EMC646SP16JS-85LL datasheet(24/65 Pages) EMLSI

24 / 65 page

EMC646SP16J

4Mx16 CellularRAM

Preliminary

Drive Strength (BCR[5:4]) Default = Outputs Use Half-Drive Strength

The output driver strength can be altered to full, one-half, or one-quarter strength to adjust for different data bus loading scenarios. The

reduced-strength options are intended for stacked chip (Flash + CelllularRAM) environments when there is a dedicated memory bus.

The reduced-drive-strength option minimizes the noise generated on the data bus during READ operations. Full output drive strength

should be selected when using a discrete CellularRAM device in a more heavily loaded data bus environment. Outputs are configured at

half-drive strength during testing. See Table 4 for additional information.

Table 4: Drive Strength

WAIT Configuration (BCR[8]) Default = WAIT Transitions One Clock Before Data Valid/Invalid

The WAIT configuration bit is used to determine when WAIT transitions between the asserted and the de-asserted state with respect to

valid data presented on the data bus. The memory controller will use the WAIT signal to coordinate data transfer during synchronous

READ and WRITE operations. When BCR[8] = 0, data will be valid or invalid on the clock edge immediately after WAIT transitions to the

de-asserted or asserted state, respectively. When A8 = 1, the WAIT signal transitions one clock period prior to the data bus going valid

or invalid. (See Figure 17.)

WAIT Polarity (BCR[10]) Default = WAIT Active HIGH

The WAIT polarity bit indicates whether an asserted WAIT output should be HIGH or LOW. This bit will determine whether the WAIT

signal requires a pull-up or pull-down resistor to maintain the de-asserted state.

Figure 17: WAIT Configuration During Burst Operation

Note: Non-default BCR setting: WAIT active LOW.

BCR[5]

BCR[4]

Drive Strength

Impedance Typ (Ω )

Use Recommendation

Full

25~30

CL = 30pF to 50pF

1/2

(default)

CL = 15pF to 30pF

104 MHz at light load

1/4

100

CL = 15pF or lower

Reserved

DQ[15:0]

WAIT

End of row

Don’t Care

WAIT

CLK

BCR[8] = 0

Data valid in current cycle

BCR[8] = 1

Data valid in next cycle

EMC646SP16JS-85LL Datasheet(PDF) 24 Page - Emerging Memory & Logic Solutions Inc

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