TOIM5232

www.vishay.com

Vishay Semiconductors

Rev. 1.3, 04-Jul-12

9

Document Number: 81749

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

Note

X: do not care



S1, S2: user-programmable bit to program the outputs S1 and S2. In

the example, S1 is set active, and S2 is inactive.



S0: IrDA pulse select



S0 = (1): 1.627 µs output



S0 = (0): 3/16 bit time pulses, not recommended



B0 to B3: baud rate select words according to the following table

below.

Notes

Bold: See example



IrDA standard only supports 2.4 kbit/s, 9.6 kbit/s, 19.2 kbit/s,

57.6 kbit/s, and 115.2 kbit/s (3.6864 MHz clock). Doubling the baud

rates is permissible by doubling the clock frequency.

In figure 2 the programming sequence is shown for a bit rate

of 12.8 kbit/s.

Fig. 2 - Programming sequence for setting the endec to a bit rate

of 12.8 kbit/s. After setting BR/D high (Ch1), the programming

sequence with the control byte (Ch2) is applied to TD_232, pin 4.

Fig. 3 - Programming sequence for setting the endec to a bit rate of

12.8 kbit/s as in figure 2 but with a 3/16 bit pulse duration (S0 = “0”).

When correctly programmed, the endec shortens the pulse

to be transmitted from the full bit duration to either 3/16 of the

bit length or to 1.627 µs (which is 3/16 of the 115.2 kbit/s bit

duration).

For

power

saving,

the

short

pulse

is

recommended.



The received optical pulse shows in case of most of the

Vishay SIR transceivers, constant pulse duration. The endec

stretches that to the correct bit time according the bit rate

setting. This is shown in the following chapters.

TABLE 1 - CONTROL BYTE (8 BIT)

FIRST CHARACTER

SECOND CHARACTER

STA

X

S2

S1

S0

B3

B2

B1

B0

0

MSB

LSB

Example

0

01

1

01

01

0

In the oscilloscope that will be shown in the reserved order with

LSB first, see figure 2.

STA

FIRST CHARACTER

SECOND CHARACTER

0

B0

B1

B2

B3

S0

S1

S2

X

LSB

MSB

Example

01

01

011

0

0

TABLE 2 - TRANSMISSION RATE SELECT

WORDS

B3

B2

B1

B1

HEX

BIT RATE

0

0

0

0

0

115.2 kHz

0

0

011

57.6 kHz

0

01

02

38.4 kHz

0

0113

19.2 kHz

01

0

0

4

14.4 kHz

01

0

1

5

12.8 kHz

01

1

0

6

9.6 kHz

0

1117

7.2 kHz

1

0

0

0

8

4.8 kHz

1

0

0

1

9

3.6 kHz

1

010

A

2.4 kHz

1

011

B

1.8 kHz

11

0

0

C

1.2 kHz

Example

0

01

0

0

1

01

0

MSB

LSB

STA

1->

2->

21038

1) Ch1: BR/D; pin 2, vertical scale: 2 V/div., horizontal scale: 200 µs/div.

2) Ch2: TD_232; pin 4; programming sequence

1->

2->

1) Ch1: BR/D, pin 2, vertical scale: 2 V/div.,

horizontal scale: 200 µs/div.

2) Ch2: TD_232, pin 4; programming sequence

21030

STA 1

0

1

0

0

1

0

0