HT9320 datasheet(5/30 Pages) HOLTEK

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Pin Description

Pin Name I/O

Internal

Connection

Description

C1~C8

R1~R5

I/O

CMOS

IN/OUT

These pins form a 5´8 keyboard matrix which can perform

keyboard input detection and dialing specification setting

functions. When on-hook (HKS=high) all the pins are set high.

While off-hook the column group (C1~C8) remains low and the

row group (R1~R5) is set high for key input detection.

For the HT9320L-X, the column group remains high and the

row group is set low for key input detection.

An inexpensive single contact 5´8 keyboard can be used as an

input device. Pressing a key connects a single column to a sin-

gle row, and actuates the system oscillator that results in a di-

aling signal output. If more than two keys are pressed at the

same time, no response occurs. The key-in debounce time is

20ms. Refer to the keyboard information for keyboard ar-

rangement and to the functional description for dialing speci-

fication selection.

OSCILLATOR

The system oscillator consists of an inverter, a bias resistor

and the necessary load capacitor on chip. Connecting a stan-

dard 3.579545MHz crystal or ceramic resonator to the X1 and

X2 terminals can implement the oscillator function. The oscil-

lator is turned off in the standby mode, and is actuated when-

ever a keyboard entry is detected.

XMUTE

NMOS OUT

XMUTE is an NMOS open drain structure pulled to VSS dur-

ing dialing signal transmission. Otherwise, it is an open cir-

cuit. XMUTE is used to mute the speech circuit when

transmitting the dial signal.

HKS

CMOS IN

This pin is used to monitor the status of the hook-switch and its

combination with HFI/HDI can control the PO pin output to

makeorbreaktheline.

HKS=VDD:On-hookstate(PO=low).ExceptforHFI/HDI

(hand-free/hold-lineco ntrolinput),other

functionsarealldisabled.

HKS=VSS:Off-hookstate(PO=high).The chipisinthestand-

bymodeandreadytoreceivethekeyinput.

CMOS OUT

This pin is a CMOS output structure which by receiving the

HKS and HFO/HDO signals, control the dialer to connect or

disconnect the telephone line.

PO outputs a low to break line when HKS is high (on-hook)

and HFO/HDO is low. PO outputs a high to make line when

HKS is low (off-hook) or HFO is high or HDO is high.

During the off-hook state, this pin also outputs the dialing

pulse train in pulse mode dialing. While in the tone mode, this

pin is always high.

HT9320

July 21, 1999

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