MAX221 MAXIM [Maxim Integrated Products], MAX221 Datasheet
MAX221
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MAX221 Summary of contents
Page 1
... BIOS or operating system by entering low- power shutdown mode when the RS-232 cable is dis- connected, or when the transmitter of the connected peripheral is off. The MAX221 wakes up and drives the INVALID pin high when an active RS-232 cable is con- nected, signaling the host that a peripheral is connect the communications port ...
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... CC TSSOP (derated 6.7mW/°C above +70°C) ................533mW SSOP (derated 7.1mW/°C above +70°C) ..................571mW Operating Temperature Range MAX221C_ _ .....................................................0°C to +70°C MAX221E_ _ ..................................................-40°C to +85°C + 0.3V) CC Maximum Junction Temperature ................................... +150°C Storage Temperature Range ........................... -65°C to +150°C Lead Temperature (soldering, 10sec) ............................ +300° ...
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Single RS-232 Transceiver ELECTRICAL CHARACTERISTICS (continued +5V ±10%, C1–C4 = 0.1µ PARAMETER SYMBOL RECEIVER INPUT Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance TRANSMITTER OUTPUT Output Voltage Swing ...
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Single RS-232 Transceiver with AutoShutdown (V = +5V, 250kbps data rate, 0.1µF capacitors, transmitter loaded with 3k and C CC TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 20kbps 120kbps 4 250kbps 2 0 250kbps -2 -4 ...
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... Figure 3 shows the input levels and timing diagram for AutoShutdown operation. A device or another system with AutoShutdown con- nected to the MAX221 may need time to wake up. Figure 4 shows a circuit that forces the transmitter on for 100ms, allowing enough time for the other system to realize that the MAX221 is awake. If the other system transmits valid RS-232 signals within that time, the RS- 232 ports on both systems remain enabled ...
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... THE AUTOSHUTDOWN LOGIC AND APPEARS AS AN OUTPUT. POWER DOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTER AND POWER SUPPLIES. Figure 2c. AutoShutdown Logic Table 2. INVALID Truth Table RS-232 SIGNAL PRESENT AT RECEIVER INPUT TO MAX221 POWER SUPPLY 30µs COUNTER INVALID R VALID TOUT ...
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... Figure 5 shows the transmitter output when exiting shut- down mode. The transmitter is loaded with 3kΩ in paral- lel with 2500pF. The transmitter output displays no ringing or undesirable transients as the MAX221 comes out of shutdown. Note that the transmitter is enabled only when the magnitude of V- exceeds approximately 3V. ...
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... Single RS-232 Transceiver with AutoShutdown 5V/div TIN = GND 5V/div TIN = V 50 s/div Figure 5. Transmitter Output Exiting Shutdown or Powering Up +5V 0 C1+ C1 C1- MAX221 C2+ C2 C2- TOUT TIN ROUT FORCEOFF CC FORCEON INVALID GND Figure 6. Loopback Test Circuit Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied ...