tza3012ahw NXP Semiconductors, tza3012ahw Datasheet - Page 9

• Manufacturer Part Number: tza3012ahw
• Description: 30 Mbits/s Up To 3.2 Gbits/s A-ratetm Fibre Optic Receiver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Setting LOSTH reference level by external resistor
If the internal D/A converter is not used, the reference
voltage level on pin LOSTH1 (or LOSTH2) can be set by
connecting an external resistor (R2) from the relevant pin
to ground. The voltage on the pin is determined by the ratio
between R2 and R1; see Fig.5. For resistor R1 a value of
10 to 20 k is recommended, giving a current of
120 to 60 A.
The LOSTH voltage equals
Voltage V
accurate reference voltage of 1.2 V. The minimum
threshold level corresponds to 0 V and the maximum to
1.2 V. Hence, the value of R2 may not be higher than R1.
The accuracy of the LOSTH voltage depends mainly on
carefully choosing the values of the two external resistors.
Instead of using resistors (R1 and R2) to set the LOS
threshold, an accurate external voltage source can also be
used.
If no resistor is connected to LOSTH1 (or LOSTH2), or an
external voltage higher than
the LOS detection circuit (including the RSSI reading for
that channel) is automatically switched off to reduce power
dissipation. This ‘auto power off’ only works if UI = V
manual control of the TZA3012AHW. In I
several I
2003 May 21
handbook, full pagewidth
30 Mbits/s up to 3.2 Gbits/s
A-rate
2
C-bus bits allow flexible configuration.
ref
represents a temperature stabilized and
fibre optic receiver
V RSSI
(V)
1.2
0.9
0.6
0.3
0
5
2
R2
------- -
R1
3
V
V
10
CC
ref
is applied to the pin,
2
C-bus mode,
Fig.4 V
32
RSSI
EE
, i.e.
as a function of V
9
Fig.5
10
2
i(p-p)
Setting the LOSTH reference level by
external resistors.
1.2 V
V ref
.
300
S RSSI
I
V i(p-p) (mV)
500
RREF
R1
10 k
MBL555
TZA3012AHW
10
LOSTH1
LOSTH2
3
R2
Product specification
RSSI
compare
LOS
MGU318
V CCA
LOS
GND