P89V52X2FN datasheet(11/56 Pages) PHILIPS

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P89V52X2_1

Preliminary data sheet

Rev. 01 — 7 June 2007

11 of 56

NXP Semiconductors

P89V52X2

80C51 with 256 B RAM, 192 B data EEPROM

6.2 Memory organization

The various P89V52X2 memory spaces are as follows:

• DATA

128 B of internal data memory space (00H:7FH) accessed via direct or indirect

addressing, using instructions other than MOVX and MOVC. All or part of the Stack

may be in this area.

• IDATA

Indirect Data. 256 B of internal data memory space (00H:FFH) accessed via indirect

addressing using instructions other than MOVX and MOVC. All or part of the Stack

may be in this area. This area includes the DATA area and the 128 B immediately

above it.

• SFR

Special Function Registers. Selected CPU registers and peripheral control and status

registers, accessible only via direct addressing.

• CODE

64 kB of Code memory space, accessed as part of program execution and via the

MOVC instruction. The P89V52X2 has 8 kB of on-chip Code memory.

6.3 System clock and clock options

6.3.1 Clock input options and recommended capacitor values for the oscillator

Shown in Figure 5 and Figure 6 are the input and output of an internal inverting amplifier

(XTAL1, XTAL2), which can be configured for use as an on-chip oscillator.

When driving the device from an external clock source, XTAL2 should be left

disconnected and XTAL1 should be driven. Power consumption can be further reduced by

programming the EXTCLK bit (UCFG.0).

At start-up, the external oscillator may encounter a higher capacitive load at XTAL1 due to

interaction between the amplifier and its feedback capacitance. However, the capacitance

will not exceed 15 pF once the external signal meets the VIL and VIH specifications.

Resonator manufacturer, supply voltage, and other factors may cause circuit performance

to differ from one application to another. C1 and C2 should be adjusted appropriately for

each design. Table 4 shows the typical values for C1 and C2 vs. resonator type for various

frequencies

Table 4.

Recommended values for C1 and C2 by crystal type

Resonator

C1 =C2

Quartz

20 pF to 30 pF

Ceramic

40 pF to 50 pF

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