Functional Description

When power is valid, the bq4011 operates as a standard

CMOS SRAM. During power-down and power-up cycles,

the bq4011 acts as a nonvolatile memory, automatically

protecting and preserving the memory contents.

Power-down/power-up control circuitry constantly

use in systems with 5% supply tolerance. The bq4011Y

10% supply tolerance.

automatically write-protects the data. All outputs

become 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

circuitry switches to the internal lithium backup supply,

processor stabilization. Normal memory operation may

resume after this time.

The internal coin cell used by the bq4011 has an

extremely long shelf life and provides data retention for

more than 10 years in the absence of system power.

As shipped from Benchmarq, the integral lithium cell is

electrically isolated from the memory. (Self-discharge in

this condition is approximately 0.5% per year.) Following

the lithium backup cell provides data retention on sub-

sequent power-downs.

bq4011/bq4011Y

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

Active

Write

LLX

Active

Absolute Maximum Ratings

Symbol

Parameter

Value

Unit

Conditions

-0.3 to 7.0

V

-0.3 to 7.0

V

Operating temperature

0 to +70

°C

Commercial

-40 to +85

°C

Industrial “N”

Storage temperature

-40 to +70

°C

Commercial

-40 to +85

°C

Industrial “N”

Temperature under bias

-10 to +70

°C

Commercial

-40 to +85

°C

Industrial “N”

Soldering temperature

+260

°C

For 10 seconds

Note:

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

should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to

conditions beyond the operational limits for extended periods of time may affect device reliability.

Aug. 1993 C

2