LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 LMH7322 Dual 700 ps High Speed Comparator with RSPECL Outputs Check for Samples: LMH7322 FEATURES DESCRIPTION * * * * * * The LMH7322 is a dual comparator with 700 ps propagation delay, low dispersion of 75 ps and an input voltage range that extends from VCC-1.5V to VEE. The devices can be operated from a wide supply voltage range of 2.7V to 12V. The adjustable hysteresis adds flexibility and prevents oscillations. Both the outputs and latch inputs of the LMH7322 are RSPECL compatible. When used in combination with a VCCO supply voltage of 2.5V the outputs have LVDS compatible levels. 1 2 * * * (VCCI = +5V, VCCO = +5V) Propagation Delay 700 ps Overdrive Dispersion 20 mV-1V 75 ps Fast Rise and Fall Times 160 ps Wide Supply Range 2.7V to 12V Input Common Mode Range Extends 200 mV Below Negative Rail Adjustable Hysteresis (RS)PECL Outputs (see Application Information) (RS)PECL Latch Inputs (see Application Information) The LMH7322 is available in a 24-pin WQFN package. APPLICATIONS * * * * * * Digital Receivers High-Speed Signal Restoration Zero-Crossing Detectors High-Speed Sampling Window Comparators High-Speed Signal Triggering Typical Application 5V ECL driver Coupled transmission line Line Termination VCCO VCCO VCCI + IN+ Q IN- RS-PECL OUTPUT VOH = 3.9V VOL = 3.5V 1/2 LMH 7322 RHYS Q RT RHREF LE levels referred to VCCO VEE LE LE 10k RT VT = VCCO-2V or VT = VEE VT -5.2V + Figure 1. (RS)ECL to RSPECL Converter 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2007-2013, Texas Instruments Incorporated LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings ESD Tolerance (1) (2) (3) Human Body Model 2.5 kV Machine Model 250V Output Short Circuit Duration See (4) (5) (6) Supply Voltages (VCCx-VEE) 13.2V Differential Voltage at Input Pins 13V Voltage at Input Pins VEE-0.2V to VCCI + 0.2V Voltage at LE Pins VEE-0.2V to VCCO+0.2V Current at Output Pins 25mA Soldering Information: See Product Folder at www.ti.com and SNOA549 -65C to +150C Storage Temperature Range Junction Temperature (1) (2) (3) (4) (5) (6) (7) (7) +150C Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test conditions, see the Electrical Characteristics. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. Human Body Model, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of JEDEC). Field-Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC). Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150C. Short circuit test is a momentary test. See next note. The maximum power dissipation is a function of TJ(MAX), JA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) - TA)/ JA. All numbers apply for packages soldered directly onto a PC Board. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. Operating Conditions (1) Supply Voltage (VCCx-VEE) Operating Temperature Range Package Thermal Resistance 2.7V to 12V (2) (3) -40C to +125C (2) (3) 24-Pin WQFN (1) (2) (3) 2 38C/W Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test conditions, see the Electrical Characteristics. The maximum power dissipation is a function of TJ(MAX), JA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) - TA)/ JA. All numbers apply for packages soldered directly onto a PC Board. Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. See Applications section for information on temperature de-rating of this device. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 12V DC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 12V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = 1 k. Boldface limits apply at temperature extremes. Symbol Parameter Conditions Min Typ -5 -2.9 -250 40 (1) (2) Max (1) Units INPUT CHARACTERISTICS IB Input Bias Current VIN Differential = 0V; RHYS = 8 k Biased at VCM IOS Input Offset Current VIN Differential = 0V TC IOS Input Offset Current TC VIN Differential = 0V VOS Input Offset Voltage TC VOS Input Offset Voltage TC VRI Input Voltage Range VRID Input Differential Voltage Range CMRR Common Mode Rejection Ratio PSRR Power Supply Rejection Ratio AV Active Gain Hyst Hysteresis A +250 0.2 -8 -2 nA/C +8 12 for CMRR 50 dB VCCI-1.5 -1 +1 25 V V 80 dB 80 dB 53 VHYS = V(HYS+) -V(HYS-) , RHYS = 0 mV V/C VEE-0.2 0V VCM VCC1-0.2 nA dB 50 75 10 mV LATCH ENABLE CHARACTERISTICS IB-LE Latch Enable Bias Current Biased at RSPECL Level 3 VOS-LE Latch Enable Offset Voltage Biased at RSPECL Level -5 VRI-LE Latch Enable Voltage Range for CMRR 50 dB VRID-LE Latch Enable Differential Voltage Range VEE+1.4 A mV VCCO-0.8 V 0.4 V OUTPUT CHARACTERISTICS VOH Output Voltage High VIN Differential = 50 mV VCCO-1.1 V mV VOL Output Voltage Low VIN Differential = 50 mV VCCO-1.5 V mV VOD Output Voltage Differential VIN Differential = 50 mV 360 mV POWER SUPPLIES IVCCI VCCI Supply Current/ Channel IVCCO VCCO Supply Current/ Channel (1) (2) Load Current Excluded 6.5 10 12 16.3 20 25 mA mA All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. 12 AC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 12V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = none.Boldface limits apply at temperature extremes. Symbol TR (1) (2) Parameter Conditions Min (1) Typ (2) Max (1) Units Maximum Toggle Rate Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 4 Gb/s Minimum Pulse Width Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 255 ps All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 3 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com 12 AC Electrical Characteristics (continued) Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 12V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = none.Boldface limits apply at temperature extremes. Symbol Parameter Min Conditions (1) Typ (2) tjitter-RMS RMS Random Jitter Overdrive = 100 mV; CL = 2 pF Center Frequency = 140 MHz Bandwidth = 10 Hz-20 MHz 702 tPDH Propagation Delay. (see Figure 19 application note) Overdrive 20 mV 818 Overdrive 50 mV 723 Input SR = Constant VIN Startvalue = VREF -100 mV Overdrive 100 mV 708 Overdrive 1V 703 Input Overdrive Dispersion tPDH @ Overdrive 20 mV 100 mV 110 tOD-disp tPDH @ Overdrive 100 mV 1V 5 Max (1) Units fs ps ps ps tSR-disp Input Slew Rate Dispersion 0.1 V/ns to 1 V/ns; Overdrive = 100 mV 48 ps tCM-disp Input Common Mode Dispersion SR = 1 V/ns; Overdrive = 100 mV; 0V VCM VCCI- 1.5V 43 ps tPDLH Q to Q Time Skew |tPDH - tPDL| Overdrive = 100 mV; CL = 2 pF 24 ps tPDHL Q to Q Time Skew |tPDL - tPDH| Overdrive = 100 mV; CL = 2 pF 45 ps tr Output Rise Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 155 ps tf Output Fall Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 155 ps tsLE Latch Setup Time 77 ps thLE Latch Hold Time 33 ps tPD_LE Latch to Output Delay Time 944 ps 5V DC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 5V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = 1 k.Boldface limits apply at temperature extremes. Symbol Parameter Conditions Min Typ -5 -2.6 (1) (2) Max (1) Units INPUT CHARACTERISTICS IB Input Bias Current VIN Differential = 0V; RHYS = 8 k Biased at VCM IOS Input Offset Current VIN Differential = 0V TC IOS Input Offset Current TC VIN Differential = 0V VOS Input Offset Voltage TC VOS Input Offset Voltage TC VRI Input Voltage Range VRID Input Differential Voltage Range CMRR Common Mode Rejection Ratio 80 dB PSRR Power Supply Rejection Ratio 80 dB AV Active Gain 53 Hyst Hysteresis -250 40 A +250 0.3 -8 -2 +8 12 for CMRR 50 dB mV V/C VEE-0.2 VCCI-1.5 V -1 +1 V 0V VCM VCC1-0.2 VHYS = V(HYS+) -V(HYS-) , RHYS = 0 nA nA/C 25 dB 50 75 10 mV LATCH ENABLE CHARACTERISTICS IB-LE Latch Enable Bias Current Biased at RSPECL Level 3 VOS-LE Latch Enable Offset Voltage Biased at RSPECL Level +5 VRI-LE Latch Enable Voltage Range for CMRR 50 dB (1) (2) 4 VEE+1.4 A mV VCCO-0.8 V All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 5V DC Electrical Characteristics (continued) Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 5V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = 1 k.Boldface limits apply at temperature extremes. Symbol VRID-LE Parameter Conditions Min Typ (1) Max (2) Latch Enable Differential Voltage Range (1) Units 0.4 V OUTPUT CHARACTERISTICS VOH Output Voltage High VCCO-1.1 V mV VOL Output Voltage Low VCCO-1.5 V mV VOD Output Voltage Differential 355 mV POWER SUPPLIES IVCCI VCCI Supply Current/ Channel IVCCO VCCO Supply Current/ Channel Load Current Excluded 6.3 10 12 mA 15.8 20 25 mA 5V AC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 5V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = none. Boldface limits apply at temperature extremes. Symbol TR tjitter_RMS tPDLH tOD-disp Min Typ Max Parameter Conditions Maximum Toggle Rate Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 3.9 Gb/s Minimum Pulse Width Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 260 ps RMS Random Jitter Overdrive = 100 mV; CL = 2 pF Center Frequency = 140 MHz Bandwidth = 10 Hz-20 MHz 572 fs Propagation Delay. (see Figure 19 application note) Overdrive 20 mV 783 Overdrive 50 mV 718 Input SR = Constant VIN startvalue = VREF - 100 mV Overdrive 100 mV 708 Overdrive 1V 708 Input Overdrive Dispersion tPDH @ Overdrive 20 mV 100 mV 75 tPDH @ Overdrive 100 mV 1V 5 (1) (2) (1) Units ps ps ps tSR-disp Input Slew Rate Dispersion 0.1 V/ns to 1 V/ns; Overdrive = 100 mV 50 ps tCM-disp Input Common Mode Dispersion SR = 1 V/ns; Overdrive = 100 mV; 0V VCM VCCI- 1.5V 24 ps tPDLH Q to Q Time Skew |tPDH - tPDL| Overdrive = 100 mV; CL = 2 pF 29 ps tPDHL Q to Q Time Skew |tPDL - tPDH| Overdrive = 100 mV; CL = 2 pF 47 ps tr Output Rise Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 160 ps tf Output Fall Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 160 ps tsLE Latch Setup Time 95 ps thLE Latch Hold Time 29 ps tPD_LE Latch to Output Delay Time 893 ps (1) (2) All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 5 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com 2.7V DC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 2.7V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = 1 k. Boldface limits apply at temperature extremes. Symbol Parameter Conditions Min Typ -5 -2.5 -250 40 (1) (2) Max (1) Units INPUT CHARACTERISTICS IB Input Bias Current VIN Differential = 0V; RHYS = 8 k Biased at VCM IOS Input Offset Current VIN Differential = 0V TC IOS Input Offset Current TC VIN Differential = 0V VOS Input Offset Voltage TC VOS Input Offset Voltage TC VRI Input Voltage Range VRID Input Differential Voltage Range CMRR Common Mode Rejection Ratio PSRR Power Supply Rejection Ratio AV Active Gain Hyst Hysteresis A +250 0.2 -8 -2 +8 12 for CMRR 50 dB VEE-0 .2 +1 25 V V 80 dB 80 dB 53 VHYS = V(HYS+) -V(HYS-) , RHYS = 0 mV V/C VCCI- 1.5 -1 0V VCM VCC1-2 nA nA/C dB 50 75 10 mV LATCH ENABLE CHARACTERISTICS IB-LE Latch Enable Bias Current Biased at RSPECL Level 3 VOS-LE Latch Enable Offset Voltage Biased at RSPECL Level -5 VRI-LE Latch Enable Voltage Range for CMRR 50 dB VRID-LE Latch Enable Differential Voltage Range VEE+1 .4 A mV VCCO0.8 V 0.4 V OUTPUT CHARACTERISTICS VOH Output Voltage High VCCO-1.1 V mV VOL Output Voltage Low VCCO-1.5 V mV VOD Output Voltage Differential 350 mV POWER SUPPLIES IVCCI VCCI Supply Current/ Channel IVCCO VCCO Supply Current/ Channel (1) (2) Load Current Excluded 6.2 10 12 mA 15.5 20 25 mA All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. 2.7V AC Electrical Characteristics Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 2.7V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = none. Boldface limits apply at temperature extremes. Symbol TR (1) (2) 6 Min Typ Max Parameter Conditions Maximum Toggle Rate Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 3.8 Gb/s Minimum Pulse Width Overdrive = 50 mV; CL = 2 pF @ 50% of Output Swing 265 ps (1) (2) (1) Units All limits are specified by testing or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 2.7V AC Electrical Characteristics (continued) Unless otherwise specified, all limits are specified for TJ = 25C, VCCI = VCCO = 2.7V, VEE = 0V, RL = 50 to VCCO-2V, VCM = 300 mV, RHYS = none. Boldface limits apply at temperature extremes. Symbol Parameter tjitter_RMS tPDH tOD-disp Min Conditions (1) Typ (2) RMS Random Jitter Overdrive = 50 mV; CL = 2 pF Center Frequency = 140 MHz Bandwidth = 10 Hz-20 MHz 551 Propagation Delay. (see Figure 19 application note) Overdrive 20 mV 783 Overdrive 50 mV 728 Input SR = Constant VIN startvalue = VREF - 100 mV Overdrive 100 mV 713 Overdrive 1V 718 Input Overdrive Dispersion tPDH @ Overdrive 20 mV 100 mV 70 tPDH @ Overdrive 100 mV 1V 5 Max Units (1) fs ps ps ps tSR-disp Input Slew Rate Dispersion 0.1 V/ns to 1 V/ns; Overdrive = 100 mV 54 ps tCM-disp Input Common Mode Dispersion SR = 1 V/ns; Overdrive = 100 mV; 0V VCM VCCI- 1.5V 12 ps tPDLH Q to Q Time Skew |tPDH - tPDL| Overdrive = 100 mV; CL = 2 pF 35 ps tPDHL Q to Q Time Skew |tPDL - tPDH| Overdrive = 100 mV; CL = 2 pF 53 ps tr Output Rise Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 165 ps tf Output Fall Time (20%-80%) Overdrive = 100 mV; CL = 2 pF 165 ps tsLE Latch Setup Time 102 ps thLE Latch Hold Time 37 ps tPD_LE Latch to Output Delay Time 906 ps VCCOA VCCOB QB QB 20 19 VCCOA 1 18 LEA 2 17 LEB LEA 3 VEEA 4 15 VEEB VCCIA 5 14 RHYSA 6 13 RHYSB INA- 7 8 VCCOB 16 LEB LMH7322 24-pin WQFN 9 10 11 12 INB- Figure 2. Schematic 21 INB+ LE LE RHREF VEE Q 22 RHREFB RHYS 23 RHREFA 1/2 LMH7322 24 INA+ IN- QA Q IN+ QA VCCO VCCO VCCI Connection Diagrams VCCIB Figure 3. Footprint Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 7 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Typical Performance Characteristics At TJ = 25C; VCCI = +5V; VCCO = +3.3V; VEE = -5V; unless otherwise specified. Propagation Delay vs. Temperature 1100 1050 1050 1000 PROPAGATION DELAY (ps) PROPAGATION DELAY (ps) Propagation Delay vs. Supply Voltage 1100 125C 950 900 850 800 85C 750 25C 700 650 -40C 600 2 3 4 VS = 12V 1000 950 900 850 VS = 2.7V 800 750 700 650 5 6 7 8 9 VS = 5V 600 -40 -20 10 11 12 SUPPLY VOLTAGE (V) 0 20 Propagation Delay vs. Overdrive Voltage 900 VCM = 0.3V to VCM + VOVERDRIVE VOD = 10 mV 800 750 VOD = 50 mV VOD = 20 mV 700 600 2 VOD = 50 mV 500 mV 1V VOD = 200 mV 650 3 4 5 6 7 8 9 VCM = 0.3V VIN_DIFF = VCM 100 mV 850 PROPAGATION DELAY (ps) PROPAGATION DELAY (ps) 950 VIN_DIFF = VCM 100 mV 850 to VCM + VOVERDIVE 800 VS = 2.7V 700 VS = 12V 650 600 10 11 12 0 200 400 Propagation Delay vs. Slew Rate VS = 2.7V PROPAGATION DELAY (ps) PROPAGATION DELAY (ps) 1000 900 800 760 VS = 5V 720 VS = 12V 700 680 660 640 850 VS = 2.7V 800 VS = 12V 750 700 VS = 5V 650 VOVERDRIVE = 100 mV 600 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 OVERDRIVE 100 mV VCM = 300 mV 600 100 200 300 400 500 600 700 800 900 1000 SLEW RATE (V/Ps) COMMON MODE VOLTAGE (V) Figure 7. 8 800 Figure 6. Propagation Delay vs. Common Mode Voltage 620 600 OVERDRIVE VOLTAGE (mV) Figure 5. 740 VS = 5V 750 SUPPLY VOLTAGE (V) 780 80 100 120 Figure . Propagation Delay vs. Supply Voltage 900 60 TEMPERATURE (C) Figure 4. 1000 40 Figure 8. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Typical Performance Characteristics (continued) At TJ = 25C; VCCI = +5V; VCCO = +3.3V; VEE = -5V; unless otherwise specified. TPD Dispersion vs. Supply Voltage Slew Rate Dispersion vs. Voltage Supply 110 90 75 DISPERSION (ps) 80 70 60 VCM = 0.3V 50 VIN_DIFF = VCM - 100 mV 40 to VCM + VOVERDIVE 30 20 VOD = 50 mV - 1V 10 0 -10 2 4 5 6 7 8 9 VCM = 300 mV 65 SR = 0.1 1 V/Ps 60 55 50 45 40 35 30 VOD = 100 mV - 1V 3 OVERDRIVE 100 mV 70 VOD = 20 mV - 100 mV SLEW RATE DISPERSION (ps) 100 25 10 11 12 2 3 4 SUPPLY VOLTAGE (V) 5 Figure 9. 8 9 10 11 12 Bias Current vs. Temperature 80 -1 VOVERDRIVE = 100 mV 70 -1.5 0 < VCM < VCCI 1.5 60 BIAS CURRENT (PA) COMMON MODE DISPERSION (ps) 7 Figure 10. Common Mode Dispersion vs. Supply Voltage 50 40 30 20 4 6 8 10 2.7V -2 -2.5 -3 12V -3.5 5V -4 V CM = 300 mV -4.5 VIN_DIFF = 0 mV IBIAS = (IIN+ + IIN-)/2 -5 -40 -20 0 20 40 10 0 2 12 60 80 100 120 TEMPERATURE (C) SUPPLY VOLTAGE (V) Figure 11. Figure 12. Input Current vs. Differential Input Voltage Maximum Toggle Rate 10 400 VCM = 2.5V VIN+ = 1.5 to 3.5V IIN- VIN- = 3.5 to 1.5V IIN+ 0 -5 IIN+ IIN- -10 DIFFERENTIAL OUTPUT (mV) 300 VS = 5V 5 INPUT CURRENT (A) 6 SUPPLY VOLTAGE (V) 200 100 0 -100 -200 OUTPUT MAX TR OUTPUT 140 MHz -300 -400 -15 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 DIFFERENTIAL INPUT VOLTAGE (V) Figure 13. -500 0 1 2 3 4 5 6 7 TIME (ns) Figure 14. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 9 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) At TJ = 25C; VCCI = +5V; VCCO = +3.3V; VEE = -5V; unless otherwise specified. Output Voltage vs. Input Voltage Hysteresis Voltage vs. Hysteresis Resistor 70 0.3 VCM = 300 mV TEMP = 25C 0.2 VS = 5V 0.1 HYSTERESIS VOLTAGE (mV) DIFFERENTIAL OUTPUT VOLTAGE (V) 0.4 = VHYS+ = VHYS- 0 RHYS = 32 k: -0.1 -0.2 RHYS = 0 -0.3 -0.4 -0.05 VS = 2.7V, 5V,12V 50 VHYS = V(HYS+) - V(HYS-) 40 30 20 10 0 -0.03 -0.01 0 0.01 0.03 0.05 DIFFERENTIAL INPUT VOLTAGE (V) Figure 15. 10 VCM = 300 mV TEMP = 25C 60 0 5 10 15 20 25 30 35 HYSTERESIS RESISTOR (k:) Figure 16. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 APPLICATION INFORMATION Introduction The LMH7322 is a high speed comparator with RS(P)ECL (Reduced Swing Positive Emitter Coupled Logic) outputs, and is compatible with LVDS (Low Voltage Differential Signaling) if VCCO is set to 2.5V. The use of complementary outputs gives a high level of suppression for common mode noise. The very fast rise and fall times of the LMH7322 enable data transmission rates up to several Gigabits per second (Gbps). The LMH7322 inputs have a common mode voltage range that extends 200 mV below the negative supply voltage thus allowing ground sensing in case of single supply. The rise and fall times of the LMH7322 are about 160 ps, while the propagation delay time is about 700 ps. The LMH7322 can operate over the full supply voltage range of 2.7V to 12V, while using single or dual supply voltages. This is a very useful feature because it provides a flexible way to interface between several high speed logic families. Several setups are shown in the application information section "Interface Between Logic Families". The outputs are referenced to the positive VCCO supply rail. The supply current is 23 mA at 5V (per comparator, load current excluded.) The LMH7322 is available in a 24-Pin WQFN package. The following topics will be discussed in this application section. * Input and output topology * Specification definitions * Propagation delay and dispersion * Hysteresis and oscillations * Output * Applying transmission lines * PCB layout Input & Output Topology All input and output pins are protected against excessive voltages by ESD diodes. These diodes are conducting from the negative supply to the positive supply. As can be seen in Figure 17, both inputs are connected to these diodes. Further protection of the inputs is provided by the two resistors of 250, in conjunction with the string of anti-parallel diodes connected between both bases of the input stage. This combination of resistors and diodes reduces excessive input voltages over the input stage, but is low enough to maintain switching speed to the output signal. Protection against excessive supply voltages is provided by a power clamp between VCC and GND. When using this part be aware of situations in which the differential input voltage level is such that these diodes are conducting. In this case the input current is raised far above the normal value stated in the datasheet tables because input current is flowing through the bypass diode string between both inputs. VCCI VCCI VCCI VCCO VCCI 250: 250: IN- IN+ VEE VEE VEE PART A Power Clamp 2X VEE PART B Figure 17. Equivalent Input Circuitry Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 11 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com The output stage of the LMH7322 is built using two emitter followers, which are referenced to the VCCO (see Figure 18.) Each of the output transistors is active when a current is flowing through any external output resistor connected to a lower supply rail. The output structure is actually the same as for all other ECL devices. Activating the outputs is done by connecting the emitters to a termination voltage which lies 2V below the VCCO. In this case a termination resistor of 50 can be used and a transmission line of 50 can be driven. Another method is to connect the emitters through a resistor to the most negative supply by calculating the right value for the emitter current in accordance with the datasheet tables. Both methods are useful, and it is up to the customer which method is used. Using 50 to the termination voltage means the introduction of an extra supply in the system, while using resistors to a negative supply means the use of resistors that are much larger than 50 and a more constant output current per stage. The following calculation will show the difference. In this example a VCCO of 2.5V is used and a VT of VCCO-2V and a negative supply of -5V. When connecting the outputs through a 50 resistor to the VT, the output currents for the high and the low state are respectively 18 mA and 10 mA. Connecting the outputs through a 400 resistor to the -5V supply the output currents for the high and the low state are respectively 16 mA and 15 mA. Higher resistor values to the VEE will further reduce power consumption but will cause a slower transition of the output stage. In the case that this will not harm your application it is a useful method to reduce power consumption. VCCO Output Q r Output Q VEE Figure 18. Equivalent Output Circuitry The output voltages for `1' and `0' have a difference of approximately 400 mV and are respectively 1.1V (for the `1') and 1.5V (for the `0') below the VCCO. This swing of 400 mV is enough to drive any LVDS input but can also be used to drive any ECL or PECL input, when the right supply voltage is chosen, especially the right level for the VCCO. Table 1. Definitions Symbol Text Description IB Input Bias Current Current flowing in or out of the input pins, when both are biased at the VCM voltage as specified in the tables. IOS Input Offset Current Difference between the input bias current of the inverting and non-inverting inputs. TC IOS Average Input Offset Current Drift Temperature coefficient of IOS. VOS Input Offset Voltage Voltage difference needed between IN+ and IN- to make the outputs change state, averaged for H to L and L to H transitions. TC VOS Average Input Offset Voltage Drift Temperature coefficient of VOS . VRI Input Voltage Range Voltage which can be applied to the input pin maintaining normal operation. VRID Input Differential Voltage Range Differential voltage between positive and negative input at which the input clamp is not working. The difference can be as high as the supply voltage but excessive input currents are flowing through the clamp diodes and protection resistors. CMRR Common Mode Rejection Ratio Ratio of input offset voltage change and input common mode voltage change. PSRR Power Supply Rejection Ratio Ratio of input offset voltage change and supply voltage change from VS-MIN to VSMAX. AV Active Gain Overall gain of the circuit. 12 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Table 1. Definitions (continued) Symbol Text Description Hyst Hysteresis Difference between the switching point `0' to `1' and vice versa. IB-LE Latch Enable Bias Current Current flowing in or out of the input pins, when both are biased at normal PECL levels. IOS-LE Latch Enable Offset Current Difference between the input bias current of the LE and LE pin. TC IOS-LE Temp Coefficient Latch Enable Offset Current Temperature coefficient of IOS-LE. VOS-LE Latch Enable Offset Voltage Voltage difference needed between LE and LE to place the part in the latched or the transparent state. TC VOS-LE Temp Coefficient Latch Enable Offset Voltage Temperature coefficient of VOS-LE. VRI-LE Latch Enable Voltage Range Voltage which can be applied to the LE input pins without damaging the device. VRID-LE Latch Enable Differential Voltage Range Differential Voltage between LE and LE at which the clamp isn't working. The difference can be as high as the supply voltage but excessive input currents are flowing through the clamp diodes and protection resistors. VOH Output Voltage High High state single ended output voltage (Q or Q) (see Figure 34). VOL Output Voltage Low Low state single ended output voltage (Q or Q) (see Figure 34). VOD average of VODH and VODL (VODH + VODL)/2. IVCCI Supply Current Input Stage Supply current into the input stage. IVCCO Supply Current Output Stage Supply current into the output stage while current through the load resistors is excluded. IVEE Supply Current VEE pin Current flowing to the negative supply pin. TR Maximum Toggle Rate Maximum frequency at which the outputs can toggle between the nominal VOH and VOL. PW Pulse Width Time from 50% of the rising edge of a signal to 50% of the falling edge. tPDH resp tPDL Propagation Delay Delay time between the moment the input signal crosses the switching level L to H and the moment the output signal crosses 50% of the rising edge of Q output (tPDH), or delay time between the moment the input signal crosses the switching level H to L and the moment the output signal crosses 50% of the falling edge of Q output (tPDL). tPDL resp tPDH Delay time between the moment the input signal crosses the switching level L to H and the moment the output signal crosses 50% of the falling edge of Q output (tPDL), or delay time between the moment the input signal crosses the switching level H to L and the moment the output signal crosses 50% of the rising edge of Q output (tPDH). tPDLH Average of tPDH and tPDL. tPDHL Average of tPDL and tPDH. tPD Average of tPDLH and tPDHL. tPDHd resp tPDLd Delay time between the moment the input signal crosses the switching level L to H and the zero crossing of the rising edge of the differential output signal (tPDHd), or delay time between the moment the input signal crosses the switching level H to L and the zero crossing of the falling edge of the differential output signal (tPDLd). tOD-disp Input Overdrive Dispersion Change in tPD for different overdrive voltages at the input pins. tSR-disp Input Slew Rate Dispersion Change in tPD for different slew rates at the input pins. tCM-disp Input Common Mode Dispersion Change in tPD for different common mode voltages at the input pins. tPDLH resp tPDHL Q to Q Time Skew Time skew between 50% levels of the rising edge of Q output and the falling edge of output (tPDLH), or time skew between 50% levels of falling edge of Q output and rising edge of Q output (tPDHL). tPD Average Q to Q Time Skew Average of tPDLH and tPDHL for L to H and H to L transients. tPDd Average Diff. Time Skew Average of tPDHd and tPDLd for L to H and H to L transients. tr / trd Output Rise Time (20% - 80%) Time needed for the (single ended or differential) output voltage to change from 20% of its nominal value to 80%. tf / tfd Output Fall Time (20% - 80%) Time needed for the (single ended or differential) output voltage to change from 80% of its nominal value to 20%. tsLE Latch Setup Time Time the input signal has to be stable before enabling the latch functionality. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 13 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Table 1. Definitions (continued) Symbol Text Description thLE Latch Hold Time Time the input signal has to remain stable after enabling the latch functionality. tPD-LE Latch to Output Delay Time Delay time between the moment the latch input crosses the switching level H to L and the moment the differential output signal crosses the 50% level. Note: input signal is opposite to output signal when latch becomes enabled. PW Voverdrive Differential Input Signal tPDLH = (tPDH + tPDL)/ 2 0 'tPDLH tPDHL = (tPDL + tPDH)/ 2 'tPDHL tf tPD = (tPDLH + tPDHL)/ 2 tr tPDH 80% or 90% tPDL Output Q 'tPDLH = | tPDH - tPDL | VO 10% or 20% 'tPDHL = | tPDL - tPDH | tPDH 'tPD = 'tPDLH + 'tPDHL)/ 2 VO Output Q tPDL 'tPDQ = | tPDH - tPDL | trd tPDHd 'tPDQ = | tPDL - tPDH | 80% or 90% Differential Output Signal 0 tPDLd tPDd = (tPDHd + tPDLd)/ 2 10% or 20% 'tPDd = | tPDHd - tPDLd | tfd Figure 19. Timing Definitions th LE Diff input LE Q output ts LE tPD LE tPDHL Figure 20. LE Timing Table 2. PIN DESCRIPTIONS Pin Name Description Comment 1. VCCOA Positive Supply Output Stage part A The supply pin for the output stage is independent of the supply pin for the input pin. This allows output levels of different logic families. 2. LEA Latch Enable Input part A Logic `1' sets the part on hold. Logic levels are RSPECL (Reduced Swing PECL) compatible. 3. LEA Latch Enable Input Not part A Logic `0' sets the part on hold. Logic levels are RSPECL compatible. 4. VEEA Negative Supply part A The supply pin for the negative supply is connected to the VEEB via a string of two anti-parallel diodes (see Figure 17) 5. VCCIA Positive Supply for Input Stage part A The supply pin for the input stage is independent of the supply for the output stage. 6. RHYSA Hysteresis Resistor part A The hysteresis voltage is determined by connecting a resistor from this pin to RHREFA. 7. INA- Negative Input part A Input for analog voltages between 200 mV below VEEA and 2V below VCCIA. 14 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Table 2. PIN DESCRIPTIONS (continued) Pin Name Description Comment 8. INA+ Positive Input part A Input for analog voltages between 200 mV below VEEA and 2V below VCCIA. 9. RHREFA Reference Voltage Hysteresis Resistor part A The hysteresis voltage is determined by connecting a resistor from this pin to RHYSA. 10. RHREFB Reference Voltage Hysteresis Resistor part B The hysteresis voltage is determined by connecting a resistor from this pin to RHYSB. 11. INB+ Positive Input part B Input for analog voltages between 200 mV below VEEB and 2V below VCCIB. 12. INB- Negative Input part B Input for analog voltages between 200 mV below VEEB and 2V below VCCIB. 13. RHYSB Hysteresis Resistor part B The hysteresis voltage is determined by connecting a resistor from this pin to RHREFB. 14. VCCIB Positive Supply for Input Stage part B The supply pin for the input stage is independent of the supply for the output stage. 15. VEEB Negative Supply part B The supply pin for the negative supply is connected to the VEEA via a string of two anti-parallel diodes (see Figure 17). 16. LEB Latch Enable Input Not part B Logic `0' sets the part on hold. Logic levels are RSPECL compatible. 17. LEB Latch Enable Input Logic part B `1' sets the part on hold. Logic levels are RSPECL compatible. 18. VCCOB Positive Supply for Output Stage part B The supply pin for the output stage is independent of the supply pin for the input pin. This allows output levels of different logic families. 19. QB Inverted Output part B Output levels are determined by the choice of VCCOB. 20. QB Output part B Output levels are determined by the choice of VCCOB. 21. VCCOB Positive Supply for Output Stage part B See other VCCOB 22. VCCOA Positive Supply for Output Stage part A See other VCCOA. 23. QA Output part A Output levels are determined by the choice of VCCOA. 24. QA Inverted Output part A Output levels are determined by the choice of VCCOA. 25. DAP Central pad at the bottom of the A & B package This pad is connected to the VEE pins and its purpose is to transfer heat outside the part. Tips & Tricks Using the LMH7322 In this section several aspects are discussed concerning special applications using the LMH7322. This concerns the LE function, the connection of the DAP in conjunction to the VEE pins and the use of this part as an interface between several logic families. The Latch Enable Pins The latch function is intended to stop the device from comparing the signals on both input pins. If the latch function is enabled, the output is frozen and the logic information on the output pins, present at that moment, is held until the latch function is disabled. The timing of this process can be seen in Figure 20. The input levels for the latch pins should comply with RSPECL, but can also be driven with PECL type of signals if the minimum supply (VCCO -VEE) is larger or equal to 3.3V. The minimum differential latch input voltage should be 100 mV. Another possibility to set the LE function in a steady state is to connect the pins via a resistor to the power supply. If the LE pin is connected to VEE via a resistor of 10 k and the LE-not pin is connected via 10 k to the VCCO pin the part is continuously on. Since the latch input stage is referenced to VCCO, the resistors to set the LE function should be connected to this voltage. This is very important when working with different voltages for VCCI and VCCO. If connected to the wrong supply, the latch function will not work. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 15 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com The DAP and the VEE Pins To ensure that both VEE pins are operating at the same voltage, both pins are connected to the DAP, and thus to each other, through bond wires. As a consequence, the DAP is at the same potential as the VEE pins and can be used to connect the device to the minimum supply voltage. A more solid VEE connection is obtained if the two VEE pins and the DAP are all connected to the minimum supply on the PCB, rather than an indirect connection through the internal bond wires. To protect the device during handling and production two anti-parallel connected diodes are connected between both VEE pins. Under normal operating conditions these diodes are shorted via the DAP. The DAP (Die Attach Paddle) functions as a heat sink which means that heat can be transferred using vias below this pad to the copper plane VEE is connected to. VEE DAP VEE Figure 21. DAP Connection Interface Between Logic Families As can be seen in the typical schematics (see Figure 1) the LMH7322 can be used to interface between different logic families. The feature that facilitates this property is the fact that the input stage and the output stage use different positive power supply pins which can be used at different supply voltages. The negative supply pins are connected together for both parts. Using the power pins at different supply voltages makes it possible to create several translations for logic families. It is possible to translate from logic at negative voltage levels such as ECL to logic at positive levels such as RSPECL and LVDS and vice versa. The drawings in the next paragraphs do not show the output resistors except the first one. This is intentionally done for simplicity. All outputs need an output resistor to a termination voltage or to the negative rail as can be seen on the front page in the Typical Application of an ECL to RSPECL converter. Interface from ECL to RSPECL The supply pin VCCI can be connected to ground because the input levels are negative and the VCCO pin must operate at 5V to create the RSPECL levels (see Figure 22). When working with ECL, the negative supply pin (VEE) can be connected to the -5.2V ECL supply voltage. 5V ECL driver Coupled transmission line Line Termination VCCO VCCO VCCI + IN+ Q IN- RS-PECL OUTPUT VOH = 3.9V VOL = 3.5V 1/2 LMH 7322 RHYS Q RT RHREF VEE LE LE 10k RT LE levels referred to VCCO VT = VCCO-2V or VT = VEE VT -5.2V + Figure 22. ECL TO RSPECL 16 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Interface from PECL to (RS)ECL The conversion from PECL to RS-ECL is possible when connecting the VCCI pin to +5V, which allows the input stage to handle these positive levels. The VCCO pin must be connected to the ground level in order to create the RSECL levels. The high level of the output of the LMH7322 is normally 1.1V below the VCCO supply voltage, and the low level is 1.5V below this supply. The output levels are now -1100 mV for the logic `1' and -1500 mV for the logic `0' (see Figure 23). In the same way the VEE can be connected to the ECL supply voltage of -5.2V. 5V PECL driver Coupled transmission line Line Termination VCCO VCCI VCCO + IN+ Q IN- PECL levels: VOH = 3.9V VOL = 3.5V RSECL levels: VOH = -1100 mV Q VOL = -1500 mV 1/2 LMH 7322 RHYS VEE RHREF LE LE 10k -5.2V + LE levels referred to VCCO Figure 23. PECL TO RSECL Interface from Analog to LVDS As seen in Figure 24, the LMH7322 can be configured to create LVDS levels. This is done by connecting the VCCO to 2.5V. As discussed before the output levels are now at VCCO -1.1V for the logic `1' and at VCCO -1.5V for the logic `0'. These levels of 1000 mV and 1400 mV comply with the LVDS levels. As can be seen in this setup, an AC coupled signal via a transmission line is used. This signal is terminated with 50. 5V 2.5V + + VCCO VCCO VCCI + 50: IN+ Q INSignal Source 1/2 LMH 7322 Q 50 50 Levels: VOH = 1.4V VOL = 1.0V RHYS VEE RHREF LE LE 10k LE levels referred to VCCO -5V + Figure 24. ANALOG TO LVDS Figure 25 shows a standard comparator setup which creates RSPECL levels because the VCCO supply voltage is +5V. In this case the VEE pin is connected to the ground level. The VCCI pin is connected to the VCCO pin because there is no need to use different positive supply voltages. The input signal is AC coupled to the positive input. To maintain reliable results the input pins IN+ and IN- are biased at 1.4V through a resistive divider using a resistor of 1 k to ground and a resistor of 2.5 k to the VCC and by adding two decoupling capacitors. Both inputs are connected to the bias level by the use of a 10 k resistor. With this input configuration the input stage can work in a linear area with signals of approximately 3 VPP (see Input Voltage Range or VRI in the Electrical Characteristics tables.) Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 17 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com 5V VCCO 2k5 Vin VCCO VCCI + IN+ Q IN- 1/2 LMH 7322 Q 10k 10k Levels: VOH = 3.9V VOL = 3.5V RHYS 10k VEE + LE LE RHREF VREF 1k 5k 5k Figure 25. Standard Setup Delay and Dispersion Comparators are widely used to connect the analog world to the digital one. The accuracy of a comparator is dictated by its DC properties, such as offset voltage and hysteresis, and by its timing aspects, such as rise and fall times and delay. For low frequency applications most comparators are much faster than the analog input signals they handle. The timing aspects are less important here than the accuracy of the input switching levels. The higher the frequencies, the more important the timing properties of the comparator become, because the response of the comparator can make a noticeable change in critical parameters such as time frame or duty cycle. A designer has to know these effects and has to deal with them. In order to predict what the output signal will do, several parameters are defined which describe the behavior of the comparator. For a good understanding of the timing parameters discussed in the following section, a brief explanation is given and several timing diagrams are shown for clarification. Propagation Delay The propagation delay parameter is described in the Table 1 section. Due to this definition there are two parameters, tPDH and tPDL (Figure 26). Both parameters do not necessarily have the same value. It is possible that differences will occur due to a different response of the internal circuitry. As a derivative of this effect another parameter is defined: tPD. This parameter is defined as the absolute value of the difference between tPDH and tPDL. PW 80% 80% VIN 50% 50% 20% 20% tPDH tPDL 80% 80% 50% Output Q 50% 20% tr 20% tf Figure 26. Propagation Delay 18 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Input Signal If tPD is not zero, duty cycle distortion will occur. For example when applying a symmetrical waveform (e.g. a sinewave) at the input, it is expected that the comparator will produce a symmetrical square wave at the output with a duty cycle of 50%. When tPDH and tPDL are different, the duty cycle of the output signal will not remain at 50%, but will be increased or decreased. In addition to the propagation delay parameters for single ended outputs discussed before, there are other parameters in the case of complementary outputs. These parameters describe the delay from input to each of the outputs and the difference between both delay times (See Figure 27.) When the differential input signal crosses the reference level from L to H, both outputs will switch to their new state with some delay. This is defined as tPDH for the Q output and tPDL for the Q output, while the difference between both signals is defined as tPDLH. Similar definitions for the falling slope of the input signal can be seen in Figure 19. time VREF Output Q tPDH time VO Output Q 'tPDLH time VO tPDL Figure 27. tPD with Complementary Outputs Both output circuits should be symmetrical. At the moment one output is switching `on' the other is switching `off' with ideally no skew between both outputs. The design of the LMH7322 is optimized so that this timing difference is minimized. The propagation delay, tPD, is defined as the average delay of both outputs at both slopes: (tPDLH + tPDHL)/2. Both overdrive and starting point should be equally divided around the VREF (absolute values). Dispersion There are several circumstances that will produce a variation of the propagation delay time. This effect is called dispersion. Amplitude Overdrive Dispersion One of the parameters that causes dispersion is the amplitude variation of the input signal. Figure 28 shows the dispersion due to a variation of the input overdrive voltage. The overdrive is defined as the `go to' differential voltage applied to the inputs. Figure 28 shows the impact it has on the propagation delay time if the overdrive is varied from 10 mV to 100 mV. This parameter is measured with a constant slew rate of the input signal. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 19 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Overdrive 100 mV Input Differential Signal + Overdrive 10 mV 0 - Output Differential Signal time -100 mV Overdrive Dispersion + Dispersion 0 time - Figure 28. Overdrive Dispersion The overdrive dispersion is caused by the switching currents in the input stage which is dependent on the level of the differential input signal. Slew Rate Dispersion Input Differential Signal The slew rate is another parameter that affects propagation delay. The higher the input slew rate, the faster the input stage switches (See Figure 29). + 0 Output Differential Signal - time Slew Rate Dispersion + Dispersion 0 time - Figure 29. Slew Rate Dispersion A combination of overdrive and slew rate dispersion occurs when applying signals with different amplitudes at constant frequency. A small amplitude will produce a small voltage change per time unit (dV/dt) but also a small maximum switching current (overdrive) in the input transistors. High amplitudes produce a high dV/dt and a larger overdrive. Common Mode Dispersion Dispersion will also occur when changing the common mode level of the input signal (Figure 30). When VREF is swept through the CMVR (Common Mode Voltage Range), It results in a variation of the propagation delay time. This variation is called Common Mode Dispersion. 20 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Input Differential Signal Vin cm + 0 Output Differential Signal - Vin cm time Common Mode Dispersion + Dispersion 0 time - Figure 30. Common Mode Dispersion All of the dispersion effects described previously influence the propagation delay. In practice the dispersion is often caused by a combination of more than one varied parameter. Hysteresis & Oscillations In contrast to an op amp, the output of a comparator has only two defined states `0' or `1.' Due to finite comparator gain however, there will be a small band of input differential voltage where the output is in an undefined state. An input signal with fast slopes will pass this band very quickly without problems. During slow slopes however, passing the band of uncertainty can take a relatively long time. This enables the comparators output to switch back and forth several times between `0' and `1' on a single slope. The comparator will switch on its input noise, ground bounce (possible oscillations), ringing etc. Noise in the input signal will also contribute to these undesired switching actions. The next sections explain these phenomena in situations where no hysteresis is applied, and discuss the possible improvement hysteresis can give. Using No Hysteresis Figure 31 shows what happens when the input signal rises from just under the threshold VREF to a level just above it. From the moment the input reaches the lowest dotted line around VREF at t=0, the output toggles on noise etc. Toggling ends when the input signal leaves the undefined area at t=1. In this example the output was fast enough to toggle three times. Due to this behavior digital circuitry connected to the output will count a wrong number of pulses. One way to prevent this is to choose a very slow comparator with an output that is not able to switch more than once between `0' and `1' during the time the input state is undefined. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 21 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Input Signal mV Vref fast output time 1 time slow output 0 1 time 0 t=0 t=1 Oscillations & Noise Figure 31. Oscillations on Output Signal In most circumstances this is not an option because the slew rate of the input signal will vary. Using Hysteresis Hysteresis can be introduced to avoid oscillations, e.g. due to noise on the input signal, especially for slow edges. For this purpose the switching level without hysteresis (VREF) is forced to a new level (A or B) at the moment the input signal crosses one of these levels. This can be seen in Figure 32. Input Signal mV Vref A B Output 1 0 t=0 t=1 Figure 32. Hysteresis In this picture the two dotted lines A and B, represent the resulting reference level at which the comparator will compare the input level against. Assume that for this situation the input signal is connected to the negative input and the switching level (VREF) to the positive input. The input level drawn in Figure 32 starts much lower as the reference level and this means that the input stage is well defined with the inverting input much lower than the non-inverting input. As a result the output will be in the high state. Internally the switching level is at level A, with the input signal sloping up, this situation remains until VIN crosses level A at t=1. Now the output toggles, and the internal switching level is lowered to level B. So before the output has the possibility to toggle again, the voltage difference between the inputs is sufficient to have a stable situation again. When the input signal comes down from high to low, the situation is stable until level B is reached at t=0. At this moment the output will toggle back, and the circuit returns to the starting situation with the inverting input at a much lower level than the non inverting input. Varying the levels A and B due to the change of the hysteresis resistor will also vary the timing of t=0 and t=1. When designing a circuit be aware of this effect. Introducing hysteresis will cause some time shift between output and input (e.g. duty cycle variations), but will eliminate undesired switching of the output. 22 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Configuring Hysteresis for the LMH7322 The LMH7322 offers the possibility to introduce hysteresis by connecting a resistor between the RHYS pin and the RHREF pin. This hysteresis setting resistor may vary between zero ohm and infinite. The current drawn from the RHYS pin determines the setting of the internal reference voltage. When no resistor is present the internal used reference voltage is set to zero (the difference between A and B level is zero, see explanation Using Hysteresis) and no hysteresis is configured. This means the output will change state when the difference between the positive en negative input signals crosses zero level. Connecting a resistor between the RHYS pin and the RHREF pin produces a difference for the A and B levels which means hysteresis is introduced and the output will change state at different levels for an up or down transition of the input signal. Due to the internal structure a current must be drawn from the RHYS pin. This can be done by connecting a resistor to the lowest supply voltage. In order to assure the RHYS pin is connected to the correct voltage level, and unwanted current variations in the hysteresis level are avoided, the RHREF and VEE are connected internally within the LMH7322. Therefore, the hysteresis resistor should only be connected between RHYS and RHREF or left open if no hysteresis is required. To select the correct resistor for the desired hysteresis voltage see Figure 33. HYSTERESIS VOLTAGE (mV) 70 VCM = 300 mV TEMP = 25C 60 VS = 2.7V, 5V,12V 50 VHYS = V(HYS+) - V(HYS-) 40 30 20 10 0 0 5 10 15 20 25 30 35 HYSTERESIS RESISTOR (k:) Figure 33. Hysteresis Voltage vs. Hysteresis Resistor With the use of a resistor to set the hysteresis voltage no external conditions will effect these setting as long as they stay within the normal operating ranges. Temperature changes may cause a variation of the hysteresis resistor dictated by the temperature coefficient of the used type. Connecting the RHYS pin to another voltage as provided by the RHREF pin is not covered in the resistor selection plot and the designer of such a circuit must be aware of abnormal behavior. The Output Output Swing Properties The LMH7322 has differential outputs which means that both outputs have the same swing but in opposite directions (See Figure 34). Both outputs swing around the common mode output voltage (VO). This voltage can be measured at the midpoint between two equal resistors connected to each output. The absolute value of the difference between both voltages is called VOD. The outputs cannot be held at the VO level because of their digital nature. They only cross this level during a transition. Due to the symmetrical structure of the circuit, both output voltages cross at VO regardless of whether the output changes from `0' to `1' or vise versa. Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 23 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com Output Q VOH VOD VO VOL Output Q Figure 34. Output Swing Loading the Output Both outputs are activated when current is flowing through a resistor that is externally connected to VT. The termination voltage should be set 2V below the VCCO. This makes it possible to terminate each of the outputs directly with 50, and if needed to connect through a transmission line with the same impedance (see Figure 35). Due to the low ohmic nature of the output emitter followers and the 50 load resistor, a capacitive load of several pF does not dramatically affect the speed and shape of the signal. When transmitting the signal from one output to any input the termination resistor should match the transmission line. The capacitive load (CP) will distort the received signal. When measuring this input with a probe, a certain amount of capacitance from the probe is parallel to the termination resistor. The total capacitance can be as large as 10 pF. In this case there is a pole at: f = 1/(2**C*R) f = 1e9/ f = 318 MHz (1) (2) (3) In this case the current IP has the same value as the current through the termination resistor. This means that the voltage drops at the input and the rise and fall times are dramatically different from the specified numbers for this part. Another parasitic capacitance that can affect the output signal is the capacitance directly between both outputs, called CPAR (see Figure 35). The LMH7322 has two complementary outputs so there is the possibility to transport the output signal by a symmetrical transmission line. In this case both output tracks form a coupled line with their own parasitics and both receiver inputs connected to the transmission line. Actually the line termination looks like 100 and the input capacitances, which are in series, are parallel to the 100 termination. The best way to measure the input signal is to use a differential probe directly across both inputs. Such a probe is very suitable for measuring these fast signals because it has good high frequency characteristics and low parasitic capacitance. VCCO VCCI IP CP RT IN+ VT + - Q CPAR Q IN- VEE RT CP IP VT Figure 35. Parasitic Capacitance 24 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 Transmission Lines & Termination Technologies The LMH7322 uses complementary RSPECL outputs and emitter followers, which means high output current capability and low sensitivity to parasitic capacitance. The use of Reduced Swing Positive Emitter Coupled Logic reduces the supply voltage to 2.7V, being the lowest possible value, and raises the maximum frequency response. Data rates are growing, which requires increasing speed. Data is not only connected to other IC's on a single PCB board but, in many cases, there are interconnections from board to board or from equipment to equipment. Distances can be short or long but it is always necessary to have a reliable connection, which consumes low power and is able to handle high data rates. The complementary outputs of the LMH7322 make it possible to use symmetrical transmission lines The advantage over single ended signal transmission is that the LMH7322 has higher immunity to common mode noise. Common mode signals are signals that are equally apparent on both lines and because the receiver only looks at the difference between both lines, this noise is canceled. Maximum Bit Rates The maximum toggle rate is defined at an amplitude of 50% of the nominal output signal. This toggle rate is a number for the maximum transfer rate of the part and can be given in Hz or in Bps. When transmitting signals in a NRZ (Non Return to Zero) format the bitrate is double this frequency number, because during one period two bits can be transmitted. (See Figure 36.) The rise and fall times are very important specifications in high speed circuits. In fact these times determine the maximum toggle rate of the part. Rise and fall times are normally specified at 20% and 80% of the signal amplitude (60% difference). Assuming that the edges at 50% amplitude are coming up and down like a sawtooth it is possible to calculate the maximum toggle rate but this number is too optimistic. In practice the edges are not linear while the pulse shape is more or less a sinewave. period period 1 2 80% VOUT Decision Level 20% 1 bit 0 0 1 0 1 0 1 0 Ideal Pulse Out Figure 36. Bit Rates Need for Terminated Transmission Lines During the 1980's and 90's, TI fabricated the 100K ECL logic family. The rise and fall time specifications were 0.75 ns, which are considered very fast. If sufficient care has not been given in designing the transmission lines and choosing the correct terminations, then errors in digital circuits are introduced. To be helpful to designers that use ECL with "old" PCB-techniques, the 10K ECL family was introduced with a rise and fall time specification of 2 ns. This was much slower and easier to use. The RSPECL output signals of the LMH7322 have transition times that extend the fastest ECL family. A careful PCB design is needed using RF techniques for transmission and termination. Transmission lines can be formed in several ways. The most commonly used types are the coaxial cable and the twisted pair telephony cable (Figure 37). D 2h d d Parallel Wire Coax Cable Figure 37. Cable Types Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 25 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com These cables have a characteristic impedance determined by their geometric parameters. Widely used impedances for the coaxial cable are 50 and 75. Twisted pair cables have impedances of about 120 to 150. Other types of transmission lines are the strip line and the micro strip line. These last types are used on PCB boards. They have the characteristic impedance dictated by the physical dimensions of a track placed over a metal ground plane (see Figure 38). top copper signal line PCB FR4 bottom copper stripline signal line Top Copper PCB FR4 bottom copper Microstrip signal lines Top Copper PCB FR4 bottom copper differential microstrip Figure 38. PBC Lines Differential Microstrip Line The transmission line which is ideally suited for complementary signals is the differential microstrip line. This is a double microstrip line with a narrow space in between. This means both lines have strong coupling and this determines the characteristic impedance. The fact that they are routed above a copper plane does not affect differential impedance, only CM-capacitance is added. Each of the structures above has its own geometric parameters, so for each structure there is different formula to calculate the right impedance. For calculations on these transmission lines visit the TI website or order RAPIDESIGNER. At the end of the transmission line there must be a termination having the same impedance as that of the transmission line itself. It does not matter what impedance the line has, if the load has the same value no reflections will occur. When designing a PCB board with transmission lines on it, space becomes an important item especially on high density boards. With a single microstrip line, line width is fixed for given impedance and a board material. Other line widths will result in different impedances. Advantages of Differential MicrostripLines Impedances of transmission lines are always dictated by their geometric parameters. This is also true for differential microstrip lines. Using this type of transmission line, the distance of the track determines the resulting impedance. So, if the PCB manufacturer can produce reliable boards with low track spacing the track width for a given impedance is also small. The wider the spacing, the wider tracks are needed for a specific impedance. For example two tracks of 0.2 mm width and 0.1 mm spacing have the same impedance as two tracks of 0.8 mm width and 0.4 mm spacing. With high-end PCB processes, it is possible to design very narrow differential microstrip transmission lines. It is desirable to use these to create optimal connections to the receiving part or the terminating resistor, in accordance to their physical dimensions. Seen from the comparator, the termination resistor must be connected at the far end of the line. Open connections after the termination resistor (e.g. to an input of a receiver) must be as short as possible. The allowed length of such connections varies with the received transients. The faster the transients, the shorter the open lines must be to prevent signal degradation. 26 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 LMH7322 www.ti.com SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 PCB Layout Considerations and Component Value Selection High frequency designs require that both active and passive components be selected from those that are specially designed for this purpose. The LMH7322 is fabricated in a 24-pin WQFN package intended for surface mount design. For reliable high speed design it is highly recommended to use small surface mount passive components because these packages have low parasitic capacitance and low inductance simply because they have no leads to connect them to the PCB. It is possible to amplify signals at frequencies of several hundreds of MHz using standard through-hole resistors. Surface mount devices however, are better suited for this purpose. Another important issue is the PCB itself, which is no longer a simple carrier for all the parts and a medium to interconnect them. The PCB becomes a real component itself and consequently contributes its own high frequency properties to the overall performance of the circuit. Good practice dictates that a high frequency design have at least one ground plane, providing a low impedance path for all decoupling capacitors and other ground connections. Care should be given especially that on-board transmission lines have the same impedance as the cables to which they are connected. Most single ended applications have 50 impedance (75 for video and cable TV applications). Such low impedance, single ended microstrip transmission lines usually require much wider traces (2 to 3 mm) on a standard double sided PCB board than needed for a `normal' trace. Another important issue is that inputs and outputs should not `see' each other. This occurs if input and output tracks are routed in parallel over the PCB with only a small amount of physical separation, particularly when the difference in signal level is high. Furthermore, components should be placed as flat and low as possible on the surface of the PCB. For higher frequencies a long lead can act as a coil, a capacitor or an antenna. A pair of leads can even form a transformer. Careful design of the PCB minimizes oscillations, ringing and other unwanted behavior. For ultra high frequency designs only surface mount components will give acceptable results. (For more information see OA-15 [SNOA367]). TI suggests the following evaluation board as a guide for high frequency layout and as an aid in device testing: LMH7322EVAL Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 27 LMH7322 SNOSAU8I - MARCH 2007 - REVISED MARCH 2013 www.ti.com REVISION HISTORY Changes from Revision H (March 2013) to Revision I * 28 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 27 Submit Documentation Feedback Copyright (c) 2007-2013, Texas Instruments Incorporated Product Folder Links: LMH7322 PACKAGE OPTION ADDENDUM www.ti.com 11-Apr-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (C) Top-Side Markings (3) (4) LMH7322SQ/NOPB ACTIVE WQFN RTW 24 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L7322SQ LMH7322SQE/NOPB ACTIVE WQFN RTW 24 250 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L7322SQ LMH7322SQX/NOPB ACTIVE WQFN RTW 24 4500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L7322SQ (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Top-Side Marking for that device. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. 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Addendum-Page 1 Samples PACKAGE MATERIALS INFORMATION www.ti.com 20-Sep-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LMH7322SQ/NOPB WQFN RTW 24 LMH7322SQE/NOPB WQFN RTW LMH7322SQX/NOPB WQFN RTW SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 24 250 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 24 4500 330.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 20-Sep-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMH7322SQ/NOPB WQFN RTW 24 1000 210.0 185.0 35.0 LMH7322SQE/NOPB WQFN RTW 24 250 210.0 185.0 35.0 LMH7322SQX/NOPB WQFN RTW 24 4500 367.0 367.0 35.0 Pack Materials-Page 2 PACKAGE OUTLINE RTW0024A WQFN - 0.8 mm max height SCALE 3.000 PLASTIC QUAD FLATPACK - NO LEAD 4.1 3.9 A B PIN 1 INDEX AREA 4.1 3.9 C 0.8 MAX SEATING PLANE 0.05 0.00 0.08 C 2X 2.5 7 20X 0.5 6 13 2X 2.5 25 2.6 0.1 1 PIN 1 ID (OPTIONAL) (0.1) TYP EXPOSED THERMAL PAD 12 18 24 19 0.5 24X 0.3 24X 0.3 0.2 0.1 0.05 C A B C 4222815/A 03/2016 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT RTW0024A WQFN - 0.8 mm max height PLASTIC QUAD FLATPACK - NO LEAD ( 2.6) SYMM 24 19 24X (0.6) 1 18 24X (0.25) (1.05) 25 SYMM (3.8) 20X (0.5) (R0.05) TYP 13 6 ( 0.2) TYP VIA 7 12 (1.05) (3.8) LAND PATTERN EXAMPLE SCALE:15X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND SOLDER MASK OPENING METAL SOLDER MASK OPENING METAL UNDER SOLDER MASK NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DEFINED SOLDER MASK DETAILS 4222815/A 03/2016 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature number SLUA271 (www.ti.com/lit/slua271). www.ti.com EXAMPLE STENCIL DESIGN RTW0024A WQFN - 0.8 mm max height PLASTIC QUAD FLATPACK - NO LEAD 4X ( 1.15) (0.675) TYP (R0.05) TYP 24 19 24X (0.6) 1 18 24X (0.25) (0.675) TYP 25 20X (0.5) SYMM (3.8) 13 6 METAL TYP 7 SYMM 12 (3.8) SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL EXPOSED PAD 25: 78% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE SCALE:20X 4222815/A 03/2016 NOTES: (continued) 5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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