tza3054a NXP Semiconductors, tza3054a Datasheet - Page 8

• Manufacturer Part Number: tza3054a
• Description: 100 Mbits/s To 3.2 Gbits/s A-rate Tm Limiting Amplifier
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13466
Objective data sheet
8.4 Setting LOSTH reference level by external resistor
The loss of signal threshold can also be programmed by applying an external voltage to
pin LOSTH (this is the default mode after power-up). The reference voltage level at pin
LOSTH can be set by connecting an external resistor (R2) from the pin to ground. The
voltage on the pin is determined by the resistor ratio between R2 and R1; see
For resistor R1 the value must be 10 k , with 1 % accuracy, thus yielding a current of
123 A. The LOSTH voltage equals
Voltage V
The minimum threshold level corresponds to 0 V and the maximum to 1.23 V. Hence, the
value of R2 may not be higher than R1. The accuracy of the LOSTH voltage depends
mainly on the matching of the two external resistors.
Apart from using resistors (R1 and R2) to set the LOS threshold an accurate external
voltage source can also be used, provided that it has a low output impedance.
Fig 6. LOS output configuration.
Fig 7. Setting the LOSTH reference level by external resistors.
R2
ref
represents a temperature stabilized and accurate reference voltage of 1.23 V.
R1
Rev. 01 — 12 August 2004
open-drain
polarity
CMOS/
LOS
1.23 V
V ref
CONTROL
R2
------ -
R1
LOGIC
LEVEL
100 Mbit/s to 3.2 Gbit/s A-rate
SHIFT
AND
I
RREF
V
R1
10 k
ref
.
LOSTH
R2
LOS compare
001aab368
CLAMP
LLD
ESD
001aab369
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
V
LOS
GND
CCO
V CCO
LOS
GND
TZA3054A
limiting amplifier
Figure
8 of 32
7.