LMV7235/LMV7239 45 nsec, Ultra Low Power, Low Voltage, Rail-to-Rail Input Comparator with Open-Drain/Push-Pull Output General Description Features The LMV7235/LMV7239 are ultra low power, low voltage, 45 nsec comparators. They are guaranteed to operate over the full supply voltage range of 2.7V to 5.5V. These devices achieve a 45 nsec propagation delay while consuming only 65µA of supply current at 5V. The LMV7235/LMV7239 have a greater than rail-to-rail common mode voltage range. The input common mode voltage range extends 200mV below ground and 200mV above supply, allowing both ground and supply sensing. The LMV7235 features an open drain output. By connecting an external resistor, the output of the comparator can be used as a level shifter. The LMV7239 features a push-pull output stage. This feature allows operation without the need of an external pull-up resistor. The LMV7235/LMV7239 are available in the 5-Pin SC70 and 5-Pin SOT23 packages, which are ideal for systems where small size and low power is critical. (VS = 5V, TA = 25°C, Typical values unless otherwise specified) 45 nsec ■ Propagation delay 65µA ■ Low supply current ■ Rail-to-Rail input ■ Open drain and push-pull output ■ Ideal for 2.7V and 5V single supply applications ■ Available in space saving packages — 5-pin SOT23 — 5-pin SC70 Applications ■ ■ ■ ■ ■ ■ ■ Portable and battery powered systems Scanners Set top boxes High speed differential line receiver Window comparators Zero-crossing detectors High speed sampling circuits Typical Application 10135902 Crystal Oscillator © 2008 National Semiconductor Corporation 101359 www.national.com LMV7235/LMV7239 45 nsec, Ultra Low Power, Low Voltage, Rail-to-Rail Input Comparator with Open-Drain/Push-Pull Output July 2, 2008 LMV7235/LMV7239 Connection Diagram 5-Pin SC70/SOT23 10135903 Top View Ordering Information Package Part Number LMV7235M7 5-pin SC70 LMV7235M7X LMV7239M7 LMV7239M7X LMV7235M5 5-pin SOT23 LMV7235M5X LMV7239M5 LMV7239M5X Marking C21 C20 C21A C20A Supplied as NSC Drawing 1k Units Tape and Reel 3k Units Tape and Reel 1k Units Tape and Reel MAA05A 3k Units Tape and Reel 1k Units Tape and Reel 3k Units Tape and Reel 1k Units Tape and Reel MF05A 3k Units Tape and Reel Simplified Schematic 10135901 www.national.com 2 If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance (Note 2) Human Model Body Machine Body Differential Input Voltage Output Short Circuit Duration Supply Voltage (V+ - V−) Soldering Information Infrared or Convection (20 sec) 260°C (lead temp) (V+) +0.3V, (V−) −0.3V ±10mA Operating Ratings Supply Voltages (V+ - V−) Temperature Range (Note 4) Storage Temperature Range Package Thermal Resistance 5-Pin SC70 5-Pin SOT23 1000V 100V ± Supply Voltage (Note 3) 6V 2.7V to 5.5V −40°C to +85°C −65°C to +150°C 478°C/W 265°C/W 235°C 2.7V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TA = 25°C, VCM = V+/2, V+ = 2.7V, V− = 0V−. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 6) Typ (Note 5) Max (Note 6) Units VOS Input Offset Voltage 0.8 6 8 mV IB Input Bias Current 30 400 600 nA IOS Input Offset Current 5 200 400 nA CMRR Common Mode Rejection Ratio 0V < VCM < 2.7V (Note 7) PSRR Power Supply Rejection Ratio V+ = 2.7V to 5V 65 85 VCM Input Common-Mode Voltage Range CMRR > 50dB V− −0.1 V− −0.2 to 2.9 VO Output Swing High (LMV7239 only) IL = 4mA, VID = 500mV V+ −0.35 V+ −0.26 V IL = 0.4mA, VID = 500mV V+ −0.02 V IL = −4mA, VID = −500mV 230 IL = −0.4mA, VID = −500mV 15 mV Sourcing, VO = 0V (LMV7239 only) (Note 3) 15 mA Sinking, VO = 2.7V (LMV7235 RL = 10k) (Note 3) 20 mA Output Swing Low (LMV7239/LMV7235) ISC Output Short Circuit Current 52 62 dB dB V+ +0.1 V+ 350 450 mV IS Supply Current No load 52 tPD Propagation Delay Overdrive = 20mV (Note 10) 68 ns Overdrive = 50mV (Note 10) 63 ns Overdrive = 100mV (Note 10) 50 ns (Note 8) 5 ns tSKEW Propagation Delay Skew (LMV7239 only) 3 85 100 V µA www.national.com LMV7235/LMV7239 Wave Soldering (10 sec) Voltage at Input/Output Pins Current at Input Pin (Note 9) Absolute Maximum Ratings (Note 1) LMV7235/LMV7239 Symbol tr Parameter Output Rise Time tf Output Fall Time ILEAKAGE Output Leakage Current (LMV7235 only) Conditions Min (Note 6) Typ (Note 5) Max (Note 6) Units LMV7239 10% to 90% 1.7 ns LMV7235 10% to 90% (Note 10) 112 ns 90% to 10% 1.7 ns 3 nA 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TA = 25°C, VCM = V+/2, V+ = 5V, V− = 0V. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 6) Typ (Note 5) Limits (Note 6) Units VOS Input Offset Voltage 1 6 8 mV IB Input Bias Current 30 400 600 nA IOS Input Offset Current 5 200 400 nA CMRR Common Mode Rejection Ratio 0V < VCM < 5V 52 67 PSRR Power Supply Rejection Ratio V+ = 2.7V to 5V 65 85 VCM Input Common-Mode Voltage Range CMRR > 50dB V− VO Output Swing High (LMV7239 only) IL = 4mA, VID = 500mV V+ −0.25 Output Swing Low (LMV7239/LMV7235) ISC Output Short Circuit Current −0.1 V− −0.2 to 5.2 dB dB V+ +0.1 V+ V V+ −0.15 V IL = 0.4mA, VID = 500mV V+ −0.01 V IL = −4mA, VID = −500mV 230 IL = −0.4mA, VID = −500mV 10 Sourcing, VO = 0V (LMV7239 only) (Note 3) 25 15 55 Sinking, VO = 5V (LMV7235 RL = 10k) (Note 3) 30 20 60 350 450 mV mV mA mA IS Supply Current No load 65 tPD Propagation Delay Overdrive = 20mV (Note 10) 62 ns Overdrive = 50mV (Note 10) 57 ns Overdrive = 100mV (Note 10) 45 ns (Note 8) 5 ns tSKEW Propagation Delay Skew (LMV7239 only) www.national.com 4 95 110 µA tr Parameter Output Rise Time tf Output Fall Time ILEAKAGE Output Leakeage Current (LMV7235 only) Conditions Min (Note 6) Typ (Note 5) Limits (Note 6) Units LMV7239 10% to 90% 1.2 ns LMV7235 10% to 90% (Note 10) 100 ns 90% to 10% 1.2 ns 3 nA Note 1: 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 guaranteed. For guaranteed specifications and the test conditions, see the Electrical characteristics. Note 2: 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). Note 3: 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 150°C. Output currents in excess of ±30mA over long term may adversely affect reliability. Note 4: The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board. Note 5: 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 guaranteed on shipped production material. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: CMRR is not linear over the common mode range. Limits are guaranteed over the worst case from 0 to VCC/2 or VCC/2 to VCC. Note 8: Propagation Delay Skew is defined as the absolute value of the difference between tPDLH and tPDHL. Note 9: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings. Note 10: A 10k pull-up resistor was used when measuring the LMV7235. The rise time of the LMV7235 is a function of the R-C time constant. 5 www.national.com LMV7235/LMV7239 Symbol LMV7235/LMV7239 Typical Performance Characteristics (Unless otherwise specified, VS = 5V, CL = 10pF, TA = 25°C). Supply Current vs. Supply Voltage Sourcing Current vs. Output Voltage 10135904 10135905 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 10135906 10135907 Sinking Current vs. Output Voltage Input Bias Current vs. Input Voltage 10135909 10135908 www.national.com 6 LMV7235/LMV7239 Input Bias Current vs. Input Voltage Propagation Delay vs. Temperature 10135911 10135910 Propagation Delay vs. Capacitive Load Propagation Delay vs. Capacitive Load 10135912 10135913 Propagation Delay vs. Input Overdrive Propagation Delay vs. Input Overdrive 10135914 10135915 7 www.national.com LMV7235/LMV7239 Propagation Delay vs. Common Mode Voltage Propagation Delay vs. Common Mode Voltage 10135916 www.national.com 10135917 8 The LMV7235/LMV7239 are single supply comparators with 45ns of propagation delay and only 65µA of supply current. The LMV7235/LMV7239 are rail-to-rail input and output. The typical input common mode voltage range of −0.2V below the ground to 0.2V above the supply. The LMV7235/LMV7239 use a complimentary PNP and NPN input stage in which the PNP stage senses common mode voltage near V− and the NPN stage senses common mode voltage near V+. If either of the input signals falls below the negative common mode limit, the parasitic PN junction formed by the substrate and the base of the PNP will turn on resulting in an increase of input bias current. If one of the input goes above the positive common mode limit, the output will still maintain the correct logic level as long as the other input stays within the common mode range. However, the propagation delay will increase. When both inputs are outside the common mode voltage range, current saturation occurs in the input stage, and the output becomes unpredictable. The propagation delay does not increase significantly with large differential input voltages. However, large differential voltages greater than the supply voltage should be avoided to prevent damage to the input stage. The LMV7239 has a push-pull output. When the output switches, there is a direct path between VCC and ground, causing high output sinking or sourcing current during the transition. After the transition, the output current decreases and the supply current settles back to about 65µA at 5V, thus conserving power consumption. The LMV7235 has an open drain that requires a pull-up resistor to a positive supply voltage for the output to switch properly. When the internal output transistor is off, the output voltage will be pulled up to the external positive voltage. COMPARATOR WITH HYSTERESIS The basic comparator configuration may oscillate or produce a noisy output if the applied differential input voltage is near the comparator's offset voltage. This usually happens when the input signal is moving very slowly across the comparator's switching threshold. This problem can be prevented by the addition of hysteresis or positive feedback. INVERTING COMPARATOR WITH HYSTERESIS The inverting comparator with hysteresis requires a three resistor network that is referenced to the supply voltage VCC of the comparator, as shown in Figure 1. When VIN at the inverting input is less than VA, the voltage at the non-inverting node of the comparator (VIN < VA), the output voltage is high (for simplicity assume VO switches as high as VCC). The three network resistors can be represented as R1||R3 in series with R2. The lower input trip voltage VA1 is defined as VA1 = VCCR2 / ((R1||R3) + R2) When VIN is greater than VA (VIN > VA), the output voltage is low, very close to ground. In this case the three network resistors can be presented as R2||R3 in series with R1. The upper trip voltage VA2 is defined as VA2 = VCC (R2||R3) / ((R1+ (R2||R3) The total hysteresis provided by the network is defined as Delta VA = VA1- VA2 To assure that the comparator will always switch fully to VCC and not be pulled down by the load the resistors, values should be chosen as follow: RPULL-UP << RLOAD 10135919 FIGURE 1. Inverting Comparator with Hysteresis 9 www.national.com LMV7235/LMV7239 Application Information LMV7235/LMV7239 7. Ground trace from the ground pin runs under the device up to the bypass capacitor, shielding the inputs from the outputs. NON-INVERTING COMPARATOR WITH HYSTERESIS A non inverting comparator with hysteresis requires a two resistor network, and a voltage reference (VREF) at the inverting input. When V IN is low, the output is also low. For the output to switch from low to high, VIN must rise up to VIN1 where VIN1 is calculated by. ZERO-CROSSING DETECTOR The inverting input is connected to ground and the non-inverting input is connected to 100mVp-p signal. As the signal at the non-inverting input crosses 0V, the comparator's output changes state. VIN1 = R1*(VREF/R2) + VREF When VIN is high, the output is also high, to make the comparator switch back to it's low state, VIN must equal VREF before VA will again equal VREF. VIN can be calculated by VIN2 = (VREF (R1+ R2) - VCCR1)/R2 The hysteresis of this circuit is the difference between VIN1 and VIN2. Delta VIN = VCCR1/R2 10135918 FIGURE 3. Zero-Crossing Detector THRESHOLD DETECTOR Instead of tying the inverting input to 0V, the inverting input can be tied to a reference voltage. The non-inverting input is connected to the input. As the input passes the VREF threshold, the comparator's output changes state. 10135924 10135921 FIGURE 4. Threshold Detector CRYSTAL OSCILLATOR A simple crystal oscillator using the LMV7239 is shown below. Resistors R1 and R2 set the bias point at the comparator's non-inverting input. Resistors R3, R4 and C1 sets the inverting input node at an appropriate DC average level based on the output. The crystal's path provides resonant positive feedback and stable oscillation occurs. The output duty cycle for this circuit is roughly 50%, but it is affected by resistor tolerances and to a lesser extent by the comparator offset. 10135920 FIGURE 2. Non-Inverting Comparator with Hysteresis CIRCUIT LAYOUT AND BYPASSING The LMV7235/LMV7239 require high speed layout. Follow these layout guidelines: 1. Use printed circuit board with a good, unbroken low-inductance ground plane. 2. Place a decoupling capacitor (0.1µF ceramic surface mount capacitor) as close as possible to VCC pin. 3. On the inputs and the output, keep lead lengths as short as possible to avoid unwanted parasitic feedback around the comparator. Keep inputs away from output. 4. Solder the device directly to the printed circuit board rather than using a socket. 5. For slow moving input signals, take care to prevent parasitic feedback. A small capacitor (1000pF or less) placed between the inputs can help eliminate oscillations in the transition region. This capacitor causes some degradation to tPD when the source impedance is low. 6. The topside ground plane runs between the output and inputs. www.national.com 10135922 FIGURE 5. Crystal Oscillator 10 LMV7235/LMV7239 IR RECEIVER The LMV7239 is an ideal candidate to be used as an infrared receiver. The infrared photo diode creates a current relative to the amount of infrared light present. The current creates a voltage across RD. When this voltage level cross the voltage applied by the voltage divider to the inverting input, the output transitions. 10135923 FIGURE 6. IR Receiver 11 www.national.com LMV7235/LMV7239 Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SC70 NS Package Number MAA05A 5-Pin SOT23 NS Package Number MF05A www.national.com 12 LMV7235/LMV7239 Notes 13 www.national.com LMV7235/LMV7239 45 nsec, Ultra Low Power, Low Voltage, Rail-to-Rail Input Comparator with Open-Drain/Push-Pull Output Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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