Datasheet

Not Recommended for New Designs
bq27505
www.ti.com SLUS884–FEBRUARY 2009
4.4 ACCESS MODES
The bq27505 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that control
data flash access permissions, according to Table 4-6. Data Flash refers to those data flash locations,
specified in Table 4-7, that are accessible to the user. Manufacture Information refers to the three 32-byte
blocks.
Table 4-6. Data Flash Access
Security Mode Data Flash Manufacture Information
FULL ACCESS R/W R/W
UNSEALED R/W R/W
SEALED None R(A); R/W(B)
Although FULL ACCESS and UNSEALED modes appear identical, only FULL ACCESS allows the
bq27505 to write access-mode transition keys.
4.5 SEALING/UNSEALING DATA FLASH
The bq27505 implements a key-access scheme to transition between SEALED, UNSEALED, and
FULL-ACCESS modes. Each transition requires that a unique set of two keys be sent to the bq27505 via
the Control( ) control command. The keys must be sent consecutively, with no other data being written to
the Control( ) register in between. Note that to avoid conflict, the keys must be different from the codes
presented in the CNTL DATA column of Table 4-2 subcommands.
When in SEALED mode, the CONTROL_STATUS [SS] bit is set, but when the UNSEAL keys are
correctly received by the bq27505, the [SS] bit is cleared. When the full-access keys are correctly
received, then the CONTROL_STATUS [FAS] bit is cleared.
Both the sets of keys for each level are 2 bytes each in length and are stored in data flash. The UNSEAL
key (stored at Unseal Key 0 and Unseal Key 1) and the FULL-ACCESS key (stored at Full-Access Key
0 and Full-Access Key 1) can only be updated when in FULL-ACCESS mode. The order of the keys is
Key 1 followed by Key 0. The order of the bytes entered through the Control( ) command is the reverse of
what is read from the part. For example, if the Key 1 and Key 0 of the Unseal Keys returns 0x1234 and
0x5678, then the Control( ) should supply 0x3412 and 0x7856 to unseal the part.
4.6 DATA FLASH SUMMARY
Table 4-7 summarizes the data flash locations available to the user, including their default, minimum, and
maximum values.
Table 4-7. Data Flash Summary
Subclass Data Min Max Default
Class Subclass Offset Name Units
ID Type Value Value Value
Configuration 2 Safety 0 OT Chg I2 0 1200 550 0.1°C
Configuration 2 Safety 2 OT Chg Time U1 0 60 2 s
Configuration 2 Safety 3 OT Chg Recovery I2 0 1200 500 0.1°C
Configuration 2 Safety 5 OT Dsg I2 0 1200 600 0.1°C
Configuration 2 Safety 7 OT Dsg Time U1 0 60 2 s
Configuration 2 Safety 8 OT Dsg Recovery I2 0 1200 550 0.1°C
Charge Inhibit
Configuration 32 0 Charge Inhibit Temp Low I2 –400 1200 0 0.1°C
Temp Low
Charge Inhibit
Configuration 32 2 Charge Inhibit Temp High I2 –400 1200 450 0.1°C
Temp High
Temp
Configuration 32 4 Temp Hys I2 0 100 50 0.1°C
Hysteresis
Configuration 34 Charge 2 Charging Voltage I2 0 4600 4200 mV
Configuration 34 Charge 4 Delta Temp I2 0 500 50 0.1°C
Copyright © 2009, Texas Instruments Incorporated GENERAL DESCRIPTION 21
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