LMC6762AIN

National Semiconductor is now part of Texas Instruments. Search http://www.ti.com/ for the latest technical information and details on our current products and services. LMC6762 Dual MicroPower Rail-To-Rail Input CMOS Comparator with Push-Pull Output General Description Features The LMC6762 is an ultra low power dual comparator with a maximum supply current of 10 µA/comparator. It is designed to operate over a wide range of supply voltages, from 2.7V to 15V. The LMC6762 has guaranteed specs at 2.7V to meet the demands of 3V digital systems. The LMC6762 has an input common-mode voltage range which exceeds both supplies. This is a significant advantage in low-voltage applications. The LMC6762 also features a push-pull output that allows direct connections to logic devices without a pull-up resistor. (Typical unless otherwise noted) n Low power consumption (max): IS = 10 µA/comp n Wide range of supply voltages: 2.7V to 15V n Rail-to-rail input common mode voltage range n Rail-to-rail output swing (Within 100 mV of the supplies, @ V+ = 2.7V, and ILOAD = 2.5 mA) n Short circuit protection: 40 mA n Propagation delay (@ V+ = 5V, 100 mV overdrive): 4 µs A quiescent power consumption of 50 µW/amplifier (@ V+ = 5V) makes the LMC6762 ideal for applications in portable phones and hand-held electronics. The ultra-low supply current is also independent of power supply voltage. Guaranteed operation at 2.7V and a rail-to-rail performance makes this device ideal for battery-powered applications. Refer to the LMC6772 datasheet for an open-drain version of this device. Applications Connection Diagram Typical Application n n n n n n n Laptop computers Mobile phones Metering systems Hand-held electronics RC timers Alarm and monitoring circuits Window comparators, multivibrators 8-Pin DIP/SO 01232001 Top View 01232016 Zero Crossing Detector © 2004 National Semiconductor Corporation DS012320 www.national.com LMC6762 Dual MicroPower Rail-To-Rail Input CMOS Comparator with Push-Pull Output August 2000 LMC6762 Absolute Maximum Ratings (Note 1) (Soldering, 10 seconds) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance (Note 2) 2 KV Differential Input Voltage (V+)+0.3V to (V−)−0.3V Voltage at Input/Output Pin (V+)+0.3V to (V−)−0.3V Supply Voltage (V+–V−) Storage Temperature Range −65˚C to +150˚C Junction Temperature (Note 4) 150˚C Operating Ratings (Note 1) 2.7 ≤ VS ≤ 15V Supply Voltage 16V Junction Temperature Range ± 5 mA Current at Input Pin LMC6762AI, LMC6762BI Current at Output Pin Current at Power Supply Pin, LMC6762 −40˚C ≤ TJ ≤ +85˚C Thermal Resistance (θJA) ± 30 mA (Notes 7, 3) 260˚C 40 mA Lead Temperature N Package, 8-Pin Molded DIP 100˚C/W M Package, 8-Pin Surface Mount 172˚C/W 2.7V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.7V, V− = 0V, VCM = V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Typ (Note 5) Conditions LMC6762AI LMC6762BI Limit Limit (Note 6) (Note 6) 5 15 8 18 Units VOS Input Offset Voltage 3 TCVOS Input Offset Voltage 2.0 µV/˚C 3.3 µV/Month mV max Temperature Drift Input Offset Voltage (Note 8) Average Drift IB Input Current 0.02 pA IOS Input Offset Current 0.01 pA CMRR Common Mode Rejection Ratio 75 dB PSRR Power Supply Rejection Ratio ± 1.35V < VS < ± 7.5V 80 dB AV Voltage Gain (By Design) 100 dB VCM Input Common-Mode CMRR > 55 dB 3.0 2.9 −0.3 Voltage Range VOH Output Voltage High ILOAD = 2.5 mA 2.5 VOL Output Voltage Low ILOAD = 2.5 mA 0.2 IS Supply Current For Both Comparators 12 (Output Low) www.national.com 2 2.9 V 2.7 2.7 min −0.2 −0.2 V 0.0 0.0 max 2.4 2.4 V 2.3 2.3 min 0.3 0.3 V 0.4 0.4 max 20 20 µA 25 25 max Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5.0V and 15.0V, V− = 0V, VCM = V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) VOS Input Offset Voltage TCVOS Input Offset Voltage V+ = 5V 2.0 Temperature Drift V+ = 15V 4.0 3 + Input Offset Voltage V = 5V (Note 8) 3.3 Average Drift V+ = 15V (Note 8) 4.0 LMC6762AI LMC6762BI Limit Limit (Note 6) (Note 6) 5 15 8 18 Units mV max µV/˚C µV/Month IB Input Current V = 5V 0.04 pA IOS Input Offset Current V+ = 5V 0.02 pA dB CMRR + Common Mode V = 5V 75 Rejection Ratio V+ = 15V 82 dB PSRR Power Supply Rejection Ratio ± 2.5V < VS < ± 5V 80 dB AV Voltage Gain (By Design) 100 VCM Input Common-Mode V+ = 5.0V 5.3 Voltage Range CMRR > 55 dB V+ = 15.0V 5.2 V 5.0 5.0 min −0.3 −0.2 −0.2 V 0.0 0.0 max 15.3 15.2 15.2 V 15.0 15.0 min −0.2 −0.2 V 0.0 0.0 max 4.8 4.6 4.6 V 4.45 4.45 min 14.8 14.6 14.6 V 14.45 14.45 min 0.4 0.4 V 0.55 0.55 max 0.4 0.4 V 0.55 0.55 max 20 20 µA 25 25 max CMRR > 55 dB −0.3 VOH Output Voltage High V+ = 5V ILOAD = 5mA V+ = 15V ILOAD = 5 mA VOL Output Voltage Low V+ = 5V 0.2 ILOAD = 5 mA V+ = 15V 0.2 ILOAD = 5 mA IS Supply Current For Both Comparators 12 (Output Low) ISC Short Circuit Current dB 5.2 Sourcing 30 Sinking, VO = 12V 45 mA (Note 7) 3 www.national.com LMC6762 5.0V and 15.0V Electrical Characteristics LMC6762 AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2. Boldface limits apply at the temperature extreme. Symbol Parameter Conditions tRISE Rise Time f = 10 kHz, CL = 50 pF, tFALL Fall Time f = 10 kHz, CL = 50 pF, Typ (Note 5) LMC6762AI LMC6762BI Limit Limit (Note 6) (Note 6) Units 0.3 µs 0.3 µs Overdrive = 10 mV (Notes 9, 10) Overdrive = 10 mV (Notes 9, 10) tPHL Propagation Delay f = 10 kHz, Overdrive = 10 mV 10 µs (High to Low) CL = 50 pF Overdrive = 100 mV 4 µs Overdrive = 10 mV 10 µs Overdrive = 100 mV 4 µs (Notes 9, 10) V+ = 2.7V, f = 10 kHz, CL = 50 pF (Notes 9, 10) tPLH Propagation Delay f = 10 kHz, Overdrive = 10 mV 6 µs (Low to High) CL = 50 pF Overdrive = 100 mV 4 µs Overdrive = 10 mV 7 µs Overdrive = 100 mV 4 µs (Notes 9, 10) V+ = 2.7V, f = 10 kHz, CL = 50 pF (Notes 9, 10) 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, 1.5 kΩ in series with 100 pF. 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 ± 30 mA over long term may adversely affect reliability. Note 4: The maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max) – TA)/θJA.All numbers apply for packages soldered directly into a PC board. Note 5: Typical Values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: Do not short circuit output to V+, when V+ is greater than 12V or reliability will be adversely affected. Note 8: Input Offset Voltage Average Drift is calculated by dividing the accelerated operating life drift average by the equivalent operational time. The Input Offset Voltage Average Drift represents the input offset voltage change at worst-case input conditions. Note 9: CL includes the probe and jig capacitance. Note 10: The rise and fall times are measured with a 2V input step. The propagation delays are also measured with a 2V input step. www.national.com 4 LMC6762 Typical Performance Characteristics V+ = 5V, Single Supply, TA = 25˚C unless otherwise specified Supply Current vs Supply Voltage (Output High) Supply Current vs Supply Voltage (Output Low) 01232020 01232021 Input Current vs Common-Mode Voltage Input Current vs Common-Mode Voltage 01232022 01232023 Input Current vs Common-Mode Voltage Input Current vs Temperature 01232025 01232024 5 www.national.com LMC6762 Typical Performance Characteristics V+ = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) ∆VOS vs ∆VCM ∆VOS vs ∆VCM 01232026 01232027 Output Voltage vs Output Current (Sourcing) ∆VOS vs ∆VCM 01232029 01232028 Output Voltage vs Output Current (Sourcing) Output Voltage vs Output Current (Sourcing) 01232031 01232030 www.national.com 6 LMC6762 Typical Performance Characteristics V+ = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Output Voltage vs Output Current (Sinking) Output Voltage vs Output Current (Sinking) 01232032 01232033 Output Voltage vs Output Current (Sinking) Output Short Circuit Current vs Supply Voltage (Sourcing) 01232034 01232035 Output Short Circuit Current vs Supply Voltage (Sinking) Response Time for Overdrive (tPLH) 01232037 01232036 7 www.national.com LMC6762 Typical Performance Characteristics V+ = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Response Time for Overdrive (tPHL) Response Time for Overdrive (tPLH) 01232038 01232039 Response Time for Overdrive (tPLH) Response Time for Overdrive (tPHL) 01232040 01232041 Response Time vs Capacitive Load Response Time for Overdrive (tPHL) 01232042 www.national.com 01232043 8 LMC6762 Application Hints 1.0 INPUT COMMON-MODE VOLTAGE RANGE At supply voltages of 2.7V, 5V and 15V, the LMC6762 has an input common-mode voltage range which exceeds both supplies. As in the case of operational amplifiers, CMVR is defined by the VOS shift of the comparator over the commonmode range of the device. A CMRR (∆VOS/∆VCM) of 75 dB (typical) implies a shift of < 1 mV over the entire commonmode range of the device. The absolute maximum input voltage at V+ = 5V is 200 mV beyond either supply rail at room temperature. 01232006 FIGURE 2. Even at Low-Supply Voltage of 2.7V, an Input Signal which Exceeds the Supply Voltages Produces No Phase Inversion at the Output At V+ = 2.7V, propagation delays are tPLH = 4 µs and tPHL = 4 µs with overdrives of 100 mV. Please refer to the performance curves for more extensive characterization. 3.0 SHOOT-THROUGH CURRENT The shoot-through current is defined as the current surge, above the quiescent supply current, between the positive and negative supplies of a device. The current surge occurs when the output of the device switches states. This transient switching current results in glitches in the supply voltage. Usually, glitches in the supply lines are compensated by bypass capacitors. When the switching currents are minimal, the values of the bypass capacitors can be reduced considerably. 01232005 FIGURE 1. An Input Signal Exceeds the LMC6762 Power Supply Voltages with No Output Phase Inversion A wide input voltage range means that the comparator can be used to sense signals close to ground and also to the power supplies. This is an extremely useful feature in power supply monitoring circuits. An input common-mode voltage range that exceeds the supplies, 20 fA input currents (typical), and a high input impedance makes the LMC6762 ideal for sensor applications. The LMC6762 can directly interface to sensors without the use of amplifiers or bias circuits. In circuits with sensors which produce outputs in the tens to hundreds of millivolts, the LMC6762 can compare the sensor signal with an appropriately small reference voltage. This reference voltage can be close to ground or the positive supply rail. 2.0 LOW VOLTAGE OPERATION Comparators are the common devices by which analog signals interface with digital circuits. The LMC6762 has been designed to operate at supply voltages of 2.7V without sacrificing performance to meet the demands of 3V digital systems. At supply voltages of 2.7V, the common-mode voltage range extends 200 mV (guaranteed) below the negative supply. This feature, in addition to the comparator being able to sense signals near the positive rail, is extremely useful in low voltage applications. 01232007 FIGURE 3. LMC6762 Circuit for Measurement of the Shoot-Through Current 9 www.national.com LMC6762 Application Hints of hysteresis, it would be reasonable to increase the value of the local bypass capacitor to 0.01 µF to reduce the voltage delta to 10 mV. (Continued) 4.0 OUTPUT SHORT CIRCUIT CURRENT The LMC6762 has short circuit protection of 40 mA. However, it is not designed to withstand continuous short circuits, transient voltage or current spikes, or shorts to any voltage beyond the supplies. A resistor is series with the output should reduce the effect of shorts. For outputs which send signals off PC boards additional protection devices, such as diodes to the supply rails, and varistors may be used. 5.0 HYSTERESIS If the input signal is very noisy, the comparator output might trip several times as the input signal repeatedly passes through the threshold. This problem can be addressed by making use of hysteresis as shown below. 01232008 FIGURE 4. Measurement of the Shoot-Through Current From Figure 3 and Figure 4 the shoot-through current for the LMC6762 can be approximated to be 0.2 mA (200 mV/1 kΩ). The duration of the transient is measured as 1 µs. The values needed for the local bypass capacitors can be calculated as follows: 01232010 FIGURE 5. Canceling the Effect of Input Capacitance The capacitor added across the feedback resistor increases the switching speed and provides more short term hysteresis. This can result in greater noise immunity for the circuit. 01232009 Area of ∆ = 1⁄2 (1 µs x 200 µA) = 100 pC 6.0 SPICE MACROMODEL A Spice Macromodel is available for the LMC6762. The model includes a simulation of: • Input common-mode voltage range • Quiescent and dynamic supply current • Input overdrive characteristics and many more characteristics as listed on the macromodel disk. Contact the National Semiconductor Customer Response Center at 1-800-272-9959 to obtain an operational amplifier spice model library disk. If the local bypass capacitor has to provide this charge of 100 pC, the minimum value of the local capacitor to prevent local degradation of VCC can be calculated. Suppose that the maximum voltage droop that the system can tolerate is 100mV, ∆Q = C * (∆V) →C = (∆Q/∆V) = 100 pC/100 mV = 0.001 µF The low internal feedthrough current of the LMC6762 thus requires lower values for the local bypass capacitors. In applications where precision is not critical, this is a significant advantage, as lower values of capacitors result in savings of board space, and cost. It is worth noting here that the delta shift of the power supply voltage due to the transient currents causes a threshold shift of the comparator. This threshold shift is reduced by the high PSRR of the comparator. However, the value of the PSRR applicable in this instance is the transient PSRR and not the DC PSRR. The transient PSRR is significantly lower than the DC PSRR. Generally, it is a good goal to reduce the delta voltage on the power supply to a value equal to or less than the hysteresis of the comparator. For example, if the comparator has 50 mV www.national.com 10 LMC6762 ZERO CROSSING DETECTOR Typical Applications ONE-SHOT MULTIVIBRATOR 01232014 01232016 FIGURE 6. One-Shot Multivibrator FIGURE 8. Zero Crossing Detector A monostable multivibrator has one stable state in which it can remain indefinitely. It can be triggered externally to another quasi-stable state. A monostable multivibrator can thus be used to generate a pulse of desired width. The desired pulse width is set by adjusting the values of C2 and R4. The resistor divider of R1 and R2 can be used to determine the magnitude of the input trigger pulse. The LMC6762 will change state when V1 < V2. Diode D2 provides a rapid discharge path for capacitor C2 to reset at the end of the pulse. The diode also prevents the non-inverting input from being driven below ground. A voltage divider of R4 and R5 establishes a reference voltage V1 at the non-inverting input. By making the series resistance of R1 and R2 equal to R5, the comparator will switch when VIN = 0. Diode D1 insures that V3 never drops below −0.7V. The voltage divider of R2 and R3 then prevents V2 from going below ground. A small amount of hysteresis is setup to ensure rapid output voltage transitions. OSCILLATOR BI-STABLE MULTIVIBRATOR 01232019 01232015 FIGURE 7. Bi-Stable Multivibrator FIGURE 9. Square Wave Generator A bi-stable multivibrator has two stable states. The reference voltage is set up by the voltage divider of R2 and R3. A pulse applied to the SET terminal will switch the output of the comparator high. The resistor divider of R1, R4, and R5 now clamps the non-inverting input to a voltage greater than the reference voltage. A pulse applied to RESET will now toggle the output low. Figure 9 shows the application of the LMC6762 in a square wave generator circuit. The total hysteresis of the loop is set by R1, R2 and R3. R4 and R5 provide separate charge and discharge paths for the capacitor C. The charge path is set through R4 and D1. So, the pulse width t1 is determined by the RC time constant of R4 and C. Similarly, the discharge path for the capacitor is set by R5 and D2. Thus, the time t2 between the pulses can be changed by varying R5, and the pulse width can be altered by R4. The frequency of the output can be changed by varying both R4 and R5. 11 www.national.com LMC6762 Typical Applications (Continued) 01232018 FIGURE 10. Time Delay Generator The output voltages of comparators 1, 2, and 3 switch to the high state when VC1 rises above the reference voltage VA, VB and VC. A small amount of hysteresis has been provided to insure fast switching when the RC time constant is chosen to give long delay times. The circuit shown above provides output signals at a prescribed time interval from a time reference and automatically resets the output when the input returns to ground. Consider the case of VIN = 0. The output of comparator 4 is also at ground. This implies that the outputs of comparators 1, 2, and 3 are also at ground. When an input signal is applied, the output of comparator 4 swings high and C charges exponentially through R. This is indicated above. Ordering Information Package Temperature Range NSC Drawing −40˚C to +85˚C www.national.com Transport Media 8-Pin Molded DIP LMC6762AIN, LMC6762BIN N08E 8-Pin Small Outline LMC6762AIM, LMC6762BIM M08A Rails LMC6762AIMX, LMC6762BIMX M08A Tape and Reel 12 Rails LMC6762 Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin Small Outline Package Order Number LMC6762AIM, LMC6762BIM, LMC6762AIMX or LMC6762BIMX NS Package Number M08A 13 www.national.com LMC6762 Dual MicroPower Rail-To-Rail Input CMOS Comparator with Push-Pull Output Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin Molded Dual-In-Line Package Order Number LMC6762AIN or LMC6762BIN NS Package Number N08E 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. 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