74HC244 是一款常見的驅動信號芯片，常用于各種單片機mcu系統中，單片機io口輸出的電流很小而244芯片就是用來放大電流，他是具有三態輸出的八路緩沖器和線路驅動器，他與74HC245的唯一區別是 74HC244是單向的，數據只能從A端流向Y端，而74HC245則是雙向的。他們的驅動能力相同。74hc244的pdf資料下載：http://www.zg4o1577.cn/f/74hc244.pdf
74HC244也常常用于隔離，比如單片機和并口等設備直連理論上可以直接用單片機的幾根I/O口接并口線，但如果電路板沒做好，可能會連帶把計算機并口燒壞，所以要加個74HC244芯片隔離一下
74HC244 是CMOS電路，74ls244 是雙極晶體管型電路，二者的特性差別很大，LS器件是淘汰型，盡量不要選用。
74HC240，74HC241，74HC244為同一系列的產品，他們的區別很小在引腳及其功能方面下面的中文資料中都有詳細的說明.
74hc244實物圖
74hc244管腳圖
下面介紹74hc244的功能：
74hc244邏輯圖和真值表
dip封裝的74hc244引腳圖
貼片74hc244引腳圖
74hc244封裝圖
74hc244真值表
74hc244及74hc241 74hc240功能表
74hc244應用電路
74hc244電流最大值
74hc244電壓溫度等操作條件
DC Electrical Specifications直流電氣規格：
| Parameter 參數 | Symbol 符號 | TEST Conditions 測試條件 | 25℃ | -40℃TO85℃ | -55℃TO125℃ | UNIT 單位 | ||||||||
| VI (V) | IO (mA) | VCC (V) | 最小 | 典型 | 最大 | 最小 | 最大 | 最小 | 最大 | |||||
| High Level Input Voltage輸入高電平電壓 | VIH | - | - | 2 | 1.5 | - | - | 1.5 | - | 1.5 | - | V | ||
| 4.5 | 3.15 | - | - | 3.15 | - | 3.15 | - | V | ||||||
| 6 | 4.2 | - | - | 4.2 | - | 4.2 | - | V | ||||||
| LOW Level Input Voltage 輸入低電平電壓 | VIL | - | - | 2 | - | - | 0.5 | - | 0.5 | - | 0.5 | V | ||
| 4.5 | - | - | 1.35 | - | 1.35 | - | 1.35 | V | ||||||
| 6 | - | - | 1.8 | - | 1.8 | - | 1.8 | V | ||||||
| HIGH Level Output Voltage輸出高電平電壓 CMOS負載 | VOH | VIH or VIL | -0.02 | 2 | 1.9 | - | - | 1.9 | - | 1.9 | - | V | ||
| -0.02 | 4.5 | 4.4 | - | - | 4.4 | - | 4.4 | - | V | |||||
| -0.02 | 6 | 5.9 | - | - | 5.9 | - | 5.9 | - | V | |||||
| HIGH Level Output Voltage輸出高電平電壓 TTL負載 | -6 | 4.5 | 3.98 | - | - | 3.84 | - | 3.7 | - | V | ||||
| -7.8 | 6 | 5.48 | - | - | 5.34 | - | 5.2 | - | V | |||||
| Low Level Output Voltage 輸出低電平電壓 CMOS負載 | VOL | VIH or VIL | 0.02 | 2 | - | - | 0.1 | - | 0.1 | - | 0.1 | V | ||
| 0.02 | 4.5 | - | - | 0.1 | - | 0.1 | - | 0.1 | V | |||||
| 0.02 | 6 | - | - | 0.1 | - | 0.1 | - | 0.1 | V | |||||
| Low Level Output Voltage輸出低電平電壓 TTL負載 | 6 | 4.5 | - | - | 0.26 | - | 0.33 | - | 0.4 | V | ||||
| 7.8 | 6 | - | - | 0.26 | - | 0.33 | - | 0.4 | V | |||||
| Input Leakage Current輸入漏電流 | II | VCC or GND | - | 6 | - | - | ±0.1 | - | ±1 | - | ±1 | μA | ||
| Quiescent Device Current靜態電流 | ICC | VCC or GND | 0 | 6 | - | - | 8 | - | 80 | - | 160 | μA | ||
DC Electrical Specifications直流電氣規格（續）
| Parameter 參數 | Symbol 符號 | TEST Conditions 條件 | 25℃ | -40℃ TO 85℃ | -55℃ TO 125℃ | UNIT 單位 | |||||||||
| VI (V) | IO (mA) | VCC (V) | 最小 | 典型 | 最大 | 最小 | 最大 | 最小 | 最大 | ||||||
| Three-State Leakage Current三態泄漏電流 | IOZ | VIL or VIH | - | 6 | - | - | ±0.5 | - | ±0.5 | - | ±10 | μA | |||
| High Level Input Voltage輸入高電平電壓 | VIH | - | - | 4.5 to 5.5 | 2 | - | - | 2 | - | 2 | - | V | |||
| LOW Level Input Voltage 輸入低電平電壓 | VIL | - | - | 4.5 to 5.5 | - | - | 0.8 | - | 0.8 | - | 0.8 | V | |||
| HIGH Level Output Voltage輸出高電平電壓 CMOS 負載 | VOH | VIH or VIL | -0.02 | 4.5 | 4.4 | - | - | 4.4 | - | 4.4 | - | V | |||
| HIGH Level Output Voltage輸出高電平電壓 TTL負載 | -6 | 4.5 | 3.98 | - | - | 3.84 | - | 3.7 | - | V | |||||
| Low Level Output Voltage 輸出低電平電壓 CMOS負載 | VOL | VIH or VIL | 0.02 | 4.5 | - | - | 0.1 | - | 0.1 | - | 0.1 | V | |||
| Low Level Output Voltage 輸出低電平電壓TTL負載 | 6 | 4.5 | - | - | 0.26 | - | 0.33 | - | 0.4 | V | |||||
| Input Leakage Current輸入漏電流 | II | VCC to GND | 0 | 5.5 | - | - | ±0.1 | - | ±1 | - | ±1 | μA | |||
| Quiescent Device Current靜態電流 | ICC | VCC or GND | 0 | 5.5 | - | - | 8 | - | 80 | - | 160 | μA | |||
| Additional Quiescent Device Current Per Input Pin: 1 UNIT Load附加靜態目前的輸入引腳： 1單位負載 | ΔICC (Note 2) | VCC -2.1 | - | 4.5 to 5.5 | - | 100 | 360 | - | 450 | - | 490 | μA | |||
| Three-State Leakage Current三態泄漏電流 | IOZ | VIL or VIH | - | 5.5 | - | - | ±0.5 | - | ±5 | - | ±10 | μA | |||
Switching Specifications開關特性規格 CL = 50pF, Input tr, tf = 6ns
| Parameter 參數 | Symbol 符號 | TEST CONDI-TIONS | VCC (V) | 25℃ | -40℃ TO 85℃ | -55℃ TO 125℃ | UNIT 單位 | ||||||
| 最小 | 典型 | 最大 | 最小 | 典型 | 最大 | 最小 | 典型 | 最大 | |||||
| Propagation Delay傳播延遲 Data to Outputs 74HC240 | tPLH, tPHL | CL = 50pF | 2 | - | - | 100 | - | - | 125 | - | - | 150 | ns |
| 4.5 | - | - | 20 | - | - | 25 | - | - | 30 | ns | |||
| CL = 15pF | 5 | - | 8 | - | - | - | - | - | - | - | ns | ||
| CL = 50pF | 6 | - | - | 17 | - | - | 21 | - | - | 26 | ns | ||
| Data to Outputs數據輸出 74HC241 | tPLH, tPHL | CL = 50pF | 2 | - | - | 110 | - | - | 140 | - | - | 165 | ns |
| 4.5 | - | - | 22 | - | - | 28 | - | - | 33 | ns | |||
| CL = 15pF | 5 | - | 9 | - | - | - | - | - | - | - | ns | ||
| CL = 50pF | 6 | - | - | 19 | - | - | 24 | - | - | 28 | ns | ||
| Data to Outputs數據輸出 74HC244 | tPLH, tPHL | CL = 50pF | 2 | - | - | 110 | - | - | 140 | - | - | 165 | ns |
| 4.5 | - | - | 22 | - | - | 28 | - | - | 33 | ns | |||
| CL = 15pF | 5 | - | 9 | - | - | - | - | - | - | - | ns | ||
| CL = 50pF | 6 | - | - | 19 | - | - | 24 | - | - | 28 | ns | ||
| Output Enable and Disable Time輸出啟用和停用時間 | tTHL, tTLH | CL = 50pF | 2 | - | - | 150 | - | - | 190 | - | - | 225 | ns |
| 4.5 | - | - | 30 | - | - | 38 | - | - | 45 | ns | |||
| 5 | - | 12 | - | - | - | - | - | - | - | ns | |||
| 6 | - | - | 26 | - | - | 33 | - | - | 38 | ns | |||
| Output Transition Time輸出過渡時間 | tTLH, tTHL | CL = 50pF | 2 | - | - | 60 | - | - | 75 | - | - | 90 | ns |
| 4.5 | - | - | 12 | - | - | 15 | - | - | 18 | ns | |||
| 6 | - | - | 10 | - | - | 13 | - | - | 15 | ns | |||
| Input Capacitance輸入電容 | CI | CL = 50pF | - | 10 | - | 10 | - | - | 10 | - | - | 10 | pF |
| Three-State Output Capacitance三態輸出電容 | CO | CL = 50pF | - | - | - | 20 | - | - | 20 | - | - | 20 | pF |
| Power Dissipation Capacitance 功耗電容 | |||||||||||||
| 74HC240 | - | CL = 15pF | 5 | - | 38 | - | - | - | - | - | - | - | pF |
| 74HC241 | - | - | 5 | - | 34 | - | - | - | - | - | - | - | pF |
| 74HC244 | - | - | 5 | - | 46 | - | - | - | - | - | - | - | pF |
| HCT 類型 | |||||||||||||
| 數據輸出傳播延遲 HCT240 | tPHL, tPLH | CL = 50pF | 4.5 | - | - | 22 | - | - | 28 | - | - | 33 | ns |
| CL = 15pF | 5 | - | 9 | - | - | - | - | - | - | - | ns | ||
| Data to Outputs 數據輸出HCT241 | tPHL, tPLH | CL = 50pF | 4.5 | - | - | 25 | - | - | 31 | - | - | 38 | ns |
| CL = 15pF | 5 | - | 10 | - | - | - | - | - | - | - | ns | ||
| Data to Outputs 數據輸出HCT244 | tPHL, tPLH | CL = 50pF | 4.5 | - | - | 25 | - | - | 31 | - | - | 38 | ns |
| CL = 15pF | 5 | - | 10 | - | - | - | - | - | - | - | ns | ||