LMH0044SQ

LMH0044 SMPTE 292M / 259M Adaptive Cable Equalizer PRELIMINARY April 2006 LMH0044 SMPTE 292M / 259M Adaptive Cable Equalizer General Description The LMH0044 SMPTE 292M / 259M adaptive cable equalizer is a monolithic integrated circuit for equalizing data transmitted over cable (or any media with similar dispersive loss characteristics). The equalizer operates over a wide range of data rates from 143 Mbps to 1.485 Gbps and supports SMPTE 292M, SMPTE 344M and SMPTE 259M. The LMH0044 implements DC restoration to correctly handle pathological data conditions (DC restoration may be bypassed for low data rate applications). The equalizer may be driven in either a single ended or differential configuration. Additional features include separate carrier detect and output mute pins which may be tied together to mute the output when no signal is present. A programmable mute reference is provided to mute the output at a selectable level of signal degradation. Features n SMPTE 292M, SMPTE 344M and SMPTE 259M compliant n Supports DVB-ASI at 270 Mbps n High data rates: 143 Mbps to 1.485 Gbps n Equalizes up to 140 meters of Belden 1694A at 1.485 Gbps or up to 350 meters of Belden 1694A at 270 Mbps n Manual bypass and output mute with a programmable threshold n Single-ended or differential input n 50Ω differential outputs n Single 3.3V supply operation n 208mW typical power consumption with 3.3V supply n Replaces the GS1574 and GS1574A Applications n SMPTE 292M, SMPTE 344M, and SMPTE 259M serial digital interfaces n Serial digital data equalization and reception n Data recovery equalization Typical Application 20177001 © 2006 National Semiconductor Corporation DS201770 www.national.com LMH0044 Absolute Maximum Ratings (Note 1) Supply Voltage Input Voltage (all inputs) Storage Temperature Range Junction Temperature Lead Temperature (Soldering 4 Sec) Package Thermal Resistance θJA 16-pin LLP θJC 16-pin LLP ESD Rating (HBM) ESD Rating (MM) −0.5V to 3.6V −0.3V to VCC+0.3V −65˚C to +150˚C +150˚C +260˚C +115˚C/W +105˚C/W 8kV 250V Recommended Operating Conditions Supply Voltage (VCC – VEE) Input Coupling Capacitance AEC Capacitor (Connected between AEC+ and AEC-) Operating Free Air Temperature (TA) 3.3V ± 5% 1.0 µF 1.0 µF 0˚C to +85˚C DC Electrical Characteristics Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3). Symbol Parameter VCMIN VSDI Input Common Mode Voltage Input Voltage Swing At LMH0044 input, (Notes 4, 6) SDO, SDO 50Ω load, differential MUTEREF Carrier not present Carrier present MUTE Input Voltage ICC Supply Current Min to mute outputs Max to force outputs active (Note 7) 63 MUTE 3.0 2.0 77 CD 2.6 0.4 Conditions Reference SDI, SDI 720 Min Typ 1.9 800 VCC – VSDO/2 750 1.3 0.7 950 Max Units V mVP−P V mVP-P V V V V V V mA VCMOUT Output Common Mode Voltage VSDO Output Voltage Swing MUTEREF DC Voltage (floating) MUTEREF Range CD Output Voltage www.national.com 2 LMH0044 AC Electrical Characteristics Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3). Symbol Parameter BRSDI Input Data Rate Maximum Equalized Cable Length (with equalizer pathological) 270 Mbps, Belden 1694A, 0.2UI output jitter, (Note 4) 270 Mbps, Belden 8281, 0.2UI output jitter, (Note 4) 1.485 Gbps, Belden 1694A, 0.25UI output jitter, (Note 4) 1.485 Gbps, Belden 8281, 0.25UI output jitter, (Note 4) tr,tf tOS ROUT RLIN RIN CIN Output Rise Time, Fall Time Mismatch in Rise/Fall Time Output Overshoot Output Resistance Input Return Loss Input Resistance Input Capacitance 20% – 80%, (Note 4) (Note 4) (Note 4) single-ended, (Note 5) (Note 8) single-ended single-ended, (Note 5) SDI, SDI 15 SDO, SDO Conditions Reference SDI, SDI Min 143 350 280 140 100 100 2 1 50 18-20 1.3 1 220 15 5 Typ Max 1485 Units Mbps m m m m ps ps % Ω dB kΩ pF Note 1: "Absolute Maximum Ratings" are those parameter values beyond which the life and operation of the device cannot be guaranteed. The stating herein of these maximums shall not be construed to imply that the device can or should be operated at or beyond these values. The table of "Electrical Characteristics" specifies acceptable device operating conditions. Note 2: Current flow into device pins is defined as positive. Current flow out of device pins is defined as negative. All voltages are stated referenced to VEE = 0 Volts. Note 3: Typical values are stated for VCC = +3.3V and TA = +25˚C. Note 4: Specification is guaranteed by characterization. Note 5: Specification is guaranteed by design. Note 6: The maximum input voltage swing assumes a nonstressing, DC-balance signal; specifically, the SMPTE-recommended color bar test signal. Pathological or other stressing signals may not be used. This specification is for 0m cable only. Note 7: Supply current depends on the amount of cable being equalized. The current is highest for short cable and decreases as the cable length is increased. Refer to Figures 1, 2. Note 8: Input return loss is dependent on board design. The LMH0044 meets this specification on the SD044 evaluation board from 5MHz to 1.5GHz. 3 www.national.com LMH0044 Connection Diagram 20177003 16-Pin LLP Order Number LMH0044SQ See NS Package Number SQB16A Pin Descriptions Pin # 1 2 3 4 5 6 7 8 VEE SDI SDI VEE AEC+ AECBYPASS MUTEREF Name Description Negative power supply (ground). Serial data true input. Serial data complement input. Negative power supply (ground). AEC loop filter external capacitor (1µF) positive connection. AEC loop filter external capacitor (1µF) negative connection. Bypasses equalization and DC restoration when high. No equalization occurs in this mode. Mute reference. Sets the threshold for CD and (with CD tied to MUTE) determines the maximum cable to be equalized before muting. MUTEREF may be unconnected for maximum equalization. Negative power supply (ground). Serial data complement output. Serial data true output. Negative power supply (ground). Positive power supply (+3.3V). Output mute. To disable the mute function and enable the output, MUTE must be tied to GND or a low level signal. To force the outputs to a muted state, tie to VCC. CD may be tied to this pin to inhibit the output when no input signal is present. MUTE has no function in BYPASS mode. Carrier detect. CD is high when no signal is present. CD has no function in BYPASS mode. Positive power supply (+3.3V). 9 10 11 12 13 14 VEE SDO SDO VEE VCC MUTE 15 16 CD VCC www.national.com 4 LMH0044 Block Diagram 20177002 Device Operation BLOCK DESCRIPTION The Equalizer Filter block is a multi-stage adaptive filter. If Bypass is high, the equalizer filter is disabled. The DC Restoration / Level Control block receives the differential signals from the equalizer filter block. This block incorporates a self-biasing DC restoration circuit to fully DC restore the signals. If Bypass is high, this function is disabled. The signals before and after the DC Restoration / Level Control block are used to generate the Automatic Equalization Control (AEC) signal. This control signal sets the gain and bandwidth of the equalizer filter. The loop response in the AEC block is controlled by an external 1µF capacitor placed across the AEC+ and AEC- pins. The Carrier Detect / Mute block generates the carrier detect signal and controls the mute function of the output. This block utilizes the CD and MUTE signals along with Mute Reference (MUTEREF). The Output Driver produces SDO and SDO. MUTE REFERENCE (MUTEREF) The mute reference sets the threshold for CD and (with CD tied to MUTE) determines the amount of cable to equalize before automatically muting the outputs. This is set by applying a voltage inversely proportional to the length of cable to equalize. As the applied MUTEREF voltage is increased, the amount of cable that can be equalized before carrier detect is de-asserted and the outputs are muted is decreased. MUTEREF may be left unconnected for maximum equalization before muting. 5 CARRIER DETECT (CD) AND MUTE Carrier detect CD indicates if a valid signal is present at the LMH0044 input. If MUTEREF is used, the carrier detect threshold will be altered accordingly. CD provides a high voltage when no signal is present at the LMH0044 input. CD is low when a valid input signal is detected. MUTE can be used to manually mute or enable SDO and SDO. Applying a high input to MUTE will mute the LMH0044 outputs. Applying a low input will force the outputs to be active. CD and MUTE may be tied together to automatically mute the output when no input signal is present. INPUT INTERFACING The LMH0044 accepts either differential or single-ended input. The input must be AC coupled. Transformer coupling is not supported. The LMH0044 correctly handles equalizer pathological signals for standard definition and high definition serial digital video, as described in SMPTE RP 178 and RP 198, respectively. OUTPUT INTERFACING The SDO and SDO outputs are internally loaded with 50Ω. They produce a 750 mVP-P differential output, or a 375 mVP-P single-ended output. www.national.com LMH0044 Application Information PCB LAYOUT RECOMMENDATIONS Please refer to the following Application Note on National’s website: AN-1372, “CLC034 PCB Layout Techniques.” The PCB layout techniques in the application note apply to the LMH0044 as well. REPLACING THE GENNUM GS1574A The LMH0044 is footprint compatible with the Gennum GS1574A. SUPPLY CURRENT VS. CABLE LENGTH The supply current (ICC) depends on the amount of cable being equalized. The current is highest for short cable and decreases as the cable length is increased. Figure 1 shows supply current vs. Belden 1694A cable length for 1.485 Gbps data and Figure 2 shows supply current vs. Belden 1694A cable length for 270 Mbps data. 20177015 FIGURE 2. Supply Current vs. Belden 1694A Cable Length, 270 Mbps 20177013 FIGURE 1. Supply Current vs. Belden 1694A Cable Length, 1.485 Gbps www.national.com 6 LMH0044 SMPTE 292M / 259M Adaptive Cable Equalizer Physical Dimensions inches (millimeters) unless otherwise noted 16-Pin LLP Order Number LMH0044SQ NS Package Number SQB16A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. 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