AT87251G2D-3CSUM【PDF 36/77 页】IC 8051 MCU 32K OTP 24MHZ 40DIP

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录3833

32页 33页 34页 35页 [36页]37页 38页 39页 40页

AT/TSC8x251G2D

4135F–8051–11/06

Lock Bit System

The TSC87251G2D products implement 3 levels of security for User’s program as

described in Table 33. The TSC83251G2D products implement only the first level of

security.

Level 0 is the level of an erased part and does not enable any security features.

Level 1 locks the programming of the User’s internal Code Memory, the Configuration

Bytes and the Encryption Array.

Level 2 locks the verifying of the User’s internal Code Memory. It is always possible to

verify the Configuration Bytes and the Lock Bits. It is not possible to verify the Encryp-

tion Array.

Level 3 locks the external execution.

Table 33.

Lock Bits Programming

Notes: 1. Returns encrypted data if Encryption Array is programmed.

2. Returns non encrypted data.

3. x means don’t care. Level 2 always enables level 1, and level 3 always enables levels

1 and 2.

The security level may be verified according to Table 34.

Table 34.

Lock Bits Verifying

Note:

1. x means don’t care.

Encryption Array

The TSC83251G2D and TSC87251G2D products include a 128-byte Encryption Array

located in non-volatile memory outside the memory address space. During verification

of the on-chip code memory, the seven low-order address bits also address the Encryp-

tion Array. As the byte of the code memory is read, it is exclusive-NOR’ed (XNOR) with

the key byte from the Encryption Array. If the Encryption Array is not programmed (still

all 1s), the user program code is placed on the data bus in its original, unencrypted form.

If the Encryption Array is programmed with key bytes, the user program code is

encrypted and cannot be used without knowledge of the key byte sequence.

Level

Lock bits

LB[2:0]

Internal

Execution

External

Execution

Verification

Programming

External

PROM read

(MOVC)

000

Enable

Enable(1)

Enable

Enable(2)

001

Enable

Enable(1)

Disable

01x(3)

Enable

Disable

31xx(3)

Enable

Disable

Level

Lock bits Data

(1)

xxxxx000

xxxxx001

xxxxx01x

xxxxx1xx

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式