关于avrio驱动能力的深入节解.docx

关于AVR I/O 的驱动能力的介绍 　　AVR单片机I/O的驱动能力在8位单片机中算一流的。大家应仔细阅读AVR器件手册中关于电气指标和典型 特性的内容。（顺便提一下，有那些8位单片机的器件手册比AVR的多？并且提供非常详细的电气指标？）。 　　讨论AVR的I/O驱动能力主要指它使用输出工作方式下的输出电流（输出为1时）和灌电流（输出为0时）。 　　参考下图，当输出高电平时，在Vcc=5V条件下，一个I/O输出电流可达40mA，但此时输出电压已降到4V左右，输出20mA时，电压降为 4.5v，（3v以上，对于CMOS讲，仍为逻辑“1”）。说明AVR的输出电流最大可为40mA。 　　当输出低电平时，I/O的倾动能力表现为灌电流。见下图， 　　在Vcc=5V条件下，一个I/O可灌入的电流也可达40mA，但此时输出电压已生到1V左右，灌入20mA时，电压生为0.5v， （0.8v以下，对于CMOS讲，仍为逻辑“0”）。说明AVR的灌入电流最大可为20mA。 　　在使用中还要注意的是： 3. Although each I/O port can sink more than the test conditions (20 mA at VCC = 5V, 10 mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed: TQFP and MLF Package: 1] The sum of all IOL, for all ports, should not exceed 400 mA. 2] The sum of all IOL, for ports A0 - A7, G2, C3 - C7 should not exceed 300 mA. 3] The sum of all IOL, for ports C0 - C2, G0 - G1, D0 - D7, XTAL2 should not exceed 150 mA. 4] The sum of all IOL, for ports B0 - B7, G3 - G4, E0 - E7 should not exceed 150 mA. 5] The sum of all IOL, for ports F0 - F7, should not exceed 200 mA. If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition. 4. Although each I/O port can source more than the test conditions (20 mA at Vcc = 5V, 10 mA at Vcc = 3V) under steady state conditions (non-transient), the following must be observed: TQFP and MLF Package: 1] The sum of all IOH, for all ports, should not exceed 400 mA. 2] The sum of all IOH, for ports A0 - A7, G2, C3 - C7 should not exceed 300 mA. 3] The sum of all IOH, for ports C0 - C2, G0 - G1, D0 - D7, XTAL2 should not exceed 150 mA. 4] The sum of all IOH, for ports B0 - B7, G3 - G4, E0 - E7 should not exceed 150 mA. 5] The sum of all IOH, for ports F0 - F7, should not exceed 200 mA. If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current greater than the listed test condition. 　　此段大家自己读，主要是说整个PORT口，以