XR3176EID-F Exar Corporation, XR3176EID-F Datasheet - Page 17

• Manufacturer Part Number: XR3176EID-F
• Description: IC TXRX RS485 DIFF 3V 14NSOIC
• Manufacturer: Exar Corporation
• Type: Transceiverr

Specifications of XR3176EID-F

• Package / Case: 14-SOIC (0.154", 3.90mm Width)
• Number Of Drivers/receivers: 1/1
• Protocol: RS422/RS485
• Voltage - Supply: 3.3V
• Mounting Type: Surface Mount
• Data Rate: 20 Mbps
• Propagation Delay Time Ns: 250 ns to 1500 ns
• Supply Current: 650 uA
• Operating Temperature Range: - 40 C to + 85 C
• Input Voltage: 3.3 V
• Mounting Style: SMD/SMT
• Product: RS-422/RS-485 Combination
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 1016-1316-5

XR3170E-3178E
th
3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8
UNIT LOAD
REV. 1.0.0
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not
specifically refer to integrated circuits. The XR3170E family helps you design equipment to meet
IEC 61000-4-2, without sacrificing board-space and cost for external ESD-protection components.
The major differences between tests done using the Human body model and IEC 61000-4-2 is a higher peak
current in IEC 61000-4-2. Series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD withstand
voltage measured to IEC 61000-4-2 is generally lower than that of human body model.
The air-gap test involves approaching the device with a charged probe. The contact discharge method
connects the probe to the device before the probe is energized.
MACHINE MODEL
The machine model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. The
objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and
assembly.
256 TRANSCEIVERS ON THE BUS
The standard RS-485 receiver input impedance is 12k Ohms (1 unit load). A standard driver can drive up to 32
th
unit loads. The XR3170E family of transceivers have only a 1/8
unit load receiver input impedance of 96k
Ohms, thereby allowing eight times as many, up to 256, transceivers to be connected in parallel on a
communication line. Any combination of these devices and other RS-485 transceivers up to a total of 32 unit
loads may be connected to the line.
LOW POWER SHUTDOWN MODE
Low-power shutdown mode is initiated by bringing both
RE
high and DE low simultaneously. While in shutdown
devices draw less than 1µA of supply current. DE and
RE
may be tied together and driven by a single control
signal. Devices are guaranteed not to enter shutdown if
RE
is high and DE is low for less than 50ns. If the
inputs are in this state for at least 600ns, the parts will enter shutdown.
Enable times
and
apply when the part is not in low-power shutdown state. Enable times
and
t
t
t
ZH
ZL
ZH(SHDN)
apply when the parts are shutdown. The drivers and receivers take longer to become enabled from
t
ZL(SHDN)
low-power shutdown
and
than from driver / receiver disable mode (
and
).
t
t
t
t
ZH(SHDN)
ZL(SHDN)
ZH
ZL
DRIVER OUTPUT PROTECTION
Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus
contention. First, a driver current limit on the output stage provides immediate protection against short circuits
over the whole common-mode voltage range. Second, a thermal-shutdown circuit forces the driver outputs into
a high-impedance state if junction temperature becomes excessive.
LINE LENGTH
The RS-485/RS-422 standard covers line lengths up to 4000ft. Maximum achievable line length is a function of
signal attenuation and noise. Termination prevents signal reflections by eliminating the impedance mismatches
on a transmission line. Line termination is generaly used if rise and fall times are shorter than the round-trip
signal propagation time
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