LMV7231SQX

LMV7231 Hex Window Comparator with 1.5% Precision and 400mV Reference September 8, 2010 LMV7231 Hex Window Comparator with 1.5% Precision and 400mV Reference General Description The LMV7231 is a 1.5% accurate Hex Window Comparator which can be used to monitor power supply voltages. The device uses an internal 400mV reference for the comparator trip value. The comparator set points can be set via external resistor dividers. The LMV7231 has 6 outputs (CO1-CO6) that signal an under-voltage or over-voltage event for each power supply input. An output (AO) is also provided to signal when any of the power supply inputs have an over-voltage or under-voltage event. This ability to signal an under-voltage or over-voltage event for the individual power supply inputs, in addition to an output to signal such an event on any of the power supply inputs adds unparalleled system protection capability. The LMV7231’s +2.2V to +5.5V power supply voltage range, low supply current, and input/output voltage range above V+ make it ideal for a wide range of power supply monitoring applications. Operation is guaranteed over the -40°C to +125°C temperature range. The device is available in a 24-pin LLP package. Features (For VS = 3.3V ±10%, Typical unless otherwise noted) ■ High accuracy voltage reference: 400 mV ■ Threshold Accuracy: ±1.5% (max) ■ Wide supply voltage range +2.2V to +5.5V ■ Input/Output voltage range above V+ ■ Internal hysteresis: 6mV ■ Propagation delay: 2.6 µs to 5.6 µs ■ Supply Current 7.7 µA per channel ■ 24 lead LLP package ■ Temperature range: -40°C to 125°C Applications ■ ■ ■ ■ ■ Power Supply Voltage Detection Battery Monitoring Handheld Instruments Relay Driving Industrial Control Systems © 2010 National Semiconductor Corporation 301149 www.national.com LMV7231 Typical Application Circuit 30114944 www.national.com 2 LMV7231 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance (Note 2) Human Body Model Machine Model Supply Voltage Voltage at Input/Output Pin Output Current Total Package Current Storage Temp Range 2000V 200V 6V 6V to (GND − 0.3V) 10mA 50mA −65°C to +150°C Junction Temperature (Note 3) For soldering specifications: see product folder at www.national.com and www.national.com/ms/MS/MS-SOLDERING.pdf 150°C Operating Ratings Supply Voltage Junction Temperature Range  (Note 3) (Note 1) 2.2V to 5.5V −40°C to +125°C 38°C/W Package Thermal Resistance, θJA 24 Lead LLP +3.3V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TA = 25°C, V+ = 3.3V ±10%, GND = 0V, and RL > 1MΩ. Boldface limits apply for TA = –10°C to +70°C. Symbol VTHR VTHF VHYST IBIAS VOL IOFF tPDHL1 tPDHL2 tPDLH1 tPDLH2 tr tf IIN(1) IIN(0) VIH VIL IS Parameter Threshold: Input Rising Threshold: Input Falling Hysteresis (VTHR − VTHF) Input Bias Current Output Low Voltage Output Leakage Current High-to-Low Propagation Delay (+IN falling) High-to-Low Propagation Delay (-IN rising) Low-to-High Propagation Delay (+IN rising) Low-to-High Propagation Delay (-IN falling) Output Rise Time Output Fall Time Digital Input Logic “1” Leakage Current Digital Input Logic “0” Leakage Current Digital Input Logic “1” Voltage Digital Input Logic “0” Voltage Power Supply Current No loading (outputs high) V+ Ramp Rate = 1.1ms V+ Step = 2.5V to 4.5V V+ Ramp Rate = 1.1ms V+ Step = 4.5V to 2.5V –400 46 0.70 × V+ 0.30 × V+ 60 84 +400 Condition RL = 10kΩ RL = 10kΩ RL = 10kΩ VIN = V+, GND, and 5.5V IL = 5mA VOUT = V+, 5.5V and 40mV of overdrive 10mV of overdrive 10mV of overdrive 10mV of overdrive 10mV of overdrive CL= 10pF, RL= 10kΩ CL = 100pF, RL = 10kΩ 2.6 5.4 5.6 2.8 0.5 0.25 0.3 0.2 1 0.2 1 Min (Note 5) 394 391.4 386 383.8 3.9 –5 –15 Typ (Note 4) 400 394 6.0 0.05 160 Max (Note 5)ns 406 408.6 401 403.2 8.8 5 15 200 250 0.4 1 6 10 10 6 Units mV mV mV nA mV μA μs μs μs μs μs μs μA μA V V μA μV μV VTHPSS VTH Power Supply Sensitivity (Note 6) 3 www.national.com LMV7231 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) FieldInduced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC). Note 3: 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 4: 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 5: Limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlations using the Statistical Quality Control (SQC) method. Note 6: VTH Power Supply Sensitivity is defined as the temporary shift in the internal voltage reference due to a step on the V+ pin. Connection Diagrams 24-Pin LLP Package (Top View) 30114942 www.national.com 4 LMV7231 Pin Descriptions Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Symbol -IN1 +IN1 -IN2 +IN2 -IN3 +IN3 -IN4 +IN4 -IN5 +IN5 -IN6 +IN6 RESERVED GND Type Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Analog Input Digital Input Power Description Negative input for window comparator 1. Positive input for window comparator 1. Negative input for window comparator 2. Positive input for window comparator 2. Negative input for window comparator 3. Positive input for window comparator 3. Negative input for window comparator 4. Positive input for window comparator 4. Negative input for window comparator 5. Positive input for window comparator 5. Negative input for window comparator 6. Positive input for window comparator 6. Connect to GND. Ground reference pin for the power supply voltage. The state of this pin determines whether the CO1-CO6 pins are active “HIGH” or “LOW”. When tied LOW the CO1-CO6 outputs will go LOW to indicate an out of window comparison. The state of this pin determines whether the AO pin is active on an over-voltage or under-voltage event. When tied LOW the AO output will be active upon an over-voltage event. 15 COPOL Digital Input 16 AOSEL Digital Input 17 AO This output is the ANDED combination of either the overOpen-Drain NMOS voltage comparator outputs or the under-voltage Digital Output comparator outputs and is controlled by the state of the AOSEL. AO pin is active “LOW”. Open-Drain NMOS Window comparator 6 NMOS open-drain output. Digital Output Open-Drain NMOS Window comparator 5 NMOS open-drain output. Digital Output Open-Drain NMOS Window comparator 4 NMOS open-drain output. Digital Output Open-Drain NMOS Window comparator 3 NMOS open-drain output. Digital Output Open-Drain NMOS Window comparator 2 NMOS open-drain output. Digital Output Open-Drain NMOS Window comparator 1 NMOS open-drain output. Digital Output Power Thermal Pad Power supply pin. Die Attach Paddle (DAP) connect to GND. 18 19 20 21 22 23 24 DAP CO6 CO5 CO4 CO3 CO2 CO1 V+ DAP Ordering Information Package 24−Pin LLP NOPB Part Number LMV7231SQ LMV7231SQE LMV7231SQX Package Marking L7231SQ Transport Media 1000 Units Tape and Reel 250 Units Tape and Reel 4500 Units Tape and Reel NSC Drawing SQA24A 5 www.national.com LMV7231 Block Diagram 30114943 www.national.com 6 LMV7231 Typical Performance Characteristics +In Input Rising Threshold Distribution V+ = 3.3V and TA =25°C unless otherwise noted. −In Input Rising Threshold Distribution 30114976 30114979 +In Input Falling Threshold Distribution −In Input Falling Threshold Distribution 30114977 30114980 +In Hysteresis Distribution −In Hysteresis Distribution 30114978 30114981 7 www.national.com LMV7231 Input Rising Threshold Voltage vs. Temperature Input Rising Threshold Voltage vs. Supply Voltage 30114946 30114947 Input Falling Threshold Voltage vs. Temperature Input Falling Threshold Voltage vs. Supply Voltage 30114948 30114949 Hysteresis vs. Temperature Hysteresis vs. Supply Voltage 30114950 30114951 www.national.com 8 LMV7231 Supply Current vs. Supply Voltage and Temperature Supply Current vs. Output Sink Current 30114952 30114971 Supply Current vs. Output Sink Current Supply Current vs. Output Sink Current 30114972 30114973 Supply Current vs. Output Sink Current Bias Current vs. Input Voltage 30114974 30114961 9 www.national.com LMV7231 Bias Current vs. Input Voltage Bias Current vs. Input Voltage 30114962 30114963 Output Voltage Low vs. Output Sink Current Output Voltage Low vs. Output Sink Current 30114964 30114965 Output Voltage Low vs. Output Sink Current Output Voltage Low vs. Output Sink Current 30114966 30114967 www.national.com 10 LMV7231 Output Short Circuit Current vs. Output Voltage Output Short Circuit Current vs. Output Voltage 30114968 30114969 Propagation Delay vs. Input Overdrive Rise and Fall Times vs. Output Pull-Up Resistor 30114960 30114970 Propagation Delay 30114975 11 www.national.com LMV7231 Application Information 3 RESISTOR VOLTAGE DIVIDER SELECTION The LMV7231 trip points can be set by external resistor dividers as shown in Figure 1 30114953 FIGURE 1. External Resistor Dividers Each trip point, over-voltage, VOV, and under-voltage, VUV, can be optimized for a falling supply, VTHF, or a rising supply, VTHR. Therefore there are 22 = 4 different optimization cases. Exiting the voltage detection window (Figure 2), entering the window (Figure 3), rising into and out of the window (Figure 4), falling into and out of the window (Figure 5). Note that for each case each trip point can be optimized for either a rising or falling signal, not both. The governing equations make it such that if the same resistor, R3, and over/under-voltage ratio, VOV/VUV, is used across the channels the same nominal current will travel through the resistor ladder. As a result R2 will also be the same across channels and only R1 needs to change to set voltage detection window maximizing reuse of resistor values and minimizing design complexity. Select the R3 resistor value to be below 100kΩ so the current through the divider ladder is much greater than the LMV7231 bias current. If the current traveling through the resistor divider is on the same magnitude of the LMV7231 IBIAS, the IBIAS current will create error in your circuit and cause trip voltage shifts. Keep in mind the greatest error due to IBIAS will be caused when that current passes through the greatest equivalent resistance, REQ = R1‖(R2+R3), which will be seen by the positive input of the window comparator, +IN. www.national.com 12 LMV7231 30114954 30114956 FIGURE 2. Exiting the Voltage Detection Window FIGURE 4. Rising Into and Out Of the Voltage Detection Window 30114955 30114957 FIGURE 3. Entering the Voltage Detection Window FIGURE 5. Falling Into and Out Of the Voltage Detection Window 13 www.national.com LMV7231 INPUT/OUTPUT VOLTAGE RANGE ABOVE V+ The LMV7231 Hex Window Comparator with 1.5% precision can accurately monitor up to 6 power rails or batteries at one time. The input and output voltages of the device can exceed the supply voltage, V+, of the comparator, and can be up to the absolute maximum ratings without causing damage or performance degradation. The typical µC input pin with crowbar diode ESD protection circuitry will not allow the input to go above V+, and thus its usefulness is limited in power supply supervision applications. The supply independent inputs of the window comparator blocks allow the LMV7231 to be tolerant of system faults. For example if the power is suddenly removed from the LMV7231 due to a system malfunction yet there still exists a voltage on the input, this will not be an issue as long as the monitored input voltage does not exceed absolute maximum ratings. Another example where this feature comes in handy is a battery sense application such as the one in Figure 6. The boards may be sitting on the shelf unbiased with V+ grounded, and yet have a fully charged battery on board. If the comparator measuring the battery had crowbar diodes, the diode from – IN to V+ would turn on, sourcing current from the battery eventually draining the battery. However, when using the LMV7231 no current, except the low input bias current of the device, will flow into the chip, and the battery charge will be preserved. POWER SUPPLY BYPASSING Bypass the supply pin, V+, with a 0.1 μF ceramic capacitor placed close to the V+ pin. If transients with rise/fall times of 100’s μs and magnitudes of 100’s mV are expected on the power supply line a RC low pass filter network as shown in Figure 7 is recommended for additional bypassing. If no such bypass network is used power supply transients can cause the internal voltage reference of the comparator to temporarily shift potentially resulting in a brief incorrect comparator output. For example if an RC network with 100Ω resistance and 10μF capacitance (1.1ms rise time) is used the voltage reference will shift temporarily the amount, VTH Power Supply Sensitivity (VTHPSS), specified in the Electrical Characteristics table. 30114959 FIGURE 7. Power Supply Bypassing POWER SUPPLY SUPERVISION Figure 8 shows a power supply supervision circuit utilizing the LMV7231. This application uses the efficient, easy to use LM25007 step-down switching regulator. This switching regulator can handle a 9V – 42V input voltage range and it’s regulated output voltage is set to 5V with R2 = R3 = 3kΩ. 30114958 FIGURE 6. Battery Sense Application The output pin voltages of the device can also exceed the supply voltage, V+, of the comparator. This provides extra flexibility and enables designs which pull up the outputs to higher voltage levels to meet system requirements. For example it’s possible to run the LMV7231 at its minimum operating voltage, V+ = +2.2V, but pull up the output up to the absolute maximum ratings to bias a blue LED, with a forward voltage of VF = +4V. In a power supply supervision application the hardwired LMV7231 is a sound solution compared to the uC with software alternative for several reasons. First, startup is faster. During startup you don’t need to account for code loading time, oscillator ramp time, and reset time. Second, operation is quick. The LMV7231 has a maximum propagation delay in the µs and isn’t affected by sampling and conversion delays related to reading data, calculating data, and setting flags. Third, less overhead. The LMV7231 doesn’t require an expensive power consuming microcontroller nor is it dependent on controller code which could get damaged or crash. Resistor R6 and capacitors C6, C7 are utilized to minimize output ripple voltage per the LM25007 evaluation board application note. The comparator voltage window is set to 5V +/- 5% by R7=1.15kΩ , R8=10Ω, R9=95.3Ω. See 3 RESISTOR VOLTAGE DIVIDER SELECTION section in the Application Information section of the datasheet for details on how to set the comparator voltage window. With components selected the output ripple voltage seen on the LM25007 is approximately 30 - 35mV and is reduced to about 4mV at the comparator input, +IN1, by the resistor divider. This ripple voltage can be reduced multiple ways. First, user can operate the device in continuous conduction mode rather than discontinuous conduction mode. To do this increase the load current of the device (see LM25007 datasheet for more details). However, make sure not to exceed the power rating of the resistors in the resistor ladder. Second, ripple can be reduced further with a bypass cap, C9, at the resistor divider. If desired a user can select a 1uF capacitor to achieve less than 3mV ripple at +IN1. However, there is a tradeoff and adding capacitance at this node will lower the system response time. www.national.com 14 LMV7231 30114944 FIGURE 8. Power Supply Supervision 15 www.national.com LMV7231 Physical Dimensions inches (millimeters) unless otherwise noted 24-Pin LLP Package NS Package Number SQA24A www.national.com 16 LMV7231 17 www.national.com LMV7231 Hex Window Comparator with 1.5% Precision and 400mV Reference Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® Solutions Temperature Sensors PLL/VCO www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Quality and Reliability Feedback/Support Design Made Easy Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/training Applications & Markets Mil/Aero PowerWise® Design University Serial Digital Interface (SDI) www.national.com/sdi www.national.com/wireless www.national.com/tempsensors SolarMagic™ THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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