®
Numonyx™ StrataFlash Embedded Memory (J3-65nm)
12.3
Power Supply Decoupling
Flash memory devices require careful power supply de-coupling. Three basic power
supply current considerations are: 1) standby current levels; 2) active current levels;
and 3) transient peaks produced when CEX and OE# are asserted and deasserted.
When the device is accessed, many internal conditions change. Circuits within the
device enable charge-pumps, and internal logic states change at high speed. All of
these internal activities produce transient signals. Transient current magnitudes depend
on the device outputs’ capacitive and inductive loading. Two-line control and correct
de-coupling capacitor selection suppress transient voltage peaks.
Because Numonyx MLC flash memory devices draw their power from VCC, VSS, and
VCCQ, each power connection should have a 0.1 µF ceramic capacitor to ground. High-
frequency, inherently low-inductance capacitors should be placed as close as possible
to package leads.
Additionally, for every eight devices used in the system, a 4.7 µF electrolytic capacitor
should be placed between power and ground close to the devices. The bulk capacitor is
meant to overcome voltage droop caused by PCB trace inductance.
December 2008
319942-02
Datasheet
37
NUMONYX [ NUMONYX B.V ]
