MAX3250EAI+T ,±50V Isolated, 3.0V to 5.5V, 250kbps, 2 Tx/2 Rx, RS-232 TransceiverApplicationsR1OUT 2 27 C2-Industrial ControlR2OUT 3 26 GNDProgrammable Logic ControllerT1IN 4 25 FA ..
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MAX325CPA+ ,Precision, Single-Supply, SPST Analog SwitchesGeneral Description ________
MAX325CSA ,Precision, Single-Supply, SPST Analog SwitchesGeneral Description ________
MAX325CSA+ ,Precision, Single-Supply, SPST Analog SwitchesApplicationsMAX323C/D 0°C to +70°C Dice*Battery-Operated Systems Sample-and-Hold CircuitsMAX323EPA ..
MAX325CSA+T ,Precision, Single-Supply, SPST Analog SwitchesFeaturesThe MAX323/MAX324/MAX325 are precision, dual, ♦ Low On-Resistance (R ), 60Ω max (33Ω typ)ON ..
MAX691AEPE+ ,Microprocessor Supervisory CircuitsElectrical Characteristics(MAX691A, MAX800L: V = +4.75V to +5.5V; MAX693A, MAX800M: V = +4.5V to +5 ..
MAX691AESE ,Microprocessor Supervisory CircuitsGeneral Description ________
MAX691AESE ,Microprocessor Supervisory CircuitsELECTRICAL CHARACTERISTICS(MAX691A, MAX800L: V = +4.75V to +5.5V, MAX693A, MAX800M: V = +4.5V to +5 ..
MAX691AESE+ ,Microprocessor Supervisory CircuitsApplications● ComputersPIN- PART TEMP RANGEPACKAGE● ControllersMAX691ACUE -0°C to +70°C 16 TSSOP● I ..
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MAX691AEWE ,Microprocessor Supervisory CircuitsGeneral Description ________
MAX3250CAI+-MAX3250EAI+-MAX3250EAI+T
±50V Isolated, 3.0V to 5.5V, 250kbps, 2 Tx/2 Rx, RS-232 Transceiver
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 TransceiverEVALUATION KIT AVAILABLE
General DescriptionThe 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 FAULTopen-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.
ApplicationsIndustrial Control
Programmable Logic Controller
Point-of-Sale Equipment
PC-to-Router Connections
Diagnostic Ports
Telecom Equipment
Benefits and FeaturesIsolation Breaks Ground Loops Due to High Common-
Mode Voltages While Maintaining Data Rate±50V Isolation250kbps Guaranteed Data RateFAULTOutput Signals Excessive Isolated-Side
Voltage
Integration of Isolation and RS-232 Saves SpaceSSOP Package
Shutdown Allows Multiple Interfaces (IrDA, RS-232,
RS-485) to be Connected to the Same UARTHigh-Impedance Transmitter and Receiver
Outputs in Shutdown20µA Supply Current in ShutdownInductorless/Transformerless Design Simplifies EMI
ComplianceLow-Cost Replacement for Opto-Isolated
TransceiversMeets EIA/TIA-232 Specifications Down to 3.0V
Typical Operating Circuit appears at end of data sheet.
PARTTEMP RANGEPIN-PACKAGEMAX3250CAI+0°C to +70°C28 SSOP
MAX3250EAI+-40°C to +85°C28 SSOP
VCC
C2-
GND
FAULT
SHDN
N.C.
ISOCOM
N.C.
C2+
ISOVCC
R1IN
R2IN
T1OUT
T2OUT
C4-
C4+
C3-
C3+
C1+
N.C.
N.C.
T2IN
T1IN
R2OUT
R1OUT
C1-
SSOPTOP VIEW
MAX3250
Pin Configuration+Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 Transceiver
Absolute Maximum RatingsStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(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 Voltages
T_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 15mW/°C above +70°C).......1201.2mW
Operating Temperature Ranges
MAX3250CAI.....................................................0°C to +70°C
MAX3250EAI...................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
Soldering Temperature (reflow).......................................+260°C
Electrical Characteristics(VCC= 3.0V to 5.5V, see Typical Operating Circuit and Table 1 for capacitor values, ISOCOM = GND, TA= TMINto TMAX, unless oth-
erwise noted. Typical values are at VCC= 3.3V and TA= +25°C.) (Note 2)
PARAMETER CONDITIONSMINTYPMAXUNITS
DC CHARACTERISTICSSupply CurrentSHDN = VCC, no load1535mA
SHDN = GND, VISOCOM = GND2045Supply Current ShutdownSHDN = GND, VISOCOM = ±50V±350µA
Maximum Ground Differential|VGND - VISOCOM|50V
Isolation ResistanceBetween GND and ISOCOM60kΩ
LOGIC INPUTSInput Logic LowT_IN, SHDN0.8V
VCC = 3.3V2.0Input Logic HighT_IN, SHDNVCC = 5.0V2.4V
Transmitter Input Hysteresis0.5V
Input Leakage CurrentT_IN, SHDN-1±0.01+1µA
RECEIVER OUTPUTSOutput Leakage CurrentSHDN = GND-10±0.05+10µA
Output-Voltage LowIOUT = 1.6mA0.4V
Output-Voltage HighIOUT = -1.0mAVCC - 0.6VCC - 0.1V
FAULT OUTPUTOutput-Voltage Low
(Open Drain)IOUT = 5mA0.4V
Output Leakage CurrentFAULT not asserted1µA
FAULT Trip Level|VGND - VISOCOM|55V
Note 1:V+ and V- can have a maximum magnitude of 7V, but their absolute difference cannot exceed 13V.
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 Transceiver
Electrical Characteristics (continued)(VCC= 3.0V to 5.5V, see Typical Operating Circuit and Table 1 for capacitor values, ISOCOM = GND, TA= TMINto TMAX, unless oth-
erwise noted. Typical values are at VCC= 3.3V and TA= +25°C.) (Note 2)
PARAMETER CONDITIONSMINTYPMAXUNITS
RECEIVER INPUTS (relative to ISOCOM)Input-Voltage Range-25+25V
VCC = 3.3V1.20.6Input Threshold LowTA = +25°CVCC = 5.0V1.30.8V
VCC = 3.3V2.41.6Input Threshold HighTA = +25°CVCC = 5.0V2.41.7V
Input Hysteresis0.5V
Input ResistanceTA = +25°C357kΩ
TRANSMITTER OUTPUTS (relative to ISOCOM)Output-Voltage SwingAll transmitter outputs loaded with 3kΩ to ISOCOM,
TA = +25°C±5.0±5.4V
Output ResistanceISOVCC = V+ = V- = 0V, VT_OUT = ±2V30010MΩ
Output Short-Circuit Current-60+60mA
Output Leakage CurrentVCC = 0 or 3V to 5.5V, VT_OUT = ±12V, SHDN = GND-25+25µA
Timing Characteristics(VCC= 3.0V to 5.5V, see Typical Operating Circuit and Table 1 for capacitor values, ISOCOM = GND, TA= TMINto TMAX, unless oth-
erwise noted. Typical values are at VCC= 3.3V and TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITSMaximum Data RateRL = 3kΩ, CL = 1000pF to ISOCOM, one transmitter,
TA = +25°C250kbps
Receiver Propagation DelayR_IN to R_OUT, CL = 150pF to GND0.4µs
Receiver Skew|tPHL - tPLH|100ns
Transmitter Skew|tPHL - tPLH| (Note 3)120ns
CL = 150pF to 1000pF
to ISOCOM630
Transition-Region Slew Rate
VCC = 3.3V, TA = +25°C,
RL = 3kΩ to 7kΩ to ISOCOM,
measured from +3V to -3V or
-3V to +3V
CL = 150pF to 2500pF
to ISOCOM430
V/µs
FAULT Propagation Delay0.3µs
Time to Shutdown0.5µs
VISOCOM = GND300Time to Exit ShutdownVISOCOM = ±50V350µs
Note 2:All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to device
ground, unless otherwise noted.
Note 3:Transmitter skew is measured at the transmitter zero crosspoints.
Typical Operating Characteristics(VCC= 3.3V, 250kbps data rate, see Typical Operating Circuit and Table 1 for capacitor values, all transmitters loaded with 3kΩandto ISOCOM, TA= +25°C, unless otherwise noted.)
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 Transceiver
MAX3250 toc05
TEMPERATURE (°C)
SUPPLY CURRENT (3510-15
SHUTDOWN CURRENT
vs. TEMPERATURE
ISOCOM = -50V
ISOCOM = 0V
ISOCOM = +50V
TIME TO EXIT SHUTDOWN
VISOCOM = 0VTOUT
5V/div
MAX3250 toc04
100μs/div
SHDN
5V/div
MAX3250 toc03
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
T1 TRANSMITTING AT 250kbps
T2 TRANSMITTING AT 20kbps
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE250kbps
120kbps
20kbps
MAX3250 toc02
LOAD CAPACITANCE (pF)
SLEW RATE (V/
SLEW RATE
vs. LOAD CAPACITANCE
-SLEW
+SLEW
FOR DATA RATES UP TO 250kbps
MAX3250 toc01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
VOUT+
VOUT-
T1 TRANSMITTING AT 250kbps
T2 TRANSMITTING AT 20kbps
COMMON-MODE FAULT RESPONSEISOCOM
50V/div
MAX3250 toc07
FAULT
5V/div
4ms/div
MAX3250 toc01
TRANSMITTER OUTPUT VOLTAGE (V)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
VOUT+
VOUT-
T1 TRANSMITTING AT 250kbps
T2 TRANSMITTING AT 20kbps
Pin Description
PINNAMEFUNCTIONC1-Negative Terminal of the Power Isolation Capacitor. Connect a 100V capacitor from C1- to C1+.
See Table 1 for values.R1OUTTTL/CMOS Receiver OutputR2OUTTTL/CMOS Receiver OutputT1INTTL/CMOS Transmitter InputT2INTTL/CMOS Transmitter Input
6, 22, 23N.C.No Connection. Not internally connected.N.C.No Connection. Leave unconnected or connect to ISOCOM.C1+Positive Terminal of the Power Isolation Capacitor. Connect a 100V capacitor from C1+ to C1-.
See Table 1 for values.C3+Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect a 0.1µF capacitor from
C3+ to C3-.V++5.5V Generated by the Charge Pump, Referenced to ISOCOM. Bypass V+ to ISOCOM with a
0.47µF capacitor.C3-Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect a 0.1µF capacitor from
C3- to C3+.C4+Positive Terminal of the Inverting Charge-Pump Capacitor. Connect a 0.47µF capacitor from
C4+ to C4-.C4-Negative Terminal of the Inverting Charge-Pump Capacitor. Connect a 0.47µF capacitor from
C4- to C4+.V--5.5V Generated by the Charge Pump, Referenced to ISOCOM. Bypass V- to ISOCOM with a 0.47µF
capacitor.ISOCOMIsolated GroundT2OUTRS-232 Transmitter OutputT1OUTRS-232 Transmitter OutputR2INRS-232 Receiver InputR1INRS-232 Receiver InputISOVCCInternally Generated Isolated Power-Supply Voltage, Referenced to ISOCOM. Bypass ISOVCC to
ISOCOM with a 2.2µF capacitor.C2+Positive Terminal of the Power Isolation Capacitor. Connect a 100V capacitor from C2+ to C2-.
See Table 1 for values.SHDNShutdown Control. Drive SHDN low to enter low-power shutdown mode. Drive SHDN high or connect
to VCC for normal operation.FAULTOvervoltage Indicator. Active low, open drain.GNDGroundC2-Negative Terminal of the Power Isolation Capacitor. Connect a 100V capacitor from C2- to C2+.
See Table 1 for values.VCC3.0V to 5.5V Supply Voltage. Bypass VCC to GND with a 1µF capacitor.
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 Transceiver
MAX3250±50V Isolated, 3.0V to 5.5V, 250kbps,
2 Tx/2 Rx, RS-232 Transceiver
Detailed DescriptionThe 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 typically draws 15mA of supply current
when unloaded. Supply current drops to 20µA when
the device is placed in shutdown mode.
The MAX3250 has two receivers and two drivers and is
guaranteed to operate at data rates up to 250kbps. The
device features a FAULTopen-drain output to signal an
excessive 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 (Figure 1). The MAX3250 is a low-cost replacement
for opto-isolated transceivers.
Isolated Power SupplyThe MAX3250 drives a high-frequency square wave into
C1 and a complementary square wave into C2. These
POWER
CONTROLLER
FAULT
SHDN
GNDC1-C2-C1+C2+ISOCOM
TOUT2
RIN2
ISOVCC
C3+
C3-
C4+
C4-
TIN1
ROUT1
ROUT2
TIN2
TOUT1
RIN1
RS-232
CHARGE
PUMPVCC
MAX3250
FAULT
DETECTOR
OSC
Figure 1. Functional Diagram
