LM612

LM612 Dual-Channel Comparator and Reference February 1995 LM612 Dual-Channel Comparator and Reference General Description The dual-channel comparator consists of two individual comparators having an input voltage range that extends down to the negative supply voltage V b The common open-collector output can be driven low by either half of the LM612 This configuration makes the LM612 ideal for use as a window comparator The input stages of the comparator have lateral PNP input transistors which maintain low input currents for large differential input voltages and swings above V a The 1 2V voltage reference referred to the Vb terminal is a two-terminal shunt-type band-gap similar to the LM185-1 2 series with voltage accuracy of g 0 6% available The reference features operation over a shunt current range of 17 mA to 20 mA low dynamic impedance and broad capacitive load range As a member of National’s Super-Block TM family the LM612 is a space-saving monolithic alternative to a multichip solution offering a high level of integration without sacrificing performance Features COMPARATORS Y Low operating current Y Wide supply voltage range Y Open-collector outputs Y Input common-mode range Y Wide differential input voltage REFERENCE Y Fixed output voltage Y Tight initial tolerance available Y Wide operating current range Y Tolerant of load capacitance 300 mA 4V to 36V Vb to (V a b 1 8V) g 36V 1 24V g 0 6% (25 C) 17 mA to 20 mA Applications Y Y Y Voltage window comparator Power supply voltage monitor Dual-channel fault monitor Connection Diagram TL H 11058 – 1 Top View Ordering Information For information about surface-mount packaging of this device please contact the Analog Product Marketing group at National Semiconductor Corporation headquarters Temperature Range Military b 55 C s TJ s a 125 C LM612AMN LM612AMJ 883 (Note 13) g 2 0% at 25 C 150 ppm C Max Reference Tolerances g 0 6% at 25 C 80 ppm C Max Industrial b 40 C s TJ a 85 C LM612AIN Package NSC Package Number N08E J08A N08E M08A 8-Pin Molded DIP 8-Pin Ceramic DIP LM612MN LM612IN LM612IM 8-Pin Molded DIP 8-Pin Narrow Surface Mount Super-BlockTM is a trademark of National Semiconductor Corporation C1995 National Semiconductor Corporation TL H 11058 RRD-B30M115 Printed in U S A Absolute Maximum Ratings (Note 1) If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Voltage on Any Pin Except VR (referred to Vb pin) (Note 2) 36V (Max) b 0 3V (Min) (Note 3) g 20 mA Current through Any Input Pin and VR Pin g 36V Differential Input Voltage Output Short-Circuit Duration (Note 4) b 65 C s TJ s a 150 C Storage Temperature Range Maximum Junction Temperature 150 C Thermal Resistance Junction-to-Ambient (Note 5) N Package 100 C W Soldering Information N Package Soldering (10 seconds) ESD Tolerance (Note 6) 260 C g 1 kV Operating Temperature Range LM612AI LM612I LM612AM LM612M b 40 C s TJ s a 85 C b 55 C s TJ s a 125 C Electrical Characteristics These specifications apply for Vb e GND e 0V V a e 5V VCM e VOUT e V a 2 IR e 100 mA unless otherwise specified Limits in standard typeface are for TJ e 25 C limits in boldface type apply over the Operating Temperature Range Symbol Parameter Conditions Typical (Note 7) LM612AM LM612AI Limits (Note 8) LM612M LM612I Limits (Note 8) Units COMPARATORS IS VOS VOS DVOS DT IB IOS AV tR ISINK Total Supply Current Offset Voltage over V a Range Offset Voltage over VCM Range Average Offset Voltage Drift Input Bias Current Input Offset Current Voltage Gain Large Signal Response Time Output Sink Current RL e 10 kX to 36V 2V s VOUT s 27V V a IN e 1 4V VbIN e TTL Swing RL e 5 1 kX V a IN e 0V VbIN e 1V VOUT e 1 5V VOUT e 0 4V IL Output Leakage Current V a IN e 1V VbIN e 0V VOUT e 36V V a Current RLOAD e % 3V s V a s 36V 4V s V a s 36V RL e 15 kX 0V s VCM s (V a b1 8V) V a e 30V RL e 15 kX 150 170 10 20 10 15 15 5 8 02 03 500 100 15 20 20 13 28 24 01 02 10 8 10 05 10 10 8 08 05 10 25 30 4 5 50 35 40 4 5 50 250 300 30 60 30 60 250 300 50 70 50 70 mA Max mA Max mV Max mV Max mV Max mV Max mV C nA Max nA Max nA Max nA Max V mV Min V mV ms ms mA Min mA Min mA Min mA Min mA Max mA 2 Electrical Characteristics These specifications apply for Vb e GND e 0V V a e 5V VCM e VOUT e V a 2 IR e 100 mA unless otherwise specified Limits in standard typeface are for TJ e 25 C limits in boldface type apply over the Operating Temperature Range (Continued) Symbol Parameter Conditions Typical (Note 7) LM612AM LM612AI Limits (Note 8) LM612M LM612I Limits (Note 8) Units VOLTAGE REFERENCE (Note 9) VR Reference Voltage 1 244 1 2365 1 2515 ( g 0 6%) 80 1 2191 1 2689 ( g 2%) 150 V Min V Max ppm C Max ppm kH ppm kH mV C 1 11 5 55 0 56 13 12 13 1 15 1 11 5 55 0 56 13 12 13 1 15 mV Max mV Max mV Max mV Max X Max X Max mV Max mV Max mV Max mV Max mVRMS D VR DT D VR kH D VR D TJ D VR D IR Average Drift with Temperature Average Drift with Time Hysteresis VR Change with Current (Note 10) TJ e 40 C TJ e 150 C (Note 11) VR 100 mA b VR 17 mA VR 10 mA b VR 100 mA (Note 12) 18 400 1000 32 0 05 01 15 20 02 06 01 01 0 01 0 01 30 R D VR DV a Resistance VR Change with V a Change DVR 10 mA to 0 1 mA 9 9 mA DVR 100 mA to 17 mA 83 mA VR V a VR V a e 5V b VR V a VR V a e 36V e 5V b e 3V en Voltage Noise BW e 10 Hz to 10 kHz Note 1 Absolute maximum ratings indicate limits beyond which damage to the component may occur Electrical specifications do not apply when operating the device beyond its rated operating conditions Note 2 Input voltage above V a is not allowed As long as one input pin voltage remains inside the common-mode range the comparator will deliver the correct output Note 3 More accurately it is excessive current flow with resulting excess heating that limits the voltages on all pins When any pin is pulled a diode drop below Vb a parasitic NPN transistor turns ON No latch-up will occur as long as the current through that pin remains below the Maximum Rating Operation is undefined and unpredictable when any parasitic diode or transistor is conducting Note 4 Shorting the Output to Vb will not cause power dissipation so it may be continuous However shorting the Output to any more positive voltage (including V a ) will cause 80 mA (typ ) to be drawn through the output transistor This current multiplied by the applied voltage is the power dissipation in the output transistor If this total power causes the junction temperature to exceed 150 C degraded reliability or destruction of the device may occur To determine junction temperature see Note 5 Note 5 Junction temperature may be calculated using TJ e TA a PD iJA The given thermal resistance is worst-case for packages in sockets in still air For packages soldered to copper-clad board with dissipation from one comparator or reference output transistor nominal iJA is 90 C W for the N package Note 6 Human body model 100 pF discharged through a 1 5 kX resistor Note 7 Typical values in standard typeface are for TJ e 25 C values in boldface type apply for the full operating temperature range These values represent the most likely parametric norm Note 8 All limits are guaranteed for TJ e 25 C (standard type face) or over the full operating temperature range (bold type face) Note 9 VR is the reference output voltage nominally 1 24V Note 10 Average reference drift is calculated from the measurement of the reference voltage at 25 C and at the temperature extremes The drift in ppm C is 106  DVR VR 25 C  DTJ where DVR is the lowest value subtracted from the highest VR 25 C is the value at 25 C and DTJ is the temperature range This parameter is guaranteed by design and sample testing Note 11 Hysteresis is the change in VR caused by a change in TJ after the reference has been ‘‘dehysterized’’ To dehysterize the reference that is minimize the hysteresis to the typical value its junction temperature should be cycled in the following pattern spiralling in toward 25 C 25 C 85 C b 40 C 70 C 0 C 25 C Note 12 Low contact resistance is required for accurate measurement Note 13 A military RETS 612AMX electrical test specification is available on request The military screened parts can also be procured as a Standard Military Drawing 3 Simplified Schematic Diagrams Comparator TL H 11058 – 2 Reference Bias TL H 11058 – 3 4 Typical Performance Characteristics (Reference) b TJ e 25 C V e 0V unless otherwise noted Reference Voltage vs Temp Reference Voltage Drift vs Time Accelerated Reference Voltage Drift vs Time Reference Voltage vs Current and Temperature Reference Voltage vs Reference Current Reference Voltage Change with Supply Voltage Step Reference AC Stability Range Reference Noise Voltage vs Frequency Reference Small-Signal Impedance vs Frequency Reference Power-Up Time Reference Voltage with 100 E 12 mA Current Step Reference Step Response for 100 mA E 10 mA Current Step TL H 11058 – 4 5 Typical Performance Characteristics (Comparators) TJ e 25 C V a e 5V Vb e 0V Supply Current vs Supply Voltage Input Bias Current vs Common-Mode Voltage Input Current vs Differential Input Voltage Output Saturation Voltage vs Sink Current Small-Signal Response Times Inverting Input Negative Transition Small-Signal Response Times Inverting Input Positive Transition Small-Signal Response Times Non-Inverting Input Positive Transition Small-Signal Response Times Non-Inverting Input Negative Transition Large-Signal Response Times Inverting Input Positive Transition Large-Signal Response Times Inverting Input Negative Transition Large-Signal Response Times Non-Inverting Input Positive Transition Large-Signal Response Times Non-Inverting Input Negative Transition TL H 11058 – 6 6 Application Information VOLTAGE REFERENCE Reference Biasing The voltage reference is of a shunt regulator topology that models as a simple zener diode With current IR flowing in the ‘‘forward’’ direction there is the familiar diode transfer function IR flowing in the reverse direction forces the reference voltage to be developed from cathode to anode Capacitors in parallel with the reference are allowed See the Reference AC Stability Range typical curve for capacitance values from 20 mA to 3 mA the reference is stable for any value of capacitance With the reference’s wide stability range with resistive and capacitive loads a wide range of RC filter values will perform noise filtering when necessary Reference Hysteresis The reference voltage depends slightly on the thermal history of the die Competitive micro-power products vary always check the datasheet for any given device Do not assume that no specification means no hysteresis COMPARATORS Either comparator or the reference may be biased in any way with no effect on the other sections of the LM612 except when a substrate diode conducts (see Electrical Characteristics Note 3) For example one or both inputs of one comparator may be outside the input voltage range limits the reference may be unpowered and the other comparator will still operate correctly The inverting input of an unused comparator should be tied to Vb and the non-inverting tied to V a Hysteresis Any comparator 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 as shown in Figure 4 TL H 11058 – 8 FIGURE 1 1 24V Reference is Developed between Cathode and Anode Current Source IR is External The reference equivalent circuit reveals how VR is held at the constant 1 2V by feedback for a wide range of reverse current TL H 11058 – 9 FIGURE 2 Reference Equivalent Circuit To generate the required reverse current typically a resistor is connected from a supply voltage higher than the reference voltage to the Reference Output pin Varying that voltage and so varying IR has small effect with the equivalent series resistance of less than an ohm at the higher currents Alternatively an active current source such as the LM134 series may generate IR TL H 11058 – 11 FIGURE 4 RS and RF Add Hysteresis to Comparator The amount of hysteresis added in Figure 4 is RS VH e V a c (RF a RS) RS for RF ll RS RF A good rule of thumb is to add hysteresis of at least the maximum specified offset voltage More than about 50 mV Va c TL H 11058 – 10 FIGURE 3 1 2V Reference 7 Application Information (Continued) of hysteresis can substantially reduce the accuracy of the comparator since the offset voltage is effectively being increased by the hysteresis when the comparator output is high It is often a good idea to decrease the amount of hysteresis until oscillations are observed then use three times that minimum hysteresis in the final circuit Note that the amount of hysteresis needed is greatly affected by layout The amount of hysteresis should be rechecked each time the layout is changed such as changing from a breadboard to a P C board Input Stage The input stage uses lateral PNP input transistors which unlike those of many op amps have breakdown voltage BVEBO equal to the absolute maximum supply voltage Also they have no diode clamps to the positive supply nor across the inputs These features make the inputs look like high impedances to input sources producing large differential and common-mode voltages The guaranteed common-mode input voltage range for an LM612 is Vb s VCM s (V a b 1 8V) over temperature This is the voltage range in which the comparisons must be made If both inputs are within this range the output will be at the correct state If one input is within this range and the other input is less than (Vb a 32V) even if this is greater than V a the output will be at the correct state If however either or both inputs are driven below Vb and either input current exceeds 10 mA the output state is not guaranteed to be correct If both inputs are above (V a b 1 8V) the output state is also not guaranteed to be correct Output Stage The comparators have a common open-collector output stage which 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 (HIGH) voltage will be pulled up to this external positive voltage To ensure that the LOW output voltage is under the TTL-low threshold the output transistor’s load current must be less than 0 8 mA (over temperature) when it turns on This impacts the minimum value of the pull-up resistor Typical Applications TL H 11058 – 12 Power Supply Monitor with Indicator 8 Physical Dimensions inches (millimeters) 8-Pin Ceramic Dual-In-Line Package (J) Order Number LM612AMJ 883 NS Package Number J08A 8-Pin Surface Mount Package (M) Order Number LM612IM NS Package Number M08A 9 LM612 Dual-Channel Comparator and Reference Physical Dimensions inches (millimeters) (Continued) 8-Pin Molded Dual-In-Line Package (N) Order Number LM612AMJ 883 LM612AMN LM612AIN LM612MN or LM612IN NS Package Number N08E LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or systems which (a) are intended for surgical implant into the body or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user National Semiconductor Corporation 1111 West Bardin Road Arlington TX 76017 Tel 1(800) 272-9959 Fax 1(800) 737-7018 2 A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness National 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