AS3953 datasheet(33/71 Pages) AMSOSRAM

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[v1-05] 2019-Feb-15

AS3953A − Detailed Description

Figure 38:

PCD-to-PICC Frame Delay Compensation

OTP Words

Write and Read Lock Words are OTP (One Time Programmable).

This means that once they are set to ‘1’, they cannot be reset

back to ‘0’. Since setting of OTP bits is an irreversible operation,

it is strongly recommended to perform it in controlled

environment.

Write Lock Word

The Write Lock Word contains write lock bits. Each EEPROM

word has a corresponding lock bit in the Write Lock Word. Once

a certain lock bit is set to ‘1’, the content of corresponding word

cannot be modified any more (it becomes read only), EEPROM

Write commands issued either through PICC interface or

through SPI interface are rejected. The lock bit of a certain

number protects the word with the same number (e.g. b5 of

lock word protects word 5). Since lock bits are OTP they cannot

be reset back to ‘0’ once they are set to ‘1’.Therefore once a

certain word is locked it cannot be unlocked any more. The lock

bits for page 0 is “don’t care” since word 0 is always read only.

Please note that setting lock bit b2 locks the Lock Word itself,

therefore once this bit is set the lock configuration cannot be

modified any more.

Read Lock Word

The Read Lock Word contains read lock bits. Each EEPROM word

has a corresponding lock bit in the Read Lock Word. Once a

certain lock bit is set to ‘1’, the content of corresponding word

cannot be read through PICC interface, it can only be read

through SPI interface. The lock bit of a certain number protects

the word with the same number (e.g. b5 of lock word protects

word 5). Since lock bits are OTP they cannot be reset back to ‘0’

once they are set to ‘1’. Therefore once a certain word is locked

it cannot be unlocked any more. The lock bits for pages 0 to 4

are “don’t care”; these pages can be read through PICC interface

even in case their corresponding lock bits are set.

fdel<1:0>

Delay [ns]

Delay [Number of 13.56 MHz Periods]

442.5

295.0

147.5

590.0

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