PC48F4400PLVB0 datasheet(46/102 Pages) NUMONYX

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Numonyx™ Wireless Flash Memory (W18)

Datasheet

November 2007

Order Number: 290701-18

Numonyx™ Wireless Flash Memory (W18)

8.0

Power and Reset Specifications

Numonyx™ Wireless Flash Memory (W18) devices have a layered approach to power

savings that can significantly reduce overall system power consumption. The APS

feature reduces power consumption when the device is selected but idle. If CE# is

deasserted, the memory enters its standby mode, where current consumption is even

lower. Asserting RST# provides current savings similar to standby mode. The

combination of these features can minimize memory power consumption, and

therefore, overall system power consumption.

8.1

Active Power

With CE# at VIL and RST# at VIH, the device is in the active mode. Refer to Section 6.1,

“DC Current Characteristics” on page 23, for ICC values. When the device is in “active”

state, it consumes the most power from the system. Minimizing device active current

therefore reduces system power consumption, especially in battery-powered

applications.

8.2

Automatic Power Savings (APS)

Automatic Power Saving (APS) provides low-power operation during a read’s active

state. During APS mode, ICCAPS is the average current measured over any 5 ms time

interval 5 µs after the following events happen:

• There is no internal sense activity;

• CE# is asserted;

• The address lines are quiescent, and at VSSQ or VCCQ.

OE# may be asserted during APS.

8.3

Standby Power

With CE# at VIH and the device in read mode, the flash memory is in standby mode,

which disables most device circuitry and substantially reduces power consumption.

Outputs are placed in a high-impedance state independent of the OE# signal state. If

CE# transitions to VIH during erase or program operations, the device continues the

operation and consumes corresponding active power until the operation is complete.

ICCS is the average current measured over any 5 ms time interval 5 µs after a CE# de-

assertion.

8.4

Power-Up/Down Characteristics

The device is protected against accidental block erasure or programming during power

transitions. Power supply sequencing is not required if VCC, VCCQ, and VPP are

connected together; so it doesn’t matter whether VPP or VCC powers-up first. If VCCQ

and/or VPP are not connected to the system supply, then VCC should attain VCCMIN

before applying VCCQ and VPP. Device inputs should not be driven before supply

voltage = VCCMIN. Power supply transitions should only occur when RST# is low.

8.4.1

System Reset and RST#

The use of RST# during system reset is important with automated program/erase

devices because the system expects to read from the flash memory when it comes out

of reset. If a CPU reset occurs without a flash memory reset, proper CPU initialization

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