ACS401 Main Features: Enables four full-duplex serial transmissio

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ACS401 Main Features: Enables four full-duplex serial transmissio

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Acapella Optical Modem
ACS401 Main Features:
Enables four full-duplex serial transmission channels through single fiber optic cable, providing eight virtual fiber paths. additional speed handshake signals. Supports Ping Pong (PPLED) LASER Duplex Devices (LDD) single fiber applications dual fiber applications using cost LED/LASER emitters Diode receiver. Link lengths with appropriate Laser. Maximum data rate kbps optimised talk-set applications. Typical (average) current consumption, including LASER drive current. Digital mode, allowing user external amplifier. Also enables ACS401 used non-fiber applications. Error Rate (BER) 10-9
Equivalent block diagram ACS401.
TxD1 TxD2 TxD3 TxD4 TxCL RxD1 RxD2 RxD3 RxD4 RxCL
Digital Filter
FIFO Compress
3B4B Encoder
PPLED
Driver Receiver Digital Filter FIFO Decompress 3B4B Decoder
PINP PINN
Single Fiber
Control Data
Status
Control Logic
XTAL
CLK9 ERRC ERRL
DR(1:3) DM(1:3) DP(1:4)
PORB
General Description:
ACS401 complete optical-modem controller/ driver/receiver supporting various user programmable, fullduplex, synchronous data rates kbps over single fiber. Communicating modems automatically maintain synchronisation with each other such that receive phase modem lined with transmit phase other, compensating propagation delay presented link. Link lengths from zero maximum distance, catered automatically.
Acapella Optical Modem
Inter-IC Encoding Technique 3B4B encoding method used communication between ACS401s, thus ensuring that there component signal. encoding decoding transparent user. Transmitter Receiver Functions Signals this specification refer signals TxD(1:4) RxD(1:4) respectively. input data transmitting modem time compressed encoded 3B4B format. receiving modem, 3B4B encoding ensures easy extraction bit-clock. received data filtered, decoded, then stored output memory. memory provides time expansion, de-jittering frequency compensation. data finally directed output pin. Operational Modes ACS401 four operational modes controlled DP(1:4). There modes operation support PPLED LASER duplex devices single fiber. addition, LED/PIN LASER/PIN supported dual fiber. Operational Mode PPLED 4-pin Duplex LASER Fibers Single Single Dual Dual
ACS401
kbps Optical Modem Long Haul Transmission Single/Dual Fiber applications
Laser
PMOS ZVP4424A
Single Fiber Diode
AGND
PINN IN4001
4-pin Laser duplex single fiber mode with external Laser drive circuitry
Mode LED/PIN dual fiber mode This dual fiber mode where used transmission separate diode used reception. This allows cost standard LEDs.
Fiber
N.B. LASERs must 4-pin LASERS. DP(1:4) combinations listed above factory test modes, should selected user. Damage PPLED/Duplex LED/PIN components result these illegal modes selected. N.B. Operational modes SETB (Pin2) MUST tied High.
diode
PINP
Fiber
PINN
LED/PIN dual fiber mode
Single Fiber
Mode 4-Pin LASER/PIN dual fiber mode This dual fiber mode where 4-pin laser used transmission separate diode used reception. necessary small number external components (shown diagram) support power regulation technique. method setting Laser power described section headed Control LASER current supply used power analogue ACS401. AGND analogue ground (pin ACS401).The loop stable when average current from monitor equals current through variable resistor VR2. voltage stable this point sets laser drive current.
PMOS ZVP4424A
single fiber mode
Mode single fiber mode This operational mode single fiber transmission, i.e. `ping-pong' type (PPLED) used both transmit receive. Connect PINP ACS401 leave PINN floating. Mode 4-pin Laser duplex single fiber mode This single fiber mode where Laser duplex device employed. This duplex device comprises 4-pin Laser transmission diode reception single housing. Duplex devices driven ACS401 half-duplex manner, potential cross-talk between transmitter receiver consequence. necessary small number external components (shown diagram) support power regulation technique. method setting Laser power described section headed Control LASER current
Laser Fiber
Diode
AGND
Fiber
IN4001
PINN
supply used power analogue ACS401. AGND analogue ground (pin ACS401).The loop stable when average current from monitor equals current through variable resistor VR2. voltage stable this point sets laser drive current.
4-pin Laser dual fiber mode with external Laser drive circuitry
Control LASER current LASER output current must each individual device accordance with manufacturer's recommendations. maximum output current Laser controlled resistor Rtrc connected between ground TRC. minimum value Rtrc avoid damage ACS401 800. LASER(current max) 100/Rtrc tolerance Whilst sets maximum current prevent damage laser during adjustment procedure), actual current Laser determined external component VR2. adjustment procedure described following section. Adjustment Procedure Select appropriate mode using pins DP(1:4) (see section headed Operational Modes). Choose value resistor Rtrc that delivers sufficient current correctly drive laser desired power, with sufficient power margin compensate temperature/voltage changes potential laser degradation. many applications value Rtrc will maximum current using resistor value output power from laser measured directly using optical-power meter that capable detecting peak opticalpower. average optical-power meter employed then correction factor must used obtain peak value LASER(peak power) Laser(average power) external component should have range decreased, output power will first detected when laser begins lase. should reduced further until desired output power achieved (within limits manufacturer's specification). current control transmit current less critical though important exceed manufacturer's recommendation maximum current. current controlled resistor Rtrc connected between ground. lower value Rtrc, greater current. lower limit Rtrc while practical maximum current inversely proportional Rtrc while Rtrc 800: LED(current) 100/Rtrc tolerance PORB Power-On Reset PORB resets device forced more. normal operation PORB should held High. Although PORB been included, e.g. factory test, modem been designed power correctly without PORB. PORB special function when used conjunction with memory lock (see section headed Diagnostic Modes). Crystal Clock Normally, parallel resonant crystal will connected between pins with appropriate padding capacitors. Alternatively, possible drive directly external clock. clock frequency purpose this specification will known XTAL frequency. operational range XTAL frequency MHz, though communicating ACS401s must clocked same nominal frequency. ACS401 been designed operate with XTAL tolerance giving relative tolerance between communicating modems. recommended frequency 9.216 MHz, results standard range synchronous communication frequencies tabulated section headed Data Rate Selection. standard frequencies generated using appropriate value XTALor external clock.
Example: generate 38.4 kbps dual channel. Select kbps dual channel using data rate selection pins DR4/3/2/1 1/1/0/0, XTAL frequency XTAL (38.4 9.216 5.5296 MHz. Other `non-standard' transmission frequencies generated same long XTAL oscillator range observed. wider range external clock frequencies also permissible please check with Acapella. Cint Capacitor XTAL frequency range ACS401 requires ceramic capacitor value between GND. frequencies lower than capacitor value recommended. essential that capacitor placed very close ACS401. DCDB Data Carrier Detect (DCDB) signal will when modems locked ready data transmission. Prior lock (DCDB High), data channels outputs RxD(1:4) forced with control lines XO(1:2) forced High. Data Rate Selection following data rates apply TxD1, TxD2, TxD3 TxD4 based 9.216 XTALor clock. `Standard' mode, Data Rate kbps kbps kbps kbps kbps kbps kbps kbps Channels Single Single Single Single Dual Dual Four Four
`Double'mode, Data Rate kbps kbps kbps kbps kbps kbps Channels Single Single Single Dual Dual Four
`standard' mode internal timing accommodates fiber length delays link budget permitting. `double'mode internal timing accommodates fiber length delays link budget permitting. `Double' mode essentially halves frequency internal clock therefore doubles period internal machine cycle, this also effect doubling duration LED/LASER transmit pulses, which turn likely lead improved link budgets, particularly where LEDs LASERs higher than recommended capacitance employed. Bandwidth Channel Product ACS401 Bandwidth Channel Product (BCP) `standard' mode `double' mode using recommended XTAL frequency 9.216 MHz. proportional XTAL frequency specified BCP(kHz) XTAL 9.216 XTAL frequency XTALoscillator. `standard'mode; `double' mode. given maximum bandwidth shared channels shown following tables both `standard' `double' modes XTAL frequency 9.216 MHz. `Standard' mode XTAL 9.216
Bandwidth channel
Channels
frequency, RxCL generated from Digital Phase-Lock Loop (DPLL) system (except where master mode been selected). DPLLmakes periodic corrections output RxCL clock compensate differences XTAL frequencies. case externally supplied transmission clock TxCL, compensation also made differences frequency between supplied data clock selected clock rate defined DR(1:4). DPLL adaptive will minimise frequency correction jitter, where XTALfrequency transmission clocks tightly toleranced. Diagnostic Modes
`Double' mode XTAL= 9.216 Bandwidth channel Channels
ACS401 eight diagnostic modes controlled DM(1:3). These shown following table. Diagnostic Mode Full-duplex Full-duplex Remote loopback Full-duplex Local loopback Full-duplex slave Full-duplex master Full-duplex Full-duplex full-duplex configuration, RxCL clock both devices tracks average frequency TxCL clock opposite link. receiving Digital Phase-Lock Loop (DPLL) system makes periodic adjustments RxCL clock ensure that average frequency exactly same far-end TxCL clock. summary, each TxCL independent master clock each RxCL slave far-end TxCL clock. Full-duplex slave slave mode TxCL RxCL clock derived from TxCL clock far-end link, such that average frequency exactly same. Clearly, essential that only modem configured slave mode time. overridden such that TxCL always configured output. Since only device modem pair configured slave mode, mode also selects active lock. Full-duplex master master mode RxCL clock internally generated from local TxCL clock. local TxCLclock producing RxCLclock internally externally generated. Master mode only valid far-end device configured slave mode farend TxCLclock derived from far-end RxCLclock. Only modem communicating pair configured master. Local Loopback local loopback mode, data looped back inside nearend modem output output. data also sent far-end modem synchronisation between modems maintained. local loopback mode data received from far-end device ignored, except maintain lock. concurrent requests occur local remote loopback, local loopback selected. local loop diagnostic mode used test data flow back from, local ACS401 does test integrity link itself. Therefore, local loopback operates independently synchronisation with second modem (DCDB High Low). Remote Loopback remote loopback mode, near-end modem sends request far-end modem loopback received data, thus returning data. far-end modem also outputs received data RxD. Both modems exercised completely, well LASERs/LEDs fiber optic link. remote loopback test normally used check integrity entire link from near-end (initiating modem). Lock Drift Memory Active Random Drift Active Drift Active
Power consumption will minimised choosing lowest BCP. Control Signals control signal XI(1:2) oversampled rate XTAL 18,432 (Hz) `standard' mode XTAL 36,864 (Hz) `double' mode signals filtered 4-bit filter ensuring that data applied these inputs easily corrupted. These signals used control data regarded critical. sampling frequency filtering dictates minimum High time data applied inputs XI(1:2) (18,432 XTAL(s) `standard' mode (36,864 XTAL `double'mode Therefore, with recommended XTAL frequency 9.216 `standard' mode operation, minimum High time data applied XI(1:2) successful propagation logic status XI(1:2) propagated over link appears far-end XO(1:2). When devices lock (DCDB High), then High. Transmission Clock TxCL ACS401 gives choice between internally externally generated transmission clocks. When held Low, TxCL configured output producing clock frequency defined DR(1:4). When held High, TxCL configured input, will accept externally produced transmission clock with tolerance with respect transmission rate determined DR(1:4). Data latched into device rising edge TxCL clock independent internal external TxCL generation. possible propagate asynchronous data through link. TxCL clock will over-sample data rate defined DR(1-4). choice TxCLclock frequency dictates sample rate asynchronous data appearing input TxD, consequently jitter output far-end. Example: DR4/3/2/1 Transmission data rate data rate 1000 kbps 19.2 kbps
With this set-up over-sample factor 19.2 6.67, giving effective jitter Receive Clock RxCL synchronous mode, data valid rising edge RxCL clock (see Figure Timing diagrams). ensure that average receive frequency same transmitted
Whilst device responding request remote loopback from far-end, requests from near-end initiate remote loopbacks will ignored. Drift Lock Communicating modems attain stable state where `transmit' window modem coincides with `receive' window other, allowing delay through optical link. Adjustments machine cycles made automatically during operation, compensate differences XTAL frequencies which would otherwise cause loss synchronisation. Drift lock synchronisation described above, depends difference XTALfrequencies each link, greater difference faster locking. Therefore, difference between XTAL frequencies very small ppm), automatic locking take tens seconds even minutes. Drift lock will operate communicating devices driven clock derived from single source (i.e. tolerance ppm). Active Lock Active lock mode used accelerate synchronisation pair communicating modems. This mode synchronises modems with less than seconds delay, adjusting machine cycles modems. Active lock reduces machine cycle device ensuring rapid lock. After synchronisation machine cycle reverts automatically normal. Note that only device configured active lock mode time, thus DM(1:3) pins must permanently wired High both devices production system. Active lock mode usually invoked temporarily power-up. This achieved ACS401 connecting DM1, together, attaching that node arrangement with capacitor resistor GND, create ramp power-up. time constant should seconds. Active lock will succeed even when communicating devices driven from clocks derived from single source (i.e. ppm). Random Lock This mode achieves moderate locking times (typically seconds, worst case seconds) with advantage that ACS401's configured peers. Communicating modems permanently configured this mode (i.e. with hard-wired DM(1:3) pins). Random lock operates even when communicating devices driven from clocks derived from single source. Random lock mode compatible with drift lock active lock. Memory Lock Following assertion reset (PORB communicating devices will initiate arbitration process where within seconds communicating modems will achieve synchronisation. establishing itself active lock modem other establishing itself drift lock modem. subsequent attempts lock, typically where fiber been disconnected fiber inserted, synchronisation will achieved within seconds. only necessary apply PORB device communicating pair initiate arbitration process. Since memory lock status (active drift) uses on-chip storage, loss power will require reset (PORB Furthermore, should there need synchronise with third modem, reset will again required. Mixing Lock modes possible combinations locking modes once modems locked, however, prior synchronisation modems configured active lock will operate. effect mixing locking modes locking speed tabulated below:
Device Mode Drift Drift Drift Drift Active Active Active Random Random Memory
Device Mode Drift Active Random Memory Active Random Memory Random Memory Memory
Locking Speed Drift Active Random Random allowed Random Random Random Random Active*
Memory lock random lock speed first synchronisation Status (`Heartbeat' Indicator LED) ACS401 HBTpin affords method driving display manner which sympathetic power consumption. pulsed indicate `locked'status (DCDB `out lock' status (DCDB frequency pulses times greater `out lock' than `lock'. `on' indicates power-up whilst frequency pulsing denotes locking status. Since display most total time, requires little power which further reduced employing high efficiency LEDs. formulas below presume `standard' mode operation; `double' mode XTAL value should divided Powered-up, locked Frequency (Hz): XTAL 1.152 Duration (s): 73,728 XTAL time (%): time. With 9.216 XTAL `standard' mode Frequency: (approx.) Duration (approx.) Powered-up locked Frequency (Hz): XTAL/ 18,432 Duration (s): 73,728 XTAL time (%): time. With 9.216 XTAL `standard' mode Frequency: (approx.) Duration (approx.) active High supply voltage Volts. display should placed between HBTpin with series resistor. resistor value function efficiency display LED, power budget. Example: Calculating resistor value voltage: (ACS401): Resistor voltage: Current LED: Resistor value: (high efficiency LED) 10-3 1500
Note: referred this section inexpensive display type should confused with that interfaces with fiber optic cable itself. (Error Detector) These signals used give indication quality optical link. Even when signal applied data, handshake TxCL inputs, ACS401 modem transmits approximately kbps over link each direction. This control data used maintain timing relative positioning `transmit'and `receive' windows. transmit control data constantly monitored make sure compatible with 3B4B format. coding error detected than will High will remain High until reset. reset asserting PORB removing fiberoptic cable from side link thereby forcing device temporarily lock.
produces pulse detection each coding error. These pulses accumulated means external electronic counter. Please note that detect coding errors data errors, nevertheless because complexity coding rules ACS401 absence detected errors these pins will give good indication high quality link. LASER/LED Considerations Since LEDs LASERs from different suppliers emit different wavelengths, recommended that LASERs/LEDs communicating pair modems obtained from same supplier. Furthermore, emission spectrum function temperature, temperature difference between ends link reduces responsivity receiving LASER/LED, resulting reduction link budget. Information given suppliers' data sheets. following manufacturers have components that will tested with ACS401 Acapella will glad assist with contact names addresses request: Suppliers ABB-Hafo (e.g.1A-212ST, 1A-212SMA) Acapella (e.g.A-ST, A-SMA) (e.g.1A-212-ST-05, 1A-212-SM-02) Honeywell (e.g.HFE4214-013, HFE4404-013) Duplex Suppliers 90-0359 Siemens 51214X Operating Wavelengths ACS401 support wavelength LED, ELED LASER, from through 1500 Power Supply Decoupling ACS401 contains highly sensitive amplifier, capable responding extremely current levels. exploit this sensitivity important reduce external noise level compared input signal from LASER/LED. modem should have independent power trace point where power enters board. Figure shows recommended power supply decoupling. LASER/LED should sited very close PINN, pins. generous ground plane should provided, especially
SETB TxD3 TxD4 CLK9 RxD2 RxD1 TxCL TxD2 ERRL TxD1 RxCL DCDB ERRC RxD4 RxD3
around sensitive PINN, pins. modem should protected from EMI/RFI sources standard ways. Link Budgets link budget difference between power coupled fiber transmit LASER/LED power required realise minimum input amplifier current receive LASER/LED/PIN. link budget normally specified dBm, represents maximum attenuation allowed between communicating LASER/LEDs. budget utilised terms cable length, cable connectors splices. usually includes operating margin allow degradation LASER/LED performance. power coupled cable, function efficiency LASER/LED, current applied LASER/LED type fiber optic cable employed. conversion current produced reverse biased LASER/LED function LASER/LED/PIN efficiency fiber type. conversion efficiency measured terms ability convert available optical power current, known responsivity, given (A/W). Some examples link budgets given tables headed, Link Budget Examples. Digital Mode ACS401 used controller data buffer which allows device used with external amplifier nonfiber applications. Check with Acapella details. Data delay skew Full Duplex Delay (FDD) control signals XI(1:2) when using recommended XTAL frequency 9.216 (FDD9.216MHz follows: FDD9.216MHz FDD9.216MHz FDD9.216MHz FDD9.216MHz (`standard'mode) (`double' mode) (`standard'mode) (`double' mode)
other XTAL frequencies, delay inversely proportional XTAL frequency using above delays constant proportionality. FDDXTAL (9.216 XTAL) FDD9.216MHz synchronous data skew between main data channels RxD1, RxD2, RxD3 RxD4 across link zero data-bits.
PINP PINN CON2 AGND CON1 PORB
ACAPELLA ACS401
1-Fiber Modem
Figure view PLCC package
Connected Internally Connected
TxCL RxCL clock pulse widths
Digital Outputs rise fall times
TxCL tsut
RxCL tsur
Transmit set-up hold times
Receive set-up hold times
Figure Timing diagrams
pins pins
CON1
47µH
SETB
ACS401
CON2
should connected together
Rtrc
ACS401
ACS401
AGND
capacitors should placed very close ACS401.
ACS401
Figure Recommended power supply layout
ACS401 TxD1 RxD1 TxD2 RxD2 TxD3 RxD3 TxD4 RxD4 Single Fiber Link
ACS401 RxD1 TxD1 RxD2 TxD2 RxD3 TxD3 RxD4 TxD4
Synchronous *Synchronous Channels Channels
Asynchronous *Asynchronous Channels Channel
Figure Full-duplex channels over single fiber
Single Fiber link
Link Budget Example (Rtrc launch current mApeak)
Fibertype Fibersize Minimum transmit couple power fiber (µW) Minimum responsivity (AW) Minimum ACS401 sensitivity (nA) Minimum input power ACS401 amplifier (µW) Link budget (dB) Plastic 1000 micron 1000 0.01 Glass 62.5 micron Glass micron 0.12
Single Fiber Duplex LASER link
Link Budget Example (LASER launch power
Fibertype Fibersize Minimum transmit couple power fiber (µW) Minimum responsivity (AW) Minimum ACS401 sensitivity (nA) Minimum input power ACS401 amplifier (µW) Link budget (dB) (single mode fiber attenuation Glass (single mode) micron 1000 0.35 1.43 28.4
Absolute Maximum Ratings
Dynamic Characteristics
Parameter
Power supply (VDD VA+) Input voltage (non-supply pins) Input current (except LAN,LAP,PINN,PINP,CNT) Input current (LAN, LAP,PINN,PINP,CNT) Storage temperature
Symbol
Tstor
-0.3
10.0
Units
Parameter
Crystal frequency (XT1, XTO) External clock (XTI) High time data rate `standard'mode `double'mode RxCLand TxCLduty cycle (with TxCL= output) Frequency deviation TxCLfrom selected value (with TxCL= input) TxCLset-up time
Symbol
XTAL fclp
9.216
Units
fclp
XTAL/576 XTAL/576
XTAL/72 XTAL/144
tsut tsur
(1/RxCL) (1/RxCL)
Operating Conditions
TxCLhold time
Parameter
Power supply (VA+ DA+) Ambient temperature range
Symbol
5.25
Units
RxCLset-up time RxCLhold time
Digital output fall time Digital output rise time
Static Digital Input Characteristics (for specified operating conditions)
Input pins: 1/2/3/4, 1/2/3, DP1/2/3/4 CKC, TXD1/2/3, PORB, TxCL(input)
Power consumption with LASER/LED peak current 50mA Single channel kbps (Note
Parameter
High Input currentIin
Symbol
Units
Note Power consumption assumes CMOS loads. Check with Acapella other bandwidth products.
Matching Characteristics (for specified operating conditions
Parameter
Crystal tolerance parallel resonate crystal recommended padding capacitors
Symbol
-100
Units
Static Digital Input Characteristics (for specified operating conditions)
Input pins: XI1, XI2, SETB.
Minimum amplifier sensitivity Maximum amplifier input current Imax Rtrc
0.8k
Parameter
High Pull-up resistor Input current (Note
Symbol
125k
340k
Units
Rtre placed between Single-Fibermode Parameters capacitance with Vr=0 with Irec=500 with Irec=1000 leakage current Vr=1.4 Laser current (max limit) Rtrc=0.8 kOhm Rtrc=40 kOhms current Rtrc=0.8 kOhm Rtrc=40 kOhm Ilaser
Iled
Note Input current mainly attributed pull-up resistor, applies when input Low.The High input current <10µA.
0.65
1.15
Lleak Pleak
Static Digital Output Characteristics (for specified operating conditions)
Output pins: RxD1/2/3, XO2, DCDB, ERRL, ERRD, RxCL, CLK9, TxCL(output), HBT. reverse bias LASER diode leakage current Vrp=4.0V LASER PINdiode reverse bias Dual-Fibermode Parameters capacitance with Vr=0 VDD-0.5 PINleakage current PINreverse bias Lleak 0.95 1.15
Parameter
Vout (Iin 4mA) except Vout High (Iout 4mA) except Vout (Iin 16mA) Vout High (Iout 16mA) load capcitance
Symbol
VDD-0.5
Units
Acapella Ltd.
Epsilon House Chilworth Research Centre Southampton SO16 England
©Copyright, Acapella Ltd., 1997
Tel. Fax.
01703 01703
Email: sales@acapella.co.uk Web: www.acapella.co.uk
Intn'l. Tel. 1703 Intn'l. Fax. 1703
interest further product development Acapella reserve right change this specification without further notice.

ACS401 Main Features: Enables four full-duplex serial transmissio

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