AS4C4M16S datasheet(21/53 Pages) ALSC

21 / 53 page

FEBRUARY 2011

AS4C4M16S

Table 17. LVTTL Interface

Reference Level of Output Signals

1.4V / 1.4V

Output Load

Reference to the Under Output Load (B)

Input Signal Levels

2.4V / 0.4V

Transition Time (Rise and Fall) of Input Signals

1ns

Reference Level of Input Signals

1.4V

3.3V

1.4V

1.2K

Ω

Output

30pF

870

Ω

Output

Z0=50

Ω

30pF

Figure 18.1 LVTTL D.C. Test Load (A)

Figure 18.2 LVTTL A.C. Test Load (B)

Transition times are measured between VIH and V IL. Transition (rise and fall) of input signals are in a fixed

slope (1 ns).

tHZ defines the time in which the outputs achieve the open circuit condition and are not at reference levels.

If clock rising time is longer than 1 ns, ( tR / 2 -0.5) ns should be added to the parameter.

10. Assumed input rise and fall time tT ( tR & tF ) = 1 ns

If tR or tF is longer than 1 ns, transient time compensation should be considered, i.e., [(tr + tf)/2 - 1] ns should

be added to the parameter.

11. Power up Sequence

Power up must be performed in the following sequence.

1) Power must be applied to VDD and VDDQ(simultaneously) when CKE=

“L”, DQM= “H” and all input signals

are held "NOP" state .

2) Start clock and maintain stable condition for minimum 200µs, then bring CKE= “H” and, it is

recommended that DQM is held "HIGH" (VDD levels) to ensure DQ output is in high impedance.

3) All banks must be precharged.

4) Mode Register Set command must be asserted to initialize the Mode register.

5) A minimum of 2 Auto-Refresh dummy cycles must be required to stabilize the internal circuitry of the

device.

* The Auto Refresh command can be issue before or after Mode Register Set command

Rev2.0 May 2014

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