外文翻譯---max232-5v的供電，多通道rs-232接口驅(qū)動(dòng)器接收器(已修改)
2025-01-29 23:34 本頁(yè)面
【正文】 附錄AMAX2325VPowered,Multichannel RS232 Drivers/Receivers The MAX232 is a dual driver/receiver that includes a capacitive voltage generator to supply TIA/EIA232F voltage levels from a single 5V supply. Each receiver converts TIA/EIA232F inputs to 5V TTL/CMOS levels. These receivers have a typical threshold of V, a typical hysteresis of V, and can accept 177。30V inputs. Each driver converts TTL/CMOS input levels into TIA/EIA232F levels. The driver, receiver, and voltagegenerator functions are available as cells in the Texas Instruments LinASIC MAX220–MAX249 contain four sections: dual chargepump DCDC voltage converters, RS232 drivers,RS232 receivers, and receiver and transmitter enable control inputs.Dual ChargePump Voltage ConverterThe MAX220–MAX249 have two internal chargepumps that convert +5V to 177。10V (unloaded) for RS232 driver operation. The first converter uses capacitor C1 to double the +5V input to +10V on C3 at the V+ output. The second converter uses capacitor C2 to invert +10V to 10V on C4 at the V output.A small amount of power may be drawn from the +10V (V+) and 10V (V) outputs to power external circuitry (see the Typical Operating Characteristics section), except on the MAX225 and MAX245–MAX247, where these pins are not available. V+ and V are not regulated, so the output voltage drops with increasing load current. Do not load V+ and V to a point that violates the minimum 177。5V EIA/TIA232E driver output voltage when sourcing current from V+ and V to external circuitry.When using the shutdown feature in the MAX222,MAX225, MAX230, MAX235, MAX236, MAX240,MAX241, and MAX245–MAX249, avoid using V+ and V to power external circuitry. When these parts are shut down, V falls to 0V, and V+ falls to +5V. For applications where a +10V external supply is applied to the V+ pin (instead of using the internal charge pump to generate +10V), the C1 capacitor must not be installed and the SHDN pin must be tied to VCC. This is because V+ is internally connected to VCC in shutdown mode.RS232 DriversThe typical driver output voltage swing is 177。8V when loaded with a nominal 5kΩ RS232 receiver and VCC =+5V. Output swing is guaranteed to meet the EIA/TIA232E and specification, which calls for 177。5V minimum driver
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