LT3669EUFD View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LT3669EUFD Datasheet PDF : 40 Pages
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LT3669/LT3669-2
APPLICATIONS INFORMATION
Receiver
The LT3669 line receiver input is connected to pin CQ1
and its output to pin RXD1. The receiver’s thresholds
are a nonlinear function of the voltage applied to L+, as
shown in Figure 14.
The receiver has a noise filter that rejects pulses on the
CQ1 line shorter than 1/16 of the bit time, i.e., 1.63μs for
SR low (COM2) and 271ns for SR high (COM3). Pulses
longer than 3.5/16 for COM2 and 5/16 for COM3 of the
bit time will be detected. Pulses with duration between
the mentioned time frame might be detected or rejected.
Figure 15 illustrates the rejection and detection bands for
a positive noise glitch.
Wake-Up
The LT3669’s WAKE output can be used to flag current
events on CQ1 when this line is overdriven by an external
device. It works in the following way:
a) if TXEN1 is high, WAKE will pull low if CQ1 is forced
opposite to its programmed level for more than 75µs.
Thus, if TXD1 is high, the CQ1 programmed level is low
(less than 2.1V from GND) and if an external device
forces CQ1 to a voltage higher than 2.95V from GND
for more than 75µs, WAKE will pull low. Similarly, if
TXD1 is low, the CQ1 programmed level is high (higher
than VL+ – 2.1V) and if an external device forces CQ1 to
a voltage lower than VL+ – 2.95V for more than 75µs,
WAKE will pull low.
VTH
12
10
5
0
0
0.52 × VL+
11.8V
9.6V
VTHH
VTHL
0.42 × VL+
IO-LINK SUPPLY RANGE
7.5 10
14
18
30
L+ SUPPLY VOLTAGE (V)
Figure 14. Receiver Thresholds vs L+ Supply Voltage
VL+
40
36692 F14
24
VTHH
UNDEFINED
REJECTED
0V
1
16
TBIT
3.5
16
TBIT
(COM2)
5
GLITCH DURATION16
TBIT
(COM3)
36692 F15
Figure 15. Receiver Noise Rejection and Detection Behavior for CQ1 Positive Glitch
For more information www.linear.com/LT3669
3669fa
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