AN2556

Electrical characteristics

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5.2

AC characteristics at 40 MHz

As the technology is different for the two devices, the I/Os present some differences in AC

behavior. Table 20 and Table 21 below list all the timing differences. Please carefully check

your design for any possible impacts.

5.2.1

External memory bus timings

Note that for CPU clock frequencies above 40 MHz (when using the ST10F273Z4Q3), some

numbers in the timing formulas become zero or negative. In most cases this is not

acceptable or meaningful. In such cases, it is necessary to relax the speed of the bus setting

time).

Output low voltage

-

2.4mA

-

V

PORT0, PORT1,

Port 4, ALE, RD,

WR, BHE,

CLKOUT, RSTOUT

PORT6, ALE,

CLKOUT, WR,

BHE, RD, RSTOUT,

RSTIN, READY

1mA

Output low voltage

(all other outputs)

-

2.4mA

-

0.4; Iol = 4mA

V

0.5mA

Output high voltage

-0.5mA

-

-8mA

-

V

PORT0,

PORT1, Port

4, ALE, RD,

WR, BHE,

CLKOUT,

RSTOUT

-1mA

PORT6, ALE,

CLKOUT, WR,

READY, BHE,

RD, RSTOUT,

RSTIN

Output high voltage

(all other outputs)

-0.25mA

-

-4mA

-V

-0.5mA

Port5 Input leakage

current

-

±0.5

-

±0.2

µA

Input leakage

current (all other

inputs)

-±1

-

±0.5

µA

Table 19.

DC characteristics (continued)

Symbol

Parameter

ST10F269Zx limit values

ST10F273Z4 limit values

Unit

Min

Max

Min

Max