LTC4310CDD-2-TRPBF View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC4310CDD-2-TRPBF' PDF : 20 Pages View PDF
LTC4310-1/LTC4310-2
Applications Information
Using the LTC4310-1 at Frequencies Above 100kHz
Users who implement custom two-wire buses may use the
LTC4310-1 at bus frequencies above 100kHz provided that
all other devices on the bus can tolerate the approximately
1µs bus rise times resulting from the LTC4310-1’s bus rise
rate regulation circuitry.
Transformer Selection Guide
As shown in Figure 1, a transformer passes transmit and
receive signals between the two LTC4310’s. The transmit
signals have 1.25V magnitude and 35ns pulse width. The
receive circuitry has an equivalent input impedance of
16.5kΩ and can receive differential signals ranging from
0.875V to 1.55V. To meet these requirements, choose a
transformer having a magnetizing inductance ranging
from 50µH to 350µH, a 1:1 turns ratio and a maximum
insertion loss of –1.5dB. For optimal common mode noise
rejection, choose a center-tapped transformer and connect
the center tap on the receiving side to local ground using a
0.01µF capacitor. Ringing at the LTC4310’s RXP and RXN
pins can effectively be damped by inserting 50Ω series
resistors between each LTC4310’s TXP and TXN pins and
the corresponding transformer primary windings.
Table 1 shows a recommended list of transformers for use
with the LTC4310. 10/100BaseTX Ethernet transformers
are inexpensive and work very well in this application for
isolation voltages up to 1500V. For applications requiring
4000V isolation, the Würth Electronics Midcom 749014012
transformer is recommended.
RF Radiated Emissions
The LTC4310 evaluation board passes CISPR22 Class B
requirements for radiated emissions. The results of
CISPR22 testing are shown in the evaluation board manual.
To reduce radiated emission levels further, enclose the
LTC4310 application circuit in a shielded enclosure.
Common Mode Transient Immunity
The LTC4310 has high immunity to common mode tran-
sients. This is tested by applying a square voltage pulse
having very fast edges between the isolated grounds. The
LTC4310 passes 20kV/us edges without corruption of the
I2C bus logic states.
Table 1. LTC4310 Recommended Transformers
MANUFACTURER
PCA Electronics
Pulse
Würth Electronics
Midcom
PART NUMBER
EPF8119S
EPF8119SE
E5017
000-7090-37R-LF1
749014012
ISOLATION
VOLTAGE
1500VRMS
1500VRMS
1500VRMS
1500VRMS
4000VRMS
FORM FACTOR (mm)
x
y
z
10.41
12.45
5.84
10.2
12.7
5.96
9.4
12.7
5.08
9.4
12.95
5.33
17
24.55
10.85
TURNS
RATIO
1:1
1:1
1:1
1:1
1:1
CENTER
TAP
Yes
Yes
Yes
Yes
Yes
OPERATING
TEMPERATURE
0°C TO 70°C
–40°C TO 85°C
0°C TO 70°C
–40°C TO 85°C
0°C TO 70°C
16
431012fa
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