MAX3471EUA+T Maxim Integrated Products, MAX3471EUA+T Datasheet - Page 7

• Manufacturer Part Number: MAX3471EUA+T
• Description: IC TXRX DIFF RS485/422 8-UMAX
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3471EUA+T

• Number Of Drivers/receivers: 1/1
• Protocol: RS422, RS485
• Voltage - Supply: 2.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Differential Transceiver for Battery-Powered Systems
Table 1. Transmitting
Z
__________ Applications Information
The MAX3471 is optimized for the unterminated bus
normally used in slow, low-power systems. With
a +2.5V supply, the part is guaranteed to drive up to
eight standard loads (for example, 64 other MAX3471s or
56 MAX3471s plus one standard load). Drive capability
increases significantly with supply. For example, with
a +5V supply, the MAX3471 typically meets the RS-485
driver output specifications (1.5V with 54 differential ter-
mination). See the
Figure 1. Driver DC Test Load
Figure 2. Receiver Enable/Disable Timing Test Load
D
= Driver output disabled
R R E E
X
X
0
1
RECEIVER
OUTPUT
A
INPUTS
B
POINT
TEST
DE
1
1
0
0
Typical Operating Characteristics .
C
_______________________________________________________________________________________
L
1k
V
Transceivers on the Bus
OD
DI
1
0
X
X
R
R
1.6µA, RS-485/RS-422, Half-Duplex,
Z
Z
S1
S2
B
0
1
D
D
V
OUTPUTS
OC
V
CC
Z
Z
A
1
0
D
D
The MAX3471 is slew-rate limited, minimizing EMI and
reducing reflections caused by improperly terminated
cables. In general, the rise time of a transmitter directly
relates to the length of an unterminated stub, which can
be driven with only minor waveform reflections. The fol-
lowing equation expresses this relationship conserva-
tively:
where t
For example, the MAX3471’s rise time is typically 1.3µs,
which results in excellent waveforms with a stub length
up to 82 feet. In general, systems operate well with
longer unterminated stubs, even with severe reflec-
tions, if the waveform settles out before the UART sam-
ples them.
Excessive output current and power dissipation caused
by faults or bus contention are prevented by foldback
current limiting. A foldback current limit on the output
stage provides immediate protection against short cir-
cuits over the whole common-mode voltage range (see
Typical Operating Characteristics ).
Table 2. Receiving
X = Don’t care
Z = Receiver output high impedance
Figure 3. Driver Test Circuit
R R E E
0
0
0
1
RISE
DI
Length = t
is the transmitter’s rise time.
DE
0
0
0
0
INPUTS
DE
Reduced EMI and Reflections
V
DRIVER
CC
RISE
A
B
Driver Output Protection
Open/Shorted
/ (10 x 1.5ns/foot)
≥ -0.05V
≤ -0.45V
A-B
V
X
O
R
DIFF
OUTPUT
RO
1
0
1
Z
C
C
L1
L2
7