MAX3160E/MAX3161E/MAX3162E
±15kV ESD-Protected, +3.0V to +5.5V, 10nA,
RS-232/RS-485/RS-422 Multiprotocol Transceivers
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magnitude of either output voltage is less than +5.5V,
the charge pumps are enabled. If the magnitude of
both output voltages exceeds +5.5V, the charge
pumps are disabled. Each charge pump requires a fly-
ing capacitor (C1, C2) and a reservoir capacitor (C3,
C4) to generate the V+ and V- supplies (see the
Functional Diagrams).
RS-485/RS-422 Transceivers
The MAX3160E/MAX3161E/MAX3162E RS-485/RS-422
transceivers feature fail-safe circuitry that guarantees a
logic-high receiver output when the receiver inputs are
open or shorted, or when they are connected to a ter-
minated transmission line with all drivers disabled (see
the Fail-Safe Section). The MAX3160E/MAX3161E/
MAX3162E also feature pin-selectable reduced slew-
rate drivers that minimize EMI and reduce reflections
caused by improperly terminated cables, allowing
error-free data transmission up to 250kbps The trans-
mitters can operate at speeds up to 10Mbps with the
slew-rate limiting disabled. Drivers are short-circuit cur-
rent limited and thermally limited to protect them
against excessive power dissipation. Half-duplex com-
munication is enabled by driving HDPLX high
(MAX3160E/MAX3161E.)
Fail-Safe
The MAX3160E/MAX3161E/MAX3162E guarantee a
logic-high RS-485 receiver output when the receiver
inputs are shorted or open, or when they are connected
to a terminated transmission line with all drivers dis-
abled. This is done by having the receiver threshold
between -50mV and -200mV. If the differential receiver
input voltage (A-B) is greater than or equal to -50mV,
RO is logic-high. If A-B is less than or equal to -200mV,
RO is logic-low. In the case of a terminated bus with all
transmitters disabled, the receiver’s differential input
voltage is pulled to 0 by the termination. This results in
a logic-high with a 50mV minimum noise margin.
RS-232 Transceivers
The MAX3160E/MAX3161E/MAX3162E RS-232 trans-
mitters are inverting-level translators that convert
CMOS-logic levels to ±5V EIA/TIA-232-compliant lev-
els. The transmitters are guaranteed at a 250kbps data
rate in slew-rate limited mode (FAST = GND) with
worst-case loads of 3kΩ in parallel with 1000pF. Data
rates up to 1Mbps can be achieved by asserting FAST.
When powered down or in shutdown, the MAX3160E/
MAX3161E/MAX3162E outputs are high impedance
and can be driven to ±13.2V. The transmitter inputs do
not have pullup resistors. Connect unused inputs to
ground or V
CC
.
The receivers convert RS-232 signals to CMOS-logic out-
put levels. All receivers have inverting outputs that
remain active in shutdown. The MAX3160E/MAX3161E/
MAX3162E permit their receiver inputs to be driven to
±25V. Floating receiver input signals are pulled to
ground through internal 5kΩ resistors, forcing the out-
puts to a logic-high. The MAX3162E has transmitter and
receiver enable pins that allow its outputs to be tri-stated.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against ESD encoun-
tered during handling and assembly. The MAX3160E/
MAX3161E/MAX3162E receiver inputs and transmitter
outputs have extra protection against static electricity
found in normal operation. Maxim’s engineers developed
state-of-the-art structures to protect these pins against
±15kV ESD, without damage. After an ESD event, the
MAX3160E/MAX3161E/MAX3162E continue working
without latchup.
The receiver inputs and transmitter outputs are charac-
terized for ±15kV ESD protection using the Human
Body Model
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
Human Body Model
Figure 13a shows the Human Body Model, and Figure
13b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
est, which is then discharged into the device through a
1.5kΩ resistor.
