Advanced Communications
ACS104A Data Sheet
Dual Fiber link optimised for performance
Link Budget Example (Rtrc set so LED launch current = 100mA peak)
Fiber type
Plastic
Glass
Glass
50 micron
80
Fiber size
1000 micron
62.5 micron
Minimum Transmit Couple power to fiber (µW)
Minimum PIN responsivity (A/W)
Minimum ACS104A sensitivity (nA)
Minimum input power to ACS104A amplifier (µW)
Link Budget (dB)
1000
0.1
500
5
120
0.6
500
0.83
21
0.6
500
0.83
19.8
7
23
Average current consumption TxD = 19.2kbps (mA)
Average current consumption TxD = 64kbps (mA)
7
7
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
62.5micron
13
Glass
50 micron
6.5
Fiber size
1000 micron
Minimum Transmit Couple power to fiber (µW)
Minimum PIN responsivity (A/W)
Minimum ACS104A sensitivity (nA)
Minimum input power to ACS104A amplifier (µW)
Link Budget (dB)
125
0.1
500
5
0.6
0.6
500
500
0.83
12
0.83
9
13.9
2.2
3.4
2
Average current consumption TxD = 19.2kbps (mA)
Average current consumption TxD = 64kbps (mA)
2.2
2.2
3.4
3.4
Calculating average current and power consumption
Average current
Iav (mA)
=
XTAL* 10 -7 (1.3 + 3*(A + U *H ) ) + Itrc (A + U * H) + Iout + Ihbt
Power
P (mW)
=
Iav (mA) * V
Terms used in current/power calculation:
XTAL
H
=
=
Crystal Oscillator Frequency, Hz
Handshake on
H=1 for handshakes active
H=0 for handshakes at DC level
Handshake constant
U = 0.001 when HD 2/1 = 0/0
U = 0.028 when HD 2/1 = 0/1
U = 0.014 when HD 2/1 = 1/0
U = 0.007 when HD 2/1 = 1/1
Active window constant
Iout
=
=
Average current sourced
from digital outputs such
as (RxD,CTS,DSR,DCD)
Average current sourced
from HBT pin.
mA
mA
Ihbt
U
A
=
=
(see section HBT Status pin)
Itrc
V
=
=
Peak Transmit current
set by TRC pin.
mA
A = 0.022 when DR 3/2/1 = 0/1/1
Voltage supply to the ACS104 V
Power formula is only accurate
for voltage supply = 5 Volts
A = 0.03
when DR 3/2/1 = 1/0/0
A = 0.045 when DR 3/2/1 = 1/0/1
A = 0.08
A = 0.11
when DR 3/2/1 = 1/1/0
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 ACS104A, the optics and all related circuitry from the RS232 data lines.
6