MAX3162 MAXIM [Maxim Integrated Products], MAX3162 Datasheet - Page 18

• Manufacturer Part Number: MAX3162
• Description: +3.0V to +5.5V, 1uA, RS-232/RS-485/422 Multiprotocol Transceivers
• Manufacturer: MAXIM [Maxim Integrated Products]

+3.0V to+5.5V, 1µA, RS-232/RS-485/422
Multiprotocol Transceivers
receiver input impedance (48kΩ), allowing up to 128
transceivers to be connected in parallel on one com-
munication 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
communication 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
485 transmitter output impedances typically go to 1/2-
unit load on the MAX3161/MAX3162, and to one-unit
load on the MAX3160.
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-
18
Table 11. MAX3161
Table 12. MAX3162
RS-485/RS-232
SHDN
______________________________________________________________________________________
X
0
1
1
1
1
1
1
1
1
1
1
0
INPUTS
RE485
X
1
0
0
0
Driver Output Protection
SHDN
0
1
1
1
1
1
1
X
Inputs open
≤-200mV
≥-50mV
A - B
X
X
CC
= GND), the RS-
HDPLX
INPUTS
X
0
0
0
1
1
1
X
OUTPUT
High-Z
High-Z
RO
1
0
1
≤-200mV
≥-50mV
Floating
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.
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.
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.
A - B
Table 13. Required Minimum Capacitance
Values
RS-485/422 Reduced EMI and Reflections
X
X
X
X
X
VOLTAGE (V)
+3.0 to +3.6
+4.5 to +5.5
+3.0 to +5.5
SUPPLY
Protection Against Wiring Faults
Truth Tables (continued)
Y(A) - Z(B)
≤-200mV
Floating
≥-50mV
X
X
X
X
X
C1 (µF)
0.047
0.1
0.1
High-Z up to V
RS-232 mode
RO/R2OUT
CBYPASS (µF)
OUTPUT
C2, C3, C4,
1
0
1
1
0
1
0.33
0.47
0.1
CC