The maximum frequency of operation for the SN74LS21D is typically 25 MHz, but it can vary depending on the specific application and operating conditions.
To ensure reliable operation in high-temperature environments, it is recommended to follow proper thermal management practices, such as providing adequate heat sinking and airflow, and ensuring that the device is operated within its specified temperature range (-40°C to 85°C).
The recommended power-on sequence for the SN74LS21D is to apply power to the VCC pin first, followed by the input signals. This helps to prevent unwanted oscillations and ensures proper device operation.
To handle EMI when using the SN74LS21D, it is recommended to follow proper PCB design practices, such as using a solid ground plane, minimizing trace lengths, and using shielding and filtering as necessary.
The maximum input voltage that can be applied to the SN74LS21D is 5.5V, which is the absolute maximum rating. However, it is recommended to operate the device within the recommended operating voltage range of 4.75V to 5.25V for optimal performance.
SN74LS21D datasheet
by Texas Instruments
