SPM and Security Subsystem
FX651
1.3
Signal List
Package
D4
Pin No.
1
2
Name
XTAL
XTALN
Signal
Type
I/P
O/P
The input to the on-chip oscillator inverter.
The inverted output of the on-chip oscillator.
To use, a crystal of frequency 3.579545MHz
should be connected between these two pins.
No other external components are necessary.
A logic input which may be used when an
external clock signal is available in place of a
crystal. The external 3.579545MHz signal is
applied to this pin and XTAL is tied to V
DD
.
When not used, this pin should be tied to V
DD
.
A logic input which controls the operating mode
of the device. In Rx, the device detects the
presence of 12kHz and 18kHz tones. In Tx, the
18kHz detect function is disabled and 18kHz is
transmitted from the TXOP pin modulated ON -
OFF by the NRZ Data pin.
A logic input used in Tx mode to ASK modulate
the TXOP pin. A logic high corresponds to no
tone and logic low corresponds to 18kHz.
The Tx mode output. It is ASK modulated by the
NRZ data input pin. It transmits 18kHz or no
tone depending upon the state of the NRZ data
input pin. This pin goes to a high impedance
state when in Rx mode.
Negative supply rail.
A bias line for the internal circuitry, held at
�½ V
DD
. It also forms the analogue ground for
the input differential amplifier. This pin must be
decoupled by a capacitor mounted close to the
device pins (see Figure 1).
Description
4
CLKIN
I/P
5
RX/TXN
I/P
6
NRZ DATA
I/P
7
TXOP
O/P
8
9
V
SS
V
BIAS
POWER
O/P
©
1997 Consumer Microcircuits Limited
4
D/651/4
CMLMICRO [ CML MICROCIRCUITS ]
