DP8422A datasheet(42/58 Pages) NSC

42 / 58 page

130 AC Timing Parameters

Two speed selections are given the DP8420A21A22A-20

and the DP8420A21A22A-25 The differences between

the two parts are the maximum operating frequencies of the

input CLKs and the maximum delay specifications Low fre-

quency applications may use the ‘‘b25’’ part to gain im-

proved timing

The AC timing parameters are grouped into sectional num-

bers as shown below These numbers also refer to the tim-

ing diagrams

1 – 36

Common parameters to all modes of operation

50 – 56

Difference parameters used to calculate

RAS low time

RAS precharge time

CAS high time and

CAS low time

100 – 121 Common dual access parameters used for Port

B accesses and inputs and outputs used only in

dual accessing

200 – 212 Refresh parameters

300 – 315 Mode 0 access parameters used in both single

and dual access applications

400 – 416 Mode 1 access parameters used in both single

and dual access applications

450 – 455 Special Mode 1 access parameters which super-

sede the 400 – 416 parameters when dual ac-

cessing

500 – 506 Programming parameters

Unless otherwise stated VCC e 50V g10% 0 k TA k

70 C the output load capacitance is typical for 4 banks of

18 DRAMs per bank including trace capacitance (see Note

Two different loads are specified

CL e 50 pF loads on all outputs except

CL e 150 pF loads on Q0–8 9 10 and WE or

CH e 50 pF loads on all outputs except

CH e 125 pF loads on RAS0–3 and CAS0–3 and

CH e 380 pF loads on Q0–8 9 10 and WE

Note 1

‘‘Absolute Maximum Ratings’’ are the values beyond which the safety of the device cannot be guaranteed They are not meant to imply that the device

should be operated at these limits The table of ‘‘Electrical Characteristics’’ provides conditions for actual device operation

Note 2

Input pulse 0V to 3V tR e tF e 25 ns Input reference point on AC measurements is 15V Output reference points are 24V for High and 08V for Low

Note 3

AC Production testing is done at 50 pF

TLF8588 – E9

FIGURE 36 Clock DELCLK Timing

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