The CY62138CV25/30/33 and CY62138CV are high-performance CMOS static RAMs organized as 256K words by 8 bits. This device features advanced circuit design to provide ultra-low active current. This is ideal for providing More Battery Life™ (MoBL^®) in portable applications. The device also has an automatic power-down feature that significantly reduces power consumption by 80% when addresses are not toggling. The device can be put into standby mode reducing power consumption by more than 99% when deselected (/CE₁ HIGH or CE₂ LOW).

Writing to the device is accomplished by taking Chip Enable 1 (/CE₁) and Write Enable (/WE) inputs LOW and Chip Enable 2 (CE₂) HIGH. Data on the eight I/O pins (I/O₀ through I/O₇) is then written into the location specified on the address pins (A₀ through A₁₇).

Reading from the device is accomplished by taking Chip Enable 1 (/CE₁) and Output Enable (/OE) LOW while forcing Write Enable (/WE) and Chip Enable 2 (CE₂) HIGH. Under these conditions, the contents of the memory location specified by the address pins will appear on the I/O pins.

The eight input/output pins (I/O₀ through I/O₇) are placed in a high-impedance state when the device is deselected (/CE₁ HIGH or CE₂ LOW), the outputs are disabled (/OE HIGH), or during a write operation (/CE₁ LOW, CE₂ HIGH and /WE LOW). See the truth table at the back of this data sheet for a complete description of read and write modes.