memory products - Al Kossow's Bitsavers

MK41 H79(N, P)-20/25/35ITANDBY MODE·he MK41H79 is in Standby Mode whenever CE isleld at or above V IH •:IGURE 5. STANDBY MODEIcc 50%'------STANOBY----....JITANDBY MODEDOC:s;T A:s;7DOC) (Vce = 5.0 V ± 10 percent)MK41H79-20 MK41H79-25 MK41H79-35SYM PARAMETER MIN MAX MIN MAX MIN MAX UNITS NOTEStpoChip Enable High to PowerDowntpu Chip Enable Low to Power Up 020 25 35 ns0 0 ns~PPLICATION;he MK41H79 operates from a 5.0 volt supply. It is:ompatible with all standard TTL families on all inlutSand outputs. The device should share a solidJround plane with any other devices interfaced witht;- particularly TTL devices. Additionally, becausehe outputs can drive rail-to-rail into high impedanceoads, the 41H79 can also interface to 5 volt CMOSIn all inputs and outputs. Refer to the normalizedlerformance curves that follow.;ince very high frequency current transients will beISsociated with the operation of the MK41H79, pow­Ir line inductance must be minimized on the cir­:uit board power distribution network. Power andJround tracegridding or separate power planes canIe employed to reduce line inductance. Addition­Illy, a high frequency decoupling capacitor shouldbe placed next to each RAM. The capacitor shouldbe 0.1 pF or larger. A pull-up resistor is also recommendedfor CLR on the MK41H79. This will ensurethat any low going system noise, coupled onto theinput, does not drive CLR below V 1H minimumspecifications.Though often times not thought of as such, thetraces on a memory board are basically untermi·nated, low impedance transmission lines. As suchthey are subject to signal reflections manifested asnoise, undershoots and excessive ringing. Seriestermination in close proximity to the TTL drivers canimprove driver/signal path impedance matching.While experimentation most often proves to be theonly practical approach to selection of series resistors,values in the range of 10 to 33 ohms oftenprove most suitable.5/10501