TOIM3000
Vishay Telefunken
Rev. 1, 01-Apr-99
2
www.vishay.de
FaxBack +1-408-970-5600
Document Number 82520
Pin Assignment and Description
Pin
1
Symbol
RESET
Function
I/O
I
Active
Resets all internal registers. Initially must be HIGH to reset internal
registers. When LOW, the TOIM3000 connects the UART to the IrDA
transceiver. Data from the UART are transmitted by the infrared trans-
mitter. Data received from the infrared receiver is routed to the UART.
When HIGH, the TOIM3000 connects the UART to the RS232 port.
Minimum hold time for reset is 1 s.
RD_UART Data channel, output to the UART
TD_UART Data out channel, data input from the UART to be transmitted
B_CLK
16 times baud rate clock, input from the UART (Baudout)
XIN
Oscillator input, 1.8432 MHz clock
(to be connected to Xout pin of the UART)
NC
Not connected
NC
Not connected
GND
Ground in common with the UART and RS232 port
S0
Must be connected to GND
S1
Must be connected to GND for output pulse length of 1.627 s,
Connected to V
CC
for pulse length of 3/16 of bit
*)
TD_232
Transmit data input from the RS232 port, TXD pin
RD_232
Receive data output to the RS232 port, RXD pin
NC
Not connected
TD_IR
Data output to infrared transmitter (e.g., TFDS4000)
RD_IR
Data receive input from the infrared transmitter (e.g., TFDS4000)
V
CC
Supply voltage
2
3
4
5
O
I
I
I
LOW
LOW
6
7
8
9
10
I
I
11
12
13
14
15
16
I
LOW
LOW
O
O
I
HIGH
LOW
*)
The use of a pulse length of 3/16 of bit duration is not recommended when both clocks, Xout and Baud-
out, of the UART are available.
Operation Description
Features of TOIM3000
The TOIM3000 uses 2 clocks from the UART: the
1.8432 MHz clock and the Baud_out clock for its inter-
nal timing processing. Both are connected to XIN and
B_CLK, respectively. The B_CLK is used as a refer-
ence for pulse stretching while XIN is taken as a time
base for pulse shortening to 1.627 s and noise filter-
ing.
Single clock operation
TOIM3000 can be operated with only a single clock. In
this case, the B_CLK and XIN are tied together and
connected to the Baudout pin of the UART. The pulse
width is then shortened to 3/16 of the bit length and
noise filtering is deactivated. S1 is to be connected to
V
CC
and S0 to GND.
We strongly recommend not to use this mode be-
cause the 3/16 pulse length at lower bit rates
consumes more power than the shorter pulse. At
a baud rate of 9600 bit/s, the ratio of power con-
sumption of both modes is a factor of 12 (!).
The TOIM3000 interfaces additionally to an RS232
level converter through two pins, RD_232 and
TD_232. These two pins provide the extra IR function
that a single TOIM3000 IC can time share with both an
infrared IrDA port and an RS232 port. Whenever RE-
SET = 0, the TOIM3000 links to the infrared
transceiver of the TFDS4000 series through RD_IR
and TD_IR pins. On the other hand, when RESET = 1,
the TOIM3000 links to the RS232 port through
RD_232 and TD_232 pins (see figure 2).