P87LPC760 View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

P87LPC760

Low power, low price, low pin count (14 pin) microcontroller with 1 kbyte OTP

Philips Electronics 

Philips Semiconductors

Low power, low price, low pin count (14 pin)

microcontroller with 1 kbyte OTP

Preliminary data

P87LPC760

Oscillator

The P87LPC760 provides several user selectable oscillator options,

allowing optimization for a range of needs from high precision to

lowest possible cost. These are configured when the EPROM is

programmed. Basic oscillator types that are supported include: low,

medium, and high speed crystals, covering a range from 20 kHz to

20 MHz; ceramic resonators; and on-chip RC oscillator.

Low Frequency Oscillator Option

This option supports an external crystal in the range of 20 kHz to

100 kHz.

Table 5 shows capacitor values that may be used with a quartz

crystal in this mode.

Table 5. Recommended oscillator capacitors for use with the low frequency oscillator option

Oscillator

Frequency

Lower Limit

VDD = 2.7 to 4.5 V

Optimal Value

Upper Limit

Lower Limit

VDD = 4.5 to 6.0 V

Optimal Value

Upper Limit

20 kHz

15 pF

15 pF

33 pF

33 pF

33 pF

47 pF

32 kHz

15 pF

15 pF

33 pF

33 pF

33 pF

47 pF

100 kHz

15 pF

15 pF

33 pF

15 pF

15 pF

33 pF

Medium Frequency Oscillator Option

This option supports an external crystal in the range of 100 kHz to

4 MHz. Ceramic resonators are also supported in this configuration.

Table 6 shows capacitor values that may be used with a quartz

crystal in this mode.

Table 6. Recommended oscillator capacitors for use with the medium frequency oscillator option

Oscillator Frequency

Lower Limit

VDD = 2.7 to 4.5 V

Optimal Value

Upper Limit

100 kHz

33 pF

33 pF

47 pF

1 MHz

4 MHz

15 pF

15 pF

15 pF

15 pF

33 pF

33 pF

High Frequency Oscillator Option

This option supports an external crystal in the range of 4 to 20 MHz.

Ceramic resonators are also supported in this configuration.

Table 7 shows capacitor values that may be used with a quartz

crystal in this mode.

Table 7. Recommended oscillator capacitors for use with the high frequency oscillator option

Oscillator

Frequency

Lower Limit

VDD = 2.7 to 4.5 V

Optimal Value

Upper Limit

Lower Limit

VDD = 4.5 to 6.0 V

Optimal Value

Upper Limit

4 MHz

15 pF

33 pF

47 pF

15 pF

33 pF

68 pF

8 MHz

16 MHz

15 pF

–

15 pF

–

33 pF

–

15 pF

15 pF

33 pF

15 pF

47 pF

33 pF

20 MHz

–

–

–

15 pF

15 pF

33 pF

On-Chip RC Oscillator Option

The on-chip RC oscillator option has a typical frequency of 6 MHz

and can be divided down for slower operation through the use of the

DIVM register. For on-chip oscillator tolerance see AC Electrical

Characteristics table. A clock output on the X2/P2.0 pin may be

enabled when the on-chip RC oscillator is used.

External Clock Input Option

In this configuration, the processor clock is input from an external

source driving the X1/P2.1 pin. The rate may be from 0 Hz up to

20 MHz when VDD is above 4.5 V and up to 10 MHz when VDD is

below 4.5 V. When the external clock input mode is used, the

X2/P2.0 pin may be used as a standard port pin. A clock output on

the X2/P2.0 pin may be enabled when the external clock input is

used.

Clock Output

The P87LPC760 supports a clock output function when either the

on-chip RC oscillator or external clock input options are selected.

This allows external devices to synchronize to the P87LPC760.

When enabled, via the ENCLK bit in the P2M1 register, the clock

output appears on the X2/CLKOUT pin whenever the on-chip

oscillator is running, including in Idle mode. The frequency of the

clock output is 1/6 of the CPU clock rate. If the clock output is not

needed in Idle mode, it may be turned off prior to entering Idle,

saving additional power. The clock output may also be enabled

when the external clock input option is selected.

2002 Mar 07

21

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