MAX3250.pdf

The MAX3250 is a 3.0V to 5.5V powered, ±50V isolated
EIA/TIA-232 and V.28/V.24 communications interface
with high data-rate capabilities. The MAX3250 is a dual
die part that operates with up to ±50V difference
between the RS-232 side and the logic side (ISOCOM
to GND). This makes the device ideal for operation in
noisy conditions with high common-mode voltages.
This feature prevents damage to the device if RS-232
lines are inadvertently short-circuited to a +24V or ±48V
power bus.
The MAX3250 is powered by a single 3V to 5.5V supply
on the logic side. Power is transferred from the logic
side to the isolated side by ±100V external capacitors.
The MAX3250 has two receivers (Rx) and two drivers
(Tx) and is guaranteed to run at data rates of 250kbps
while maintaining RS-232 output levels. The trans-
ceivers have a proprietary low-dropout transmitter out-
put stage, delivering true RS-232 performance from a
3V to 5.5V supply with a dual charge pump. The device
features a FAULT open-drain output to signal an exces-
sive isolated-side voltage condition on any of the RS-
232 inputs. This output can drive an alarm LED or can
be monitored by the processor to prevent operation
under these conditions. The receiver outputs are high
impedance in shutdown, allowing multiple interfaces
(IrDA, RS-232, RS-485) to be connected to the same
UART.
The MAX3250 is available in a space-saving 28-pin
SSOP package.