FT28C010 datasheet(10/30 Pages) FORCE

10 / 30 page

SYSTEM CONSIDERATIONS

Because the FT28C010 is frequently used in large memory

arrays it is provided with a two line control architecture

for both read and write operations. Proper usage can

provide the lowest possible power dissipation and elimi-

nate the possibility of contention where multiple I/O pins

share the same bus.

To gain the most benefit it is recommended that CE be

decoded from the address bus and be used as the

primary device selection input. BothOE and WE would

then be common among all devices in the array. For a

read operation this assures that all deselected devices

are in their standby mode and that only the selected

device(s) is outputting data on the bus.

Because the FT28C010 has two power modes, standby

and active, proper decoupling of the memory array is of

prime concern. Enabling CE will cause transient current

spikes. The magnitude of these spikes is dependent on

the output capacitive loading of the I/Os. Therefore, the

larger the array sharing a common bus, the larger the

transient spikes. The voltage peaks associated with the

current transients can be suppressed by the proper

selection and placement of decoupling capacitors. As a

minimum, it is recommended that a 0.1 µF high fre-

quency ceramic capacitor be used between V CC and

VSS at each device. Depending on the size of the array,

the value of the capacitor may have to be larger.

In addition, it is recommended that a 4.7µF electrolytic

bulk capacitor be placed between VCC and VSS for each

eight devices employed in the array. This bulk capacitor

is employed to overcome the voltage droop caused by

the inductive effects of the PC board traces.

Active Supply Current vs. Ambient Temperature

ICC (RD) by Temperature over Frequency

Standby Supply Current vs. Ambient Temperature

–55

–10

+125

0.15

0.2

0.25

0.3

AMBIENT TEMPERATURE (°C)

0.05

+35

+80

VCC = 5V

0.1

–55

–10

+125

AMBIENT TEMPERATURE (°C)

+35

+80

VCC = 5V

315

5.0 VCC

FREQUENCY (MHz)

–55→C

+25→C

+125→C

FT28C010-xxxxx-X

Rev 1.1

10/30

2011

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