BQ26501_16 Datasheet, PDF (25/33 Pages) Texas Instruments – HANDHELD APPLICATIONS

Not Recommended For New Designs
bq26501
ą
SLUS586B − OCTOBER 2003 − REVISED MARCH 2004
APPLICATION INFORMATION
Command Byte
The command byte of the bq26501 consists of eight contiguous valid command bits. The command byte
contains two fields: W/R command and address. The command byte values are shown in the following table:
NAME
BIT 7
W/R
BIT 6
AD6
BIT 5
AD5
BIT 4
AD4
BIT 3
AD3
BIT 2
AD2
BIT 1
AD1
BIT 0
AD0
MODE
REGISTER
W/R
AD[6]
AD[5]
AD[4]
AD[3]
AD[2]
AD[1]
AD[0]
DESCRIPTION
W/R indicates whether the command bytes is a read or write command. A “1” indicates a write command and
that the following eight bits should be written to the register specified by the address field of the command byte,
while a “0” indicates that the command is a read. On a read command, the bq26501 outputs the requested
register contents specified by the address field portion of the command Byte.
The seven bits labeled AD6 through AD0 containing the address portion of the register to be accessed
Reading 16 bit Registers
Since 16-bit values are only read 8 bits at a time with the HDQ interface, it is possible that the device may update
the register value between the time the host reads the first and second bytes. To prevent any system issues,
any 16-bit values read by the host should be read using the following protocol. The entire read sequence should
complete in less than 0.8 s, the fastest rate at which any register pair is updated.
1. Read high byte (H0)
2. Read low byte (L0)
3. Read high byte (H1)
4. If H1 = H0, then valid result is H0, L0
5. Otherwise, read low byte (L1) and valid result is H1, L1.
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