em91450 ELAN Microelectronics Corp, em91450 Datasheet - Page 7

• Manufacturer Part Number: em91450
• Description: Tone/pulse Dialer With Lcd Interface And I.p.p. Detect Function
• Manufacturer: ELAN Microelectronics Corp

* This specification are subject to be changed without notice.
Special Note:
A 300 ms delay time (Tdly) at the first Off-Hook or turn on Handfree that is a special designed to avoid a rapid
key entry (dummy number ) in this time duration ,and a long distance call number follows. For example,
Off-Hook , "3" ,............ , "0" ,1,2,3......
The dummy number "3" is not detected by the centered office or PABX ,but the following numbers "0" ,1,2,3...
long distance call can be dialed out normally since the leading number "3" is not the Lock-number defined in
EM91450 series. To prevent the unavoidable long distance call, then EM91450 inhibits the key entry during
Tdly.
Operating flow chart
Truth table
<Note> : HF = Handfree
• Turn on Handfree (HF) function. (HFO pin switched to "High")
Note : F=floating (high impedance); H=logic "High"; L=logic "Low" level.
Operating state
(1) On-hook, idle state
(2) Off-hook line
(3) Off-hook, HF line
(4) On-hook, HF line
(5) Off-hook, HD line
(6) On-hook, HD line
(7) IPP state
HD = Hold
Dummy key
XMUTE are I/O port, so Input will effect state situation change, and which state dialer stay will
effect output level.
HD
HD
Hold-line State
Hand-free State
Lock number key
On-hook
On-hook
(6)
(4)
HF
HF
HF
HKS=Hi
Input
HKS
H
H
H
H
L
L
L
HKS=Lo
HKS=Hi
XMUTE
Hand-free State
On-hook State
XMUTE
HKS=Lo
Off-hook
(1)
=Hi
H/F
H/F
H/F
H/F
(3)
L/L
L/L
L/L
I/O
HD
HF
HF
HKS=Hi
XMUTE=Lo
HKS=Lo
HF
Pin level
HF
PO
Hold-line State
TONE/PULSE DIALER WITH LCD INTERFACE
F
F
F
F
F
F
F
Off-hook State
Off-hook
(5)
(2)
HD
IPP State
HD
Output
HFO
HKS=Lo
(7)
H
H
H
L
L
L
L
AND I.P.P. DETECT FUNCTION
HDO
H
H
H
L
L
L
L
EM91450 SERIES
DTMF
active
2.10.1999
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