8

2

Advanced Communications

ACS102A Data Sheet

Single Fiber link

Link Budget Example (Rtrc set so LED launch current = 50mA peak)

Fiber type

Plastic

Glass

Glass

Fiber size

1000 micron

62.5micron

50 micron

Minimum Transmit Couple power to fiber (µW)

1000

60

40

Minimum LED responsivity (A/W)

0.01

0.16

0.16

Minimum ACS102A sensitivity (nA)

500

500

500

Minimum input power to ACS102A amplifier (µW)

50

3.1

3.1

Link Budget (dB)

10

13

11

Average current consumption TxD = 19.2kbps (mA)

3.8

3.8

3.8

Average current consumption TxD = 64kbps (mA)

7.2

7.2

7.2

Dual Fiber link optimised for performance

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

Fiber type

Plastic

Glass

Glass

Fiber size

1000 micron

62.5 micron

50 micron

Minimum Transmit Couple power to fiber (µW)

1000

120

80

Minimum PIN responsivity (A/W)

0.1

0.6

0.6

Minimum ACS102A sensitivity (nA)

500

500

500

Minimum input power to ACS102A amplifier (µW)

5

0.83

0.83

Link Budget (dB)

23

21

19.8

Average current consumption TxD = 19.2kbps (mA)

7

7

7

Average current consumption TxD = 64kbps (mA)

14

14

7.6

Dual Fiber link optimised for low power & low cost optical components

Link Budget Example (Rtrc set so LED launch current = 12.5mA peak)

Fiber type

Plastic

Glass

Glass

Fiber size

1000 micron

62.5micron

50 micron

Minimum Transmit Couple power to fiber (µW)

125

13

6.5

Minimum PIN responsivity (A/W)

0.1

0.6

0.6

Minimum ACS102A sensitivity (nA)

500

500

500

Minimum input power to ACS102A amplifier (µW)

5

0.83

0.83

Link Budget (dB)

13.9

12

9

Average current consumption TxD = 19.2kbps (mA)

2.2

2.2

2.2

Average current consumption TxD = 64kbps (mA)

3.4

3.4

3.4

Calculating average current and power consumption

Average current

I

=

Power

P (mW)

=

I

* V

Terms used in current/power calculation:

XTAL

=

Crystal Oscillator Frequency, Hz

I

out

=

Average current sourced

mA

H

=

Handshake on

from digital outputs such

H=1 for handshakes active

as (RxD,CTS,DSR,DCD)

H=0 for handshakes at DC level

I

hbt

=

Average current sourced

mA

U

=

Handshake constant

from HBT pin.

U = 0.001

when HD 2/1 = 0/0

(see section HBT Status pin)

U = 0.028

when HD 2/1 = 0/1

U = 0.014

when HD 2/1 = 1/0

I

trc

=

Peak Transmit current

mA

U = 0.007

when HD 2/1 = 1/1

set by TRC pin.

A

=

Active window constant

A = 0.022

when DR 3/2/1 = 0/1/1

V

=

Voltage supply to the ACS102 V

A = 0.03

when DR 3/2/1 = 1/0/0

Power formula is only accurate

A = 0.045

when DR 3/2/1 = 1/0/1

for voltage supply = 5 Volts

A = 0.08

when DR 3/2/1 = 1/1/0

A = 0.11

when DR 3/2/1 = 1/1/1

Note :

An application note on power extraction from the RS232 lines is available from Acapella. This shows a typical example

circuit diagram for powering the ACS102A, the optics and all related circuitry from the RS232 data lines.