EM91450 SERIES
TONE/PULSE DIALER WITH LCD INTERFACE
AND I.P.P. DETECT FUNCTION
FUNCTIONAL BLOCK DIAGRAM
HFO
SDO
HDO RMUTE
Keyboard
interface
(column)
COL1
COL2
Row/Column
programming counter
Output circuit
COL3
COL4/KT
latch
Memory
D/A
&
DTMF
I/O circuit
Oscillator
XMUTE
converter
decoder
XIN
XOUT
Timing/Control circuit
Input circuit
Keyboard
interface
(Row)
ROW1
ROW4
Pulse
generator
PO
VDD
HKS
DRING
HFI
PIN DESCRIPTIONS
Symbol
Function
ROW1~ROW4
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.
COL1~COL3
COL4/KT
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.
XIN and XOUT
XMUTE
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.
VDD and VSS
HFI
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).
HFO
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.
DTMF
* This specification are subject to be changed without notice.
2.10.1999
3
ELAN [ ELAN MICROELECTRONICS CORP ]
