W91550DN datasheet(3/32 Pages) WINBOND

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W91550DN SERIES

Publication Release Date: November 1997

- 3 -

Revision A3

PIN DESCRIPTION

SYMBOL

I/O

FUNCTION

Column,

Row

Inputs

−49

−53

The keyboard input may be used with either the standard 4

× 7

keyboard, an inexpensive single contact (form A) keyboard or

electronic input.

A valid key entry is defined by a single row being connected to a

single column.

XT, XT

54, 55

I, O A built-in inverter provides oscillation with an inexpensive

3.579545MHz crystal. Most crystals do not vary by more than 0.02%.

The oscillator oscillates in off-hook or handfree mode but oscillation

ceases in on-hook mode or when the handfree mode is released.

T/P MUTE

The T/P MUTE is a conventional CMOS N-channel open drain

output. The output transistor is switched on during pulse and tone

mode dialing sequences and flash breaks. Otherwise, it is switched

off.

HPM MUTE

The HPM MUTE is a conventional CMOS inverter output. During

pulse dialing, flash break, hold, and mercury mute functions, this pin

will output an active high. Otherwise, it remains in a low state.

KMUTE

The KMUTE is a CMOS N-channel open drain output. The output

transistor is switched on only during the mute function. Otherwise, it is

switched off.

MODE

Pulling mode pin to VSS places the dialer in tone mode.

Pulling mode pin to VDD places the dialer in pulse mode.

Pulse or tone mode can be selected any time.

HKS

Hook switch input.

HKS

= VDD: On-hook state. Chip in sleeping mode, no operation.

HKS

= VSS: Off-hook state. Chip enable for normal operation.

HKS

pin is pulled to VDD by internal resistor.

This pin is a CMOS inverter output. The timing diagram is shown as

Figure 1(a), 1(b), 1(c), 1(d). Flash key will cause DP to go active in

either pulse mode or tone mode.

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