HM64YLB36514 Series

Rev.0.10, May.15.2003, page 6 of 22

Programmable Impedance Output Drivers

Output buffer impedance can be programmed by terminating the ZQ pin to V

(RQ). The value of RQ is five times the output impedance desired. The allowable value of RQ to

guarantee impedance matching with a tolerance of 15% is 250

Ω. If the status of ZQ pin is open, output

impedance is maximum value. Maximum impedance also occurs with ZQ connected to V

The

impedance update of the output driver occurs when the SRAM is in high-Z. Write and deselect operations

will synchronously switch the SRAM into and out of high-Z, therefore will trigger an update. The user

may choose to invoke asynchronous

G updates by providing a G setup and hold about the K clock, to

guarantee the proper update. At power up, the output buffer is in high-Z. It will take 4,096 cycles for the

impedance to be completely updated.