【正文】 nd C4 can be increased without changing C1’s ,do not increase C1 without also increasing the values of C2,C3,and C4,to maintain the proper ratios (C1 to the other capacitors).When using the minimum required capacitor values,make sure the capacitor value does not degrade excessively with in doubt,use capacitors with a larger nominal capacitor’s equivalent series resistance (ESR),which usually rises at low temperatures,influences the amount of ripple on V+ and V.Table 2. Required Minimum Capacitor ValuesVcc(V)C1(uf)C2,C3,C4(uF)MAX3222/MAX3232/MAX3241 to to to MAX3237 to to to to PowerSupply DecouplingIn most circumstances,a bypass capacitor is applications that are sensitive to powersupply noise,decouple VCC to ground with a capacitor of the same value as chargepump capacitor bypass capacitors as close to the IC as possible.Operation Down to Transmitter outputs will meet EIA/TIA562 levels of177。 with supply voltages as low as .Transmitter Outputs whenExiting ShutdownAs they bee active,the two transmitter outputs are shown going to opposite RS232 levels (one transmitter input is high,the other is low).Each transmitter is loaded with 3k? in parallel with 2500pF. The transmitter outputs display no ringing or undesirable transients as they e out of that the transmitters are enabled only when the magnitude of V exceeds approximately 3V.Mouse DriveabilityThe MAX3241 has been specifically designed to powerserial mice while operating from lowvoltage power has been tested with leading mouse brands from manufacturers such as Microsoft and MAX3241 successfully drove all serial mice tested and met their respective current and voltage 1 shows the transmitter output voltages under increasing load current at 4b shows a typical mouse connection using the MAX3241.High Data RatesThe MAX3222/MAX3232/MAX3241 maintain the RS232177。 minimum transmitter output voltage even at high data 2 shows a transmitter loopback test 3 shows a loopback test result at 120kbps,and Figure 4 shows the same test at Figure 3,all transmitters were driven simultaneously at 120kbps into RS232 loads in parallel with Figure 4,a single transmitter was driven at 235kbps,and all transmitters were loaded with an RS232 receiver in parallel with 1000pF.Figure 1. MAX3241 Transmitter Output Voltage vs. Load Current per TransmitterFigure 2. Loopback Test CircuitFigure 3. MAX3241 Loopback Test Result at 120kbpsFigure 4. MAX3241 Loopback Test Result at 235kbpsFigure 5. MAX3237 Loopback Test Result at 1000kbps(MBAUD = VCC)from：MAX3222/MAX3232/MAX3237/MAX324低功耗、1Mbps、真RS232收發(fā)器。概述MAX3222/MAX3232/MAX3237/MAX3241收發(fā)器采用專有的低壓差發(fā)送器輸出級。MAX322MAX3232和MAX3241確保在120kps數(shù)據(jù)速率下維持RS232輸出電平。MAX3237在正常工作模式下可確保250kbps的數(shù)據(jù)速率，MegaBaudTM在工作模式下保證1Mbps的速率，同時保持RS232輸出電平。MAX3222/MAX3232具有2路接收器和2路驅動器。MAX3222提供1UA關斷模式，有效降低能耗并延長便攜式產(chǎn)品的電池使用壽命。關斷模式下，接收器保持有效狀態(tài)，對外部設備(例如調制解調器)進行檢測，僅消耗1UA電源電流。MAX3222和MAX232兼容。MAX3241提供一個完整串口（3路驅動器/5路接收器），設計用筆記本電腦和亞筆記本電腦。MAX3237（5路驅動器/3路接收器）可理想用于高速調制解調器。這兩款器件都具有關斷模式，關斷時所有接收器保持有效狀態(tài)，僅消耗1UA電源電流。接收器R1（MAX3237/MAX3241）和R2（MAX3241）除標準輸出外還提供附加輸出。這些附加輸出始終保持有效，可以對調制解調器等外部設備進行檢測，電路（可能已完全撤出VCC電源）中無需正向偏執(zhí)報復二極管。MAX322MAX3232以及MAX3241采用節(jié)省空間的TSSOP和SSOP封裝。應用（1）筆記本電腦、亞筆記本電腦與掌上電腦（2）高速調制解調器（3）電池供電設備（4）手持式設備（5）外設（6）打印機下一代期間特征（1）低電源電流：300μA（MAX3222/MAX3232/MAX3241）為500μA（MAX3237）（2）保證數(shù)據(jù)傳輸率：120kbps（MAX3222/MAX3232/MAX3241）250kbps的（MAX3237正常操作）1Mbps的（MAX3237 MegaBaud操作）（3）1μA的低功耗接收器主動關閉（MAX3222/MAX3237/MAX3241）（4）流通式引腳（MAX3237）（5）符合規(guī)格的EIA/（6）保證鼠標驅動性（MAX3241）（7）引腳兼容工業(yè)標準MAX242（MAX3222）與工業(yè)標準的MAX232（MAX3232）引腳兼容（8）保證轉換率：6V/μs（MAX3222/MAX3232/MAX3237/MAX3241）24V/μs（MAX3237 MegaBaud操作）定購信息部分溫度范圍密碼封轉MAX3222CUP+0℃ to +70℃20 TSSOP U20+2MAX3222CAP+0℃ to +70℃20 SSOP A20+1MAX3222CWN+0℃ to +70℃18SO W18+1MAX3222CPN+0℃ to +70℃18 Plastic Dip p18+5注：+表示無鉛封裝。引腳配置：絕對最大額定值VCC........................................................................................ to +6VV+(Note1) ............................................................................... to +7VV(Note1) ................................................................................+ to 7VV++V(Note1)..........................................................................+13VInputVoltagesT_IN,SHDN,EN ..................................................................... to +6VMBAUD.................................................................................. to (VCC + )R_IN ..........................................................................................177。25V輸出電壓：T_OUT.......................................................................................177。R_OUT...................................................................................... to (VCC + )短路持續(xù)時間：T_OUT .......................................................................................連續(xù)連續(xù)功率消散(TA = +70176。C)：16Pin TSSOP (derate 176。C above +70176。C) ........................533mW16Pin Narrow SO (derate 176。C above +70176。C) ................696mW16Pin Wide SO (derate 176。C above +70176。C) ....................762mW16Pin Plastic DIP (derate 176。C above +70176。C)................842mW18Pin SO (derate 176。C above +70176。C)...............................762mW18Pin Plastic DIP (derate 176。C above +70176。C) ................889mW20Pin SSOP (derate 176。C above +70176。C) ..........................559mW20Pin TSSOP (derate 176。C above +70176。C) ..........................640mW28Pin TSSOP (derate 176。C above +70176。C) ..........................696mW28Pin SSOP (derate 176。C above +70176。C) ..........................762mW28Pin SO (derate 176。C above +70176。C) .............................1W工作溫度范圍：MAX32__C__................................................................................0176。C to +70176。CMAX32__E__ ...............................................................................40176。C to +85176。C存儲溫度范圍 ...