The secret of the MAX17201/05/11/15 can only be updated or cleared 5 times total. New units have their secret value already cleared to all 0s. Clearing or updating the Secret uses one Secret update cycle.
The configuration NVRAM memory can only be updated 7 times by the user. Copying the NVRAM uses one NVRAM update cycle.
The two types of updates are handled independently of one another. The number of writes remaining for each update type can be determined by following these procedures:
Determining the Number of Remaining Updates for the Secret
The internal secret can only be updated or cleared 5 times total. The number of remaining updates can be calculated using the following procedure:
1. Write 0xE2FE to the Command register (060h).
2. Wait tRECALL (5mS).
3. Read memory address 1E6h.
4. Decode address 1E6h data as shown in the following table.
Each secret update has redundant indicator flags for reliability. Logically OR the upper and lower bytes together then count the number of 1s to determine how many updates have already been used. The first update occurs in manufacturing test to clear the secret memory prior to shipping to the user.
Determining the Number of Remaining Updates for Configuration NVRAM
The configuration memory can only be updated 7 times by the user (First update occurs during manufacturing test). The number of remaining updates can be calculated using the following procedure:
1. Write 0xE2FA to the Command register (060h).
2. Wait tRECALL (5mS).
3. Read memory address 1EDh.
4. Decode address 1EDh data as shown in the following table.
Each block write has redundant indicator flags for reliability. Logically OR the upper and lower bytes together then count the number of 1s determine how many updates have already been used. The first update occurs in manufacturing test prior to shipping to the user