em91401 ELAN Microelectronics Corp, em91401 Datasheet - Page 3

• Manufacturer Part Number: em91401
• Description: Tone/pulse Switchable Dialer With Lcd Interface And Dual-tone Melody Generator
• Manufacturer: ELAN Microelectronics Corp

FUNCTIONAL BLOCK DIAGRAM
PIN DESCRIPTIONS
* This specification are subject to be changed without notice.
ROW1~ROW4
COL1~COL3
COL4/KT
XIN and XOUT
XMUTE
V
HFI
HFO
DTMF
DD
Symbol
and V
SS
COL4/KT
XOUT
ROW1
ROW2
ROW3
ROW4
COL1
COL2
COL3
COL5
XIN
Keyboard scan pins of column group. In idle state, these pins stay “High impedance”
Keyboard
Keyboard
Keyboard scan pins of row group. In idle state (HKS is “High” and HFO is “Low”),
these pins stay “High impedance” level to prevent power consumption. Otherwise,
these pins switch to “High” level for detecting keyboard entry. These pins will output
600 Hz signal while keyboard is scanning.
level. Otherwise these pins switch to “Low” 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.
The Tone/Pulse MUTE signal output pin that is NMOS open-drain output structure.
This pin will switch to “Low” level during Tone/Pulse dialing and hold function .
Otherwise, this pin stays “High impedance” level.
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. Beside this, in the line hold
duration, this pin will issue dual-tone music for telephone line.
Oscillator
interface
(column)
interface
(Row)
VDD
SDO
Timing/Control circuit
HFO HDO
HFI
Output circuit
Input circuit
TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE
HKS
RMUTE
(Melody)
Memory
DRING
XMUTE
Function
VDD
decoder
generator
latch
programming counter
Pulse
&
AND DUAL-TONE MELODY GENERATOR
Row/Column
converter
D/A
PO
DTMF
EM91401 SERIES
10.1.1997
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