TOIM4232 datasheet(4/14 Pages) VISHAY

4 / 14 page

www.vishay.com

Document Number 82546

Rev. 1.5, 06-Jun-06

TOIM4232

Vishay Semiconductors

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 chan-

nels 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 pro-

grammed 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 rec-

ommended using 1.627 µs output pulses to save bat-

tery 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 con-

sumes more power than the shorter pulse. At a

data rate of 9600 bit/s, the ratio of power con-

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

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.

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)

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)

Input leakage no pull-up/down

VIN = VDD or GND

- 10

± 1

μA

Output HIGH voltage

IOH = - 2.0 mA

VOH

2.0

IOH = - 0.5 mA

VOH

2.4

Output LOW voltage

IOL = + 2.0 mA

VOL

0.4

Consumption current standby

inputs grounded, no output load

VCC = 3.3 V, T = 25 °C

ISB

1µA

Consumption current dynamic

inputs grounded, no output load

VCC = 3.3 V, T = 25 °C

ICC

2mA

Parameter

Test Conditions

Symbol

Min

Typ.

Max

Unit

First Character

Second Character

LSB

TOIM4232 Datasheet(PDF) 4 Page - Vishay Siliconix

TOIM4232 Datasheet(HTML) 4 Page - Vishay Siliconix

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Datasheet Download

Link URL