ST M48T254V User Manual

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3.3V, 16 Mbit (2 Mb x 8 bit) TIMEKEEPER

FEATURES SUMMARY

■ 3.3V ± 10%

■ INTEGRATED ULTRA LOW POWER SRAM,

REAL TIME CLOCK, POWER-FAIL CONTROL
CIRCUIT, BATTERY AND CRYSTAL

■ REAL TIME CLOCK KEEPS TRACK OF

TENTHS/HUNDREDTHS OF SECONDS,
SECONDS, MINU TES, HOURS, DAYS, D ATE,
MONTHS, and YEARS.

■ CLOCK FUNCTION IS TRAN S P ARE N T TO

RAM OPERATION.

■ PRECISION POWER MONITORING and

POWER SWITCHING CIRCUITRY

■ AUTOMATIC WRITE-PROTECTION WHEN

V

IS OUT - OF-TOLERA NC E

CC

■ POWER-FAIL DESELECT VOLTAGE:

= 3.3V ± 10%; 2.8V ≤ V

–V

CC

■ BATTERY LOW (BL)

■ 10 YEARS of DATA RETENTION and CLOCK

OPERATION IN THE ABSENCE OF POWER

■ SNAPHAT HOUSING (BATTERY/CRYSTAL)

IS REPLACEABLE

■ 100ns ACCESS (READ = WRITE)

PFD

≤ 2.97V

M48T254V

®

SRAM WITH PHANTOM CLOCK

Figure 1. 168-ball PBGA Module

M48T254V

168-ball PBGA

Module (ZA)

Figure 2. SNAPHAT Crystal/Battery

SNAPHAT (SH)

Crystal/Battery

Rev. 2.0

1/24May 2003

M48T254V

TABLE OF CONTENTS

SUMMARY DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 3. Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Table 1. Signal Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 4. PBGA Connections (Top View) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 5. Hardware Hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 6. M48T254V PBGA Module Solution (Side/Top) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Table 2. Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

DC AND AC PARAMETERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 3. DC and AC Measurement Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 7. AC Testing Load Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 4. Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 5. DC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

OPERATION MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

READ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

WRITE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 6. Operating Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 8. Memory READ Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 9. Memory WRITE Cycle, WRITE Enable Controlled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 10. Memory WRITE Cycle, Chip Enable Controlled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 7. AC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Data Retention Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 11. Power Down/Up Mode AC Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 8. Power Down/Up Trip Points DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

PHANTOM CLOCK OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Figure 12. Comparison Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Clock Register Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

AM-PM/12/24 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Oscillator Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Zero Bits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 9. RTC Register Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 13. Phantom Clock READ Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 14. Phantom Clock WRITE Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Battery Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 11. SNAPHAT Battery Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

PACKAGE MECHANICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2/24

M48T254V

SUMMARY DESCRIPTION

®

The M48T254V TIMEKEEPER
8 non-volatile static RAM and real time clock orga­nized as 2,097,152 words by 8 bits. The special
BGA package provides a fully i ntegrated battery
back-up memory and real time clock solution. In
the event of power instability or absence, a self­contained battery maintains the timekeeping oper­ation and provides power for a CMOS static RAM.
Control circuitry monitors V
protection to prevent data corruption in the memo­ry and RTC.

RAM is a 2Mbit x

and invokes write

CC

The clock keeps track of tenths/hundredths of sec­onds, seconds, minutes , hou rs, day, date, month,
and year information. The last day of the month is
automatically adjusted for months with less than
31 days, including leap year correction.

The clock operates in one of two formats:

– a 12-hour mode with an AM/PM indicator; or
– a 24-hour mode

The M48T254V is a 168-ball PBGA module that in­tegrates the RTC, the battery, and SRAM in one
package.

Figure 3. Logic Diagram Table 1. Signal Names

A0 - A20 Address Inputs
DQ0 - DQ7 Data Input/Output
CE
WE
OE
BL

Chip Enable
WRITE Enable Inputs
Output Enable
Battery Low Output (Open Drain)

A0 – A20

CE

WE

V

CC

M48T254V

DQ0 – DQ7

BL

OE

NC No Connect
V

CC

V

SS

AI04217

V

SS

Supply Voltage
Ground

3/24

M48T254V

Figure 4. PBGA C on nec ti ons (Top View)

404139

A8

CC

V

V

1

CC

A7

2

A6

3
4

A5

5

GND

A4

6
7

A3
A2

8
9

A1

A0

DQ0

A9

DQ1

38

A10

DQ2

37

36

A11

GND

M48T254V

GND

DQ3

35

A12

34

A13

DQ4

33

A14

DQ5

32

A15

DQ6

31

A16

DQ7

30

V

BL

CC

V

CC

A17

A18
A19

GND

A20

CE
OE

WE

29
28
27
26

25

24
23

22
21

11

10

Note: Thi s di agram is TOP VI E W perspecti ve (view through package).

12

13

14

15

16

17

18

19

20

AI04216

4/24

Figure 5. Hardware Hookup

3.3V

CE
OE

WE

M41T315V

V

CC

CEI
OE
WE

CEO

D
Q

DQ0

V

A19
A20

3.3V

OUT

3.3V

M40Z300W

V

CC

E

THS
V

SS

M40Z300W

V

CC

E
A
B
THS

V

SS

E1
E2
E3

E4

V

V

OUT

RST

BL

OUT

CON
CON
CON

CON

RST

BL

A0-A18

19

V

CC

M68Z512W

E

G

3.3V
(Not Bonded)

To Battery Monitor Circuitry

A0-A18

19

V

CC

M68Z512W

E

G

8

W

8

W

DQ0-DQ7

.1µF

DQ0-DQ7

V

.1µF

E

A0-A18

19

V

CC

M68Z512W

E

E

G

A0-A18

19

CC

M68Z512W

G

M48T254V

DQ0-DQ7

8

W

WE

OE

DQ0-DQ7

8

W

WE

OE

AI04215

5/24

M48T254V

Figure 6. M4 8T2 54V PBGA Mod ul e So lu tion (Si de / Top)

AI04214b

MAXIMUM RATING

Stressing the device ab ove the rating listed in the
“Absolute Maximum Ratings” table may cause
permanent damage to the device. These are
stress ratings only and operation of the dev ice at
these or any other conditions above those indicat-

not implied. Exposure to Absol ute Maxim um Ra t­ing conditions for extended periods may affect de­vice reliability. Refer also to the
STMicroelectronics SURE Program and other rel­evant quality documents.

ed in the Operating sections of this specification is

Table 2. Absolute Maximum Ratings

Symbol Parameter Value Unit

T
T

V

T

STG

SLD

CC

V

I

P

A

IO

O

D

Operating Temperature 0 to 70 °C
Storage Temperature (VCC, Oscillator Off)

Lead Solder Temperature for 10 seconds 260 °C
Supply Voltage (on any pin relative to Ground) –0.3 to +4.6 V

Input or Output Voltages
Output Current 20 mA
Power Dissipation 1 W

–40 to 85 °C

–0.3 to V

CC

+ 0.3

V

CAUTION! Negative undershoots be l ow –0.3V are not al lowed on any pin while in the Battery Back-up Mode.

6/24

DC AND AC PARAMETERS

This section summarizes the operat ing and mea­surement conditions, as well as the DC and AC
characteristics of the device. The parameters in
the following DC and AC Characteristic tables are

ment Conditions listed in the rel evant tables. De­signers should check that the operating conditions
in their projects match the measurement condi­tions when using the quoted parameters.

derived from tests performed under the M easure-

Table 3. DC and AC Measurement Conditions

Parameter M41T254V

V

Supply Voltage

CC

Ambient Operating Temperature 0 to 70°C
Load Capacitance (C
Input Rise and Fall Times ≤ 5ns
Input Pulse Voltages 0 to 3V
Input and Output Timing Ref. Voltages 1.5V

Note: Out put Hi-Z is defined as the poin t where data is no l onger driven.

)

L

3.0 to 3.6V

50pF

Figure 7. AC Testing Load Circuit

M48T254V

DEVICE

645Ω

UNDER

TEST

CL = 50 pF

1.75V

AI04644

Table 4. Capacitance

Symbol

C

IN

C

OUT

(3)

C

IO

Note: 1. Effective capacitance measure d wi th power supply at 3V. Sampled only; not 100% tested.

2. At 25°C, f = 1MHz.

3. Outputs were dese l ected.

Input Capacitance (A0-A18, OE, WE, CE)40pF
Input Capacitance (A19-A20) 10 pF
Output Capacitance (BL)20pF

Input / Output Capacitance 40 pF

Parameter

(1,2)

Min Max Unit

7/24

M48T254V

Table 5. DC Characteristics

Sym Parameter

Test Condition

(1)

M48T254V

Unit

Min Typ Max

Input Leakage Current

I

LI

I

Output Leakage Current

LO

I

Supply Current 50 mA

CC1

I

Supply Current (TTL Standby)

CC2

I

VCC Power Supply Current CE = V

CC3

(2)

V

V

V

V

PFD

V

Note: 1. Valid fo r Ambient Operating Temperature: TA = 0 to 70°C; VCC = 3.0 to 3.6V (except where noted).

Input Low Voltage –0.3 0.6 V

IL

(2)

Input High Voltage 2.2

IH

Output Low Voltage (Open Drain)

(3)

OL

Output Low Voltage

V

Output High Voltage

OH

(2)

Power Fail Deselect 2.80 2.97 V

(2)

Battery Back-up Switchover

SO

2. All vol t ages are referenced to Ground.

3. For BL

pin (Open Drain).

0V ≤ V

0V ≤ V

OUT

CE

I

= 10mA

OL

= 2.0mA

I

OL

I

= –1.0mA

OH

IN

= V

CCI

≤ V

≤ V

IH

– 0.2

CC

CC

57mA
23mA

2.4 V

2.5

±4 µA
±4 µA

V

+ 0.3

CC

0.4 V

0.4 V

V

V

8/24