In the datasheet, the rise and fall times of general-purpose general-purpose logic ICs are specified in the operating ranges in which their functional operation is guaranteed. Use general-purpose logic ICs within the operating ranges to prevent a malfunction due to output oscillation etc.
If a slowly rising or falling signal (a low slew rate signal) is applied to an input, a current spike occurs during switching, causing VCC and GND bounce, which might result in output oscillation or a malfunction.
Use ICs with a Schmitt-trigger input for slowly changing inputs. However, in the case of excessively slowly changing inputs, even ICs with a Schmitt-trigger input might not be able to suppress noise on power supply or signal lines, resulting in output oscillation or instability.
The table-1 shows the rise and fall times of a typical IC*1 in each series.
Type |
Series Name |
CMOS Logic IC Series No. |
One-Gate Logic (L-MOS) Equivalents |
Operating Voltage Range VCC(V) |
Propagation Delay time *1 tpLH, tpHL (ns) |
Output Current*2, IOUT (mA) |
Rise and fall time @3.3 V |
Rise and fall time @5 V |
---|---|---|---|---|---|---|---|---|
For 5-V Systems |
Standard |
3 to 18 |
200 |
±0.51 |
0~10 [μs/V]*4 |
0~5 [μs/V]*4 |
||
High Speed |
2 to 6 |
23 |
±4.0 or 6.0 |
0~1 [μs/V] |
0~500 [ns/V] |
|||
4.5 to 5.5 |
31 |
0~500 [ns/V] |
||||||
Advanced |
2 to 5.5 |
8.5 |
±24 |
0~100 [ns/V] |
0~20 [ns/V] |
|||
4.5 to 5.5 |
9.0 |
0~10 [ns/V] |
||||||
Very High Speed |
2 to 5.5 |
8.5 |
±8.0 |
0~100 [ns/V] |
0~20 [ns/V] |
|||
10 |
- *3 |
- *3 |
||||||
4.5 to 5.5 |
9.5 |
0~20 [ns/V] |
||||||
1.8 to 5.5 |
8.5 |
± 16 |
0~20 [ms/V] |
0~1 [ms/V] |
||||
For low-voltage Systems |
Low Voltage |
1.65 to 3.6 |
6.5 |
± 24 |
0~10 [ns/V] |
|||
Very Low Voltage |
1.2 to 3.6 |
4.2 |
± 24 |
0~10 [ns/V] |
*1:典型IC(TC4001、TC74HC244、TC74HCT244、TC74AC244、TC74ACT244、74VHC244、74VHC9541(An-Yn)、VHCT244、VHCV244、74LCX244和TC74VCX244)在-40至85°C时的最大传输延迟时间,但TC4001显示的是25°C时最大传输延迟时间。
*2:数据表的直流特性表中规定了输出电流值。此外,绝对最大额定值还指定了电流。
*3:未指定上升和下降时间,因为TC74VHC9系列和74VHC9系列带有施密特触发器输入端。
*4:数据表中未指定上升和下降时间。上面显示的数值仅应作为设计创建指南。
以下文档也包含相关信息。