toim4232-tr1 Vishay, toim4232-tr1 Datasheet - Page 4

• Manufacturer Part Number: toim4232-tr1
• Description: Sir Endec For Irda Applications Integrated Interface Circuit
• Manufacturer: Vishay

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.
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4
Input leakage no pull-up/down
Output HIGH voltage
Output LOW voltage
Consumption current standby
Consumption current dynamic
Parameter
V
I
I
I
inputs grounded, no output load
V
inputs grounded, no output load
V
OH
OH
OL
IN
CC
CC
= + 2.0 mA
= V
= - 2.0 mA
= - 0.5 mA
= 3.3 V, T = 25 °C
= 3.3 V, T = 25 °C
DD
Test Conditions
or GND
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)
Symbol
X
V
V
V
I
I
CC
I
SB
OH
OH
OL
L
First Character
S2
S1
- 10
Min
2.0
2.4
S0
Typ.
± 1
2
B3
Document Number 82546
Second Character
B2
Max
0.4
10
Rev. 1.5, 06-Jun-06
1
B1
Unit
mA
PA
µA
V
V
V
LSB
B0