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| MIC841/842 Comparator with 1.25% Reference and Adjustable Hysteresis General Description The MIC841 and MIC842 are micropower, precision voltage comparators with an on-chip voltage reference. Both devices are intended for voltage monitoring applications. External resistors are used to set the voltage monitor threshold. When the threshold is crossed, the outputs switch polarity. The MIC842 incorporates a voltage reference and comparator with fixed internal hysteresis; two external resistors are used to set the switching threshold voltage. The MIC841 provides a similar function with user adjustable hysteresis; this part requires three external resistors to set the upper and lower thresholds (the difference between the threshold voltages being the hysteresis voltage). Both the MIC841 and MIC842 are available with push-pull or open-drain output stage. The push-pull output stage is configured either active high or active low; the open-drain output stage is only configured active low. Supply current is extremely low (1.5A, typical), making it ideal for portable applications. The MIC841/2 is supplied in Micrel's TeenyTM 5-pin SC-70 package. Data sheets and support documentation are found on the Micrel web site: www.micrel.com. Features * * * * * * * * 1.5V to 5.5V operating range 1.5A typical supply current 1.25% voltage threshold accuracy 10nA max input leakage current over temperature 10s propagation delay Externally adjustable hysteresis (MIC841) Internal 20mV hysteresis (MIC842) Output options - Push-pull, active high - Push-pull, active low - Open drain, active low * Open drain output can be pulled to 6V regardless of VDD * Immune to brief input transients * TeenyTM 5-pin SC-70 package Applications * * * * Smart phones PDAs Precision battery monitoring Battery chargers ______________________________________________________________________________________________________________________ Typical Application Threshold Detection with Adjustable Hysteresis TeenyTM is a trademark of Micrel, Inc. Threshold Detector with Internal Fixed Hysteresis Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com March 2011 M9999-030811-B Micrel, Inc. MIC841/2 Ordering Information Part Number MIC841HBC5 MIC841LBC5 MIC841NBC5 MIC842HBC5 MIC842LBC5 MIC842NBC5 MIC841HYC5 MIC841LYC5 MIC841NYC5 MIC842HYC5 MIC842LYC5 MIC842NYC5 Marking B13 B14 B15 B16 B17 B18 B13 B14 B15 B16 B17 B18 Hysteresis Adjustment External External External Internal Internal Internal External External External Internal Internal Internal Output Stage Push Pull Push Pull Open Drain Push Pull Push Pull Open Drain Push Pull Push Pull Open Drain Push Pull Push Pull Open Drain Output Function Active High Active Low Active High Active High Active Low Active High Active High Active Low Active High Active High Active Low Active High Temperature Range -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C Pb-Free Package SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 SC-70-5 March 2011 2 M9999-030811-B Micrel, Inc. MIC841/2 Pin Configuration MIC841 SC-70-5 (C5) MIC842 SC-70-5 (C5) Pin Description MIC841 Pin Number 1 2 3 Pin Name HTH GND LTH OUT 4 OUT OUT 5 VDD Pin Function High Threshold Input. HTH and LTH monitor external voltages. Ground. Low Threshold Input. LTH and HTH monitor external voltages. ("H" Version) Active-Low Push-Pull Output. OUT asserts low when VLTH < VREF. OUT remains low until VHTH > VREF. ("L" Version) Active-High Push-Pull output. OUT asserts high when VLTL < VREF. OUT remains high until VHTH > VREF. ("N" Version) Active-Low, Open-Drain Output. OUT asserts low when VLTH < VREF. OUT remains low until VHTH > VREF. Power Supply Input Pin Description MIC842 Pin Number 1 2 3 Pin Name INP GND NC OUT 4 OUT OUT 5 VDD Pin Function Threshold Input. INP monitors an external voltage. Ground No Connect. Not internally connected. ("H" Version) Active-Low, Push-Pull Output. OUT asserts low when VINP < VREF. OUT remains low until VINP > (VREF+ VHYST). ("L" Version) Active-High, Push-Pull Output. OUT asserts high when VINP < VREF. OUT remains high until VINP > (VREF+ VHYST). ("N" Version) Active-Low, Open-Drain Output. OUT asserts low when VINP < VREF. OUT remains low until VINP > (VREF+ VHYST). Power Supply Input March 2011 3 M9999-030811-B Micrel, Inc. MIC841/2 Absolute Maximum Ratings(1) Supply Voltage (VDD)....................................... -0.3V to +7V Input Voltage (VINP, VLTH, VLTL) .......................................+7V Output Current (IOUT) .................................................20mA Storage Temperature (TS)........................ -65C to +150C ESD Rating, Note 3 ....................................................... 1kV Operating Ratings(2) Supply Voltage (VDD)................................... +1.5V to +5.5V Input Voltage (VINP VLTH, VLTL)........................... -0.3V to 6V VOUT (`H' and `L' versions)............................................... VDD VOUT (`N' version) ............................................................. 6V Ambient Temperature Range (TA) ............. -40C to +85C Junction Temperature (TJ) ........................................ 150C Package Thermal Resistance (JA).................... 256.5C/W Electrical Characteristics(4) 1.5V VDD 5.5V; TA = +25C, bold values indicate -40C TA +85C, unless noted. Symbol IDD IINP VREF VHYST tD Parameter Supply Current Input Leakage Current Reference Voltage Hysteresis Voltage, (Note 5) Propagation Delay 0C to 85C -40C to 85C MIC842 only VINP = 1.352V to 1.128V VINP = 1.143V to 1.367V ISINK = 1.6mA, VDD 1.6V ISINK = 100A, VDD 1.2V ISOURCE = 500A, VDD 1.6V ISOURCE = 50A, VDD 1.2V 1.225 1.219 8 Condition Output not asserted Min Typ 1.5 0.005 1.240 1.240 20 12 8 0.05 0.005 0.99VDD 0.99VDD 0.3 0.4 Max 3 10 1.256 1.261 35 Units A nA V V mV s s V V V V Output Voltage-Low VOUT (Note 6) Output Voltage-High Notes: 1. 2. 3. 4. 5. 6. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Specification for packaged product only. VHTH = VREF + VHYST. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be de-asserted down to VDD = 1.2V. March 2011 4 M9999-030811-B Micrel, Inc. MIC841/2 Block Diagrams March 2011 5 M9999-030811-B Micrel, Inc. MIC841/2 Application Information Output The MIC841N and MIC842N outputs are an open-drain MOSFET, so most applications will require a pull-up resistor. The value of the resistor should not be too large or leakage effects may dominate. 470k is the maximum recommended value. Note that the output of "N" version may be pulled up as high as 6V regardless of the ICs supply voltage. The "H" and "L" versions of the MIC841 and MIC842 have a push-pull output stage, with a diode clamped to VDD. Thus, the maximum output voltage of the "H" and "L" versions is VDD. See "Electrical Characteristics." When working with large resistors on the input to the devices, a small amount of leakage current can cause voltage offsets that degrade system accuracy. The maximum recommended total resistance from VIN to ground is 3M. The accuracy of the resistors can be chosen based upon the accuracy required by the system. The inputs may be subjected to voltages as high as 6V steady-state without adverse effects of any kind regardless of the ICs supply voltage. This applies even if the supply voltage is zero. This permits the situation in which the IC's supply is turned off, but voltage is still present on the inputs. See "Electrical Characteristics." Figure 1. MIC841 Example Circuit Once the desired trip points are determined, set the VIN(HI) threshold first. For example, use a total of 1M = R1 + R2 + R3. For a typical single-cell lithium ion battery, 3.6V is a good "high threshold" because at 3.6V the battery is moderately charged. Solving for R3: 1M VIN(HI) - 3.6 V - 1.24 R3 R3 = 344k Programming the MIC841 Thresholds The low-voltage threshold is calculated using: R1 + R2 + R3 VIN(LO ) - VREF R 2 + R3 Once R3 is determined, the equation for VIN(LO) can be used to determine R2. A single lithium-ion cell, for example, should not be discharged below 2.5V. Many applications limit the drain to 3.1V. Using 3.1V for the VIN(LO) threshold allows calculation of the two remaining resistor values. 1M VIN(LO ) - 3.1V - 1.24 R2 + 344k The high-voltage threshold is calculated using: R1 + R2 + R3 VIN(HI) - VREF R3 R2 = 56k 1M - (R2 - R3) = R1 R1 = 600k The accuracy of the resistors can be chosen based upon the accuracy required by the system. where, for both equations: In order to provide the additional criteria needed to solve for the resistor values, the resistors can be selected such that they have a given total value, that is, R1 + R2 + R3 = RTOTAL. A value such as 1M for RTOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. March 2011 6 M9999-030811-B Micrel, Inc. MIC841/2 Input Transients The MIC841/2 is inherently immune to very short negative-going "glitches." Very brief transients may exceed the VIN(LO) threshold without tripping the output. As shown in Figure 4, the narrower the transient, the deeper the threshold overdrive that will be ignored by the MIC841/2. The graph represents the typical allowable transient duration for a given amount of threshold overdrive that will not generate an output. VIN VIN(HI) VIN(LO) VHYSTERISIS 0V OUT H AND N VERSIONS 0V OUT L VERSION 0V Figure 2. Output Response and Hysteresis Programming the MIC842 Thresholds The voltage threshold is calculated using: R1 + R2 VIN(LO ) - VREF R2 where: VREF = 1.240V Figure 4. Input Transient Response Figure 3. MIC842 Example Circuit In order to provide the additional criteria needed to solve for the resistor values, the resistors can be selected such that they have a given total value, that is, R1 + R2 = RTOTAL. A value such as 1M for RTOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. March 2011 7 M9999-030811-B Micrel, Inc. MIC841/2 Package Information MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel's terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2005 Micrel, Incorporated. March 2011 8 M9999-030811-B |
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