DS32EL0124 DS32ELX0124 125 MHz — 312.5 MHz Deserializer with DDR LVDS Parallel Interface General Description Features The DS32EL0124/DS32ELX0124 integrates clock and data recovery modules for high-speed serial communication over FR-4 printed circuit board backplanes, balanced cables, and optical fiber. This easy-to-use chipset integrates advanced signal and clock conditioning functions, with an FPGA friendly interface. The DS32EL0124/DS32ELX0124 deserializes up to 3.125 Gbps of high speed serial data to 5 LVDS outputs without the need for an external reference clock. With DC-balance decoding enabled, the application payload of 2.5 Gbps is deserialized to 4 LVDS outputs. The DS32EL0124/DS32ELX01214 deserializers feature a remote sense capability to automatically signal link status conditions to its companion DS32EL0421/ELX0421 serializers without requiring an additional feedback path. The parallel LVDS interface of these devices reduce FPGA I/O pins, board trace count and alleviates EMI issues, when compared to traditional single-ended wide bus interfaces. The DS32EL0124/ELX0124 is programmable through a SMBus interface as well as through control pins. ■ ■ ■ ■ ■ Applications ■ ■ ■ ■ ■ ■ Imaging: Industrial, Medical Security, Printers Displays: LED walls, Commercial Video Transport Communication Systems Test and Measurement Industrial Bus ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 5-bit LVDS parallel data interface Programmable Receive Equalization Selectable DC-balance decoder Selectable De-scrambler Remote Sense for automatic detection and negotiation of link status No external receiver reference clock required LVDS parallel interface Programmable LVDS output clock delay Supports output data-valid signaling Supports keep-alive clock output On chip LC VCOs Redundant serial input (ELX device only) Retimed serial output (ELX device only) Configurable PLL loop bandwidth Configurable via SMBus Loss of lock and error reporting 48-pin LLP package with exposed DAP Key Specifications ■ ■ ■ ■ ■ 1.25 to 3.125 Gbps serial data rate 125 to 312.5 MHz DDR parallel clock -40° to +85°C temperature range > 8 kV ESD (HBM) protection 0.5 UI Minimum Input Jitter Tolerance (1.25 Gbps) Typical Application 30043101 © 2008 National Semiconductor Corporation 300431 www.national.com DS32EL0124/DS32ELX0124 125 — 312.5 MHz Deserializer with DDR LVDS Parallel Interface July 29, 2008 DS32EL0124/DS32ELX0124 Pin Diagrams 30043102 www.national.com 2 DS32EL0124/DS32ELX0124 30043103 3 www.national.com DS32EL0124/DS32ELX0124 Pin Descriptions Pin Name Pin Number I/O, Type Description VDD33 1, 15, 18, 35 I, VDD 3.3V supply VDD25 7, 25, 35 I, VDD 2.5V supply VDD_PLL 28 I, VDD 3.3V supply LF_CP 27 Analog Loop filter capacitor connection LF_REF 26 Analog Loop filter ground reference Exposed Pad 49 GND Exposed Pad must be connected to GND by 9 vias. RxIN0+ RxIN0- 16 17 I, CML Non-inverting and inverting high speed CML differential inputs of the deserializer. These inputs are internally terminated. RxIN1+ RxIN1- 19 20 I, CML DS32ELX0124 only. Non-inverting and inverting high speed CML differential inputs of the deserializer. These inputs are internally terminated. TxOUT+ TxOUT- 21 22 O, CML DS32ELX0124 only. Retimed serialized high speed output. Non-inverting and inverting speed CML differential outputs of the deserializer. These outputs are internally terminated. O, LVDS Deserializer output clock. RxCLKOUT+/- are the non-inverting and inverting LVDS recovered clock output pins. CML I/O LVDS Parallel Data Bus RxCLKOUT+ RxCLKOUT- 37 38 RxOUT[0:4]+/- 39, 40, 41, 42, 43, 44, 45, O, LVDS 46, 47, 48 Deserializer output data. RxOUT[0:4]+/- are the non-inverting and inverting LVDS deserialized output data pins. Control Pins LT_EN 2 I, LVCMOS DS32ELX0124 only. When held high, retimed serialized high speed output is enabled. RX_MUX_SEL 12 I, LVCMOS DS32ELX0124 only. RX_MUX_SEL selects the input of the deserializer. 0 = RxIN0+/- selected 1 = RxIN1+/- selected VOD_CTRL 14 I, LVCMOS DS32ELX0124 only. VOD control. The deserializer loop through output amplitude can be adjusted by connecting this pin to a pull-down resistor. The value of the pull-down resistor determines the VOD. Use the following equation to determine the value of the pull-down resistor. DC_B RS 5 6 I, LVCMOS DC-balance and Remote Sense pins. See Application section for device behavior. RESET 30 I, LVCMOS Reset pin. When held low, reset the device. 0 = Device Reset 1 = Normal operation LOCK 31 O, LVCMOS Lock indication output. pin goes low when the deserializer is locked to the incoming data stream and begins to output data and clock on RxOUT and RxCLKOUT respectively. 0 = Deserializer locked 1 = Deserializer not locked SCK I, SMBus 33 SMBus compatible clock. SDA I/O, SMBus 32 SMBus compatible data line. SMB_CS I, SMBus 34 SMBus chip select. When held high, SMBus management control is enabled. GPIO0 3 I/O, LVCMOS Software configurable IO pins. GPIO1 4 I/O, LVCMOS Software configurable IO pins. GPIO2 11 I/O, LVCMOS Software configurable IO pins. SMBus Other www.national.com 4 Pin Number I/O, Type NC 2 ,8, 9, 10, 12, 13, 14, 19, Misc. 20, 21, 22, 23, 24, 29 No Connect, for DS32EL0124 8, 9, 10, 13, 23, 24, 29 No Connect, for DS32ELX0124 Misc DS32EL0124/DS32ELX0124 Pin Name Description 5 www.national.com DS32EL0124/DS32ELX0124 Recommended Operating Conditions Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (VDD33) Supply Voltage (VDD25) LVCMOS Input Voltage LVCMOS Output Voltage CML Input/Output Voltage LVDS Output Voltage Junction Temperature Storage Temperature Range Lead Temperature Range Soldering (4 sec.) Package Thermal Resistance Min Typ Supply Voltage (VDD33) 3.135 3.3 Supply Voltage (VDD25) 2.375 2.5 Supply Noise Amplitude from 10 Hz to 50 MHz Ambient Temperature (TA) −40 +25 SMBus Pull–Up Resistor to 1000 VSDD Value −0.3V to +4V -0.3V to +3.0V −0.3V to (VDD33 + 0.3V) -0.3V to (VDD33 + 0.3V) -0.3V to 3.6V -0.3V to +3.6V +125°C −65°C to +150°C θJA ESD Susceptibility HBM Max 3.465 2.625 100 Units V V mVP-P +85 °C Ω +260°C +25.0°C/W ≥8 kV Power Supply Characteristics Symbol IDD25 Parameter 2.5V supply current Loop Through Driver Disabled 2.5V supply current Loop Through Driver Enabled IDD33 3.3V supply current Loop Through Driver Disabled 2.5V supply current Loop Through Driver Enabled PD Power Consumption Loop Through Driver Disabled Power Consumption Loop Through Driver Enabled www.national.com Typ Max 1.25 Gbps Condition 50 59 2.5 Gbps 62 73 3.125 Gbps 69 79 1.25 Gbps 88 99 2.5 Gbps 100 112 3.125 Gbps 107 120 1.25 Gbps 105 121 2.5 Gbps 105 121 3.125 Gbps 105 121 1.25 Gbps 111 127 2.5 Gbps 111 127 3.125 Gbps 111 127 1.25 Gbps 475 560 2.5 Gbps 500 600 3.125 Gbps 520 620 1.25 Gbps 590 690 2.5 Gbps 620 730 3.125 Gbps 640 750 6 Min Unit mA mA mW Over recommended operating supply and temperature ranges unless otherwise specified. Applies to LT_EN, GPIO0, GPIO1, GPIO2, RX_MUX_SEL, DC_B, RESET, RS, LOCK. (Notes 2, 4, 5) Symbol Parameter Conditions Min Typ Max Units VIH High Level Input Voltage 2.0 VDD V VIL Low Level Input Voltage GND 0.8 V VOH High Level Output Voltage IOH = -2mA VOL Low Level Output Voltage IOL = 2mA VCL Input Clamp Voltage ICL = −18 mA IIN Input Current VIN = 0.4V, 2.5V, or VDD33 IOS Output Short Circuit Current VOUT = 0V (Note 6) TOLJIT Serial Input Jitter Tolerance RJ = 0.18 UI DJ = 0.37 UI SJ increased until failure 1.25 Gbps f < 10 kHz f > 1 MHz 30 0.5 2.5 Gbps f < 10 kHz f > 1 MHz 50 0.3 2.7 3.2 V 0.3V -0.9 -40 −1.5 V 40 μA -45 3.125 Gbps f < 10 kHz f > 1 MHz V mA UI 70 0.3 SMBus Electrical Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions Min Typ Max Units 0.8 V 2.1 VSDD V 2.375 3.465 V VSIL Data, Clock Input Low Voltage VSIH Data, Clock Input High Voltage VSDD Nominal Bus Voltage ISLEAKB Input Leakage Per Bus Segment ±200 µA ISLEAKP Input Leakage Per Pin ±10 µA CSI Capacitance for SDA and SCK 10 pF SCK and SDA pins 7 www.national.com DS32EL0124/DS32ELX0124 LVCMOS Electrical Characteristics DS32EL0124/DS32ELX0124 SMBus Timing Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions Min Typ Max Units 100 kHz fSMB Bus Operating Frequency 10 tBUF Bus free time between top and start condition 4.7 μs tHD:STA Hold time after (repeated) start condition. After this period, the first clock is generated 4.0 µs tSU:STA Repeated Start Condition Setup Time 4.7 µs tHD:DAT Data Hold Time 300 ns tSU:DAT Data Setup Time 250 ns tLOW Clock Low Time 4.7 tHIGH Clock High Time 4.0 tSU:CS SMB_CS Setup Time (Note 3) 30 ns tHS:CS SMB_CS Hold Time (Note 3) 100 ns tPOR Time in which the device must be operational after (Note 3) power on (Note 3) (Note 3) µs 50 µs 500 ms Max Units 310 mV 35 mV 1.375 V 35 mV LVDS Electrical Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter VOD Differential Output Voltage ΔVOD Changes in VOD between complimentary output states VOS Offset Voltage ΔVOS Change in VOS between complimentary states IOS Output Short Circuit Current Conditions RL = 100Ω Min Typ 230 1.125 VOUT = 0V, RL = 100Ω (Note 6) 1.25 -50 mA LVDS Timing Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions Min Typ Max Units tROTR LVDS low-to-high transition time 300 ps tROTF LVDS high-to-low transition time 300 ps tROCP LVDS output clock period tRODC RxCLKOUT Duty Cycle tRBIT LVDS output bit width tROSC RxOUT Setup to RxCLKOUT OUT tROHC RxOUT Hold to RxCLKOUT OUT tRODJ LVDS Output Deterministic Jitter tRORJ tROTJ LVDS Output Random Jitter Peak-to-Peak LVDS Output Jitter www.national.com 2T 45 50 % T ns 800 ps 800 ps RxCLKOUT (Note 3) 18 RxOUT0–4 (Note 3) 43 RxCLKOUT (Note 3) 2.5 RxOUT0–4 (Note 3) 2.5 RxCLKOUT (Note 3) 51 RxOUT0–4 (Note 3) 70 8 ns 55 ps ps ps tRLA tLVSK Parameter Deserializer Lock Time LVDS Output Skew Conditions Min Typ (Note 3) 1.25 Gbps 22 2.5 Gbps 90 3.125 Gbps 115 LVDS Differential Output Skew between + and - pins 20 Max Units ms ps CML Input Timing Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol TOLJIT Parameter Serial Input Jitter Tolerance Conditions Min Typ RJ = 0.18 UI DJ = 0.37 UI SJ increased until failure 1.25 Gbps f < 10 kHz f > 1 MHz 30 0.5 2.5 Gbps f < 10 kHz f > 1 MHz 50 0.3 3.125 Gbps f < 10 kHz f > 1 MHz 70 0.3 Max Units UI CML Input Electrical Specifications Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions VID Differential input voltage (Note 3) VIN Single ended input voltage (Note 3) IIN Input Current RIT Input Termination Min Max Units 230 2200 mV 115 1100 mV -300 50 μA 116 Ω 84 Typ 100 CML Retimed Loop Through Output Electrical Specifications, DS32ELX0124 Only Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions Min Typ Max Units V Output differential voltage VOD_CTRL resistor = 9.09 kΩ (Note 3) RLTOT Output termination 50Ω 40 50 60 75Ω 60 75 90 ΔRLTOT Mismatch in output termination resistors 1.15 1.45 VLTOD 5 9 Ω % www.national.com DS32EL0124/DS32ELX0124 Symbol DS32EL0124/DS32ELX0124 CML Retimed Loop Through Output Timing Specifications, DS32ELX0124 Only Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 2, 5) Symbol Parameter Conditions Min Typ Max Units tJIT Additive Output Jitter (Note 3) 24 35 ps tOS Output Overshoot (Note 3) 1.5 8 % tLTR Retimed output driver differential low to high transition time (Note 3) 74 105 tLTF Retimed output driver differential high to low transition time (Note 3) 74 105 tLTRFMM Mismatch in Rise/Fall Time (Note 3) 5 15 tLTDE Retimed driver de-emphasis width 1 ps ps % UI Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. Note 2: The Electrical and Timing Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed. Note 3: Parameter is guaranteed by characterization and is not tested at production. Note 4: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except VOD and ΔVOD. Note 5: Typical values represent most likely parametric norms for VCC = +3.3V and TA = +25°C, and at the Recommended Operation Conditions at the time of product characterization and are not guaranteed. Note 6: Output short circuit current (IOS) is specified as magnitude only, minus sign indicates direction only. www.national.com 10 DS32EL0124/DS32ELX0124 Timing Diagrams 30043106 FIGURE 1. SMBus Timing Parameters 30043110 FIGURE 2. LVDS Output Transition Time 30043111 FIGURE 3. Deserializer (LVDS Interface) Setup/Hold and High/Low Times 11 www.national.com DS32EL0124/DS32ELX0124 30043114 FIGURE 4. Reset to Lock Time 30043113 FIGURE 5. Deserializer Propagation Delay 30043104 FIGURE 6. CML to LVDS Bit Map www.national.com 12 POWER SUPPLIES The DS32EL0124 and DS32ELX0124 have several power supply pins, at 2.5V as well as 3.3V. It is important that these pins all be connected and properly bypassed. Bypassing should consist of parallel 4.7μF and 0.1μF capacitors as a minimum, with a 0.1μF capacitor on each power pin. A 22 μF capacitor is required on the VDDPLL pin which is connected to the 3.3V rail. These devices have a large contact in the center on the bottom of the package. This contact must be connected to the system GND as it is the major ground connection for the device. LOOP FILTER The DS32EL0124 and DSELX0124 have an internal clock data recovery module (CDR), which is used to recover the input serial data. The loop filter for this CDR is external, and for optimum results, a 30nF capacitor should be connected between pins 26 and 27. See the Typical Interface Circuit (Figure 11). REMOTE SENSE The remote sense feature can be used when a DS32EL0421 or DS32ELX0421 serializer is directly connected to a DS32EL0124 or DS32ELX0124 deserializer. Active components in the signal path between the serializer and the deserializer may interfere with the back channel signaling of the devices. When remote sense is enabled, the deserializer will cycle through five states to successfully establish a link and align the data. The state diagram for the deserialiezr is shown in Figure 7. The deserialzer will remain in the low power IDLE state until it receives an input signal. Once the CDR of the deserializer has locked to the input clock, the device will enter the LINK DETECT state. While in this state, the serializer will monitor the line to see if the deserializer is present. If a deserializer is detected the serializer will enter the LINK ACQUISITION state. The serializer will transmit the entire training pattern and then enter the NORMAL state. If the deserializer is unable to successfully lock or maintain lock, it will break the link sending the serializer back to the IDLE or LINK DETECT states. POWER UP It is recommended, although not necessary, to bring up the 3.3V power supply before the 2.5V supply. If the 2.5V supply is powered up first, an initial current draw of approximately 600mA from the 2.5V rail may occur before settling to its final value. Regardless of the sequence, both power rails should monotonically ramp up to their final values. POWER MANAGEMENT These devices have two methods to reduce power consumption. To enter the first power save mode, the on board host FPGA or controlling device can cease to output the DDR transmit clock. To further reduce power, a write to the power down register will put the device in its lowest power mode. RESET There are three ways to reset these devices. A reset occurs automatically during power-up. The device can also be reset by pulling the RESET pin low, with normal operation resuming when the pin is driven high again. The device can also be reset by writing to the reset register. This reset will put all of the register values back to their default values, except it will not affect the address register value if the SMBus default address has been changed. DC-BALANCE DECODER The DS32EL0124 and DS32ELX0124 have a built-in DC-balance decoder to support AC-coupled applications. When enabled, the output signal RxOUT4+/-, is treated as a data valid bit. If RxOUT+/- is low, then the data output from RxOUT0RxOUT3 has been successfully decoded using the 8b/10b coding scheme. If RxOUT4+/- is high and the outputs RxOUT0 -RxOUT3 are high then an invalid 8b/10b code was received, signifying a bit error. If RxOUT4+/- is high and the outputs RxOUT0 -RxOUT3 are low then an idle character has been received. The default idle character is a K28.5 code. In order to properly receive other Kcodes, they must first be programmed into the deserializer via the SMBus. LVDS OUTPUTS The DS32EL0124 and DS32ELX0124 has standard LVDS outputs, compatible with ANSI/TIA/EIA-644. It is recommended that the PCB trace between the FPGA and the deserializer output be no more than 40-inches. Longer PCB traces may introduce signal degradation as well as channel skew which could cause serialization errors. The connection between the host and the DS32EL0124 or DS32ELX0124 should be over a controlled impedance transmission line with impedance that 13 www.national.com DS32EL0124/DS32ELX0124 matches the termination resistor – usually 100Ω. Setup and hold times are specified in the LVDS Switching Characteristics table, however the clock delay can be adjusted by writing to register 30’h. Functional Description DS32EL0124/DS32ELX0124 30043115 FIGURE 7. Deserializer State Diagram DS32ELX0124, each input can have its own independent equalizer settings. It is recommended to use RxIN0+/- as the primary input. Due to its close proximity to the loop through driver, RxIN1 has a typical performance less than RxIN0, with regards to cable length performance. When interfacing to RxIN1+/- and transmitting with the loop through driver on TxOUT+/-, it is important to follow good layout practices as described in the layout guidelines section and in the LVDS Owner’s Manual. Poor layout techniques can result in excessive cross talk coupled into RxIN1. DESCRAMBLER If the descrambler is enabled, the serialized data is descrambled after being recovered by the CDR to according to the polynomial specified in the DS32EL0421 datasheet. Using the scrambler/descrambler helps to lower EMI emissions by spreading the spectrum of the data. Scrambling also creates transitions for a deserializer’s CDR to properly lock onto. The scrambler is enabled or disabled by default depending on how the DC_B and RS pins are configured. To override the default scrambler setting two register writes must be performed. First, write to register 22’h and set bit 5 to unlock the descrambler register. Next write to register 21’h and change bit 5 to the desired value. Please note that NRZI decoder has its own control bits in registers 22'h and 21'h. CML OUTPUT INTERFACING (DS32ELX0124 ONLY) The retimed loop through serial outputs of the DS32ELX0124 provide low-skew differential signals. Internal resistors connected from TxOUT+ and TxOUT- to VDD25 terminate the outputs. The output level can be programmed by adjusting the pull-down resistor to the VOD_CTRL pin. The output terminations can also be programmed to be either 50 or 75 ohms. The output buffer consists of a current mode logic(CML) driver with user configurable de-emphasis control, which can be used to optimize performance over a wide range of transmission line lengths and attenuation distortions resulting from low cost CAT(-5, -6, -7) cable or FR4 backplane. Output de-emphasis is user programmable through SMBus interface. Users can control the strength of the de-emphasis to optimize for a specific system environment. Please see the Register Map for details. CML INPUT INTERFACING The DS32ELX0124 has two inputs to support redundancy and failover applications. Either input can be selected by using the RX_MUX_SEL pin or internal control registers. Whichever input is selected will be routed to the CDR of the deserializer. Only one input may be selected at a time. The input stage is self-biased and does not need any external bias circuitry. The DS32EL0124 and DS32ELX0124 include integrated input termination resistors. These deserializers also support a wide common mode input from 50mV to Vcc 50mV and can be DC-coupled where there is no significant Ground potential difference between the interfacing systems. The serial inputs also provides input equalization control in order to compensate for loss from the media. The level of equalization is controlled by the SMBus interface. For the www.national.com 14 TABLE 1. Device Configuration Table Remote Sense Pin (RS) DC-Balance Pin(DC_B) Configuration 0 0 Remote Sense enabled DC-Balance enabled Data Alignment De-Scrambler and NRZI decoder disabled by default 0 1 Remote Sense enabled DC-Balance disabled Data Alignment De-Scrambler and NRZI decoder enabled by default 1 0 Remote Sense disabled DC-Balance enabled Data Alignment De-Scrambler and NRZI decoder enabled by default 1 1 Remote Sense disabled DC-Balance disabled No Data Alignment De-Scrambler and NRZI decoder disabled by default 15 www.national.com DS32EL0124/DS32ELX0124 characters are transmitted. If the deserializer receives a SYNC character, then the LVDS data outputs will all be logic low and the Data Valid outputs will be logic high. If the deserializer detects a DC-Balance code error, the output data pins will be set to logic high with the Data Valid output also set to logic high. In the case where DC-Balance is enabled and Remote Sense is disabled, with RS set to high and DC_B set to low, an external device must toggle the Data Valid input to the serializer periodically to ensure constant lock. With these pin settings the devices can interface with other active component in the high speed signal path, such as fiber modules. When both Remote Sense and DC-Balance are disabled, RS and DC_B pins set to high, the LVDS lane alignment is not maintained. In this configuration, data formatting is handled by an FPGA or external source. In this mode the deserializer locks to incoming random data. To achieve lock during the clock acquisition phase, the incoming data should have a “101” or “010” transition density of approximately 25%. Scrambling and NRZI encoding can be implemented to help improve the transition density of the data. This pin setting also allows for the devices to interface with other active components in the high speed signal path. DEVICE CONFIGURATION There are four ways to configure the DS32EL0124 and DS32ELX0124 devices, these combinations are shown in Table 1. Refer to Figure 7 to see how the combinations of the RS and DC_B pins change the link startup behavior of the deserializers. When connecting to a serializer other than the DS32EL0421 or DS32ELX0421, Remote Sense should be disabled. The descrambler and NRZI decodeer shown in Table 1 can be enabled or disabled through register programming. When Remote Sense is enabled, with RS pin tied low, the deserializer must be connected directly to a DS32EL0421/ DS32ELX0421 serializer without any active components between them. The Remote Sense module features both an upstream and downstream communication method for the serializer to detect a deserializer and vice versa. This feature is used to pass link status information between the 2 devices. If DC-Balance is enabled, the maximum number of parallel LVDS lanes is four. The fifth lane becomes a Data Valid signal (TXIN4±). Every time a DS32EL0421/DS32ELX0421 serializer establishes a link to a DS32EL0124/DS32ELX0124 deserializer with DC-Balance enabled, the Data Valid input to the serializer must be held high for 20 LVDS clock periods. If the Data Valid input to the serializer is logic high, then SYNC DS32EL0124/DS32ELX0124 9. The Host de-selects the device by driving its SMBus CS signal Low. The WRITE transaction is completed, the bus goes IDLE and communication with other SMBus devices may now occur. SMBus INTERFACE The System Management Bus interface is compatible to SMBus 2.0 physical layer specification. The use of the Chip Select signal is required. Holding the SMB_CS pin HIGH enables the SMBus port, allowing access to the configuration registers. Holding the SMB_CS pin LOW disables the device's SMBus, allowing communication from the host to other slave devices on the bus. In the STANDBY state, the System Management Bus remains active. When communication to other devices on the SMBus is active, the SMB_CS signal for the deserializer must be driven LOW. The address byte for all DS32EL0124 and DS32ELX0124 devices is B0'h. Based on the SMBus 2.0 specification, these devices have a 7-bit slave address of 1011000'b. The LSB is set to 0'b (for a WRITE), thus the 8-bit value is 1011 0000'b or B0'h. The SCK and SDA pins are 3.3V LVCMOS signaling and include high-Z internal pull up resistors. External low impedance pull up resistors maybe required depending upon SMBus loading and speed. Note, these pins are not 5V tolerant. Reading a Register To read a register, the following protocol is used (see SMBus 2.0 specification). 1. The Host (Master) selects the device by driving its SMBus Chip Select (SMB_CS) signal HIGH. 2. The Host drives a START condition, the 7-bit SMBus address, and a “0” indicating a WRITE. 3. The Device (Slave) drives the ACK bit (“0”). 4. The Host drives the 8-bit Register Address. 5. The Device drives an ACK bit (“0”). 6. The Host drives a START condition. 7. The Host drives the 7-bit SMBus Address, and a “1” indicating a READ. 8. The Device drives an ACK bit “0”. 9. The Device drives the 8-bit data value (register contents). 10. The Host drives a NACK bit “1”indicating end of the READ transfer. 11. The Host drives a STOP condition. 12. The Host de-selects the device by driving its SMBus CS signal Low. The READ transaction is completed, the bus goes IDLE and communication with other SMBus devices may now occur. Transfer of Data via the SMBus During normal operation the data on SDA must be stable during the time when SCK is HIGH. There are three unique states for the SMBus: START A HIGH to LOW transition on SDA while SCK is HIGH indicates a message START condition. STOP A LOW to HIGH transition on SDA while SCK is HIGH indicates a message STOP condition. IDLE If SCK and SDA are both HIGH for a time exceeding tBUF from the last detected STOP condition or if they are HIGH for a total exceeding the maximum specification for tHIGH then the bus will transfer to the IDLE state. SMBus Configurations Many different configurations of the SMBus are possible and depend upon the specific requirements of the applications. Several possible applications are described. Configuration 1 The deserializer SMB_CS may be tied High (always enabled) since it is the only device on the SMBus. See Figure 8. SMBus Transactions The devices support WRITE and READ transactions. See Register Description Table for register address, type (Read/ Write, Read Only), default value and function information. Configuration2 Since the multiple SER devices have the same address, the use of the individual SMB_CS signals is required. To communicate with a specific device, its SMB_CS is driven High to select the device. After the transaction is complete, its SMB_CS is driven Low to disable its SMB interface. Other devices on the bus may now be selected with their respective chip select signals and communicated with. See Figure 9. Writing to a Register The devices support WRITE and READ transactions. See Register Description Table for register address, type (Read/ Write, Read Only), default value and function information. 1. The Host (Master) selects the device by driving its SMBus Chip Select (SMB_CS) signal HIGH. 2. The Host drives a START condition, the 7-bit SMBus address, and a “0” indicating a WRITE. 3. The Device (Slave) drives the ACK bit (“0”). 4. The Host drives the 8-bit Register Address. 5. The Device drives an ACK bit (“0”). 6. The Host drive the 8-bit data byte. 7. The Device drives an ACK bit (“0”). 8. The Host drives a STOP condition. www.national.com Configuration 3 The addressing field is limited to 7-bits by the SMBus protocol. Thus it is possible that multiple devices may share the same 7-bit address. An optional feature in the SMBus 2.0 specification supports an Address Resolution Protocol (ARP). This optional feature is not supported by the DS32EL0124/ DS32ELX0124 devices. Solutions for this include: the use of the independent SMB_CS signals, independent SMBus segments, or other means. 16 DS32EL0124/DS32ELX0124 30043107 FIGURE 8. SMBus Configuration 1 30043108 FIGURE 9. SMBus Configuration 2 30043109 FIGURE 10. SMBus Configuration 3 17 www.national.com DS32EL0124/DS32ELX0124 together if an application requires a data throughput of more than 3.125 Gbps. By utilizing the data valid signal of each device, the system can be properly deskewed to allow for a single cable, such as CAT-6, DVI-D, or HDMI, to carry data payloads beyond 3.125 Gbps. The ELXEVK01 evaluation kit includes sample IP for a link aggregation system to operate at an application throughput of 6.25 Gbps. Link aggregation configurations can also be implemented in applications which require longer cable lengths. In these type of applications the data rate of each serializer and deserializer chipset can be reduced, such that the applications' net data throughput is still the same. Since each high speed channel is now operating at a fraction of the original data rate, the loss over the cable is reduced, allowing for greater lengths of cable to be used in the system. Applications Information GPIO PINS The GPIO pins can be useful tools when debugging or evaluating the system. For specific GPIO configurations and functions refer to registers 2, 3, 4, 5 and 6 in the device register map. GPIO pins are commonly used when there are multiple deserializers on the same SMBus. In order to program individual settings into each serializer, they will each need to have a unique SMBus address. To reprogram multiple deserializers on a single SMBus, configure the first deserializer such that the SMBus lines are connected to the FPGA or host controller. The CS pin of the second serializer should be tied to GPIO0 of the first deserializer, with the CS pin of the next deseriazlier tied to GPIO0 of its preceding deserializer. By holding all of the GPIO0 pins low, the first deserializer’s address may now be reprogrammed by writing to register 0. The first deserializer’s GPIO pin can now be asserted and the second deserializer’s address may now be reprogrammed. REACH EXTENSION The DS32ELX0124 deserializer contains a retimed loop through CML serial output. The loop through driver also has programmable de-emphasis making this device capable of reach extension applications. HIGH SPEED COMMUNICATION MEDIA Using the deserializer’s integrated equalizer blocks in combination with the DS32EL0421 or DS32ELX0421’s integrated de-emphasis block allows data to be transmitted across a variety of media at high speeds. Factors that can limit device performance include excessive input clock jitter, noisy power rails, EMI from nearby noisy components and poor layout techniques. Although many cables contain wires of similar gauge and shielding, performance can vary greatly depending on the quality of the connector. The DS32ELX0124 also has a programmable de-emphasis block on its retimed loop through output TxOUT+/-. The deemphasis setting for the loop through driver is programmed through the SMBus. DAISY CHAINING The loop through driver of the DS32ELX0124 deserializer can be used to string together deserializers in a daisy chain configuration. This allows a single data source such as a DS32EL0421 serializer to communicate to multiple receiving systems. LAYOUT GUIDELINES It is important to follow good layout practices for high speed devices. The length of LVDS input traces should not exceed 40 inches. In noisy environments the LVDS traces may need to be shorter to prevent data corruption due to EMI. Noisy components should not be placed next to the LVDS or CML traces. The LVDS and CML traces must have a controlled differential impedance of 100Ω. Do not place termination resistors at the CML inputs or output, the DS32EL0124 and DS32ELX0124 have internal termination resistors. It is recommended to avoid using vias. Each pair of vias creates an impedance mismatch in the transmission line and result in reflections, which can greatly lower the maximum distance of the high speed data link. If vias are required, they should be placed symmetrically on each side of the differential pair. For more tips and detailed suggestions regarding high speed board layout principles, please consult the LVDS Owner’s Manual. REDUNDANCY APPLICATIONS The DS32ELX0124 has two high speed CML serial inputs. SMBus register control allows the host device to monitor for errors or link loss on the active input channel. This enables the host device, usually an FPGA, to switch to the secondary input if problems occur with the primary input. LINK AGGREGATION Multiple DS32EL0421/DS32ELX0421 serializers and D32EL0124/DS32ELX0124 deserializers can be aggregated www.national.com 18 DS32EL0124/DS32ELX0124 30043105 FIGURE 11. Typical Interface Circuit 19 www.national.com DS32EL0124/DS32ELX0124 reserved; these are for internal testing and should not be written to. Some register bits require an override bit to be set before they can be written to. Register Map The register information for the deserializer is shown in the table below. Some registers have been omitted or marked as Addr (Hex) Name 00 Device ID 01 Reset 02 03 04 05 www.national.com GPIO0 Config GPIO1 Config GPIO2 Config GP In Bits Field R/W Default SMBus Address 0 Reserved 0 7:1 Reserved 0 0 Software Reset R/W 0 Reset the device. Does not affect device ID. 7:4 GPIO0 Mode R/W 0 0000: GP Out 0001: Signal Detect RxIN0 0010: BIST Status All Others: Reserved 3:2 GPIO0 R Enable R/W 01'b 00: Pullup/Pulldown disabled 01: Pulldown Enabled 10: Pullup Enabled 11: Reserved 1 Input Enable R/W 0 0: Input buffer disabled 1: Input buffer enabled 0 Output Enable R/W 1'b 0: Output Tri-State™ 1: Output enabled 7:4 GPIO1 Mode R/W 0 0000: Power On Reset 0001: GP Out 0010: Signal Detect RxIN1 0011:CDR Lock All Others: Reserved 3:2 GPIO1 R Enable R/W 01'b 00: Pullup/Pulldown disabled 01: Pulldown Enabled 10: Pullup Enabled 11: Reserved 1 Input Enable R/W 0 0: Input buffer disabled 1: Input buffer enabled 0 Output Enable R/W 1 0: Output Tri-State™ 1: Output enabled 7:4 GPIO2 Mode R/W 0 0000: GP Out 0001: Always on Clock Out 0010: LVDS Tx CLK 0011: CDR CLK All Others: Reserved 3:2 GPIO2 R Enable R/W 01'b 00: Pullup/Pulldown disabled 01: Pulldown Enabled 10: Pullup Enabled 11: Reserved 1 Input Enable R/W 0 0: Input buffer disabled 1: Input buffer enabled 0 Output Enable R/W 1'b 0: Output Tri-State™ 1: Output enabled 7:3 Reserved 2 GP In 2 R 0 Input value on GPIO2 1 GP In 1 R 0 Input value on GPIO1 0 GP In 0 R 0 Input value on GPIO0 20 R/W 58'h Description 7:1 Some systems will use all 8 bits as the device ID. This will shift the value from 58’h to B0’h 06 Name GP Out Bits Field R/W Default Description 7:3 Reserved 0 2 GP Out 2 R/W 0 Output value on GPIO2 1 GP Out 1 R/W 0 Output value on GPIO1 0 GP Out 0 R/W 0 Output value on GPIO0 7 LVDS Always On Clock R/W 0 1: Disable 0: When not locked switch to Always On Clock 6:3 Reserved 2 Reverse Data Order R/W 0 0: Normal 1: Reverse output data order 1 Reset Channel R/W 0 Reset input high speed channel 0 Digital Power Down R/W 0 Power down parallel, seria-toparallell, and always on clock 7 Reserved 6 NRZ Decode Enable R/W 0 Enable NRZ decoding of incoming data; requires an override bit 5 Descramble Enable R/W 0 Enabled the descrambler, requires an override bit 4 Rx Mux R/W 0 RX_MUX_SEL control register. requires an override bit 3 Decode Bypass R/W 0 Bypass DC Balance decoder. requires an override bit 2 Training Sequence Enable R/W 0 Enable training sequence. requires an override bit 1:0 Device Configuartion MSB: Remote Sense enable, active low LSB: DC balance encoder enable, active low requires an override bit 7 Reserved 6 NRZ Override R/W 0 Unlock bit 6 of register 21'h 5 Descramble Override R/W 0 Unlock bit 5 of register 21'h 4 Rx Mux Override R/W 0 Unlock bit 4 of register 21'h 3 Reserved 2 Decode Bypass Override R/W 0 Unlock bit 3 of register 21'h 1 Traning Override R/W 0 Unlock bit 2 of register 21'h 0 Device Config Override R/W 0 Unlock bits 1 and 0 of register 21'h 07 — 1F Reserved 20 21 22 Device Config 0 Device Config 1 Device Config Override 0 0 R/W 0 0 0 23 — 26 Reserved 21 www.national.com DS32EL0124/DS32ELX0124 Addr (Hex) DS32EL0124/DS32ELX0124 Addr (Hex) 27 28 Name LVDS Per Channel Enable LVDS Config Bits Field R/W Default Description 7 LVDS VOD High R/W 0 0: LVDS VOD normal operation. Setting used in Electrical Characteristics Table 1: Increases VOD. Allows for longer traces to be driven, but consume more power 6 LVDS Control R/W 0 1: Allow SMBus to control LVDS per channel enable 5 RxCLKOUT Enable R/W 0 Enables RxCLKOUT output driver 4 RxOUT4 Enable R/W 0 Enables RxOUT4 output driver 3 RxOUT3 Enable R/W 0 Enables RxOUT3 output driver 2 RxOUT2 Enable R/W 0 Enables RxOUT2 output driver 1 RxOUT1 Enable R/W 0 Enables RxOUT1 output driver 0 RxOUT0 Enable R/W 0 Enables RxOUT0 output driver 7 Reserved 6 LVDS Reset R/W 0 Resets LVDS block 5 LVDS Clock Rate R/W 1 0:RxCLKOUT is DDR/2 1: RxCLKOUT is DDR 4 LVDS Clock Invert R/W 0 Inverts the polarity of the RxCLKOUT signal 3:2 LVDS Clock Delay R/W 10'b 000: No clock delay 111: Max clock delay, 1000 ps See tLVDL in LVDS Switching Characteristics for more details 1:0 Reserved 0 7:4 Reserved 0 3 Event Count Select R/W 0 0: Select CDR Event Counter for reading. Events include loss of signal detect or loss of CDR lock. 1: Select Data Event Counter for reading 2 Reset CDR Error Count R/W 0 Reset s CDR event count 1 Reset Link Error Count R/W 0 Reset data event count 0 Enable Count R/W 0 Enable event coutners 7:5 Reserved 4 Accumulate Error Enable R/W 0 1: Enable counting accumulation of errors 3 8b/10b Error disable R/W 0 1: Disables 8b/10b decode errors from being counted or flagged on LOCK pin 2 Clear Event Counter R/W 0 1: clears errors in both the current and previous state of teh errors count 1 Select Error Count R/W 0 0: Number of errors in current run 1: Number of errors within the selected timing window 0 Normal Error Disable R/W 0 1: Disable exiting NORMAL state when the number of errors exceeds the error threshold 7:0 Error Threshold R/W 10'h Error threshold above which part stops transmittion of data — LSB 0 29 — 2A Reserved 2B Event Config 2C Reserved 2D Error Monitor 2E www.national.com Error Threshold LSBs 0 22 2F Name Error Threshold MSBs Bits Field R/W Default R/W 0 Description 7:0 Error Threshold Error threshold above which part stops transmittion of data — MSB 7 Reserved 6:4 Frequency Range R 111'b 001: Reserved 010: 1 — 1.3 Gbps 011: 1.2 — 1.8 Gbps 100: 1.5 — 2.1 Gbps 101: 1.9 — 2.7 Gbps 110: 2.4 — 3.2 Gbps 111: No Lock 3:2 BIST Status R 0 00: BIST passed 01: BIST failed to capture PREAMBLE 10: BIST pattern mode failed 11: BIST data sequence failed 1 BIST Done R 0 BIST pattern done. Set when not using repeat. 0 BIST Allign Done R 0 Alignment of incoming data done 30 — 3A Reserved 3B Data Rate 0 3C Reserved 3D Event Status 7:0 Event Count R 0 Count of errors that caused a loss of link 3E Error Status LSBs 7:0 Data Error Count R 0 Number of errors in data — LSB 3F Errors Status MSBs 7:0 Data Error Count R 0 Number of errors in data — MSB 40 — 49 Reserved 49 60 61 62 Loop Through Driver Config 7:5 EQ Attenuator EQ Boost Control Reserved 0 0: 75Ω 1: 50 Ω 000: Level 7 001: Level 8 (Highest output) 010: Level 5 011: Level 6 (Normal output) 100: Level 4 101: Level 3 110: Level 2 111: Level 1 (Lowest output) 4 Termination Select R/W 1 3:1 Output Amplitude Adjust R/W 011'b 0 Reserved 7:4 Reserved 3 Attenuator 0 Override R/W 0 Overrides attenuation control in EQ 0 2 Attenuator 1 Override R/W 0 Overrides attenuation control in EQ 1 1 Attenuator 0 Enable R/W 0 1: enables attenuatorfor for EQ 0. Requires bit 3 to be set 0 Attenuator 1 Enable R/W 0 Enables attenuato for EQ 1. Requires bit 2 to be set.r 7:5 EQ 0 Boost Control 0 Sets EQ level for RxIN0. Requires override bit 4:2 EQ 1 Boost Control 0 Sets EQ level for RxIN1. Requires override bit 1:0 Reserved 0 0 0 Reserved 23 www.national.com DS32EL0124/DS32ELX0124 Addr (Hex) DS32EL0124/DS32ELX0124 Addr (Hex) 63 67 www.national.com Name EQ Override Control LT De-Emphasis Control Bits Field R/W Default Description 7 Reserved 6 Reserved 1 5 EQ 0 Enable R/W 1 1: Enables EQ for RxIN0 4 EQ 1 Enable R/W 0 1: Enables EQ for RxIN1 3:0 Reserved 0 7 Reserved 0 5:6 De-Emphasis Setting 0 4:0 Reserved 0 1 24 00: Off 01: Low 10: Med 11: Max DS32EL0124/DS32ELX0124 Physical Dimensions inches (millimeters) unless otherwise noted NS Package Number SQA48A (See AN-1187 for PCB Design and Assembly Recommendations) 25 www.national.com DS32EL0124/DS32ELX0124 125 — 312.5 MHz Deserializer with DDR LVDS Parallel Interface Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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