ACS411CS View Datasheet(PDF) - Semtech Corporation

Part Name

Description

MFG CO.

ACS411CS

Acapella Optical Modem IC

Semtech Corporation 

Link Budgets

The link budget is the difference between the power

coupled to the fiber via the transmit Laser/LED and

the power required to realise the minimum input-

amplifier current via the receive PIN/LED. The link

budget is normally specified in dB, and represents

the maximum attenuation allowed between

communicating Lasers/LEDs. The budget is utilised

in terms of the cable length, cable connectors and

splices. It usually includes an operating margin to

allow for degradation in LASER/LED performance.

The power coupled to the cable is a function of the

efficiency of the Laser/LED, the current applied to

the Laser/LED and the type of the fiber optic cable

employed.

Twin Fiber LED link (880nm LED + PIN)

Link Budget Example (Rtset set so LED launch current = 100 mA peak)

Fiber type Glass (multimode)

Fiber size 62.5micron

Minimum transmit couple power to fiber (µW)

100

Minimum PIN responsivity (A/W)

0.1

Minimum ACS9020 sensitivity (nA)

1500

Minimum input power to ACS9020 amplifier (µW)

20

Link budget (dB) (multi mode fiber attenuation = 3 dB/km)

8.24

Twin Fiber LASER link (1310nm Laser and PIN)

Link Budget Example (Rtset set so LASER launch current = 25 mA peak)

Fiber type Glass (single mode)

Fiber size 9 micron

Minimum transmit couple power to fiber (µW)

1000

Minimum PIN responsivity (A/W)

0.8

Minimum ACS9020 sensitivity (nA)

1500

Minimum input power to ACS9020 amplifier (µW)

4

Link budget (dB) (single mode fiber attenuation = 0.3 dB/km) 27

Single Fiber LASER link (1310nm and 1510nm WDM device)

Link Budget Example (Rtset set so LASER launch current = 25 mA peak)

Fiber type Glass (single mode)

Fiber size 9 micron

Minimum transmit couple power to fiber (µW)

1000

Minimum PIN responsivity (A/W)

0.8

Minimum ACS9020 sensitivity (nA)

1500

Minimum input power to ACS9020 amplifier (µW)

4

Link budget (dB) (single mode fiber attenuation = 0.3 dB/km) 27

ACS411CS PRE-RELEASE Issue 6.0 July 1999.

Figure 14: Link bugdet examples.

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