Datasheet

+3.0V to+5.5V, 1µA, RS-232/RS-485/422
Multiprotocol Transceivers
ceivers to be connected in parallel on one communica-
tion line. The MAX3161/MAX3162 have a 1/8-unit load
receiver input impedance (96kΩ), allowing up to 256
transceivers to be connected in parallel on one com-
munication line. Any combination of these devices
and/or other RS-485 transceivers with a total of 32-unit
loads or fewer can be connected to the line.
The MAX3160/MAX3161/MAX3162 RS-485 driver out-
puts are 1/8-unit load when disabled This impedance
may be reduced if the D1 pin is toggled at a high fre-
quency. With no power applied (V
CC
= GND), the RS-
485 transmitter output impedances typically go to 1/2-
unit load on the MAX3161/MAX3162, and to one-unit
load on the MAX3160.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or by bus con-
tention. The first, 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 ). The second, a ther-
mal shutdown circuit, forces the driver outputs into a
high-impedance state if the die temperature becomes
excessive.
Protection Against Wiring Faults
EIA/TIA-485 standards require a common input voltage
range of -7V to +12V to prevent damage to the device.
The MAX3160/MAX3161/MAX3162 inputs are protected
to RS-232 levels of ±25V for the receiver inputs and
±13.2V for the transmitter/driver outputs. This provides
additional protection for the RS-485 transceivers
against ground differential or faults due to miswiring.
RS-485/422 Reduced EMI and Reflections
The MAX3160/MAX3161/MAX3162 can be configured
for slew-rate limiting by pulling FAST low. This minimizes
EMI and reduces reflections caused by improperly ter-
minated cables. Operation in slew-rate limited mode
reduces the amplitudes of high-frequency harmonics.
SUPPLY VOLTAGE
(V)
C1 (µF)
C2, C3, C4, C
BYPASS
(µF)
+3.0 TO +3.6 0.1 0.1
+4.5 TO +5.5 0.047 0.33
+3.0 TO +5.5 0.1 0.47
Table 13. Required Minimum Capacitance
Values
INPUTS OUTPUT
RS485/RS232 SHDN HDPLX A - B Y(A) - Z(B) RO/R2OUT
1 0 X X X High-Z up to V
CC
1 1 0 -50mV X 1
1 1 0 -200mV X 0
1 1 0 Floating X 1
1 1 1 X -50mV 1
1 1 1 X -200mV 0
1 1 1 X Floating 1
0 X X X X RS-232 Mode
Table 11. MAX3161
INPUTS OUTPUT
SHDN RE485 A - B RO
0 X X High-Z
X 1 X High-Z
1 0 -50mV 1
1 0 -200mV 0
1 0 Inputs Open 1
Table 12. MAX3162
Truth Tables (continued)
18
Maxim Integrated
MAX3160/MAX3161/MAX3162