Adaptive Cable Equalizer for IEEE 1394b

Transcription

1 EQCO400T Features Adaptive Cable Equalizer for IEEE 1394b Functional Description Multi-Rate Adaptive Equalization Supports IEEE 1394b - S400, S200 and S100 data rates Seamless connection with compliant PHY Carrier Detect functionality with direct Light Emitting Diode driving capability Low Power 140mW or 14mW 3.3V Single 3.3V supply 16-pin QFN package 0.18 µm CMOS Typical Equalization Performance 1394 Rating Range * using Cat 5e Cat 6 S m 130m S m 110m S400 70m 90m * Measurements performed in lab conditions The EQCO400T is a multi-rate adaptive equalizer, designed to restore signals received over Cat 5 or Cat 6 Unshielded Twisted Pair (UTP) cable. The signals shall be NRZ (non-return-to-zero) encoded, DC balanced with a maximum run length of 10 bits, and have a speed between 100Mbps and 500Mbps. In particular, the EQCO400T is optimized to create long-haul IEEE 1394b-2002 connections over Cat 5 or Cat 6 cable at the S400 data rate, but it can also be used at S200 and S100. Figure 1 illustrates one side of a typical long-haul connection. The EQCO400T connects seamlessly to any IEEE 1394b-2002 compliant physical layer controller (PHY). The connection reach depends on the performance of the equalizer, but also on the quality of the connectors and cables, and the input jitter tolerance of the PHY. IEEE 1394b PHY EQCO400T Transformer + Common Mode Choke Common Mode Choke + Transformer Cat 5 / Cat 6 RJ45 and UTP cable Figure 1 One side of a long-haul IEEE Std 1394b-2002 connection NV Phone February 2006 Prinses Elisabethlaan 50 phelfet@eqcologic.com 1030 Brussels, Belgium

2 Pin Assignment GND INP 1 12 OUTP VCC 2 GND Pad 11 VCC INN 3 10 OUTN GND CLI LED Figure 2 EQCO400T Pin Layout PIN PIN NAME TYPE DESCRIPTION NUMBER 2, 11 VCC Power Connect to +3.3V of power supply 5, 13 GND Power Connect to ground of power supply 6 CLI Output Cable Length Indicator Analog voltage that gives an estimate of the length of the cable being equalized. A higher voltage results in more compensation to recover the signal. Leave unconnected when not used. 7 LED Output Carrier Detect with Light Emitting Diode driver HIGH voltage at LED indicates valid input signal; differential outputs are turned on. LED can source up to 3mA to directly drive a Light Emitting Diode. LOW voltage at LED indicates no signal or amplitude of transmitted signal too low; differential outputs are muted. Connect to a Light Emitting Diode, or leave unconnected when not used. 1, 3 INP, INN Input Differential serial input 10, 12 OUTP, OUTN Output Differential serial output EQCO400T Prelim Datasheet v1.2 Page2 of 12 February 2006

3 Figure 3 Illustration of Equalizer Principle Equalizer Operation The EQCO400T is an equalizer with unique characteristics: Auto-adaptive Variable gain Multi-speed Carrier detect/auto-mute to save power Auto-adaptive The EQCO400T has multiple equalization stages to compensate for attenuation of the cable, as illustrated in Figure 3. The number of stages needed to restore the signal is automatically determined by the device, using a time-continuous feedback loop that measures the frequency components in the signal. Upon the detection of a valid signal, this loop converges within a few microseconds. Variable Gain The EQCO400T has variable gain to work independently of the transmit amplitude of the line driver. The equalizer can be used with any IEEE1394b compliant transmitter. The standard requires a transmit amplitude in the range of 300mV to 800mV. Multi-Speed The EQCO400T works from 100Mbps to 500Mbps. In particular, it supports the S400, S200 and S100 data rates specified in the IEEE Standard 1394b Carrier detect with Light Emitting Diode driver The EQCO400T will automatically mute its output driver when no valid incoming signal is detected (i.e. signal with amplitude <40mV). This reduces the power consumption from 140mW to less than 14mW. EQCO400T Prelim Datasheet v1.2 Page3 of 12 February 2006

4 Carrier Detect with Light Emitting Diode driver LED INP INN Equalizer Output driver OUTP OUTN CLI Figure 4 EQCO400T Block Diagram Electrical connections Pin Characteristics INP, INN Both inputs are terminated by 55Ω to VCC on chip. It is advised to use both a common mode choke and transformer isolation on the inputs and outputs to UTP OUTP, OUTN 1.4 The output drivers are implemented using 1.2 current mode logic (CML) with source matching for the 110Ω transmission line. 1 CLI Cable Length Indicator (CLI) is an analog output. It outputs a voltage proportional to length of the cable connected at INP and INP. An increase in cable length gives an increase in the output voltage at CLI. Figure 5 illustrates the voltage at CLI for a typical Cat 6 cable. LED LED is an output that indicates the detection of sufficient signal power at the differential inputs INP and INN. If the received signal at the serial inputs is either not present or too small, the voltage at the LED pin is set to LOW. Voltage (V) cable length (m) Figure 5 CLI output voltage vs Systimax Cat 6 cable length If there is sufficient signal power detected, the voltage will be set HIGH and the LED pin can source up to 3mA. This can be used to directly drive a Light Emitting Diode. The Light Emitting Diode would be ON when a signal is detected, and OFF otherwise. It is advised to use a high efficiency Light Emitting Diode. EQCO400T Prelim Datasheet v1.2 Page4 of 12 February 2006

5 Electrical characteristics PARAMETER CONDITIONS MIN TYP MAX UNITS Power supply voltage 3.3 V Power supply current Output driver enabled 40 ma LED is HIGH Output driver disabled 4 ma LED is LOW CONTROL AND STATUS LED output HIGH Differential input voltage 1.5 V voltage swing at cable input > 250mV LED output LOW Differential input voltage GND 0.8 V voltage swing at cable input < 40mV LED drive current Differential input voltage 3 ma swing at cable input > 250mV INPUT Input data rate EQCO400T Mb/s Differential input V INP V INN measured at mv voltage swing cable input Common-mode input V voltage Input resistance Single ended; to VCC 55 Ω OUTPUT Differential output V OUTP V OUTN ; 50Ω load 440 mv voltage swing Common-mode output VCC - V voltage V OUTP V OUTN / 2 Output voltage with Single ended; LED is VCC V disabled driver LOW Output resistance Single ended; to VCC 55 Ω Rise/Fall time 20% to 80% ps EQCO400T Prelim Datasheet v1.2 Page5 of 12 February 2006

6 Application Information Connector pins and cable connection The EQCO400T does not support autocrossover. If required, this must be implemented external to the device. To be the same as 100BaseT Ethernet, IEEE Std 1394b-2002 recommends data is transmitted out on RJ45 pins 1 and 2, and received on pins 3 and 6. If both sides of the long-haul UTP connection are configured in this way, a crossover cable or patch cord must be used. If one side of the UTP connection transmits data on RJ45 pins 1 and 2 and receives data on pins 3 and 6, and the other side transmits data on RJ45 pins 3 and 6 and receives data on pins 1 and 2, a straight-through cable must be used. If reach is the first priority and if a closed system is created, it is recommended to use pins 1 and 2 for transmit (receive) and pins 7 and 8 for receive (transmit). This reduces NEXT crosstalk significantly, which will give a bonus on the maximum cable span, especially on Cat 5. Typical Application Circuit To improve isolation from the noise on the board power plane, it is recommended to power the equalizer through a ferrite bead. A 0.1 μf decoupling capacitor should be placed as close as possible to each VCC pin. Ground vias should be placed as close as possible to the device GND pins to minimize inductance. To reduce EMI, it is advised to place a capacitor of 6.8pF in between TPB and TPB* of the PHY. This reduces the rise/fall time of the transmitted signals. The capacitor should be put as close as possible to the pins of the PHY. PCB layout Because signals are strongly attenuated after a long cable, special attention must be paid on the PCB layout between the RJ45 connector and the EQCO400T. The EQCO400T should be as close as possible to the RJ45 connector. Traces between the RJ45, the common mode choke, the transformer and the EQCO400T should be either single-ended 55Ω traces, or differential traces with a differential impedance of 110Ω. To avoid noise pickup, these traces should be far enough away from other traces carrying digital signals or fast switching signals. Figure 6 illustrates a typical schematic implementation. Data is transmitted on pins 1,2 of RJ45. Data is received on pins 3,6. Please contact for support or cross-checking of PCB designs. A reference design is also available on request. EQCO400T Prelim Datasheet v1.2 Page6 of 12 February 2006

7 Figure 6 Example schematic implementation EQCO400T Prelim Datasheet v1.2 Page7 of 12 February 2006

8 Package Information A 16 pin Micro Lead frame Package (MLP) also known as Quad Flat No Lead (QFN) package is used. The package outline conforms to JEDEC MO-220. Dimensions in Figure 7 are in millimetres. SIDE VIEW BOTTOM VIEW Figure 7 Package dimension Document History VERSION DATE CHANGE Preliminary 1.1 February 2006 New document Preliminary 1.2 February 2006 Updated section Application information Added section Package Information EQCO400T Prelim Datasheet v1.2 Page8 of 12 February 2006

9 Appendix 1: Typical operating characteristics (Measured at VCC = 3.3V, Temp = +25ºC, data pattern = PRBS) Auto-adaptive Before Equalizer After Equalizer 2m CAT6 cable ; EQCO400T auto-adaptive Total Jitter ~ 0.2 UI Rx on pair 3,6 ; S400β ; 630mV Tx ampl Crosstalk source: Tx on pair 1,2 ; S400β ; 630mV Tx ampl 30m CAT6 cable ; EQCO400T auto-adaptive Total Jitter ~ 0.2 UI Rx on pair 3,6 ; S400β ; 630mV Tx ampl Crosstalk source: Tx on pair 1,2 ; S400β ; 630mV Tx ampl EQCO400T Prelim Datasheet v1.2 Page9 of 12 February 2006

10 Before Equalizer After Equalizer 60m CAT6 cable ; EQCO400T auto-adaptive 90m CAT6 cable ; EQCO400T auto-adaptive Total Jitter ~ 0.2 UI Total Jitter ~ 0.4 UI Rx on pair 3,6 ; S400β ; 630mV Tx ampl Rx on pair 3,6 ; S400β ; 630mV Tx ampl Crosstalk source: Crosstalk source: Tx on pair 1,2 ; S400β ; 630mV Tx ampl Tx on pair 1,2 ; S400β ; 630mV Tx ampl EQCO400T Prelim Datasheet v1.2 Page10 of 12 February 2006

11 CAT5e The crosstalk generated in a CAT5e system is much higher than in a CAT6 system. This reduces the maximum cable length. 70m CAT5e cable ; EQCO400T auto-adaptive 70m CAT5e cable ; EQCO400T auto-adaptive Total Jitter ~ 0.4 UI Total Jitter ~ 0.2 UI Rx on pair 3,6 ; S400β ; 630mV Tx ampl Rx on pair 3,6 ; S400β ; 630mV Tx ampl Crosstalk source: No crosstalk source Tx on pair 1,2 ; S400β ; 630mV Tx ampl Variable gain 80m CAT6 cable ; EQCO400T auto-adaptive 80m CAT6 cable ; EQCO400T auto-adaptive Total Jitter ~ 0.3 UI Total Jitter ~ 0.2 UI Rx on pair 3,6 ; S400β ; 300mV Tx ampl Rx on pair 3,6 ; S400β ; 800mV Tx ampl No crosstalk source No crosstalk source EQCO400T Prelim Datasheet v1.2 Page11 of 12 February 2006

12 Multi-speed 110m CAT6 cable ; EQCO400T auto-adaptive 130m CAT6 cable ; EQCO400T auto-adaptive Total Jitter ~ 0.25 UI Total Jitter < 0.3 UI Rx on pair 3,6 ; S200β ; 630mV Tx ampl Rx on pair 3,6 ; S100β ; 630mV Tx ampl No crosstalk source No crosstalk source Tx on pair 1,2 ; S200β ; 630mV Tx ampl Tx on pair 1,2 ; S100β ; 630mV Tx ampl EQCO400T Prelim Datasheet v1.2 Page12 of 12 February 2006