MSP 34x1G
PRELIMINARY DATA SHEET
Pins 71, 72 XTAL_IN, XTAL_OUT – Crystal Input and
Output Pins (Fig. 4–16)
These pins are connected to an 18.432 MHz crystal
oscillator which is digitally tuned by integrated shunt
capacitances. An external clock can be fed into
XTAL_IN.
The
audio
clock
output
signal
AUD_CL_OUT is derived from the oscillator. External
capacitors at each crystal pin to ground (AVSS) are
required. It should be verified by layout, that no supply
current for the digital circuitry is flowing through the
ground connection point.
Pin 73, TP – This pin enables factory test modes. For
normal operation, it must be left vacant.
Pin 74, AUD_CL_OUT – Audio Clock Output
(Fig. 4–16)
This is the 18.432 MHz main clock output.
Pins 75, 76, NC – Pins not connected.
Pins 77, 78, D_CTR_I/O_1/0 – Digital Control Input/
Output Pins (Fig. 4–15)
These pins serve as general purpose input/output
pins. Pin D_CTR_I/O_1 can be used as an interrupt
request pin to the controller.
Pin 79, ADR_SEL – I2C Bus Address Select
(Fig. 4–14)
By means of this pin, one of three device addresses
for the MSP can be selected. The pin can be con-
nected to ground (I2C device addresses 80/81hex), to
+5 V supply (84/85hex), or left open (88/89hex).
Pin 80, STANDBYQ – Stand-by
In normal operation, this pin must be High. If the
MSP 34x1G is switched off by first pulling STANDBYQ
low and then (after >1 µs delay) switching off the 5 V,
but keeping the 8-V power supply (‘Stand-by’-mode),
the SCART switches maintain their position and func-
tion.
* Application Note:
All ground pins should be connected to one low-resis-
tive ground plane. All supply pins should be connected
separately with short and low-resistive lines to the
power supply. Decoupling capacitors from DVSUP to
DVSS, AVSUP to AVSS, and AHVSUP to AHVSS are
recommended as closely as possible to these pins.
Decoupling of DVSUP and DVSS is most important.
We recommend using more than one capacitor. By
choosing different values, the frequency range of
active decoupling can be extended. In our application
boards we use: 220 pF, 470 pF, 1.5 nF, and 10 µF. The
capacitor with the lowest value should be placed near-
est to the DVSUP and DVSS pins.
54
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