VISHAY TOIM4232 Technical data

SIR Endec for IrDA Applications
Integrated Interface Circuit

Description

The TOIM4232 Endec IC provides proper pulse shap­ing for the SIR IrDA
as of the 4000-series. For transmitting the TOIM4232
shortens the RS232 output signal to IrDA compatible
electrical pulses to drive the infrared transmitter. In
the receive mode, the TOIM4232 stretches the
received infrared pulses to the proper bit width
depending on the operating bit rate. The IrDA bit rate
varies from 2.4 kbit/s to 115.2 kbit/s.The TOIM4232 is
using a crystal clock 3.6864 MHz for its pulse stretch­ing and shortening. The clock can be generated by
the internal oscillator. An external clock can be used,
too. The TOIM4232 is programmable to operate from
1200 bit/s to 115.2 kbit/s by the communication soft­ware through the RS232 port. The output pulses are
software programmable as either 1.627 µs 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.

ULC Technology: High performance gate array
package using multiple metal layer CMOS technology
featuring sub-micron channel lengths (0.35 µm).

®

front end infrared transceivers

TOIM4232

Vishay Semiconductors

18080

Features

• Pulse shaping function (shortening
and stretching) used in SIR IrDA
applications

• Directly interfaces the SIR transceiver
TFD..- and TFB..- series to an RS232 port

• Programmable baud clock generator (1200 Hz to

115.2 kHz), 13 baud rates

• 3/16 bit pulse duration or 1.627 µs pulse select­able

• SO16 - package

• 2.7 V to 3.6 V operation voltage, 5 V tolerant inputs

• Low operating current

• Lead (Pb)-free device

• Device in accordance to RoHS 2002/95/EC and
WEEE 2002/96EC

®

e3

Ordering Information

Part Number Qty / Reel

TOIM4232-TR1 500 pcs

Block Diagram

Document Number 82546

Rev. 1.4, 07-Dec-05

TD_232

RD_232

BR/D

RESET

GND

Vcc

Endec

Baud
Generator

Logic

Osci llator

X1

TD_IR

RD_IR

TD_LED

RD_LED
S1

S2

Vcc_SD

X2

18079

www.vishay.com

1

TOIM4232

Vishay Semiconductors

Pin Assignment and Description

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
bit/s, sets pulse width to 1.627 µs. The V

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.

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.

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/

3 RD_232 Received signal data output of stretched signal to the RS232 RXD line

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

5V

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

10 RD_LED Receive LED indicator driver. Use 180 Ω current limiting resistor in series

11 NC No connection

12 S1 User Programmable Bit. Can be used to turn ON/ OFF a front-end infrared

13 S2 User Programmable Bit. Can be used to turn ON/ OFF a front-end infrared

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

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

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

CC

supply of a 4000 series transceiver (e.g., TFDU4100). V

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

TFDx4xxx). Output polarity: Inverted RESET input.

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

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

BR/ D = 1, Programming mode:

D return to LOW.

(using level converter).

the level converter).

to LED to connect to V

to LED to connect to V

_SD output is simply an inverted

CC

shutdown

CC

. (VCC = 3.3 V)

CC

. (VCC = 3.3 V)

CC

OHIGH

IHIGH

OLOW

OLOW

OLOW

OLOW

OLOW

HIGH

www.vishay.com

2

Document Number 82546

Rev. 1.4, 07-Dec-05

TOIM4232

Vishay Semiconductors

Block diagram of application circuit

Operating the interface circuit at a PC COM - port.
When operating directly with an UART with 3 V - or
5 V - logic, in the application circuit no level converter
is necessary.

DTR

RTS

TXD

RXD

RS232 9 pin
connector

18081

Level
converter

RESET VCC_SD

BR/D TD_IR

TD_232 RD_IR

RD_232

TOIM4232

X1

C1

R1

100 kΩ

3.6864 MHz

2x22pF

VCC

TXD

RXD

TFDU4100

X2

TFDS420x
TFDU4300

C2

Table 1.
Recommended Application Circuit Components

Component Recommended Value Vishay Part Number

C1 22 pF VJ 1206 A 220 J XAMT

C2 22 pF VJ 1206 A 220 J XAMT

R1 100 kΩ CRCW-1206-1003-F-RT1

Quartz Crystal 3.686400 MHz XT49S - 20 - 3.686400M

Absolute Maximum Ratings

Parameter Test Conditions Symbol Min Ty p. Max Unit

Supply voltage V

CC

- 0.5 3.6 V

Input voltage all pins - 0.5 5.5 V

Output voltage all pins - 0.5 V

Output sinking current, max all pins I

Junction temperature, max T

Ambient temperature
(operating)

Storage temperature T

Soldering temperature T

O

J

T

amb

stg

sldr

- 25 85 °C

- 25 85 °C

+ 0.5 V

CC

8mA

125 °C

260 °C

DC Characteristics

Parameter Test Conditions Symbol Min Ty p. Max Unit

Operating voltage V

VCC = 3.3 V ± 5 %, operating temperature = - 55 °C to + 125 °C

Parameter Test Conditions Symbol Min Ty p. Max Unit

Input HIGH voltage inputs tolerate levels as high as

5.5 V max. all inputs are Schmitt
trigger inputs

Input LOW voltage V

Input Schmitt trigger hysteresis V

V

CC

IH

IL

hyst

2.7 3.3 3.6 V

1.7 2.0 V

0.8 1.1 V

0.6 V

Document Number 82546

Rev. 1.4, 07-Dec-05

www.vishay.com

3

TOIM4232

Vishay Semiconductors

Parameter Test Conditions Symbol Min Ty p. Max Unit

Input leakage no pull-up/down VIN = VDD or GND I

Output HIGH voltage I

Output LOW voltage I

Consumption current standby inputs grounded, no output load

Consumption current dynamic inputs grounded, no output load

= - 2.0 mA V

OH

I

= - 0.5 mA V

OH

= + 2.0 mA V

OL

V

= 3.3 V, T = 25 °C

CC

V

= 3.3 V, T = 25 °C

CC

L

OH

OH

OL

I

SB

I

CC

- 10 ± 1 10 µA

2.0 V

2.4 V

0.4 V

1µA

2mA

Operation Description

Figure 2 shows a typical example of an RS232 port
interface. The TOIM4232 connects to an RS232 level
converter on one side, and an infrared transceiver on
the other. The internal TOIM4232 baud rate generator
can be software controlled.

When BR/D = 0, the TOIM4232 interprets the chan­nels TD_232 to TD_IR and RD_IR to RD_232 as data
channels.

On the other hand, whenever BR/D = 1, the
TOIM4232 interprets TD_232 as Control Word for
setting the Baud rate. The Baud rate can be pro­grammed to operate from 1200 bit/s to 115.2 kbit/s.
As RS232 level converter, EIA232 or MAX232 or
equivalent are recommended.

When using the TOIM4232 directly connected to an
UART it is compatible to 5 V TTL and 3.3 V CMOS
logic.

Typical external resistors and capacitors are needed
as shown in the TFDx4xxx references.

The output pulse duration can also be programmed,
see chapter "Operation Description". It is strongly rec­ommended using 1.627 µs output pulses to save bat­tery power. As frequency determining component a
Vishay XT49M Crystal is recommended, when no
external clock is available.

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 (!).

In this case the TOIM4232 interprets the 7 LSBs at
the TD_232 input as a 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.

Control Byte (8 bit)

First Character Second Character

X S2 S1 S0 B3 B2 B1 B0

LSB

X: Do not care
S1, S2: User programmble bit to program the outputs
S1 and S2
S0: Irda pulse select
S0 = (1): 1.627 µs pulses
S0 = (0): 3/16 bit time pulses, not recommended
B0 .. B3: Baud rate select words

Example:
To set TOIM4232 at COM2 port (2F8) to 9600 bit/s
with 3/16 bit time pulse duration send to the
TOIM4232 in programming mode in e.g. "Basic"

OUT &H2F8, (&H6)

For same port, 9600 bit/s and 1.627 µs pulse duration
send

OUT &H2F8, (&H16)

For additionally activating S1 send

OUT &H2F8, (&H36)

Programming the TOIM4232

For correct, data rate dependent timing the
TOIM4232 is using a built-in baud rate generator.
This is used when no external clock is not available as
in RS232 IR-dongle applications. For programming
the BR/D pin has to be set active, BR/D = 1.

www.vishay.com

4

Document Number 82546

Rev. 1.4, 07-Dec-05

Baud Rate Select Words

B3 B2 B1 B0

00000 115.2 k

0011 57.6 k

0102 38.4 k

0113 19.2 k

1004 14.4 k

1015 12.8 k

1106 9.6 k

1117 7.2 k

10008 4.8 k

0019 3.6 k

010A 2.4 k

011B 1.8 k

100C 1.2 k

101D forbidden

110E forbidden

111F forbidden

Note: IrDA standard only supports 2.4, 9.6, 19.2, 57.6, and 115.2 kbit/s.

2nd

Char

Baud Rate

TOIM4232

Vishay Semiconductors

Software for the TOIM4232
UART Programming

For proper operation, the RS232 must be programmed (using 8 bit, 1 stop, no parity) to send a two character control word, YZ. The control
word YZ is composed of two characters, written in hexadecimal, in format: YZ. The transfer rate for programming must be identical with
the formerly programmed data rate, or after resetting the TOIM4232, the default rate of 9600 bit/s is used.

Step. RESET BR/ D TD_UART RD_UART RD_IR TD_IR Description and Comments

1HighXXXXXResets all internal registers. Resets to

2LowXXXXXWait at least 2 ms, to allow start-up of

3LowHighXXXXWait at least 7 µs. TOIM4232 now is set

4LowHighYZ

with Y = 1

for 1.627 µs

Y = 0

3/16 bit

length

5 Low Low DATA DATA DATA DATA With BR/D = 0, TOIM4232 is in the data

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

X X X Sending the Control Word YZ.

IrDA default data rate of 9600 bit/s

internal clock. When external clock is

used: Wait at least 7 µs.

to the Control Word programming mode

Examples: Send "1Z" if 1.627 µs pulses

are intended to be used. Otherwise

send "0Z" for 3/16 bit period pulses.

"Y6" keeps the 9.6 kbit/s data rate.

Z = 0 sets to 115.2 kbit/s, see

programming table.

Wait at least 1 µs for hold-time.

communication mode. Both RESET

and BR/D must be kept LOW ("0")

during data transmission.

Reprogramming to a new data rate can

be resumed by restarting from step 3.

The UART itself also must set to the

correct data rate *).

Document Number 82546

Rev. 1.4, 07-Dec-05

www.vishay.com

5