What Is Column Address Strobe (CAS) Latency?
Definition Of CAS Latency
Column Address Strobe (CAS) latency, also called CL, is the READ command and the available moment data. The interval is specified in nanoseconds in asynchronous DRAM. In contrast, the interval is specified in clock cycles in synchronous DRAM.
As the latency depends on the number of clock ticks rather than the absolute time, the exact time for the SDRAM module to respond to CAS events may vary depending on the use of the same module if the clock rate is different.
The CAS latency for the RAM module is the number of clock cycles that RAM needs to access a particular data set in one of its columns and make the data available on its output pins.
In general, a RAM kit with a CAS of 16 requires 16 RAM clock cycles to complete this task. That is, the lower the CAS latency, the less RAM is required. Besides, you should note that CAS latency can be described in several ways. Specifically, the RAM kit with a CAS delay of 16 can be written as CAS 16 or CL16. Furthermore, two different RAM kit may have the same data transfer rate.
RAM Speed VS RAM Latency
Although the data transfer rate of RAM indicates how many giant transfers RAM can perform in a second, CAS latency is also vital for understanding RAM performance.
CAS latency tells RAM the total number of cycles required to send data, but to better understand the overall latency of that RAM, the duration of each cycle should also be taken into account.
Though DDR4 RAM is updated with higher storage density and power efficiency than DDR3 RAM, its CAS latency tends to be higher. The CAS latency for DDR3 RAM is typically 9 or 10, while the CAS latency for DDR4 is at least 15. However, due to its faster clock speed, newer standards have better overall performance.
The Column Address Strobe (CAS) Latency is not hard to understand. After going through this page, you may have a better understanding of it.