saa5290ps NXP Semiconductors, saa5290ps Datasheet - Page 50

• Manufacturer Part Number: saa5290ps
• Description: Economy Teletext And Tv Microcontrollers
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9.22
The oscillator circuit is a single-stage inverting amplifier in
a Pierce oscillator configuration. The circuitry between
XTALIN and XTALOUT is basically an inverter biased to
the transfer point. A crystal must be used as the feedback
element to complete the oscillator circuitry. It is operated in
parallel resonance. XTALIN is the high gain amplifier input
and XTALOUT is the output. To drive the device externally
XTALIN is driven from an external source and XTALOUT
is left open-circuit.
1998 Dec 14
handbook, halfpage
handbook, halfpage
Economy teletext and TV microcontrollers
Fig.18 Oscillator circuit driven from external source.
(1) The values of C1 and C2 depend on the crystal specification:
C1 = C2 = 2C
Clock generator
not connected
external clock
not connected
Fig.17 Oscillator circuit.
L
.
C1
C2
(1)
(1)
XTALOUT
OSCGND
XTALIN
XTALOUT
OSCGND
XTALIN
MLC110
MLC111
50
9.23
The externally applied RESET signal (active HIGH) is
used to initialize the microcontroller core, in addition to the
teletext decoder. However, the teletext decoder
incorporates a separate internal reset function which is
activated on the rising edge of the analog supply pin, V
The purpose of this internal reset circuit is to initialize the
teletext decoder when returning from the “text standby
mode”.
To ensure correct device operation for both “text standby”
and “power-on” modes, it is recommended that the internal
reset signal is active for between 10 to 15 ms. The RESET
signal should only be applied after the power supplies
(V
have stabilized.
DDM
, V
Reset signal
DDA
and V
DDT
) and the external crystal oscillator
SAA5x9x family
Preliminary specification
DDA
.