MIC841/842. General Description. Features. Applications. Typical Application. Comparator with Reference

Transcription

1 MIC8/ MIC8/8 Comparator with General Description The MIC8 and MIC8 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 MIC8 incorporates a voltage reference and comparator with fixed internal hysteresis; two external resistors are used to set the switching threshold voltage. The MIC8 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 MIC8 and MIC8 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 (.µa, typical), making it ideal for portable applications. The MIC8/ is supplied in s Teeny -lead SC-70 package. Data sheets and support documentation can be found on s web site at Features Optimized for PDAs, cellular telephones, pagers, and other battery-powered devices Output can be pulled up to 6V regardless of supply voltage (8NBC only) High ±.% voltage threshold accuracy Built in hysteresis for noise suppression (MIC8) Extremely low.µa typical supply current Immune to brief input transients Teeny -lead SC-70 package Applications PDAs Pagers Cordless phones Consumer electronics Embedded controllers Personal electronics Teeny Typical Application R R R MIC8 VDD HTH V V > V HTH V REF =.V.V.V R R MIC8 VDD V V REF =.V.V.V Threshold ion with Hysteresis Set by a Third External Resistor Threshold or with Internal Fixed Hysteresis Teeny is a trademark of, Inc., Inc. 80 Fortune Drive San Jose, CA 9 USA tel + (08) fax + (08) January 00 MIC8/

2 MIC8/ Ordering Information Hysteresis Output Output Part Number Marking Adjustment Stage Function Temp. Range Pb-Free Package MIC8HBC B External Push Pull Active High 0 C to +8 C SC-70- MIC8LBC B External Push Pull Active Low 0 C to +8 C SC-70- MIC8NBC B External Open Drain Active High 0 C to +8 C SC-70- MIC8HBC B6 Internal Push Pull Active High 0 C to +8 C SC-70- MIC8LBC B7 Internal Push Pull Active Low 0 C to +8 C SC-70- MIC8NBC B8 Internal Open Drain Active High 0 C to +8 C SC-70- MIC8HYC B External Push Pull Active High 0 C to +8 C SC-70- MIC8LYC B External Push Pull Active Low 0 C to +8 C SC-70- MIC8NYC B External Open Drain Active High 0 C to +8 C SC-70- MIC8HYC B6 Internal Push Pull Active High 0 C to +8 C SC-70- MIC8LYC B7 Internal Push Pull Active Low 0 C to +8 C SC-70- MIC8NYC B8 Internal Open Drain Active High 0 C to +8 C SC-70- MIC8/ January 00

3 MIC8/ Pin Configuration HTH NC Bxx VDD MIC8 SC-70- (C) Bxx VDD MIC8 SC-70- (C) Pin Description MIC8 Pin Number Pin Name Pin Function HTH 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 V REF, is asserted and the condition is latched until V < V REF. Ground. 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 V REF, is de-asserted and the condition is latched until V HTH > V REF. ( N Version) Output: Active-high, open-drain output. This output is de-asserted and latched when V <V REF, indicating a low voltage condition. This state remains latched until V HTH > V REF. ( H Version) Output: Push-pull output. This output is de-asserted and latched when V < V REF, indicating a low voltage condition. This state remains latched until V HTH > V REF. ( L Version) Output: Push-pull output. This output is asserted and latched when V < V REF, indicating a low voltage condition. This state remains latched until V HTH > V REF. Power Supply (Input): Independent supply input for internal circuitry. Pin Description MIC8 Pin Number Pin Name Pin Function Input: Analog input to the comparator. When P >V REF +V HYST, V is asserted, and the condition is held until P <V REF. Ground. NC No Connect. ( N Version) Output: Active-high, open-drain output. This output is de-asserted when P <V REF, indicating a low voltage input. The output is asserted when P >V REF +V HYST. ( H Version) Output: Push-pull output. This output is de-asserted and latched when P < V REF, indicating a low voltage condition. This state remains latched until P > V REF +V HYST. ( L Version) Output: Push-pull output. This output is asserted and latched when P < V REF, indicating a low voltage condition. This state remains latched until P > V REF +V HYST. Power Supply (Input): Independent supply input for internal circuitry. January 00 MIC8/

4 MIC8/ Absolute Maximum Ratings () Supply Voltage ( )... 0.V to +7V Input Voltage (P )...+7V Output Current (I )... 0mA Storage Temperature (T S )... 6 C to +0 C ESD Rating, Note... kv Operating Ratings () Supply Voltage ( )... +.V to +.V Input Voltage (P )... 0.V to 6V Ambient Temperature Range (T A )... 0 C to +8 C Junction Temperature (T J )... Internally Limited Package Thermal Resistance (θ JA )... 0 C/W Electrical Characteristics ().V.V; T A = + C, bold values indicate 0 C T A +8 C; unless noted. Symbol Parameter Condition Min Typ Max Units I DD Supply Current output not asserted. µa I Input Leakage Current na V REF Voltage 0 C to 8 C..0.6 V 0 C to 8 C V V HYST Hysteresis Voltage, (Note ) MIC8 only 8 0 mv t D Propagation Delay P =.V to.8v µs P =.V to.67v 8 µs V Output Voltage-Low I SINK =.6mA,.6V V (Note 6) I SINK = 00µA,.V V Output Voltage-High I SOURCE = 00µA,.6V 0.99 V I SOURCE = 0µA,.V 0.99 V Notes:. 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,.k in series with 00pF.. Specification for packaged product only.. V HTH = V REF + V HYST. 6. operating range is.v to.v. Output is guaranteed to be de-asserted down to =.V. MIC8/ January 00

5 MIC8/ Block Diagrams V HTH Low-Voltage R S V TH V HTH.V.V MIC8H MIC8H Low-Voltage V HTH R S V TH V HTH.V.V MIC8L MIC8L Low-Voltage V HTH R S V TH V HTH.V MIC8N.V MIC8N January 00 MIC8/

6 MIC8/ Applications Information Output The MIC8N and MIC8N 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. 70kΩ 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 MIC8 and MIC8 have a push-pull output stage, with a diode clamped to. Thus, the maximum output voltage of the H and L versions is. 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 to ground is MΩ. 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. Programming the MIC8 Thresholds The low-voltage threshold is calculated using: R+ R + R VIN(LO) = VREF R + R The high-voltage threshold is calculated using: R+ R + R VIN(HI) = VREF R where, for both equations: VREF =.0V 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, R + R + R = R TOTAL. A value such as MΩ for R TOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. Once the desired trip points are determined, set the (HI) threshold first. For example, use a total of MΩ = R + R + R. For a typical single-cell lithium ion battery,.6v is a good high threshold because at.6v the battery is moderately charged. Solving for R: V.6V. M IN(HI) = = Ω R R = kω Once R is determined, the equation for (LO) can be used to determine R. A single lithium-ion cell, for example, should not be discharged below.v. Many applications limit the drain to.v. Using.V for the (LO) threshold allows calculation of the two remaining resistor values. M (LO) =.V =. Ω R + k R = 6kΩ MΩ ( R R)= R R= 600kΩ The accuracy of the resistors can be chosen based upon the accuracy required by the system. Programming the MIC8 Thresholds The voltage threshold is calculated using: R+ R VIN(LO) = VREF R where: VREF =.0V R R VDD MIC8N 70k V Figure. MIC8 Example Circuit R R R 60k % 6k % 0k % MIC8N VDD HTH 70k V 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, R + R = R TOTAL. A value such as MΩ for R TOTAL is a reasonable value because it draws minimum current but has no significant effect on accuracy. Figure. MIC8 Example Circuit MIC8/ 6 January 00

7 MIC8/ Input Transients The MIC8/ is inherently immune to very short negativegoing glitches. Very brief transients may exceed the (LO) threshold without tripping the output. As shown in Figure, the narrower the transient, the deeper the threshold overdrive that will be ignored by the MIC8/. The graph represents the typical allowable transient duration for a given amount of threshold overdrive that will not generate an output. MAX. TRANSIENT DURATION (µs) Input Transient Response RESET COMP. OVERDRIVE, V REF V (mv) Figure. Input Transient Response January 00 7 MIC8/

8 MIC8/ Package Information 0.6 (0.06) BSC. (0.0). (0.0).0 (0.09).80 (0.07).0 (0.087).80 (0.07).00 (0.09) 0.80 (0.0).0 (0.0) 0.80 (0.0) DIMENSIONS: MM (INCH) 0.8 (0.007) 0.0 (0.00) 0.0 (0.0) 0. (0.006) 0.0 (0.00) 0.00 (0.000) SC-70 (C) 0.0 (0.0) 0.0 (0.00) MICREL, INC. 80 FORTUNE DRIVE SAN JOSE, CA 9 USA TEL + (08) FAX + (08) WEB The information furnished by in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by for its use. reserves the right to change circuitry and specifications at any time without notification to the customer. 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 Products for use in life support appliances, devices or systems is at Purchaser s own risk and Purchaser agrees to fully indemnify for any damages resulting from such use or sale. 00, Incorporated. MIC8/ 8 January 00