AT89LP51RB2 datasheet(12/254 Pages) ATMEL

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3722A–MICRO–10/11

AT89LP51RB2/RC2/IC2 Preliminary

2.3.9

Security

The AT89LP51RB2/RC2/IC2 does not support the external access pin (EA). Therefore it is not

possible to execute from external program memory in address range 0000H–1FFFH. When the

third Lockbit is enabled (Lock Mode 4) external program execution is disabled for all addresses

above 1FFFH. This differs from AT89C51RB2/RC2/IC2 where Lock Mode 4 prevents EA from

being sampled low, but may still allow external execution at addresses outside the 8K internal

space.

2.3.10

Programming

The AT89LP51RB2/RC2/IC2 supports a richer command set for In-System Programming (ISP).

Existing AT 8 9C5 1 RB2/RC2 / I C 2 pr ogr a mme rs sho u ld be a ble t o progr a m the

AT89LP51RB2/RC2/IC2 in byte mode. In page mode the AT89LP51RB2/RC2/IC2 only supports

programming of a half-page of 64 bytes and therefore requires an extra address byte as com-

pared to AT89C51RB2/RC2/IC2. Furthermore the device signature is located at addresses

0000H, 0001H and 0003H instead of 0000H, 0100H and 0200H.

Table 2-3.

Compatibility Mode versus Fast Mode Summary

Feature

Compatibility

Fast

Instruction Fetch in System Clocks

Instruction Execution Time in System Clocks

6, 12, 18 or 24

1, 2, 3, 4 or 5

Default System Clock Divisor

Default Timer Prescaler Divisor

Pin Sampling Rate (INT0, INT1, T0, T1, T2, T2EX)

Prescaler Rate

System Clock

Minimum RST input pulse in System Clocks

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