bq2022

SLUS526B − OCTOBER 2002 − REVISED OCTOBER 2003

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complement of the page address indicated by the hex value stored in the associated page address redirection

byte. A value of FDh in the redirection byte for page 1, for example, indicates that the updated data are now

in page 2. The details for reading and programming the EPROM status memory portion of the bq2022 are given

in the Memory Function Commands section.

Table 2. EPROM Status Bytes

ADDRESS

(HEX)

PAGE

00h

Write protection bits

BIT0 − write protect page 0

BIT1 − write protect page 1

BIT2 − write protect page 2

BIT3 − write protect page 3

BIT4 to 7 − bitmap of used pages

01h

Redirection byte for page 0

02h

Redirection byte for page 1

03h

Redirection byte for page 2

04h

Redirection byte for page 3

05h

Reserved

06h

Reserved

07h

Factory programmed 00h

Error Checking

To validate the data transmitted from the bq2022, the host generates a CRC value from the data as they are

received. This generated value is compared to the CRC value transmitted by the bq2022. If the two CRC values

are found in the CRC Generation Section of this data sheet.

Customizing the bq2022

The 64-bit ID identifies each bq2022. The 48-bit serial number is unique and programmed by Texas

Instruments. The default 8-bit family code is 09h; however, a different value can be reserved on an individual

customer basis. Contact your Texas Instruments sales representative for more information.

Bus Termination

Because the drive output of the bq2022 is an open-drain N-channel MOSFET, the host must provide a source

current or a 5-k

Ω external pullup, as shown in the typical application circuit in Figure 1.

HOST

bq2022

VPU

CPU

1

Communications

Controller

2

SDQ

3

VSS

VSS

UDG−02055

Figure 1. Typical Applications Circuit