
Zarlink Semiconductor Inc.
Description
The MT3x7xB is a family of high performance DTMF receivers which decode all 16 tone pairs into a 4-bit binary
code. These devices incorporate an AGC for wide dynamic range and are suitable for end-to-end signalling. The
MT3x70B provides an early steering (ESt) logic output to indicate the detection of a DTMF signal and requires
external software guard time to validate the DTMF digit. The MT3x71B, with preset internal guard times, uses a
delay steering (DStD) logic output to indicate the detection of a valid DTMF digit. The 4-bit DTMF binary digit can be
clocked out synchronously at the serial data (SD) output. The SD pin is multiplexed with call progress detector
output. In the presence of supervisory tones, the call progress detector circuit indicates the cadence (i.e., envelope)
of the tone burst. The cadence information can then be processed by an external microcontroller to identify specific
call progress signals. The MT327xB and MT337xB can be used with a crystal or a ceramic resonator without
additional components. A power-down option is provided for the MT317xB and MT337xB.
Figure 2 - Pin Connections
Pin Description
Pin #
Name Description
337xBN 337xBS 327xB 317xB
3211INPUTDTMF/CP Input. Input signal must be AC coupled via
capacitor.
642-OSC2Oscillator Output.
7633OSC1
(CLK)
Oscillator/Clock Input. This pin can either be driven by:
1) an external digital clock with defined input logic levels.
OSC2 should be left open.
2) connecting a crystal or ceramic resonator between
OSC1 and OSC2 pins.
8944V
SS
Ground. (0V)
13 11 5 5 SD Serial Data/Call Progress Output. This pin serves the dual
function of being the serial data output when clock pulses are
applied after validation of DTMF signal, and also indicates
the cadence of call progress input. As DTMF signal lies in
the same frequency band as call progress signal, this pin
may toggle for DTMF input. The SD pin is at logic low in
powerdown state.
10
18
17
16
15
14
13
12
11
VDD
NC
NC
ESt/DStD
NC
ACK
NC
SD
NC
1
2
3
4
5
6
7
8
9
NC
INPUT
PWDN
OSC2
NC
OSC1
NC
NC
VSS
INPUT
PWDN
CLK
VSS
VDD
ACK
SD
INPUT
OSC2
OSC1
VSS
VDD
ESt/
ACK
SD
MT3170B/71B MT3270B/71B MT3370BS/71BS
8 PIN PLASTIC DIP
18 PIN PLASTIC SOIC
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
1
2
3
4
5
6
7
8
9
10
11
12
20
19
18
17
16
15
14
13
NC
NC
INPUT
PWDN
NC
NC
OSC1
OSC2
VSS
20 PIN SSOP
NC
VDD
NC
NC
ACK
SD
NC
NC
ESt/DStD
DStD
ESt/
DStD
MT3370BN/71BN
NC
NC
