MIC841/2 Micrel MIC841/842 Comparator with Reference General Description The MIC841 and MIC842 are micropower, precision voltage comparators with an on-chip voltage reference. Teeny™ Features 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. • Optimized for PDAs, cellular telephones, pagers, and other battery-powered devices • Output can be pulled up to 6V regardless of supply voltage (841NBC5 only) • High ±1.25% voltage threshold accuracy • Built in hysteresis for noise suppression (MIC842) • Extremely low 1.5µA typical supply current • Immune to brief input transients • Teeny™ 5-lead SC-70 package 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 high. Supply current is extremely low (1.5µA, typical), making it ideal for portable applications. Applications • • • • • • The MIC841/2 is supplied in Micrel’s Teeny™ 5-lead SC-70 package. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. PDAs Pagers Cordless phones Consumer electronics Embedded controllers Personal electronics Typical Application VIN VDD MIC841 R1 5 3 R2 1 VDD OUT VIN VDD 4 LTH HTH GND 2 VOUT MIC842 VLTH > V HTH VREF = 1.24V 1.5V ≤ V DD ≤ 5.5V R1 5 1 R3 VDD OUT INP GND 4 2 VOUT VREF = 1.24V 1.5V ≤ VDD ≤ 5.5V R2 Threshold Detection with Hysteresis Set by a Third External Resistor Threshold Detector with Internal Fixed Hysteresis Teeny™ is a trademark of Micrel, Inc. Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com January 2005 1 MIC841/2 MIC841/2 Micrel Ordering Information Part Number Marking Hysteresis Adjustment Output Stage Output Function Temp. Range Pb-Free Package MIC841HBC5 B13 External Push Pull Active High –40°C to +85°C SC-70-5 MIC841LBC5 B14 External Push Pull Active Low –40°C to +85°C SC-70-5 MIC841NBC5 B15 External Open Drain Active High –40°C to +85°C SC-70-5 MIC842HBC5 B16 Internal Push Pull Active High –40°C to +85°C SC-70-5 MIC842LBC5 B17 Internal Push Pull Active Low –40°C to +85°C SC-70-5 MIC842NBC5 B18 Internal Open Drain Active High –40°C to +85°C MIC841HYC5 B13 External Push Pull Active High –40°C to +85°C SC-70-5 MIC841LYC5 B14 External Push Pull Active Low –40°C to +85°C SC-70-5 MIC841NYC5 B15 External Open Drain Active High –40°C to +85°C SC-70-5 MIC842HYC5 B16 Internal Push Pull Active High –40°C to +85°C SC-70-5 MIC842LYC5 B17 Internal Push Pull Active Low –40°C to +85°C SC-70-5 MIC842NYC5 B18 Internal Open Drain Active High –40°C to +85°C SC-70-5 MIC841/2 2 SC-70-5 January 2005 MIC841/2 Micrel Pin Configuration NC GND INP LTH GND HTH 3 2 3 1 2 1 Bxx Bxx 4 5 4 5 OUT VDD OUT VDD MIC842 SC-70-5 (C5) MIC841 SC-70-5 (C5) Pin Description MIC841 Pin Number Pin Name 1 HTH High-Voltage Threshold (Input): Analog input to a comparator. This is the voltage input assigned to detect a high-voltage condition. When the level on this pin exceeds VREF, OUT is asserted and the condition is latched until VLTH < VREF. 2 GND Ground. 3 LTH Low-Voltage Threshold (Input): Analog input to a comparator. This is the voltage input assigned to detect a low voltage condition. When the level on this pin falls below VREF, OUT is de-asserted and the condition is latched until VHTH > VREF. 4 OUT (“N” Version) Output: Active-high, open-drain output. This output is de-asserted and latched when VLTH <VREF, indicating a low voltage condition. This state remains latched until VHTH > VREF. OUT (“H” Version) Output: Push-pull output. This output is de-asserted and latched when VLTH < VREF, indicating a low voltage condition. This state remains latched until VHTH > VREF. OUT (“L” Version) Output: Push-pull output. This output is asserted and latched when VLTH < VREF, indicating a low voltage condition. This state remains latched until VHTH > VREF. 5 VDD Pin Function Power Supply (Input): Independent supply input for internal circuitry. Pin Description MIC842 Pin Number Pin Name 1 INP Input: Analog input to the comparator. When VINP > VREF + VHYST, VOUT is asserted, and the condition is held until VINP < VREF. 2 GND Ground. 3 NC 4 OUT (“N” Version) Output: Active-high, open-drain output. This output is de-asserted when VINP < VREF, indicating a low voltage input. The output is asserted when VINP > VREF + VHYST. OUT (“H” Version) Output: Push-pull output. This output is de-asserted and latched when VINP < VREF, indicating a low voltage condition. This state remains latched until VINP > VREF + VHYST. OUT (“L” Version) Output: Push-pull output. This output is asserted and latched when VINP < VREF, indicating a low voltage condition. This state remains latched until VINP > VREF + VHYST. 5 January 2005 VDD Pin Function No Connect. Power Supply (Input): Independent supply input for internal circuitry. 3 MIC841/2 MIC841/2 Micrel Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VDD) ..................................... –0.3V to +7V Input Voltage (VINP) ...................................................... +7V Output Current (IOUT) ................................................. 20mA Storage Temperature (TS) ....................... –65°C to +150°C ESD Rating, Note 3 ...................................................... 1kV Supply Voltage (VDD) .................................. +1.5V to +5.5V Input Voltage (VINP) ......................................... –0.3V to 6V Ambient Temperature Range (TA) ............. –40°C to +85°C Junction Temperature (TJ) ....................... Internally Limited Package Thermal Resistance (θJA) ...................... 450°C/W Electrical Characteristics(4) 1.5V ≤ VDD ≤ 5.5V; TA = +25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted. Symbol Parameter Condition Min IDD Supply Current output not asserted IINP Input Leakage Current VREF Reference Voltage Typ Max Units 1.5 3 µA 0.005 10 nA 0°C to 85°C 1.225 1.240 1.256 V –40°C to 85°C 1.219 1.240 1.261 V 8 20 35 mV VHYST Hysteresis Voltage, (Note 5) MIC842 only tD Propagation Delay VINP = 1.352V to 1.128V 12 µs VINP = 1.143V to 1.367V 8 µs VOUT Output Voltage-Low (Note 6) Output Voltage-High ISINK = 1.6mA, VDD ≥ 1.6V 0.05 0.3 V ISINK = 100µA, VDD ≥ 1.2V 0.005 0.4 V ISOURCE = 500µA, VDD ≥ 1.6V 0.99VDD V ISOURCE = 50µA, VDD ≥ 1.2V 0.99VDD V Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 4. Specification for packaged product only. 5. VHTH = VREF + VHYST. 6. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be de-asserted down to VDD = 1.2V. MIC841/2 4 January 2005 MIC841/2 Micrel Block Diagrams VDD 5 VIN VDD VDD VIN 5 Low-Voltage Detect High-Voltage Detect INP LTH VLTH VTH 3 1 OUT OUT R Q 4 4 High-Voltage Detect HTH VHTH VDD S Q 1 1.24V Bandgap Reference MIC842H 1.24V Bandgap Reference 2 GND MIC841H 2 GND VDD 5 VIN VDD VIN VDD Low-Voltage Detect 5 LTH VLTH VTH OUT R Q 1 OUT 4 High-Voltage Detect HTH VHTH High-Voltage Detect INP 3 VDD 4 S Q 1 1.24V Bandgap Reference 1.24V Bandgap Reference MIC842L 2 GND MIC841L 2 GND VDD 5 VIN VDD Low-Voltage Detect VDD VIN 5 LTH VLTH INP 3 R Q High-Voltage Detect HTH VHTH VTH OUT VDD High-Voltage Detect OUT 1 4 4 S Q 1 1.24V Bandgap Reference 1.24V Bandgap Reference MIC842N 2 GND MIC841N 2 January 2005 GND 5 MIC841/2 MIC841/2 Micrel Once the desired trip points are determined, set the VIN(HI) threshold first. Applications 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. 470kΩ 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.” For example, use a total of 1MΩ = 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: 1MΩ VIN(HI) = 3.6V = 1.24 R3 R3 = 344kΩ 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. 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 3MΩ. 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.” 1MΩ VIN(LO) = 3.1V = 1.24 R2 + 344k R2 = 56kΩ 1MΩ − (R2 − R3) = R1 R1 = 600kΩ The accuracy of the resistors can be chosen based upon the accuracy required by the system. Programming the MIC841 Thresholds The low-voltage threshold is calculated using: VIN(LO) Programming the MIC842 Thresholds The voltage threshold is calculated using: R1 + R2 + R3 = VREF R2 + R3 R1 + R2 VIN(LO) = VREF R2 The high-voltage threshold is calculated using: R1 + R2 + R3 VIN(HI) = VREF R3 where: VREF = 1.240V where, for both equations: VIN VREF = 1.240V MIC842N 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 1MΩ for RTOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. VIN R1 5 1 VDD OUT INP GND 470k 4 VOUT 2 R2 VDD Figure 2. MIC842 Example Circuit MIC841N R1 604k 1% 5 1 R2 56k 1% R3 340k 1% 3 VDD OUT 4 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 1MΩ for RTOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. 470k VOUT LTH HTH GND 2 Figure 1. MIC841 Example Circuit MIC841/2 6 January 2005 MIC841/2 Micrel Input Transients The MIC841/2 is inherently immune to very short negativegoing “glitches.” Very brief transients may exceed the VIN(LO) threshold without tripping the output. MAX. TRANSIENT DURATION (µs) As shown in Figure 3, 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. Input Transient Response 140 120 100 80 60 40 20 0 1 10 100 1000 RESET COMP. OVERDRIVE, VREF–VLTH (mV) Figure 3. Input Transient Response January 2005 7 MIC841/2 MIC841/2 Micrel Package Information 0.65 (0.0256) BSC 1.35 (0.053) 2.40 (0.094) 1.15 (0.045) 1.80 (0.071) 2.20 (0.087) 1.80 (0.071) DIMENSIONS: MM (INCH) 1.00 (0.039) 1.10 (0.043) 0.80 (0.032) 0.80 (0.032) 0.10 (0.004) 0.00 (0.000) 0.30 (0.012) 0.15 (0.006) 0.18 (0.007) 0.10 (0.004) 0.30 (0.012) 0.10 (0.004) SC-70 (C5) 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 The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. MIC841/2 8 January 2005