ZHCSDO4B May 2015 – May 2018
PRODUCTION DATA.
The bq27546-G1 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 bq27546-G1 via the Control() command. The keys must be sent consecutively with no other data being written to the Control() register in between.
NOTE
To avoid conflict, the keys must be different from the codes presented in the CNTL DATA column ofTable 8 subcommands.
When in SEALED mode the [SS] bit of CONTROL_STATUS is set, but when the UNSEAL keys are correctly received by the bq27546-G1, the [SS] bit is cleared. When the full-access keys are correctly received the CONTROL_STATUS [FAS] bit is cleared.
Both Unseal Key and Full-Access Key have two words and are stored in data flash. The first word is Key 0 and the second word is Key 1. The order of the keys sent to bq27546-G1 are Key 1 followed by Key 0. The order of the bytes for each key entered through the Control() command is the reverse of what is read from the part. For an example, if the Unseal Key is 0x56781234, key 1 is 0x1234 and key 0 is 0x5678. Then Control() should supply 0x3412 and 0x7856 to unseal the part. The Unseal Key and the Full-Access Key can only be updated when in FULL ACCESS mode.