EM91450 SERIES
TONE/PULSE DIALER WITH LCD INTERFACE
AND I.P.P. DETECT FUNCTION
FUNCTIONAL BLOCK DIAGRAM
SDO
COL1
COL2
COL3
COL4/KT
Keyboard
interface
(column)
Output circuit
Row/Column
programming counter
HFO HDO
RMUTE
XMUTE
I/O circuit
Memory
latch
&
decoder
D/A
converter
DTMF
XIN
XOUT
Oscillator
Timing/Control circuit
ROW1
Keyboard
interface
(Row)
VDD
HFI
HKS
DRING
Input circuit
Pulse
generator
PO
ROW4
PIN DESCRIPTIONS
Symbol
ROW1~ROW4
Function
Keyboard scan pins of row group. In idle state (HKS is "High" and HFO is "Low"),
these pins stay ÒHigh impedanceÓ level to prevent power consumption. Otherwise,
these pins switch to ÒHighÓ level for detecting keyboard entry. These pins will output
600 Hz signal while keyboard is scanning.
Keyboard scan pins of column group. In idle state, these pins stay "High impedance"
level. Otherwise these pins switch to ÒLowÓ level for detecting keyboard entry. These
pins will output 600 Hz signal while keyboard is scanning.
The fourth column group pin of the keyboard that also provides the keytone output
. Normally, this pin stays "Low" level for detecting keyboard entry. After a valid
keyboard entry, this pin will output keying confirmation tone that is 600 Hz signal and
30 ms duration. To prevent signal interference, while DTMF issue, it will disable key
tone output except function key.
Oscillator input and output pins. A 3.579545 MHz crystal or ceramic resonator must
be crossed connection to XIN and XOUT pins which generate system clock.
Input/Output structure pin. The output is a open drain structure. Input is schmitt trigger
structure. This pin will be input pin during ON-HOOK status for illegal parallel phone
detect input pin and will be output pin in OFF-HOOK condition for control speech
network.
Positive and negative power supply input pins. Recommended operating voltage from
2.0Vdc to 5.5Vdc.
Handfree inputs pin which accepts falling edge signal to turn "on" or turn "off"
handfree function. This pin is hysteresis input structure and built-in pull up resistor
(typically 200 Kohms).
Handfree outputs pin that is designed to control telephone line for on-hook dialing or
control speakerphone circuit for handfree conversation. When handfree function is
executed, this pin will switch to"High". Otherwise, this pin stays "Low" level.
The DTMF (Dual Tone Multi-Frequency) and music signals output pin. Normally,
this pin stays "Low" level. In Tone dialing mode, this pin will output DTMF signal
that is corresponding to keyboard 0 .. 9, * and # keys.
2.10.1999
3
COL1~COL3
COL4/KT
XIN and XOUT
XMUTE
V
DD
and V
SS
HFI
HFO
DTMF
* This specification are subject to be changed without notice.
~
EMC [ ELAN MICROELECTRONICS CORP ]
