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Document Number 82546

Rev. 1.5, 06-Jun-06

TOIM4232

Vishay Semiconductors

Pin Assignment and Description

*) Crystal should be connected as shown in figure 2. In addition connect a 100 k

Ω resistor from Pin 6 to Pin 7 and from Pin 6 and Pin 7 a

22 pF capacitor to ground, respectively. When an external clock is available connect it to Pin 6 leaving Pin 7 open. The external resistor

of 100 k

Ω is used to accelerate the start of oscillation after reset or power - on. The value depends on the "Q" of the resonator. With low

Q resonators it is not necessary. The start - up time of the oscillator is between 30 µs (with piezo resonators) and above 2 ms with high Q

quartzes.

**) All Vishay Semiconductor SIR transceivers fulfill this condition

Pin Number

Symbol

Description

I/O

Active

1

RESET

Resets all internal registers. Initially must be HIGH ("1") to reset internal

registers. When HIGH, the TOIM4232 sets the IrDA default bit rate of 9600

reset signal which allows to shut down of a TFDx4x00 transceiver when

applying the reset signal to the TOIM4232. When using devices with

external SD like TFDS4203, the reset line can be used directly as shut

down signal. RESET pin can be controlled by either the RTS or DTR line

through RS232 level converter. Minimum hold time for resetting is 1 µs.

Disables the oscillator when active.

HIGH

2BR/ D

Baud Rate control/ Data.

BR/ D = 0, data communication mode:

RS232 TXD data line is connected (via a level shifter) to TD_232 input pin.

The TXD - signal is appropriately shortened and applied to the output

TD_IR, driving the TXD input of the IR transceiver. The RXD line of the

transceiver is connected to the RD_IR input. This signal is stretched to the

correct bit length according the programmed bit rate and is routed to the

RS232 RXD line at the RD_232 pin.

BR/ D = 1, Programming mode:

Data received from the RS232 port is interpreted as Control Word. The

Control Word programs the baud rate width will be effective as soon as BR/

D return to LOW.

3

RD_232

Received signal data output of stretched signal to the RS232 RXD line

(using level converter).

OHIGH

4

TD_232

Input of the signal to be transmitted from the RS232 port TXD line (passing

the level converter).

IHIGH

Outputs an inverted RESET signal. Can be used to shut down the power

output function. This pin can be used to shut down a transceiver (e.g.,

TFDx4xxx). Output polarity: Inverted RESET input.

OLOW

6

X1

Crystal input clock, 3.6864 MHz nominal. Input for external clock *)

I

7X2

Crystal *)

I

8

GND

Ground in common with the RS232 port and IrDA transceiver ground

9

TD_LED

Transmit LED indicator driver. Use 180

Ω current limiting resistor in.series

OLOW

10

RD_LED

Receive LED indicator driver. Use 180

Ω current limiting resistor in series

OLOW

11

NC

No connection

12

S1

User Programmable Bit. Can be used to turn ON/ OFF a front-end infrared

transceiver (e.g., an infrared module at the adapter front)

OLOW

13

S2

User Programmable Bit. Can be used to turn ON/ OFF a front-end infrared

transceiver (e.g., an infrared module at the adapter back)

OLOW

14

TD_IR

Data output of shortened signal to the infrared transceiver

O

HIGH

15

RD_IR

Data input from the infrared transceiver, min. pulse duration 1.63 µs **)

I

LOW

16

VCC

Supply voltage

I