Texas Instruments BQ4015YMA-70, BQ4015MA-85, BQ4015MA-70, BQ4015YMA-85 Datasheet

bq4015/Y

512Kx8 Nonvolatile SRAM

Features

Data retention for at least 10

➤

years without power

Automatic write-protection during

➤

power-up/power-down cycles

Conventional SRAM operation,

➤

including unlimited write cycles

Internal isolation of battery be

➤

fore power application

Industry standard 32-pin DIP

➤

pinout

34-pin LIFETIME LITHIUM™

➤

module

Module completely

-

surface-mounted

Pin Connections

A

18

A

16

A

14

A

12 A

7

A

6

A

5

A

4

A

3

A

2

A

1

A

0

DQ

0

DQ

1

DQ

2

V

SS

32-Pin DIP Module

32

1 2

3 4 5 6 7 8 9 10 11 12 13 14 15 16

31 30

29 28 27 26 25 24 23 22 21 20 19 18 17

PN401501.eps

V A

A WE A A A A OE A CE DQ DQ DQ DQ DQ

CC 15

17

13 8 9 11

10

7 6 5 4 3

Snap-on power-source for

-

lithium battery backup

Replaceable power-source

-

(part number: bq40MS)

General Description

The CMOS bq4015/Y is a nonvola tile 4,194,304-bit static RAM organ

ized as 524,288 words by 8 bits. The

integral control circuitry and lith ium energy source provide reliable nonvolatility coupled with the un limited write cycles of standard SRAM.

The control circuitry constantly monitors the single 5V supply for an out-of-tolerance condition. When V

falls out of tolerance, the SRAM

CC

NC

1

A15

2

A16

3

NC

4

V

CC

5

WE

6

OE

7 8

CE

DQ

9

7

10

DQ

6

11

DQ

5

12

DQ

4

13

DQ

3

14

DQ

2

15

DQ

1

16

DQ

0

17

V

SS

34-Pin LIFETIME LITHIUM Module

34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18

PN4015Yncm.eps

is unconditionally write-protected to prevent an inadvertent write opera tion.

At this time the integral energy source is switched on to sustain the memory until after V valid.

The bq4015/Y uses extremely low

standby current CMOS SRAMs, cou

pled with small lithium coin cells to

provide nonvolatility without long

write-cycle times and the write-cycle

limitations associated with EE

PROM.

The bq4015/Y requires no external circuitry and is compatible with the industry-standard 4Mb SRAM pin out.

Pin Names

A0–A18 Address inputs

DQ0–DQ7 Data input/output

A18 A17 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0

CE

OE

WE

NC No connect

V

CC

V

SS

Chip enable input

Output enable input

Write enable input

Supply voltage input

Ground

CC

-

returns

-

Selection Guide

Part

Number

Maximum

Access

Time (ns)

Negative

Supply

Tolerance

Part

Number

Maximum

Access

Time (ns)

bq4015x -70 70 -5% bq4015Yx -70 70 -10%

bq4015x -85 85 -5% bq4015Yx -85 85 -10%

Note: x = MA for PDIP or MS for LIFETIME LITHIUM module.

5/99 E

1

Negative

Supply

Tolerance

bq4015/Y

Functional Description

When power is valid, the bq4015/Y operates as a stan dard CMOS SRAM. During power-down and power-up cycles, the bq4015/Y acts as a nonvolatile memory, auto matically protecting and preserving the memory con tents.

Power-down/power-up control circuitry constantly moni tors the V V

. The bq4015 monitors for V

PFD

use in systems with 5% supply tolerance. The bq4015Y monitors for V with 10% supply tolerance.

When V automatically write-protects the data. All outputs be come high impedance, and all inputs are treated as “don’t care.” If a valid access is in process at the time of power-fail detection, the memory cycle continues to com pletion. If the memory cycle fails to terminate within time t

WPT

supply for a power-fail-detect threshold

CC

= 4.37V typical for use in systems

PFD

falls below the V

CC

, write-protection takes place.

= 4.62V typical for

PFD

threshold, the SRAM

PFD

Block Diagram

As V circuitry switches to the internal lithium backup supply, which provides data retention until valid V

-

When V

cell voltage, the supply is switched back to V

V

continues for a time t processor stabilization. Normal memory operation may

resume after this time.

The internal coin cells used by the bq4015/Y have an ex tremely long shelf life and provide data retention for more than 10 years in the absence of system power.

As shipped from Unitrode, the integral lithium cells of the MT-type module are electrically isolated from the

memory. (Self-discharge in this condition is approxi

mately 0.5% per year.) Following the first application of V

provides data retention on subsequent power-downs.

The LIFETIME LITHIUM package option is shipped as two parts.

falls past V

CC

returns to a level above the internal backup

CC

ramps above the V

CC

, this isolation is broken, and the lithium backup

CC

and approaches 3V, the control

PFD

is applied.

CC

threshold, write-protection

PFD

(120ms maximum) to allow for

CER

. After

CC

-

OE

WE

Power

CE

1024K x 8

SRAM

Block

Power-Fail

Control

CE

CON

Lithium Cell

2

A

0–A18

DQ0–DQ

V

CC

7

BD4015.eps

bq4015/Y

Truth Table

Mode CE WE OE I/O Operation Power

Not selected H X X High Z Standby

Output disable L H H High Z Active

Read L H L D

Write L L X D

OUT

IN

Absolute Maximum Ratings

Symbol Parameter Value Unit Conditions

V

CC

V

T

OPR

T

STG

T

BIAS

T

SOLDER

Note: Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation

DC voltage applied on VCCrelative to V

SS

DC voltage applied on any pin excluding V relative to V

SS

Operating temperature

Storage temperature

Temperature under bias

CC

-0.3 to 7.0 V

V

T

0 to +70 °C Commercial

-40 to +85 °C Industrial “N”

-40 to +70 °C Commercial

-40 to +85 °C Industrial “N”

-10 to +70 °C Commercial

-40 to +85 °C Industrial “N”

Soldering temperature +260 °C For 10 seconds

should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to con ditions beyond the operational limits for extended periods of time may affect device reliability.

Active

V

+ 0.3

≤

CC

-

3

bq4015/Y

Recommended DC Operating Conditions (T

= T

OPR

)

A

Symbol Parameter Minimum Typical Maximum Unit Notes

V

CC

V

SS

V

IL

V

IH

Supply voltage

Supply voltage 0 0 0 V

Input low voltage -0.3 - 0.8 V

Input high voltage 2.2 - VCC+ 0.3 V

4.5 5.0 5.5 V bq4015Y

4.75 5.0 5.5 V bq4015

Note: Typical values indicate operation at TA= 25°C.

DC Electrical Characteristics (T

= T

OPR

, V

CCmin

A

V

CC

V

≤

CCmax

)

Symbol Parameter Minimum Typical Maximum Unit Conditions/Notes

I

V

I

LI

LO

OH

OL

SB1

SB2

Input leakage current - -

Output leakage current - -

1

±

1

±

AVIN= VSSto V

µ

= VIHor OE = VIHor

CE

A

µ

WE

= V

IL

Output high voltage 2.4 - - V IOH= -1.0 mA

Output low voltage - - 0.4 V IOL= 2.1 mA

Standby supply current - 3 5 mA CE = V

Standby supply current - 0.1 1 mA

CE

≥

0V≤V or V

IN

IH

V

- 0.2V,

CC

0.2V,

≤

IN

V

≥

CC

- 0.2

Min. cycle, duty = 100%,

= VIL, I

I

CC

Operating supply current - - 90 mA

CE A17 < V A18 < V

V

PFD

V

SO

Power-fail-detect voltage

Supply switch-over voltage - 3 - V

4.55 4.62 4.75 V bq4015

4.30 4.37 4.50 V bq4015Y

= 0mA,

I/O

or A17 > VIH,

IL

or A18 > V

IL

Note: Typical values indicate operation at TA= 25°C, VCC= 5V.

IH

Capacitance (T

= 25°C, F = 1MHz, VCC= 5.0V)

A

Symbol Parameter Minimum Typical Maximum Unit Conditions

C

I/O

C

IN

Input/output capacitance - - 8 pF Output voltage = 0V Input capacitance - - 10 pF Input voltage = 0V

Note: These parameters are sampled and not 100% tested.

4