P8XCL580HFT View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'P8XCL580HFT' PDF : 80 Pages View PDF
Philips Semiconductors
Low voltage 8-bit microcontrollers with
UART, I2C-bus and ADC
Product specification
P80CL580; P83CL580
18 OSCILLATOR CIRCUITRY
The on-chip oscillator circuitry of the P8xCL580 is a
single-stage inverting amplifier biased by an internal
feedback resistor. The oscillator circuit is shown in Fig.30.
For operation as a standard quartz oscillator, no external
components are needed, except for the 32 kHz option.
When using external capacitors, ceramic resonators, coils
and RC networks to drive the oscillator, five different
configurations are supported (see Table 48 and Fig.29).
In the Power-down mode the oscillator is stopped and
XTAL1 is pulled HIGH. The oscillator invertor is switched
off to ensure no current will flow regardless of the voltage
at XTAL1, for configurations (a), (b), (c), (d), (e) and (g) of
Fig.29.
To drive the device with an external clock source, apply the
external clock signal to XTAL1, and leave XTAL2 to float,
as shown in Fig.29(f). There are no requirements on the
duty cycle of the external clock, since the input to the
internal clocking circuitry is buffered by a flip-flop.
Various oscillator options are provided for optimum
on-chip oscillator performance; these are specified in
Table 48 and shown in Fig.29. The required option should
be stated when ordering.
Table 48 Oscillator options
OPTION
Oscillator 1
Oscillator 2
Oscillator 3
Oscillator 4
RC oscillator
APPLICATION
For 32 kHz clock applications with external trimmer for frequency adjustment. A 4.7 MΩ bias resistor
is needed for use in parallel with the crystal; see Fig.29(c).
Low-power, low-frequency operations using LC components; see Fig.29(e).
Medium frequency range applications.
High frequency range applications.
RC oscillator configuration; see Figs 29(g) and 31.
handbook, full pagewidth
STANDARD
QUARTZ
OSCILLATOR
XTAL1
XTAL2
QUARTZ OSCILLATOR
WITH EXTERNAL
CAPACITORS
XTAL1
XTAL2
32 kHz
OSCILLATOR
XTAL1
XTAL2
(a)
(b)
(c)
CERAMIC
RESONATOR
XTAL1
XTAL2
(d)
LC - OSCILLATOR
XTAL1
XTAL2
(e)
EXTERNAL CLOCK
XTAL1
XTAL2
n.c.
(f)
RC - OSCILLATOR
XTAL1
n.c.
VDD
(g)
XTAL2
MLA577
1997 Mar 14
Fig.29 Oscillator configurations.
51
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