M48T08 datasheet(20/27 Pages) STMICROELECTRONICS

20 / 27 page

M48T08, M48T08Y, M48T18

20/27

Figure 14. Power Down/Up Mode AC Waveforms

Note: Inputs may or may not be recognized at this time. Caution should be taken to keep E1 high or E2 low as VCC rises past VPFD (min).

Some systems may perform inadvertent WRITE cycles after VCC rises above VPFD (min) but before normal system operations begin.

Even though a power on reset is being applied to the processor, a reset condition may not occur until after the system clock is running.

Table 10. Power Down/Up AC Characteristics

Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted).

2. VPFD (max) to VPFD (min) fall time of less than tF may result in deselection/write protection not occurring until 200µs after VCC pass-

es VPFD (min).

3. VPFD (min) to VSS fall time of less than tFB may cause corruption of RAM data.

Table 11. Power Down/Up Trip Points DC Characteristics

Note: 1. All voltages referenced to VSS.

2. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted).

3. At 55°C, VCC = 0V; tDR = 8.5 years (typ) at 70°C. Requires use of M4T32-BR12SH SNAPHAT

® top when using the SOH28 package.

Symbol

Parameter(1)

Min

Max

Unit

tPD

E1 or W at VIH or E2 at VIL before Power Down

0µs

(2)

VPFD (max) to VPFD (min) VCC Fall Time

300

µs

tFB

(3)

VPFD (min) to VSS VCC Fall Time

µs

VPFD (min) to VPFD (max) VCC Rise Time

0µs

tRB

VSS to VPFD (min) VCC Rise Time

1µs

trec

E1 or W at VIH or E2 at VIL before Power Up

1ms

tPFX

INT Low to Auto Deselect

µs

tPFH

VPFD (max) to INT High

120

µs

Symbol

Parameter(1,2)

Min

Typ

Max

Unit

VPFD

Power-fail Deselect Voltage

M48T08

4.5

4.6

4.75

M48T18/T08Y

4.2

4.3

4.5

VSO

Battery Back-up Switchover Voltage

3.0

tDR

Expected Data Retention Time

10(3)

YEARS

AI00566

VCC

INPUTS

INT

(PER CONTROL INPUT)

OUTPUTS

DON'T CARE

HIGH-Z

tFB

tPFX

tPFH

trec

tPD

tRB

tDR

VALID

NOTE

(PER CONTROL INPUT)

RECOGNIZED

VPFD (max)

VPFD (min)

VSO

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