IR Adapters at the serial port toim3232.pdf

Not for new designs

TOIM3232

Vishay Telefunken

Integrated Interface Circuits

ULC Technology:

High-performance gate array package using dual metal layer CMOS technology,

featuring sub-micron channel length (0.8 m)

Description

The TOIM3232 IC provides proper pulse shaping for

the front end infrared transceivers of the 4000-series

(4000-series devices are infrared transceiver

compliant to the IrDA standard made by Vishay

Telefunken), as specified by the IrDA standard. In the

transmit mode, the TOIM3232 shortens the RS232

output signal to IrDA compatible electrical pulses to

drive the infrared. In the receive mode, the TOIM3232

stretches the received infrared pulses to the proper bit

width at the operating bit rate. The IrDA bit rate varies

between 2.4 kbit/s to 115.2 kbit/s.

The TOIM3232 is using a crystal clock 3.6864 MHz for

its pulse stretching and shortening. The clock can be

generated by the internal oscillator or an external clock

can be used, too. The TOIM3232 is programmable to

operate from 1200 bit/s to 115.2kbit/s by the

communication software through the RS232 port. The

output pulses are software programmable as either

1.627 s or 3/16 of bit time. The typical power

consumption is very low with about 10 mW in

operational state and in the order of a few microwatts

in standby mode.

Pulse shaping function (shortening and stretching)

used in infrared IrDA standard applications

Programmable baud clock generator

(1200 Hz to 115 kHz), 13 baud rates

Directly interfaces the infrared transceiver

TFDx4xxx series to RS232 port

SO16L package

3 V and 5 V operation

Low operating current

Block Diagram

V CC

TD_232

Pulse

shaper

TD_IR

RD_232

RD_IR

TD_LED

BR/D

Clock

generator

Logic

RD_LED

RESET

V CC _SD

Oscillator

GND

Figure 1. Block diagram

Document Number 82521

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Rev. A1.1, 02-Apr-01

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Features

TOIM3232

Vishay Telefunken

Not for new designs

Pin Assignment and Description

Symbol

Function

I/O Active

RESET Resets all internal registers. Initially must be HIGH (“1”) to reset internal

registers. When HIGH, the TOIM3232 sets the IrDA default bit rate of

9600, sets pulse width to 1.627 s. Then the TOIM3232 enters the

front-end (TFDS400) power saving mode by setting VCC _ SD low and

therefore switching off the transceiver. When RESET returns to LOW,

the TOIM3232 sets VCC_SD HIGH switching on the front-end device,

and sets the new baud rate in the 1.627 s pulse width mode. In the

application the RESET pin can be controlled by either the RTS or DTR

line through RS232 level converter. Minimum hold time for reset: 1 s.

HIGH

BR/ D

Baud Rate control/ Data.

When BR/ D = 0, RD_232 data is transmitted to the IrDA transmitter pin

TD_IR, while RD_IR is routed to the transmitter pin TD_232. When

BR/ D = 1, data received from the RS232 port is interpreted as the

Control Word. The Control Word programs the baud rate and pulse

width will be effective as soon as BR/ D return to LOW.

RD_232 Received signal data output of stretched signal to the RS232 port

(using level converter).

HIGH

TD_232 Input of the signal to be transmitted from the RS232 port (passing the

level converter).

HIGH

V CC _SD V CC shutdown output function. This pin can be used to shut down a

transceiver (e.g., TFDx4xxx). Output polarity: Inverted RESET input.

LOW

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

Crystal *)

GND

Ground in common with the RS232 port and IrDA transceiver ground

TD_LED Transmit LED indicator driver. Use 270 current limiting resistor in

series to LED to connect to V CC. (V CC = 5 V)

LOW

RD_LED Receive LED indicator driver. Use 270 current limiting resistor in

series to LED to connect to V CC. (V CC = 5 V)

LOW

No connection

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

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

LOW

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

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

LOW

TD_IR Data output of shortened signal to the infrared transceiver TFDx4xxx

HIGH

RD_IR Data input from the infrared transceiver TFDx4xxx

LOW

V CC

Supply voltage

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

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Rev. A1.1, 02-Apr-01

Not for new designs

TOIM3232

Vishay Telefunken

Operation Description

Figure KEIN MERKER shows a typical example of an

RS232 port interface. The TOIM3232 connects to an

RS232 level converter on one side, and an infrared

transceiver on the other. Software can be written to

program the TOIM3232 baud rate generator. When

BR/D = 0, the TOIM3232 interprets TD_232 data as

data transmitted to the TFDS4000. On the other hand,

whenever BR/D = 1, the TOIM3232 interprets

TD_232 as Control Word. Baud rate can be

programmed to operate from 1200 bit/s to 115 kbit/s.

As RS232 level converter, EIA232 or MAX232 or

equivalent are recommended.

Typical external resistors and capacitors are needed

as shown in the TFDx4xxx references.

The output pulse length can be programmed, see

chapter “Operation Description”. To use 1.627 s

output pulses is strongly recommended to save

battery power. A resonator like a Matura Ceramic

Resonator (CERALOCK )

Control Byte (8 bit)

First Character

Second character

LSB

where

Do not care

S1, S2:

User programmable bit to program the

outputs S1 and S2

S0:

IrDA pulse select

= (1) 1.627 s output pulses

= (0) 3/16 bit time pulses,

not recommended

B0 .. B3:

Baud rate select words

) CSAC3.68MGC-TC is

Baud Rate Select Words

recommended.

We strongly recommend not to use this 3/16 mode

because 3/16 pulse length at lower bit rates

consumes more power than the shorter pulse. At

a data rate of 9600 bit/s, the ratio of power

consumption of both modes is a factor of 12 (!).

Note:

IrDA standard only supports 2.4, 9.6, 19.2, 57.6, and

115.2 kbit/s.

2nd

Char

Baud

Rate

Features of TOIM3232

The baud rate at which an RS232 serial port

communicates with the external adapter is

programmable inside the TOIM3232. This

programmable baud rate is especially useful when the

baud clock and the UART oscillator clock are not

available and must be regenerated. When BR/D = 0,

the TOIM3232 interprets the signals at TD_232 as

transmit and RD_IR as received data. On the other

hand, whenever BR/D = 1, the TOIM3232 interprets

the 7 LSBs at the TD_232 input as the Control Word.

The operating baud rate will change to its supposedly

new baud rate when the BR/D returns back to

LOW (“0”) Set the UART to 8 bit, no parity, 1 stop bit.

0 ÁÁÁ

0 ÁÁÁÁ

0 ÁÁÁ

0 ÁÁÁÁ

115.2 k

0 ÁÁÁ

0 ÁÁÁÁ

1 ÁÁÁ

1 ÁÁÁÁ

57.6 k

0 ÁÁÁ

1 ÁÁÁÁ

0 ÁÁÁ

2 ÁÁÁÁ

38.4 k

0 ÁÁÁ

1 ÁÁÁÁ

1 ÁÁÁ

3 ÁÁÁÁ

19.2 k

14.4 k

0 ÁÁÁ

1 ÁÁÁ

0 ÁÁÁÁ

1 ÁÁÁ

5 ÁÁÁÁ

12.8 k

0 ÁÁÁ

1 ÁÁÁ

1 ÁÁÁÁ

0 ÁÁÁ

6 ÁÁÁÁ

9.6 k

0 ÁÁÁ

1 ÁÁÁ

1 ÁÁÁÁ

1 ÁÁÁ

7 ÁÁÁÁ

7.2 k

1 ÁÁÁ

0 ÁÁÁ

0 ÁÁÁÁ

0 ÁÁÁ

8 ÁÁÁÁ

4.8 k

1 ÁÁÁ

0 ÁÁÁ

0 ÁÁÁÁ

1 ÁÁÁ

9 ÁÁÁÁ

3.6 k

1 ÁÁÁ

0 ÁÁÁ

1 ÁÁÁÁ

0 ÁÁÁ

A ÁÁÁÁ

2.4 k

1.8 k

1.2 k

Document Number 82521

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TOIM3232

Vishay Telefunken

Not for new designs

Software for the TOIM3232

The control word is composed of two characters, written in hexadecimal, in format: YZ.

UART Programming

For proper operation, the RS232 must be programmed

to send a START bit plus an 8 bit data word, YZ and

no STOP bit for every word sent. The transfer rate for

programming must be identical with the formerly

programmed data rate, or after resetting the

TOIM3232, the default rate of 9600 bit/s is used.

Software algorithm

Step RESET BR/D RD_UART TD_UART RD_IR TD_IR

Comments

1 ÁÁÁÁ

HIGH ÁÁÁÁ

X ÁÁÁÁÁ

X ÁÁÁÁ

Resets all internal registers. Resets

IrDA default data rate of 9600 bit/s.

2 ÁÁÁÁ

LOW ÁÁÁÁ

X ÁÁÁÁÁ

X ÁÁÁÁ

X ÁÁÁÁÁÁÁÁÁÁÁÁ

Wait at least 7 s.

3 ÁÁÁÁ

LOW ÁÁÁÁ

HIGH ÁÁÁÁÁ

X ÁÁÁÁ

X ÁÁÁÁÁÁÁÁÁÁÁÁ

Wait at least 7 s.

The TOIM3232 now enters the

Control Word (programming) mode.

4 ÁÁÁÁ

LOW ÁÁÁÁ

HIGH ÁÁÁÁÁ

with Y = 1

for

1.627 s

Y = 0

for 3/16 bit

length

X ÁÁÁÁ

Sending the Control Word YZ.

Send ‘1Z’ if 1.627 s pulses are

used. Otherwise send ‘0Z’ if 3/16 bit

pulses are used. ‘Y6’ keeps the 9.6

kbit/s data rate, whereas the ’0Z’

selects the 3/16 bit length pulses.

Z = 0 sets to 115.2 kbit/s. Wait at

least 1 s for hold-time.

5 ÁÁÁÁ

LOW ÁÁÁÁ

LOW ÁÁÁÁÁ

DATA

DATA ÁÁÁÁ

DATA ÁÁÁÁÁÁÁÁÁÁÁÁ

Data communication between the

TOIM3232 and the RS232 port has

been established by BR/D LOW.

The TOIM3232 now enters the data

transmission mode. Both RESET

and BR/D must be kept LOW (‘0’)

during data mode. Software can

reprogram a new data rate by

restarting from step 3.

The UART also must be set to the

correct data rate *).

For programming the UART, refer to e.g., National Semiconductor’s data sheet of PC 16550 UART.

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Document Number 82521

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TOIM3232

Vishay Telefunken

Absolute Maximum Ratings

Parameter

Symbol Min.

Typ.

Max.

Unit

Supply voltage

V CC

– 0.5

+ 7

Input/ output voltage

all pins

– 0.5 ÁÁÁÁ

V CC + 0.5 ÁÁÁÁ

Output sinking current all pins

I out ÁÁÁ

8 ÁÁÁÁ

Junction temperature

T j

125

Ambient temperature (operating)

T amb ÁÁÁ

0 ÁÁÁÁ

70 ÁÁÁÁ

Storage temperature

T stg ÁÁÁ

– 25 ÁÁÁÁÁÁÁÁ

+ 85 ÁÁÁÁ

Soldering temperature t = 20 s @ 215

T sld

215

230

DC Characteristics

V CC = 5 V

10% **), operating temperature 0 70

Parameter

Test Conditions

Symbol Min.

Typ. Max.

Unit

Input HIGH voltage

V IH ÁÁÁ

2.2 ÁÁÁÁ

Input LOW voltage

V IL ÁÁÁ

0.8 ÁÁÁÁ

Schmitt trigger

Positive threshold

Negative threshold

V T+

V T–

1.1

1.4

Input leakage

no pull-up/ down

V IN = V DD or GND

I L

Output HIGH voltage ÁÁÁÁÁÁÁÁÁÁÁÁ

I OH = –3.2 mA

V OH ÁÁÁ

2.4 ÁÁÁÁ

Output LOW voltage ÁÁÁÁÁÁÁÁÁÁÁÁ

I OL = + 3.2 mA

V OL ÁÁÁ

0.4 ÁÁÁÁ

Current consumption

Standby

Dynamic

Inputs grounded, no output load *)

V CC = 5 V, T = 25

I SB

I DD

Oscillator inactivated.

**)

Operation at V CC = 3 V is also specified. For data compare TEMIC Matra MHS ULC technology data sheet.

Application

RS232 9 pin

connector

Level

converter

TOIM3232

TFDS4000

Table 1. Recommended Application Circuit Components

Compo-

nent

Recom-

mended

Value

Vishay Part Number

DTR

RESET

VCC_SD

VCC

RTS

BR/D

TD_IR

TxD

22 pF

VJ 1206 A 220 J XAMT

TxD

TD_232

RD_IR

RxD

22 pF

VJ 1206 A 220 J XAMT

RxD

RD_232

100 k

CRCW–1206–1003–F–RT1

Crystal 3.684 MHz

100 k

3.6864 MHz

2 x 22 pF

Figure 2. RS232 Port interface

(external infrared adapter)

Document Number 82521

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