BQ27000 Datasheet, PDF (24/29 Pages) Texas Instruments – SINGLE CELL Li-Ion AND Li-Pol BATTERY GAS GAUGE IC FOR PORTABLE APPLICATIONS (bqJUNIOR)

bq27000, bq27200
SLUS556B – SEPTEMBER 2004 – REVISED NOVEMBER 2004
Host enables E2PROM
programming mode. Write data
0xDD to address 0x6E
Host writes data in addresses
0x76 − 0x7F
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Host reads data
address 0x76
21−V pulse applied to
PROG pin for 50 ms
Programmed
0x7F?
Host increments
address and reads
No
Yes
Write data 0x00 to
address 0x6E
UDG−04099
Figure 6. EEPROM Programming Flow
It is not required that addresses 0x76 — 0x7F be programmed at the same time or in any particular order. The
programming method illustrated in Figure 6 can be used to program any of the bytes as long as the sequence of
Enable, Write, Read, Apply Programming Pulse, and Disable is followed.
Communicating With the bq27000 (HDQ interface)
The bq27000 includes a single-wire HDQ serial data interface. Host processors, configured for either polled or
interrupt processing, can use the interface to access various bq27000 registers. The HDQ pin is an open-drain
device, which requires an external pullup resistor. The interface uses a command-based protocol, where the host
processor sends a command byte to the bq27000. The command directs the bq27000 either to store the next
eight bits of data received to a register specified by the command byte or to output the eight bits of data from a
register specified by the command byte.
The communication protocol is asynchronous return-to-one and is referenced to V_SS. Command and data bytes
consist of a stream of eight bits that have a maximum transmission rate of 5 Kbits/s. The least-significant bit of a
command or data byte is transmitted first. Data input from the bqJUNIOR can be sampled using the pulse-width
capture timers available on some microcontrollers. A UART can also be configured to communicate with the
bq27000.
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