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 dualdie 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 transceivers have a proprietary low-dropout transmitter output stage, delivering true RS-232 performance from a 3V to 5.5V supply with a dual charge pump. The device features aFAULT open-drain output to signal an excessive isolated-side voltage condition on any of the RS232 inputs. This output can drive an alarm LED or ca 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.
All Voltages Referenced to GND, Unless Otherwise Noted.
VCC...........................................................................-0.3V to +6V
ISOCOM................................................................................±80V
ISOVCC to ISOCOM....................................................-0.3V to +6V
V+ to ISOCOM (Note 1)..............................................-0.3V to +7V
V- to ISOCOM (Note 1)..............................................+0.3V to -7V
V+ + |V-| (Note 1)....................................................................13V
Input VoltagesT_IN,
SHDN..........................................................................-0.3V to +6V
R_IN to ISOCOM.....................................................................±25V
Output Voltages
T_OUT to ISOCOM................................................................±13.2V
R_OUT.............................................................-0.3V to (VCC+ 0.3V)
FAULT...........................................................................-0.3V to +6V
C1-, C2-...........................................................-0.3V to (VCC+ 0.3V)
C1+, C2+, C3+, C3-, C4+, C4-
to ISOCOM..................................................-0.3V to (ISOVCC+ 0.3V)
T_OUT Current.....................30mA (continuous), 50mA (peak, 10µs)
R_IN Current........................30mA (continuous), 50mA (peak, 10µs)
ISOCOM Current...........30mA (continuous), 50mA (peak, 10µs)
Short-Circuit Duration T_OUT to ISOCOM........................Continuous
Continuous Power Dissipation (TA= +70°C)
28-Pin SSOP (derate 9.5mW/°C above +70°C)....................762mW
Operating Temperature Ranges
MAX3250CAI.....................................................0°C
Required Field 
