Philips Semiconductors

P89C669

80C51 8-bit microcontroller family with extended memory

Product data

Rev. 02 — 13 November 2003

17 of 33

9397 750 12299

© Koninklijke Philips Electronics N.V. 2003. All rights reserved.

7.4 Security bits

The P89C669 has security bits to protect users’ firmware codes. With none of the

security bits programmed, the code in the program memory can be verified. When

only security bit 1 (see Table 6) 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 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.

[1]

P - programmed. U - unprogrammed.

[2]

Any other combination of security bits is not defined.

8.

Limiting values

[1]

The following applies to the Limiting values:

a) Stresses above those listed under Limiting values may cause permanent damage to the device. This is a stress rating only and

functional operation of the device at these or any conditions other than those described in Section 9 “Static characteristics” and

Section 10 “Dynamic characteristics” of this specification is not implied.

b) This product includes circuitry specifically designed for the protection of its internal devices from the damaging effects of excessive

static charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying greater than the rated maxima.

otherwise noted.

Table 6:

EPROM security bits

Security Bits[1][2]

Bit 1

Bit 2

Bit 3

Protection description

1

U

U

U

No program security features enabled. Flash is

programmable and verifiable.

2

P

U

U

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.

3

P

P

U

Same as 2, also verification is disabled.

4

P

P

P

Same as 3, external execution is disabled.

Table 7:

Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol

Parameter

Conditions

Min

Max

Unit

operating temperature

under bias

0

+70

°C

−40

+85

°C

storage temperature range

−65

+150

°C

0

+13

V

−0.5

V

-

20

mA

P

power dissipation

based on package heat

transfer, not device power

consumption

-

1.5

W