The MAX3238E/MAX3248E transceivers use Maxim’s
revolutionary AutoShutdown Plus? feature to achieve
10nA supply current. These devices shut down the onboard
power supply and drivers when they do not sense
a valid signal transition on either the receiver or transmitter
inputs. This occurs if the RS-232 cable is disconnected
or if the transmitters of the connected peripheral are
turned off. The devices turn on again when a valid transition
is applied to any RS-232 receiver or transmitter input.
AutoShutdown Plus automatically achieves this power
savings through its on-board circuitry, as no changes are
required to the existing BIOS or operating system.
All RS-232 inputs and outputs, as well as the logic I/O
pins, have enhanced ESD protection to ±15kV. The additional
ESD protection on the logic I/O pins makes the
MAX3238E/MAX3248E ideal for cell phone data cable
applications because it eliminates the need for costly
external TransZorb? or protection schemes.
The MAX3238E/MAX3248E contain five drivers and three
receivers and are 3V-powered EIA/TIA-232 and V.28/V.24
communication interfaces intended for cell phones, data
cables, and modem applications. A proprietary, high-efficiency,
dual charge-pump power supply and a lowdropout
transmitter combine to deliver true RS-232
performance from a single +3.0V to +5.5V supply. A
guaranteed data rate of 250kbps provides compatibility
with popular software for communicating with personal
computers.
The MAX3238E and the MAX3248E differ only in their
input logic thresholds. The MAX3238E has standard logic
thresholds, while the MAX3248E has low-level logic
thresholds of 0.6V to 1.2V, which are ideal for 1.8V systems.
The transmitter