1
Features
Selectable Data Rates
1200, 2400 and 4800 Baud
Full-Duplex FFSK
Rx and Tx Bandpass Filters
Clock Recovery and Carrier
Detect Facilities
Rx and Tx Enable Functions
Publication D/469/6 April 1998
Pin Selected Xtal/Clock Inputs
1.008MHz or 4.032MHz
Radio and General Applications
Data-Over-Radio
PMR and Cellular Signalling
Portable Data Terminals
Personal/Cordless Telephone
CML Semiconductor Products
PRODUCT INFORMATION
FX469
Brief DescriptionBrief DescriptionBrief DescriptionBrief DescriptionBrief Description Rx, Tx and Carrier Detect paths each contain a
bandpass filter to ensure the provision of optimum
signal conditions both in the modem and for the Tx
modulation circuitry.
The FX469 demonstrates a high sensitivity and
good bit-error-rate under adverse signal conditions;
the carrier detect time constant is set by an external
capacitor, whose value should be arranged as
required to further enhance this product's performance
in high noise environments.
This low-power device requires few external
components and is available in small outline plastic
(S.O.I.C) and cerdip DIL packages.
The FX469 is a single-chip CMOS LSI circuit which
operates as a full-duplex pin-selectable 1200, 2400 or
4800 baud FFSK Modem. The mark and space
frequencies are 1200/1800, 1200/2400 and 2400/4800
Hz respectively. Tone frequencies are phase
continuous; transitions occur at the zero crossing point.
Employing a common Xtal oscillator with a choice of
two clock frequencies (1.008MHz or 4.032MHz) to
provide baud-rate, transmit frequencies, and Rx and Tx
synchronization, the transmitter and receiver operate
entirely independently including individual section
powersave functions.
The FX469 includes on chip circuitry for Carrier Detect
and Rx Clock recovery, both of which are made
available as output pins.
Fig.1 Functional Block Diagram
CLOCK
OSCILLATOR DIVIDER
DATA
LATCH
DIGITAL
PLL
RECTIFIER
S/N
COMPARATOR
NOISEFILTER RECTIFIER
RxFILTERRxENABLE
4800BAUDSELECT
DATA
FILTER
DIGITAL
FILTER
LIMITER LIMITER
RETRIGGERABLE
MONOSTABLE
TxGENERATOR
XTAL/CLOCK
CLOCKRATE
TxDATAI/P
RxSIGNALI/P
TxSIGNALO/P
UNCLOCKED
DATAO/P
CLOCKED
DATAO/P
RxSYNCO/P
BANDPASSO/P
CARRIERDETECTO/P
CARRIERDETECTTIMECONSTANT
TxSYNCO/P
TxFILTER
XTAL
f
..n
V
DD
V
SS
V
BIAS
1200/2400BAUDSELECT
TxENABLE
FX469 1200/2400/4800 Baud
FFSK Modem
FX469P package discontinued
2
Pin Number Function
DW
1
2
3
4
5
6
7
8
9
10
Xtal/Clock : The input to the on-chip inverter, for use with either a 1.008MHz or a 4.032MHz
Xtal or external clock. Clock frequency selection is by the “Clock Rate” input pin. The
selection of this frequency will affect the operational Data Rate of this device. Refer to Baud
Selection information on the next page. Operation of any CML microcircuit without a Xtal or
clock input may cause device damage. To minimise damage in the event of a Xtal/drive
failure. it is recommended that the power rail (VDD) is fitted with a current limiting device
(resistor or fast-reaction fuse).
XtalN : Output of the on-chip inverter.
Tx Sync O/P : A squarewave, produced on-chip, to synchronize the input of logic data and
transmission of the FFSK signal (See Figure 4).
Tx Signal O/P : When the transmitter is enabled, this pin outputs the (140-step pseudo
sinewave) FFSK signal (See Figure 4).
With the transmitter disabled, this output is set to a high-impedance state.
Tx Data I/P : Serial logic data to be transmitted is input to this pin.
Tx EnableN : A logic ‘0’ will enable the transmitter (See Figure 4). A logic ‘1’ at this input will
put the transmitter into powersave whilst forcing “Tx Sync Out” to a logic ‘1’ and “Tx Signal
Out” to a high-impedance state. This pin is internally pulled to VDD.
Bandpass O/P : The output of the Rx Bandpass Filter. This output impedance is typically
10kW and may require buffering prior to use.
Rx Enable : The control of the Rx function. The control of other outputs is given below.
Rx Enable = Rx Function Clock Data O/P Carrier Detect Rx Sync Out
“1” = Enabled Enabled Enabled Enabled
“0” = Powersave “0” “0” 1” or “0”
VBIAS: The output of the on-chip analogue bias circuitry. Held internally at VDD/2, this pin
should be decoupled to VSS by a capacitor (C2). (See Figure 2.
This bias voltage is maintained under all powersave conditions.
VSS: Negative supply rail (GND).
J/P6
1
2
3
5
6
7
8
9
10
11
LG/LS
1
2
3
5
7
8
9
10
11
12
FX469
FX469P package discontinued
3
Pin Number Function
DW
11
12
13
14
15
16
17
18
19
20
Unclocked Data O/P: The recovered asynchronous serial data output from the receiver.
Clocked Data O/P: The recovered synchronous serial data output from the receiver.
Data is latched out by the recovered clock, available at the “Rx Sync O/P,” (See Figure 5).
Carrier Detect O/P: When an FFSK signal is being received this output is a logic ‘1.’
Rx Signal I/P: The FFSK signal input for the receiver. This input should be coupled via a
capacitor, C3.
Rx Sync O/P: A flywheel squarewave output. This clock will synchronize to incoming Rx
FFSK data (See Figure 5).
1200/2400 Baud Select: A logic ‘1’ on this pin selects the 1200 baud option.
Tone frequencies are: one cycle of 1200Hz represents a logic ‘1,’ one-and-a-half cycles of
1800Hz represents a logic ‘0.’ A logic ‘0’ on this pin selects the 2400 baud option.
Tone frequencies are: one-half cycle of 1200Hz represents a logic ‘1,’ one cycle of 2400Hz
represents a logic ‘0.’ This function is also used, in part, to select the 4800 baud option. This
pin has an internal 1MW pullup resistor.
Operational Data Rate Configurations are illustrated in the table below.
Xtal/Clock Frequency 1.008MHz 4.032MHz
Clock Rate pin 0 0 1 1 1
1200/2400 Select pin 1 0 1 0 0
4800 Select pin 0 0 0 0 1
Baud Rate 1200 2400 1200 2400 4800
4800 Baud Select: A logic ‘1’ on this pin combined with a logic ‘0’ on the 1200/2400 Baud
Select pin will select the 4800 option (1MW pulldown resistor).
Tone frequencies are: one-half cycle of 2400Hz represents a logic ‘1,’ one cycle of 4800Hz
represents a logic ‘0.’ This state can only be achieved using a 4.032MHz Xtal input.
Clock Rate: A logic input to select and allow the use of either a 1.008MHz or 4.032MHz
Xtal/clock. Logic ‘1’ = 4.032MHz, logic ‘0’ = 1.008MHz. This input has an internal pulldown
resistor (1.008MHz).
Carrier Detect Time Constant : Part of the carrier detect integration function. The value of
C4 connected to this pin will affect the carrier detect response time and hence noise
performance (See Figure 2, Note 3).
VDD: Positive supply rail. A single 5-volt supply is required.
No internal connection, do not use.
J/P6
12
13
14
15
17
16
18
19
20
22
4,
21
LG/LS
13
14
15
16
18
19
20
21
22
24
4, 6, 17,
23
FX469
FX469P package discontinued
4
FX469J
XTAL/CLOCK
Tx SYNC O/P
Tx SIGNAL O/P
Tx DATA I/P
BANDPASS O/P
Rx ENABLE
UNCLOCKED DATA O/P
CLOCKED DATA O/P
Rx SIGNAL I/P
CARRIER DETECT O/P
Rx SYNC O/P
1
2
3
4
5
6
7
8
9
10
11
22
21
20
19
18
17
16
15
14
13
12
R1
C1
C2
C6
C3
C4
C5
C7
V
SS
V
SS
V
SS
V
DD
V
DD
V
DD
V
BIAS
X1XTAL
Tx ENABLE 1200/2400 BAUD SELECT
CLOCK RATE
4800 BAUD SELECT
CARRIER DETECT
TIME CONSTANT
Application Information
Component Value Tolerance
R11.0MW ±10%
C133.0pF
C21.0µF ±20%
C30.1µF
C40.1µF ±10%
C51.0µF ±20%
C61.0µF
C733.0pF
X11.008MHz See
or ‘Clock-Rate’
4.032MHz Pin
Notes
1. VBIAS may be decoupled to VSS and VDD using C2 and C6
when input signals are referenced to the VBIAS pin. For
input signals referenced to VSS, decouple VBIAS to VSS
using C2 only.
2. Use C5 when input signals are referenced to VSS, to
decouple VDD.
3. The value of C4 determines the Carrier Detect time
constant. A long time constant results in improved noise
immunity but increased response time. C4 may be varied
to trade-off response time for noise immunity.
4. C7 reduces Xtal voltage overshoot. Refer to CML Xtal
Application Note D/XT/2 December 1991.
ERROR
DETECTOR
MILLI-
AMMETER
TRUE RMS
VOLTMETER TRUE RMS
VOLTMETER
CARRIER
DETECT
O/P HIGH
DETECTOR
MILLI-
AMMETER
OSCILLOSCOPE
BUFFER
(INTERFACE)
CIRCUIT
SS
V
SS
V
DD
V
DD
V
Tx
DATA
I/P
Tx SYNC
Tx
SIGNAL
O/P
Rx
SIGNAL
I/P Rx
SYNC
CLOCKED
DATA O/P
CARRIER
DETECT
O/P
PREAMBLE &
PSEUDO-RANDOM
DATA
GENERATOR
TELEPHONE
CHANNEL
SIMULATOR
(with attenuator
&
5kHz BW noise gen)
FX469
TRANSMITTER
(components
as Fig. 2)
FX469
RECEIVER
(components
as Fig. 2)
Fig.3 Suggested FX469 Test Set-Up
Fig.2 External Components
FX469P package discontinued
5
Application InfApplication Inf
Application InfApplication Inf
Application Information ......ormation ......
ormation ......ormation ......
ormation ......
Tx
ENABLE
Tx
SYNC
Tx DATA
2400 BAUD
Tx OUTPUT
1200 BAUD
Tx OUTPUT
OPEN CIRCUIT
OPEN CIRCUIT
OPEN CIRCUIT
OPEN CIRCUIT
DC = Don’t Care
DV = Data Valid
DV
DC DV
DC DV
DC DC
t
ESET
t
TxD
t
DSETDSET
t
DH
t
TDR
t
TDR
Fig.4 Transmitter Timing
Characteristics Note Min. Typ. Max. Unit
Tx Delay, Signal to Disable Time tESET 3 2.0 - 800 µs
Data Set-Up Time tDSET 1 2.0 - - µs
Data Hold Time tDH 2.0 - - µs
Tx Delay to O/P Time tTxD - 1.2 - µs
Tx Data Rate Period tTDR 3 - 833 - µs
Rx Data Rate Period tRDR 3 800 - 865 µs
Undetermined State - - 2.0 µs
Internal Rx Delay tID - 1.5 - ms
1. Consider the Xtal/Clock tolerance.
2. All Tx timings are related to the Tx Sync Output.
3. 1200 baud example.
Fig.5 Rx Timing Diagram
Rx
SIGNAL I/P
1200 BAUD
Rx
SIGNAL I/P
2400/4800 BAUD
Rx
SYNC O/P
(1200Hz)
CLOCKED
DATA O/P
1
1
0
0
LOGIC ’1’
t
ID
t
RDR Undetermined
State
LOGIC ’0’
LOGIC ’1’ LOGIC ’0’
FX469P package discontinued
6
Specification
Absolute Maximum Ratings
Exceeding the maximum rating can result in device damage. Operation of the device outside the operating limits is
not implied.
Supply voltage -0.3 to 7.0V
Input voltage at any pin (ref VSS = 0V) -0.3 to (VDD + 0.3V)
Sink/source current (supply pins) +/- 30mA
(other pins) +/- 20mA
Total device dissipation @ TAMB 25°C 800mW Max.
Derating 10mW/°C
Operating temperature range:FX469DW/LG/LS/P6 -30°C to +70°C (plastic)
FX469J -30°C to +85°C (cerdip)
Storage temperature range: FX469DW/LG/LS/P6 -40°C to +85°C (plastic)
FX469J -55°C to +125°C (cerdip)
Operating Limits
All device characteristics are measured under the following conditions unless otherwise specified:
VDD = 5.0V, TAMB = 25°C. Audio Level 0dB ref: = 300mVrms. Xtal/Clock = 4.032MHz.
Signal-to-Noise Ratio measured in the Bit-Rate Bandwidth Baud Rate = 1200 baud.
Characteristics See Note Min. Typ. Max. Unit
Static Values
Supply Voltage 4.5 5.0 5.5 V
Supply CurrentRx EnabledTx Disabled - 3.6 - mA
Rx and Tx Enabled - 4.5 - mA
Rx and Tx Disabled - 650 - µA
Logic ‘1‘ Level 1 4.0 - - V
Logic ‘0’ Level 1 - - 1.0 V
Digital Output Impedance - 4.0 - kW
Analogue and Digital Input Impedance 100 - - kW
Tx Output Impedance - 0.6 1.0 kW
On-Chip Xtal Oscillator
RIN 10.0 - - MW
ROUT 5.0 - 15.0 kW
Inverter d.c. Voltage Gain 10.0 - 20.0 V/V
Gain Bandwidth Product 4.1 - - MHz
Xtal Frequency 2 - 1.008 - MHz
Xtal Frequency 2 - 4.032 - MHz
Dynamic Values
Receiver
Signal Input Dynamic RangeSNR = 50dB 3, 4 100 230 1000 mVrms
Bit Error Rate SNR = 12dB 4
1200 Baud - 2.5 - 104
2400 Baud - 1.5 - 103
4800 Baud - 1.5 - 103
SNR = 20dB 4
1200/2400/4800 Baud - <1.0 - 108
Receiver SynchronizationSNR =12dB 7
Probability of Bit 16 Being Correct - 0.995 -
Carrier Detect 5, 10
Sensitivity 7, 8 - - 150 mVrms
Probabilty of C.D. Being High
After Bit 16 SNR = 12dB 5, 9 0.995
0dB Noise No Signal 9 0.05
FX469P package discontinued
7
Specification ......
Characteristics See Note Min. Typ. Max. Unit
Transmitter Output
Tx Output Level - 775 - mVrms
Output Level Variation
1200/1800Hz or 1200/2400Hz or 2400/4800Hz 0 - ±1.0 dB
Output Distortion - 3.0 5.0 %
3rd Harmonic Distortion - 2.0 3.0 %
Logic ‘1’ Carrier Frequency 1200 Baud 6 - 1200 - Hz
2400 Baud 6 - 1200 - Hz
4800 Baud 6 - 2400 - Hz
Logic ‘0’ Carrier Frequency 1200 Baud 6 - 1800 - Hz
2400 Baud 6 - 2400 - Hz
4800 Baud 6 - 4800 - Hz
Isochronous Distortion
1200Hz - 1800Hz/1800Hz - 1200Hz - 25.0 40.0 µs
1200Hz - 2400Hz/2400Hz - 1200Hz - 20.0 30.0 µs
2400Hz - 4800Hz/4800Hz - 2400Hz - 10.0 20µs
Notes 1. With reference to VDD = 5.0 volts.
2. Xtal frequency, type and tolerance depends upon system requirements.
3. See Figure 5 (variation of BER with Input Signal Level).
4. SNR = Signal-to-Noise Ratio in the Bit-Rate Bandwidth.
5. See Figure 2.
6. Dependent upon Xtal tolerance.
7. 10101010101 ...01 pattern.
8. Measured with a 150mVrms input signal (no noise); 1200/2400 baud operation.
9. Reference (0dB) level for C.D. probability measurements is 230mVrms.
10.For 1200 and 2400 baud operation only; when operating at 4800 baud the Carrier Detect output
should be ignored.
Fig.6 Typical Variation of Bit Error Rate with Input Level
150 200 300 500 700 800
INPUTSIGNALLEVEL(mVrms)
BIT ERROR RATE
25010050
1x10
-5
1x10
-4
1x10
-3
1x10
-2
1x10
-1
10dB SNR
*
12dB SNR
*
20dB SNR
*
*
BITRATEBANDWIDTH
FX469P package discontinued
8
Application Information
BIT ERROR RATE (log scale)
SNR
(
dB
)
BIT RATE BANDWIDTH
(
lin scale
)
0
10
-5
10
-4
2
4
6
8
10
-3
10
-2
2x10
-2
1234 5678
9
10 11 12 13 14 15 16
IDEAL COHERENT FFSK
FX469
Fig.7 Rx Bit-Error-Rate vs Signal-to-Noise Ratio
Package Outlines
The FX469 is available in the package styles outlined
below. Mechanical package diagrams and specifications
are detailed in Section 10 of this document.
Pin 1 identification marking is shown on the relevant
diagram and pins on all package styles number
anti-clockwise when viewed from the top.
Handling Precautions
The FX469 is a CMOS LSI circuit which includes input
protection. However precautions should be taken to
prevent static discharges which may cause damage.
NOT TO SCALE
Max. Body Length 27.38mm
Max. Body Width 9.75mm
NOT TO SCALE
Max. Body Length 12.95mm
Max. Body Width 7.59mm
FX469DWFX469DW
FX469DWFX469DW
FX469DW 20-pin plastic S.O.I.C. (D3) FX469JFX469J
FX469JFX469J
FX469J 22-pin cerdip DIL (J3)
FX469P package discontinued
9
Ordering Information
FX469DW 20-pin surface mount S.O.I.C.
FX469J 22-pin cerdip DIL
FX469LGFX469LG
FX469LGFX469LG
FX469LG 24-pin quad plastic encapsulated
bent and cropped
(L1)
FX469LSFX469LS
FX469LSFX469LS
FX469LS 24-lead plastic leaded chip carrier
(L2)
FX469P6FX469P6
FX469P6FX469P6
FX469P6 22-pin plastic DIL
NOT TO SCALE
Max. Body Length 10.40mm
Max. Body Width 10.40mm
NOT TO SCALE
Max. Body Length 10.25mm
Max. Body Width 10.25mm
FX469LGFX469LG
FX469LGFX469LG
FX469LG 24-pin quad plastic encapsulated
bent and cropped (L1) FX469LSFX469LS
FX469LSFX469LS
FX469LS 24-lead plastic leaded chip
carrier (L2)
NOT TO SCALE
Max. Body Length 27.94mm
Max. Body Width 9.14mm
FX469P6FX469P6
FX469P6FX469P6
FX469P6 22-pin plastic DIL
Package Outlines ......
CML does not assume any responsibility for the use of any circuitry described. No circuit patent licences are implied
and CML reserves the right at any time without notice to change the said circuitry.
FX469P package discontinued
CML Product Data
In the process of creating a more global image, the three standard product semiconductor
companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc
(USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst
maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA)
Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML Micro-
circuits.
These companies are all 100% owned operating companies of the CML Microsystems Plc
Group and these changes are purely changes of name and do not change any underlying legal
entities and hence will have no effect on any agreements or contacts currently in force.
CML Microcircuits Product Prefix Codes
Until the latter part of 1996, the differentiator between products manufactured and sold from
MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX
respectively. These products use the same silicon etc. and today still carry the same prefixes.
In the latter part of 1996, both companies adopted the common prefix: CMX.
This notification is relevant product information to which it is attached.
Company contact information is as below:
CML Microcircuits
(UK)Ltd
COMMUNICATION SEMICONDUCTORS
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CML Microcircuits
(Singapore)PteLtd
COMMUNICATION SEMICONDUCTORS
CML Microcircuits
(USA) Inc.
COMMUNICATION SEMICONDUCTORS
Oval Park, Langford, Maldon,
Essex, CM9 6WG, England
Tel: +44 (0)1621 875500
Fax: +44 (0)1621 875600
uk.sales@cmlmicro.com
www.cmlmicro.com
4800 Bethania Station Road,
Winston-Salem, NC 27105, USA
Tel: +1 336 744 5050,
0800 638 5577
Fax: +1 336 744 5054
us.sales@cmlmicro.com
www.cmlmicro.com
No 2 Kallang Pudding Road, 09-05/
06 Mactech Industrial Building,
Singapore 349307
Tel: +65 7450426
Fax: +65 7452917
sg.sales@cmlmicro.com
www.cmlmicro.com
D/CML (D)/1 February 2002
FX469P package discontinued
