JAJSIP3 February 2020 SN74HCS21-Q1
PRODUCTION DATA.
The inputs and outputs to this device have both positive and negative clamping diodes as depicted in Figure 8.
CAUTION
Voltages beyond the values specified in the Absolute Maximum Ratings table can cause damage to the device. The input negative-voltage and output voltage ratings may be exceeded if the input and output clamp-current ratings are observed.