SN54LS221_TI 具有施密特触发器输入的双路单稳态多谐振荡器

SN54LS221的基本参数

制造厂商：TI
产品类别：逻辑和电压转换
技术类目：专用逻辑 IC - 单稳多谐振荡器（单稳态）
功能描述：具有施密特触发器输入的双路单稳态多谐振荡器
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SN54LS221的产品详情：

The '221 and 'LS221 devices are monolithic dual multivibrators with performance characteristics virtually identical to those of the '121 devices. Each multivibrator features a negative-transition- triggered input and a positive-transition-triggered input, either of which can be used as an inhibit input.

Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse. Schmitt-trigger input circuitry (TTL hysteresis) for B input allows jitter-free triggering from inputs with transition rates as slow as 1 V/s, providing the circuit with excellent noise immunity, typically of 1.2 V. A high immunity to V_CC noise, typically of 1.5 V, is also provided by internal latching circuitry.

Once fired, the outputs are independent of further transitions of the A and B inputs and are a function of the timing components, or the output pulses can be terminated by the overriding clear. Input pulses can be of any duration relative to the output pulse. Output pulse length can be varied from 35 ns to the maximums shown in the above table by choosing appropriate timing components. With R_ext = 2 k and C_ext = 0, an output pulse typically of 30 ns is achieved, which can be used as a dc-triggered reset signal. Output rise and fall times are TTL compatible and independent of pulse length. Typical triggering and clearing sequences are shown as a part of the switching characteristics waveforms.

Pulse-width stability is achieved through internal compensation and is virtually independent of V_CC and temperature. In most applications, pulse stability is limited only by the accuracy of external timing components.

Jitter-free operation is maintained over the full temperature and V_CC ranges for more than six decades of timing capacitance (10 pF to 10 µF) and more than one decade of timing resistance (2 k can be used. Also, the range of jitter-free output pulse widths is extended if V_CC is held to 5 V and free-air temperature is 25°C. Duty cycles as high as 90% are achieved when using maximum recommended R_T. Higher duty cycles are available if a certain amount of pulse-width jitter is allowed.

The variance in output pulse width from device to device typically is less than ±0.5% for given external timing components. An example of this distribution for the '221 is shown in Figure 3. Variations in output pulse width versus supply voltage and temperature for the '221 are shown in Figures 4 and 5, respectively.

Pin assignments for these devices are identical to those of the SN54123/SN74123 or SN54LS123/SN74LS123 so that the '221 or 'LS221 devices can be substituted for those products in systems not using the retrigger by merely changing the value of R_ext and/or C_ext; however, the polarity of the capacitor must be changed.

SN54LS221的优势和特性：

Dual Versions of Highly Stable SN54121 and SN74121 One Shots
SN54221 and SN74221 Demonstrate Electrical and Switching Characteristics That Are Virtually Identical to the SN54121 and SN74121 One Shots
Pinout Is Identical to the SN54123, SN74123, SN54LS123, and SN74LS123
Overriding Clear Terminates Output Pulse

SN54LS221的参数（英文）：

Number of channels (#)
2
Supply voltage (Min) (V)
4.75
Supply voltage (Max) (V)
5.25
Technology Family
LS
Input type
Schmitt-Trigger
Output type
Push-Pull
ICC (uA)
27000
IOL (Max) (mA)
4
IOH (Max) (mA)
-0.4
Features
Standard speed (tpd > 50ns)

SN54LS221具体的完整产品型号参数及价格（美元）：

SN54LS221的完整型号有：76042012A、7604201EA、7604201FA、JM38510/31402B2A、JM38510/31402BEA、JM38510/31402BFA、M38510/31402B2A、M38510/31402BEA、M38510/31402BFA、SN54LS221J、SNJ54LS221FK、SNJ54LS221J、SNJ54LS221W，以下是这些产品的关键参数及官网采购报价：

76042012A，工作温度：-55 to 125，封装：LCCC (FK)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网76042012A的批量USD价格：23.508（1000+）

7604201EA，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网7604201EA的批量USD价格：10.038（1000+）

7604201FA，工作温度：-55 to 125，封装：CFP (W)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网7604201FA的批量USD价格：20.586（1000+）

JM38510/31402B2A，工作温度：-55 to 125，封装：LCCC (FK)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网JM38510/31402B2A的批量USD价格：19.362（1000+）

JM38510/31402BEA，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网JM38510/31402BEA的批量USD价格：11.435（1000+）

JM38510/31402BFA，工作温度：-55 to 125，封装：CFP (W)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网JM38510/31402BFA的批量USD价格：21.809（1000+）

M38510/31402B2A，工作温度：-55 to 125，封装：LCCC (FK)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网M38510/31402B2A的批量USD价格：19.362（1000+）

M38510/31402BEA，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网M38510/31402BEA的批量USD价格：11.435（1000+）

M38510/31402BFA，工作温度：-55 to 125，封装：CFP (W)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网M38510/31402BFA的批量USD价格：21.809（1000+）

SN54LS221J，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SN54LS221J的批量USD价格：7.277（1000+）

SNJ54LS221FK，工作温度：-55 to 125，封装：LCCC (FK)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SNJ54LS221FK的批量USD价格：23.508（1000+）

SNJ54LS221J，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SNJ54LS221J的批量USD价格：10.038（1000+）

SNJ54LS221W，工作温度：-55 to 125，封装：CFP (W)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SNJ54LS221W的批量USD价格：20.586（1000+）

SN54LS221的评估套件：

SN54LS221的电路图解：

SN54LS221的评估套件：