SPFMIT302 - Infineon Technologies

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 1

SPF MIT3 02

Plastic Fiber Optic Transmitter including Bigfoot™ IC for MOST®

Preliminary Data Sheet

Safety Hints:

Applications of new chip technologies leads to increasing optical efficiency and growing and

higher levels of optical performance. We therefore recommend that the current versions of the

IEC 825-1 and EN 60825-1 standards are taken into account right from the outset, i.e. at the

equipment development stage, and that suitable protection facilities are provided.

The data sheet of the 4-pin MOST Optical Transmitter (MIT3 02) has to be taken as preliminary.

Samples which are delivered before the qualification and the production release are engineering

samples.

Features Description

Excellent solution for converting high

speed data from TTL to Plastic Optical Fiber

(POF)

•High speed transmitter up to 50 Mbaud

•TTL Data Input (Logic to Light Function)

•650 nm for working in a low attenuation

range of PMMA Fiber

•High coupled power in1000 micron plastic

fiber

•Low cost

Applications

•Optical Transmitter for MOST Systems

The MOST BigfootTx Plastic Fiber Optic Transmitter

is a highly integrated CMOS IC combined with a High

speed LED designed to transmit up to 25Mbit/sec

optical data which is biphase coded at up to

50Mbaud.

The internal peaking circuit minimizes PWD.

The current through the LED will be setup by an

external resistor connected to VCC. This makes it

possible to control the optical output power of the

LED.

MOST BigfootTx

1: TX_DATA

2: GND

3: Vcc

4: Control

¥

Actual design status:

Bigfoot IC

Revision

package type device marking Data sheet is valid

since

J CAI date code,

MIT3 02

15-Jan-03

MIT3 02

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 2

Maximum Ratings

Parameter Symbol Min Max Unit

Storage Temperature Range TSTG -40 100 °C

Junction Temperature TJ-40 100 °C

Soldering Temperature

(>2.5 mm from case bottom t≤5s)

TS- 235 °C

Power Dissipation PTOT - 300 mW

Power Supply Voltage VCCMax -0.5 6.0 V

Recommended Operating Conditions

Parameter Symbol Min Max Unit

Supply Voltage VCC 4.75 5.25 V

Operating Temperature Range

(Rext =13.5 kOhm)

TA-40 85 °C

All the data in this specification refers to the operating conditions above unless

otherwise stated.

Optical Signal Characteristics

(22.5 Mbit/s MOST Data, Vcc=4.75 .. 5.25 V)

Parameter Symbol Min Typ Max Unit

Peak wavelength at TA=25°C λ Peak25 640 650 660 nm

Temperature coefficient λPeak TCλ- 0.16 - nm/K

Peak wavelength at TA=-40..85°C λ Peak 630 650 670 nm

Spectral bandwidth (FWHM) Delta λ-2030nm

Average Output Power coupled into plastic fiber

at TA=25°C, Rext=15 kOhm, see Note 1

Popt25, O -7.4

(185)

-5.2

(300)

-3.6

(435)

dBm

(µW)

Temperature coefficient Popt TCPopt -- 0.4-%/K

Average Output Power coupled into plastic fiber

at TA=-40..85°C, Rext=15 kOhm, see Note 1

Popt -8.6

(140)

-5.2

(300)

-3.1

(490)

dBm

(µW)

Average Output Power coupled into plastic fiber

at TA=-40..85°C, Rext=15 kOhm, over lifetime,

see Note 1

Popt, lifetime -9.6

(110)

-5.2

(300)

-2.1

(615)

dBm

(µW)

Gain in Popt when using 13.5 KOhm instead of

15 KOhm

0.35 0.4 0.45 dB

Optical Rise Time (20% - 80%) tr-46ns

Optical Fall Time (20% - 80%) tf-46ns

Extinction Ratio re10 11 - dB

Pulse Width Variation, see Note 2 tPWV 20.9 - 24.4 ns

Average Pulse Width Distortion, see Note 2 tAPWD -0.5 - 1.5 ns

Note 1: The output power coupled into plastic fiber Popt is measured with a large area detector at the

end of a short length of a fiber (about 30 cm), which is ideally coupled to the Sidelooker. This value

must not be used for calculating the power budget for a fiber optic system with a long fiber because the

numerical aperture of plastic fibers decreases on the first meters.

Therefore the fiber seems to have a higher attenuation over the first few meters compared with the

specified value.

Due to the direct coupling of the fiber to the LED at the end of the short fiber UMD (uniform mode

distribution) will be observed. Therefore the following section of the cable has higher losses compared

with EMD (equilibrium mode distribution).

Note 2: The electrical input signal fulfills tPWV(min) = 22.9 ns and tPWV(max) = 24.1 ns. For further details

see page 3.

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 3

Pulse Width Variation (tPWV) and Average Pulse Width Distortion (tAPWD)

The SPF MIT3 02 generates negative Puls Width Distortion. This means the optical output signal is

shortened compared to the electrical input signal. Therefore the parameters tPWV and tAPWD do not meet

the MOST Specification of Physical Layer Rev 1.0 (MOST SPL Rev. 1.0) either at the electrical input

signal (SP1 in the MOST SPL Rev. 1.0) or at the optical output signal (SP2 in the MOST SPL Rev.

1.0). This characteristic is shown in the following table.

Parameter Symbol Min Max Min Max Unit Remarks

Electrical

Input Signal

Optical

Output Signal

Pulse Width

Variation

tPWV 22.9 24.1 20.9 24.4 nsa

Average Pulse

Width Distortion

tAPWD 1.0 1.5 -0.5 1.5 ns

Optical Output Signal

according to MOST

Specification of

Physical Layer Rev.

1.0

Pulse Width

Variation

tPWV 21.1 23.1 19.1 23.4 nsb

Average Pulse

Width Distortion

tAPWD -0.5 0.5 -2.0 0.5 ns

Electrical Input

Signal according to

MOST Specification

of Physical Layer

Rev. 1.0

Based on this table, the MOST System may be considered by two aspects:

a) In order to meet the MOST SPL Rev 1.0 at SP2 the tPWV and tapwd at SP1 have to be longer than

described in the MOST SPL Rev. 1.0. This can be achived e.g. by using OS8104 as MOST transceiver

chip.

b) If the MOST SPL Rev. 1.0 is met regarding tPWV and tapwd at SP1, then the output signal SP2 is

systematically shortened. Within a MOST System, this characteristic can be compensated by the

optical receiver which detects the signal at SP3. For this compensation, the optical receiver has to be

specified in a range which is smaller than the range described in the MOST SPL Rev. 1.0. For a

detailed evaluation of system behavior, see paper “OS8300 Revision J behavior on SP2 (optical output

signal)” from Oasis SiliconSystems.

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 4

DC Characteristics

Note 3: The current through the LED and therefore the optical output power and overall power

consumption depends on the settings of Rext. The nominal value for Rext is 15K. With Rext=30K the

optical output power is about –3dB of the nominal value. Typical behaviour see Fiure below.

Important: The external resistor of Rext must be within the range of 13.5K to 33K. For values of

Rext out of this range functionality may not be given over the whole temperature range and the

device lifetime. Using values below 13K for Rext can damage the transmitter.

Note 4: The transmitter jumps to low power mode after TX DATA is low for max. 18µs If the transmitter

is in low power mode it is switched ON 5µs (max.) after TX DATA starts toggling.

AC Electrical Characteristics

Parameter Test Conditions Symbol Min Typ Max Unit

Parameter Symbol Min Typ Max Unit

Low Level Input Voltage VIL -0.3 - 0.8 V

High Level Input Voltage VIH 2.0 - VCC + 0.3 V

Input Leakage Current

(VCC=5.0V, VI=0.0V or VI=5.0V)

IL--+/- 20µA

Input Capacitance CI-- 7 pF

Input Resistance RI100 - - kOhm

Supply Current (Rext = 15 kOhm) ON state,

biphase coded data, see Note 3

ICC -25 35 mA

Supply Current (Rext = 15 kOhm) OFF state,

see Note 4

ILP2 -- 1 mA

Power Supply

Rejection Ratio

25 MHz Power Supply

Noise

PSRR - 30 - dB

Power Up Time Zero à MOST Data TPU 1.0 2.5 5.0 µs

Power Down Time MOST Data à Zero TPD - - 18.0 µs

Input Rise Time tTLH --5ns

Input Fall Time tTHL --5ns

SPF MIT3 02

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15-Jan-03 OASIS SiliconSystems AG Page 5

Typical Output Signal

Measured with fast optical receiver (Graviton SPD-1) with 15 kOhm external resistor and 22.579 Mbit/s

MOST Data at TA=25°C.

Typical Dependency of Average Output Power Popt on external Resistor Rext

(22.5 MBit MOST Data/ VCC=5 V / TA=25°C)

0

20

40

60

80

100

120

140

160

5 101520253035404550

External Resistor Rext [KOhm]

Average Optical Power [%]

optical power

range for Rext:

13.5 K..33 K

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 6

Mechanical Design MIT3 02: CAI package (cavity as interface)

Lot number, production week, component type are given on CAI backside by laser

marking (for details see marking specification).

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 7

Application Circuit:

*1) Place these components as close

as possible to their corresponding

pins of the FOT.

*2) Values can change due to different

light output power of the LED.

*3) This is just a proposal for the Rext

application. There can be used also

other circuits to switch Rext from

15K to 30K.

Design & Layout rules:

• The 100nF bypass capacitors of the FOTs must be located as close as possible between the pins

Vcc and GND of the FOTs. Use ceramic caps and tantalum caps with low ESR.

• Also the inductor/ferrite bead (receiver) and the -3dB - control circuit (transmitter) must be placed

as close as possible to the FOTs. We prefer ferrite beads (e.g. type 74279214 Würth Elektronik)

since the d.c. resistance is very low. If other inductors are used the d.c. resistor should be less than

3Ohm.

• For EMC a ferrite bead should be connected to the power supply close to the transmitter and the

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 8

receiver. Do not use only one ferrite bead together for receiver and transmitter!

• For the ground connection a ground plane is recommended (Y-structure). That means the ground

planes of the transmitter, the receiver and the shielding must be separated. The three ground

planes should be connected together behind the bypass capacitors (refer to the PCB design below).

This ground signal should be connected directly to the ground plane of the MOST controller (e.g.

OS8104) and the power supply on the top layer and/or bottom layer and ground layer as it is

indicated in the example below.

• If a multi layer design is used the ground layer must have the same ground separation like shown

for the top layer!

• A serial resistor in the Rx/Tx data line will also reduce EMC - problems. For Rx the resistor must be

placed near the receiver - for Tx the resistor must be placed near the MOST controller chip. The

value depends from the distance between the FOTs and the MOST chip (< 5cm) and can be in the

range of up to 150R. Higher values for the resistors will increase jitter and can therefore cause

locking problems of the MOST PLL!

• The Rx/Tx signals should not be routed parallel over a long distance but may be embedded with

ground copper, if possible.

• The GND pin and the pin of Rext (15K - resistor) of the transmitter are used for heat dissipation.

Therefore there should be a good connection to the PCB à no isolation gaps! Both pins should dip

into a copper area (see layout example below).

Layout example:

The reference board from OASIS Silicon Systems follows the requirements above. The schematic is

very similar to the example above, but does not include the connection to the power supply, the

OS8104 or the microcontroller.

The examples below for top- and bottom layer is the layout of the reference design board and shows

how the layout around the optical receiver and transmitter should look like.

It is strongly recommended to follow this examples in your design to get best performance!

Note:

The buffer circuit (IC1), the connectors and jumpers in the middle to the right section of the schematic

are only for use of the reference board and will not be necessary for your HW - design.

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 9

Top Layer with 180° version of the pigtail:

GND - BUS to OS8104 and Power Supply

Bottom Layer (seen from the top side of the PCB): Bottom Layer: Bottom side / positions

GND - BUS to OS8104 and Power Supply

SPF MIT3 02

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Other items:

• The shown circuit for the –3dB attenuation is just a proposal. Also any other circuit which can

double the value of Rext is permitted.

• Due to the fact that the optical average level jumps if the power control signal (/-3dB) is

toggled there can occur LOCK/coding – errors at the following device for a short time. This is

not very critical, since it does occur only in diagnosis mode. After a time of 10ms the device should

lock again if the optical attenuation between the devices is not too high.

• The Rx and Tx signals can be measured by using standard probes (>1M/<10pF). However, if the

signal quality is very bad and the LOCK signal of the MOST chip is flaky connecting a passive probe

to the Rx signal can cause the MOST chip to lock better or worse to the signal. This is due to the

capacitance of the analog probe which is usually in the range of 8..12pF and shifts the phase and

PWD of the signal. In this case an active probe with a capacitance of less than 1pF is

recommended.

• The reference test board which corresponds to the layout examples above is available at the

Oasis Silicon System AG.

SPF MIT3 02

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15-Jan-03 OASIS SiliconSystems AG Page 11

History of Design and Specification Status of MOST Transmitter:

Data Sheet

Status

Bigfoot IC

Revision

device

marking

comments, cause of change,

important differences to last Status

02-Dec-02 J Date code

MIT3 02

New release

15-Jan-03 J date

code,

MIT3 02

p. 2: Update of Note 2

p. 3: Section Pulse Width Variation (tPWV) and Average Pulse

Width Distortion (tAPWD) added

SPF MIT3 02

Preliminary Product Information Infineon AG CONFIDENTIAL

15-Jan-03 OASIS SiliconSystems AG Page 12

Notes: