8XC554 NXP Semiconductors, 8XC554 Datasheet - Page 73

• Manufacturer Part Number: 8XC554
• Description: This data sheet describes the 6 clock version of the 8xC554
• Manufacturer: NXP Semiconductors

1. P – programmed. U – unprogrammed.
2. Any other combination of the security bits is not defined.
Philips Semiconductors
EPROM CHARACTERISTICS
The 87C554 contains three signature bytes that can be read and
used by an EPROM programming system to identify the device. The
signature bytes identify the device as an 87C554 manufactured by
Philips:
(030H) = 15H indicates manufactured by Philips Components
(031H) = 93H indicates 87C554
(60H) =
Program Verification
If security bits 2 or 3 have not been programmed, the on-chip
program memory can be read out for program verification.
Table 12. Program Security Bits for EPROM Devices
NOTES:
2003 Jan 28
80C51 8-bit microcontroller – 6-clock operation
16K/512 OTP/ROMless, 7 channel 10 bit A/D, I
high I/O, 64L LQFP
PROGRAM LOCK BITS
1
2
3
4
01H
SB1
U
P
P
P
SB2
U
U
P
P
SB3
1, 2
U
U
U
P
PROTECTION DESCRIPTION
No Program Security features enabled. (Code verify will still be encrypted by the Encryption Array if
programmed.)
MOVC instructions executed from external program memory are disabled from fetching code bytes from
internal memory, EA is sampled and latched on Reset, and further programming of the EPROM is disabled.
Same as 2, also verify is disabled.
Same as 3, external execution is disabled.
2
C, PWM, capture/compare,
73
Security Bits
With none of the security bits programmed the code in the program
memory can be verified. When only security bit 1 (see Table 12) is
programmed, MOVC instructions executed from external program
memory are disabled from fetching code bytes from the internal
memory, EA is latched on Reset and all further programming of the
EPROM is disabled. When security bits 1 and 2 are programmed, in
addition to the above, verify mode is disabled.
When all three security bits are programmed, all of the conditions
above apply and all external program memory execution is disabled.
80C554/87C554
Product data