AN4536 Application Note Rev. 2.0 1/2014
Freescale Semiconductor
21
OTP Overview
2.4.4
Direct OTP Fuse Read
The OTP_FUSE_READ_EN bit allows the reading of the uncorrected fuse values when it is set HIGH. If ECC is not
enabled, or there is no programming error, the values loaded into the TBBOTP registers are identical to the fuse
values. If ECC is enabled and a single-bit error occurs during programming, the fuse values may be different from
the values loaded into the TBBOTP registers. The values loaded into the TBBOTP registers are the error-corrected
values.
Table 31
shows the OTP FUSE READ EN register.
2.5
Fuse Programming and Error Correction Code (ECC)
2.5.1
OTP Fuse Control Register
An example script for OTP programing is shown in section
OTP Programming Example
. The OTP_FUSE_CTLx
registers, located in the Extended Page 2, must be written to in order to program fuses. There are ten such registers,
one for each bank, Refer to
Table 32
and
Table 33
for a description of the registers.
Table 31. OTP Fuse Read Enable Register
FSL Extended Page 1
I
2
C Data Bits
Addr
Register Name
7
6
5
4
3
2
1
0
80
OTP FUSE READ EN
–
–
–
–
–
–
–
OTP_FUSE_READ_EN
0
0
0
0
0
0
0
0
Table 32. General OTP Fuse Control Register Bits
FSL Extended Page 2
I
2
C
Data Bits
Reg Name
7
6
5
4
3
2
1
0
OTP_FUSE_CTLx
–
–
–
–
ANTIFUSEx_EN
ANTIFUSEx_ LOAD
ANTIFUSEx_ RW
BYPASSx
Table 33. OTP Fuse Control Bits Description
Bit
Name
Description
0
BYPASSx
Multiplexor that selects between the value stored in the digital fuse latch
and the value on the TBBOTP register
0 = Select from digital latch
1 = Select from TBBOTP register
1
ANTIFUSEx_RW
Allows programming the fuse bank when VDDOTP is 8.25 V
0 = Disable program fuse
1 = Enable program fuse
2
ANTIFUSEx_LOAD
Clock input to the digital latch that stores the state of the analog fuse cell,
it is active high and is pulsed while the ANTIFUSE_EN bit is high to load
the value of the analog fuse state into the digital latch.
3
ANTIFUSEx_EN
Turns on the bias to the analog fuse cell so that it can be written to or read
from
0 = Analog bias disabled
1 = Analog bias enabled
4-7
Not used
Not used