MT8870DS1 Zarlink, MT8870DS1 Datasheet - Page 16

• Manufacturer Part Number: MT8870DS1
• Description: DTMF RX 3.58MHz CMOS 5V 18-Pin SOIC Tube
• Manufacturer: Zarlink

Specifications of MT8870DS1

• Package: 18SOIC
• Operating Frequency: 3.58 MHz
• Typical Supply Current: 3 mA
• Typical Operating Supply Voltage: 5 V
• Minimum Operating Supply Voltage: 4.75 V
• Maximum Operating Supply Voltage: 5.25 V

A)
B)
C)
D)
E)
F)
G)
V
ESt
St/GT
Q
StD
TOE
t
t
t
t
t
t
t
t
REC
REC
ID
DO
DP
DA
GTP
GTA
EXPLANATION OF EVENTS
EXPLANATION OF SYMBOLS
V
ESt
St/GT
Q
StD
TOE
in
1
-Q
in
EVENTS
1
-Q
4
4
TONE BURSTS DETECTED, TONE DURATION INVALID, OUTPUTS NOT UPDATED.
TONE #n DETECTED, TONE DURATION VALID, TONE DECODED AND LATCHED IN OUTPUTS
END OF TONE #n DETECTED, TONE ABSENT DURATION VALID, OUTPUTS REMIAN LATCHED UNTIL NEXT VALID
TONE.
OUTPUTS SWITCHED TO HIGH IMPEDANCE STATE.
TONE #n + 1 DETECTED, TONE DURATION VALID, TONE DECODED AND LATCHED IN OUTPUTS (CURRENTLY HIGH
IMPEDANCE).
ACCEPTABLE DROPOUT OF TONE #n + 1, TONE ABSENT DURATION INVALID, OUTPUTS REMAIN LATCHED.
END OF TONE #n + 1 DETECTED, TONE ABSENT DURATION VALID, OUTPUTS REMAIN LATCHED UNTIL NEXT VALID
TONE.
DTMF COMPOSITE INPUT SIGNAL.
EARLY STEERING OUTPUT. INDICATES DETECTION OF VALID TONE FREQUENCIES.
STEERING INPUT/GUARD TIME OUTPUT. DRIVES EXTERNAL RC TIMING CIRCUIT.
4-BIT DECODED TONE OUTPUT.
DELAYED STEERING OUTPUT. INDICATES THAT VALID FREQUENCIES HAVE BEEN PRESENT/ABSENT FOR THE
REQUIRED GUARD TIME THUS CONSTITUTING A VALID SIGNAL.
TONE OUTPUT ENABLE (INPUT). A LOW LEVEL SHIFTS Q
MAXIMUM DTMF SIGNAL DURATION NOT DETECED AS VALID
MINIMUM DTMF SIGNAL DURATION REQUIRED FOR VALID RECOGNITION
MAXIMUM TIME BETWEEN VALID DTMF SIGNALS.
MAXIMUM ALLOWABLE DROP OUT DURING VALID DTMF SIGNAL.
TIME TO DETECT THE PRESENCE OF VALID DTMF SIGNALS.
TIME TO DETECT THE ABSENCE OF VALID DTMF SIGNALS.
GUARD TIME, TONE PRESENT.
GUARD TIME, TONE ABSENT.
t
REC
A
DECODED TONE # (n-1)
t
DP
t
GTP
MT8870D/MT8870D-1
t
PSrD
t
Figure 11 - Timing Diagram
PQ
t
REC
Zarlink Semiconductor Inc.
TONE #n
B
16
t
QStD
C
# n
1
-Q
t
ID
4
t
TO ITS HIGH IMPEDANCE STATE.
DA
t
GTA
#n + 1
TONE
E
HIGH IMPEDANCE
t
PTD
t
DO
D
F
TONE
#n + 1
# (n + 1)
t
PTE
G
Data Sheet
V
TSt