DATA BULLETIN
MX214/224
Features
CTCSS Highpass Filter
Good Recovered Audio Quality
Fixed and Rolling Code Modes
Serial (MX214) and Parallel (MX224)
Loading Options
32 Programmable Split Points
Half-Duplex Capability
POWERSAVE
LOAD / LATCH
SERIAL CLOCK
ENABLE / MUTE
CLEAR / SCRAMBLE
Rx / Tx (SER / PAR)
A0
A1
A2
A3
A4
(SERIAL DATA IN)
CK
B
EN
⋅
PS
⋅
Rx
Rx IN
PS
BIAS
Tx
⋅
PS
Tx
⋅
PS
Tx IN
FILTER 1
PS
BIAS
CK
A
C6
Tx
Tx
FILTER 2
CK
A
Rx
MUTE
BIAS
FILTER 3
CK
3
CTCSS
F
C2
C
5
FILTER 4
CK
4
Rx
F
C1
Rx
Rx
CK
A
F
C1
F
C2
PS
CK
3
CK4
ROM
CLOCK
DIVIDER
INPUT LATCHES
EN / MUTE
CLEAR / SCRAMBLE
Rx / Tx
Variable Split Band
Inverter
Applications
Mobile Radio Voice Security
Cellular Telephone Voice
Security
XTAL / CLOCK
1MHz
OSC
XTAL
1MHz
V
DD
CLOCK
DIVIDER
CK
B
CK
B
CLOCK
SWITCHING
Rx / Tx
V
BIAS
V
SS
Rx
PS
⋅
EN
⋅
Tx
Tx OUT
PS + EN
⋅
Tx
Tx
SCRAMBLE
BIAS
Σ
CK
4
CLEAR
PS
⋅
MUTE
⋅
Rx
Rx OUT
BIAS
Tx
Rx
BIAS
BIAS
PS + EN
⋅
Rx
The MX214/224 Variable Split Band Inverters are designed for mobile and cellular radio voice security
applications. Digital control functions are loaded serially into the MX214. The MX224 is loaded in parallel.
The MX214/224 ICs include a highpass filter that rejects subaudio frequencies, ensuring full CTCSS
compatibility. This CTCSS filter is not included on the earlier generation MX204 VSB Inverter.
The MX214/224 splits the voiceband (300-2700Hz) into upper and lower subbands, and inverts each subband
about itself. The ‘split point’ (defined as the frequency where the voice band is subdivided), is externally
programmable to 32 distinct values in the 300 to 3000Hz range. In the ‘fixed code’ mode, a single point is
used. Fixed mode operation nets approximately 4 mutually exclusive secure channels.
In ‘rolling code’ mode, the split point is changed many times per second, usually under control of a
microprocessor. Rolling code scrambling requires synchronization, offers higher security than fixed code
operation, and provides a much greater number of mutually exclusive secure channels.
The MX214/224 offers a recovered audio product close to that of a telephone. The on-chip ‘ Mute’ function is
useful when implementing rolling code continuous synchronization schemes. ‘Powersave’ and
‘Clear/Scramble’ controls are also included on-chip. Timing and filter clocks are derived internally from an
on-chip 1MHz reference oscillator driven by a 1MHz crystal or clock pulse input.
The MX214 and the MX224 operate from a single 5.0V supply and available in the following packges:
22-pin CDIP (MX214J/MX224J), 22-pin PDIP (MX214P/MX224P), and 24-pin PLCC (MX214LH/MX224LH).
1998
MX-COM, Inc.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480112.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CMLMICRO [ CML MICROCIRCUITS ]
