LM612 Dual-Channel Comparator and Reference General Description Features 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. 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. Reference Tolerances g 0.6% at 25§ C, 80 ppm/§ C Max Temperature Range Package NSC Package Number 8-Pin Molded DIP N08E 8-Pin Ceramic DIP J08A LM612IN 8-Pin Molded DIP N08E LM612IM 8-Pin Narrow Surface Mount M08A Military b 55§ C s TJ s a 125§ C Industrial b 40§ C s TJ a 85§ C LM612AMN LM612AIN LM612AMJ/883 (Note 13) g 2.0% at 25§ C, 150 ppm/§ C Max LM612MN Super-BlockTM is a trademark of National Semiconductor Corporation. C1995 National Semiconductor Corporation TL/H/11058 RRD-B30M115/Printed in U. S. A. LM612 Dual-Channel Comparator and Reference February 1995 Absolute Maximum Ratings (Note 1) Thermal Resistance, Junction-to-Ambient (Note 5) N Package 100§ C/W 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 Soldering Information N Package Soldering (10 seconds) 260§ C ESD Tolerance (Note 6) 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 Total Supply Current V a Current, RLOAD e % , 3V s V a s 36V 150 170 250 300 250 300 mA Max mA Max VOS Offset Voltage over V a Range 4V s V a s 36V, RL e 15 kX 1.0 2.0 3.0 6.0 5.0 7.0 mV Max mV Max VOS Offset Voltage over VCM Range 0V s VCM s (V a b1.8V) V a e 30V, RL e 15 kX 1.0 1.5 3.0 6.0 5.0 7.0 mV Max mV Max DVOS DT Average Offset Voltage Drift IB Input Bias Current IOS Input Offset Current AV Voltage Gain tR ISINK IL 15 mV/§ C 5 8 25 30 35 40 nA Max nA Max 0.2 0.3 4 5 4 5 nA Max nA Max RL e 10 kX to 36V, 2V s VOUT s 27V 500 100 50 50 V/mV Min V/mV Large Signal Response Time V a IN e 1.4V, VbIN e TTL Swing, RL e 5.1 kX 1.5 2.0 Output Sink Current V a IN e 0V, VbIN e 1V, VOUT e 1.5V 20 13 10 8 10 8 mA Min mA Min VOUT e 0.4V 2.8 2.4 1.0 0.5 0.8 0.5 mA Min mA Min 0.1 0.2 10 10 mA Max mA Output Leakage Current V a IN e 1V, VbIN e 0V, VOUT e 36V 2 ms ms 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 LM612AM LM612AI Limits (Note 8) LM612M LM612I Limits (Note 8) 1.244 1.2365 1.2515 ( g 0.6%) 1.2191 1.2689 ( g 2%) 18 80 150 Typical (Note 7) Conditions Units VOLTAGE REFERENCE (Note 9) VR Reference Voltage DVR DT Average Drift with Temperature DVR kH Average Drift with Time DVR DTJ Hysteresis (Note 11) DVR DIR VR Change with Current VR[100 mA] b VR[17 mA] 0.05 0.1 1 1.1 1 1.1 mV Max mV Max VR[10 mA] b VR[100 mA] (Note 12) 1.5 2.0 5 5.5 5 5.5 mV Max mV Max (Note 10) TJ e 40§ C TJ e 150§ C V Min V Max ppm/§ C Max 400 1000 ppm/kH ppm/kH 3.2 mV/§ C R Resistance DVR[10 mA to 0.1 mA] /9.9 mA DVR[100 mA to 17 mA] /83 mA 0.2 0.6 0.56 13 0.56 13 X Max X Max DVR DV a VR Change with V a Change VR[V a e 5V] b VR[V a e 36V] 0.1 0.1 1.2 1.3 1.2 1.3 mV Max mV Max VR[V a e 5V] b VR[V a e 3V] 0.01 0.01 1 1.5 1 1.5 mV Max mV Max en Voltage Noise BW e 10 Hz to 10 kHz 30 mVRMS 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 TimesÐInverting Input, Negative Transition Small-Signal Response TimesÐInverting Input, Positive Transition Small-Signal Response TimesÐNon-Inverting Input, Positive Transition Small-Signal Response TimesÐNon-Inverting Input, Negative Transition Large-Signal Response TimesÐInverting Input, Positive Transition Large-Signal Response TimesÐInverting Input, Negative Transition Large-Signal Response TimesÐNon-Inverting Input, Positive Transition Large-Signal Response TimesÐNon-Inverting Input, Negative Transition TL/H/11058 – 6 6 Application Information Capacitors in parallel with the reference are allowed. See the Reference AC Stability Range typical curve for capacitance valuesÐfrom 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. 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. Reference Hysteresis The reference voltage depends, slightly, on the thermal history of the die. Competitive micro-power products varyÐalways 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 . 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. 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 – 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. 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. 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. 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. 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