TFDU4100/TFDS4500/TFDT4500

TELEFUNKEN

Semiconductor

Pending—Rev. A, 03-Apr-98

5

Pre-Release Information

Optoelectronic Characteristics (Cont’d)

Parameter

Symbol

Unit

Transmitter

Current limiting resistor is series to

0.3

0.4

A

Logic Low Transmitter Input Voltage

0

0.8

V

Logic High Transmitter Input Voltage

2.4

V

Current limiting resistor in series to

±15_

45

140

200

mW/sr

Output Radiant Intensity

Logic Low Level

0.04

mW/sr

Angle of Half Intensity

α

±24

_

Peak Wavelength of Emission

880

900

nm

Halfwidth of Emission Spectrum

60

nm

Optical Rise Time, Fall Time

115.2 kHz square wave signal, duty

cycle 1:1

200

600

ns

Optical Overshoot

25

%

Rising Edge Peak–to–Peak Jitter

Over a period of 10 bits, independent

of information content

0.2

µs

Notes

a.

b.

The algebraic convention whereby the most negative value is a minimum and the most positive a maximum.

c.

Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing.

d.

e.

In agreement with IEC 825 eye safety limit

Recommended Circuit Diagram

The only required components for designing an IrDA 1.2

compatible design using TEMIC SIR transceivers are a

current

limiting

resistor

to

the

IRED.

However,

depending on the entire system design and board layout,

additional components may be required (see Figure 1).

It is recommended that the capacitors C1 and C2 are

positioned as near as possible to the transceiver power

supply pins, as in the proposed layout in Figure 1. A

tantalum capacitor should be used for C1, while a ceramic

capacitor should be used for C2 to suppress RF noise.

Also, when connecting the described circuit to the power

supply, low impedance wiring should be used.

R1 is used for controlling the current through the IR

emitter. For increasing the output power of the IRED, the

value of the resistor should be reduced. Similarly, to

reduce the output power of the IRED, the value of the

resistor should be increased. For typical values of R1 see

Fig 2. For IrDA compliant operation, a current control

resistor of 8–12

Ω is recommended. The upper drive

current limitation is dependent on the duty cycle and is

given by the absolute maximum ratings on the data sheet

and the eye safety limitations given by IEC825–1.

IRED

Cathode

Rxd

GND

IRED

Anode

Txd

SC

NC

TFDx4x00

R1

C1

C2

R2

Rxd

Txd

GND

SC

Note: Outlined components are optional depending on quality of

power supply.

Figure 1. Recommended Application Circuit

R2, C1 and C2 are optional and dependent on the quality