外文翻譯--- max232-5v的供電多通道rs-232接口驅動器接收器-文庫吧
2025-01-02 23:34 本頁面
【正文】 output levels under worstcase conditions. These include a minimum 3kΩ load, VCC = +, and maximum operating temperature. Unloaded driver output voltage ranges from (V+ ) to (V +).Input thresholds are both TTL and CMOS inputs of unused drivers can be left unconnected since 400kΩ input pullup resistors to VCC are built in (except for the MAX220). The pullup resistors force theoutputs of unused drivers low because all drivers internal input pullup resistors typically source 12μA, except in shutdown mode where the pullups are outputs turn off and enter a highimpedance state—where leakage current is typically microamperes (maximum 25μA)—when in shutdown mode, in threestate mode, or when device power is removed. Outputs can be driven to 177。15V. The power supply current typically drops to 8μA in shutdown mode. The MAX220 does not have pullup resistors to force the outputs of the unused drivers low. Connect unused inputs to GND or VCC.The MAX239 has a receiver threestate control line, and the MAX223, MAX225, MAX235, MAX236, MAX240, and MAX241 have both a receiver threestate controlline and a lowpower shutdown control. Table 2 shows the effects of the shutdown control and receiver three state control on the receiver outputs. The receiver TTL/CMOS outputs are in a highimpedance, threestate mode whenever the threestate enable line is high (for the MAX225/MAX235/MAX236/MAX239–MAX241), and are also highimpedance whenever the shutdown control line is high.When in lowpower shutdown mode, the driver outputs are turned off and their leakage current is less than 1μA with the driver output pulled to ground. The driver output leakage remains less than 1μA, even if the transmitter output is backdriven between 0V and (VCC + 6V). Below , the transmitter is diode clamped to ground with 1kΩ series impedance. The transmitter is also zener clamped to approximately VCC + 6V, with a series impedance of 1kΩ. The driver output slew rate is limited to less than 30V/μs as required by the EIA/TIA232E and specifications. Typical slew rates are 24V/μs unloaded and 10V/μs loaded with 3Ω and 2500pF.RS232 ReceiversEIA/TIA232E and specifications define a voltage level greater than 3V as a logic 0, so all receivers invert. Input thresholds are set at and , so re
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