I/O Switching Power for Sync SRAM - KBA82208

Version: *A

 

Question:

Is the IDD (VDD operating supply current) current specified in the sync SRAM datasheets sum of both the core current and
I/O current?

 

Answer:

No. The current specified in the datasheets indicate just the current consumption by the core of the memory (IDD). The current drawn by the I/Os (IDDQ) is not specified in the datasheets as this value depends on the load driven by the I/O’s of the device and the number of I/O’s switching. Please use the power calculator tool in the following link to calculate the I/O switching power for sync SRAM products:

http://www.cypress.com/?docID=23984

For example, let us consider a QDR-II memory (for example, CY7C1315KV18 - Density 512 K x 36)

  1. Activity factor ‘α’ =1 (Because the data gets transferred on both edges of the clock, 0.5 for Standard Sync and NoBL)
  2. Maximum Clock Frequency ‘f’ is 333 MHz
  3. Load Capacitance CL is 5 pF (This value depends on the actual board layout and the load capacitance seen by the output pin of the memory)
  4. Number of Switching I/Os N is 36 (This will be the number of I/Os driving the load)
  5. VDDQ is 1.9 V maximum
      Based on the formula, P = α f CL VDDQ2 N
      I/O Switching Power is 216 mW
      IDDQ is 113 mA

Customers must use this to design their power circuitry accordingly.