AS1976, AS1977 D a ta S he e t U l t r a - L o w C u r r e n t , 1 . 8 V C o m pa r a t o r s 1 General Description 2 Key Features The AS1976/AS1977 are very low-current comparators that can operate beyond the rail voltages and are guaranteed to operate down to 1.8V ! CMOS Push/Pull Output Sinks and Sources 8mA (AS1976) Low input bias current, current-limiting output circuitry, and ultra-small packaging make these comparators ideal for low-power 2-cell applications including powermanagement and power-monitoring systems. ! CMOS Open-Drain Output Voltage Extends Beyond VCC (AS1977) ! Ultra-Low Supply Current: 200nA ! Internal Hysteresis: 3mV ! 3V-to5V Logiv-Level Translation ! Guaranteed to Operate Down to +1.8V ! Input Voltage Range Operates 200mV Beyond the Rails ! Crowbar Current-Free Switching ! No Phase Reversal for Overdriven Inputs ! 5-pin SOT23 Package The comparators are available as the standard products listed in Table 1. Table 1. Standard Products Model Output Type Current AS1976 Push/Pull 200nA AS1977 Open-Drain 200nA The AS1976 push/pull output can sink or source current. The AS1977 open-drain output can be pulled beyond VCC to a maximum of 6V > VEE. This open-drain model is ideal for use as a logic-level translator or bipolar-tounipolar converter. Large internal output drivers provide rail-to-rail output swings with loads up to 8mA. Both devices feature builtin battery power-management and power-monitoring circuitry. The AS1976/AS1977 are available in a 5-pin SOT23 package. 3 Applications The devices are ideal for battery monitoring/management, mobile communication devices, laptops and PDAs, ultra-low-power systems, threshold detectors/discriminators, telemetry and remote systems, medical instruments, or any other space-limited application with low power-consumption requirements. Figure 1. Block Diagram 5 VCC AS1976/ AS1977 3 IN+ 4 + – 1 OUT IN2 VEE www.austriamicrosystems.com Revision 1.01 1 - 17 AS1976/AS1977 Data Sheet - P i n o u t 4 Pinout Pin Assignments Figure 2. Pin Assignments (Top View) 5 VCC OUT 1 VEE 2 AS1976/ AS1977 IN+ 3 4 IN- Pin Descriptions Table 2. Pin Descriptions Pin Number Pin Name 1 OUT Comparator Output 2 VEE Negative Supply Voltage 3 IN+ Comparator Non-Inverting Input 4 IN- Comparator Inverting Input 5 VCC Positive Supply Voltage Description www.austriamicrosystems.com Revision 1.01 2 - 17 AS1976/AS1977 Data Sheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 3 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Section 6 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 3. Absolute Maximum Ratings Parameter Min Supply Voltage VCC to VEE Max Units +7 V Voltage Inputs IN+, IN- VEE - 0.3 VCC + 0.3 V Output Voltage AS1976, AS1978 VEE - 0.3 VCC + 0.3 V Output Current -50 +50 mA Output Short-Circuit Duration 10 s Continuous Power Dissipation 571 mW Operating Temperature Range -40 +85 ºC Storage Temperature Range -65 +150 ºC Package Body Temperature www.austriamicrosystems.com +260 ºC Revision 1.01 Comments Derate at 7.31mW/ºC above +70ºC The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/ JEDEC J-STD-020C “Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is matte tin (100% Sn). 3 - 17 AS1976/AS1977 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics VCC = +5V, VEE = 0, VCM = 0, TAMB = -40 to +85ºC (unless otherwise specified). Typ values are at TAMB = +25ºC. Table 4. AS1976/AS1977 Electrical Characteristics Symbol Parameter Conditions Min VCC Supply Voltage Range Inferred from the PSRR test 1.8 ICC Supply Current Typ VCC = 1.8V 0.2 VCC = 5V, TAMB = +25ºC 0.21 VCC = 5V, TAMB = TMIN to TMAX VCM VOS VHB IB Input Common-Mode Voltage Range Input Offset Voltage Input-Referred Hysteresis Input Bias Current -0.2V ≤ VCM ≤ (VCC + 0.2V), 1 TAMB = +25ºC 3 2 TAMB = +25ºC 5.5 V 0.5 µA VCC + 0.2 1 V 5 mV -0.2V ≤ VCM ≤ (VCC + 0.2V), TAMB = TMIN to TMAX -0.2V ≤ VCM ≤ (VCC + 0.2V) Units 0.9 VEE - 0.2 Inferred from CMRR test Max 10 3 0.15 TAMB = TMIN to TMAX mV 1 2 IOS Input Offset Current PSRR Power-Supply Rejection Ratio VCC = 1.8 to 5.5V, TAMB = +25ºC 0.05 1 mV/V CMRR Common-Mode Rejection Ratio (VEE - 0.2V) ≤ VCM ≤ (VCC + 0.2V), TAMB = +25ºC 0.2 3 mV/V TAMB = +25ºC, AS1976 only VCC = 5.5V, ISINK = 8mA 220 500 VCC - VOH Output Voltage Swing High 10 nA TAMB = TMIN to TMAX, AS1976 only VCC = 5.5V, ISINK = 8mA TAMB = +25ºC AS1976 only VCC = 1.8V, ISOURCE = 1mA 650 mV 80 TAMB = TMIN to TMAX, AS1976 only VCC = 1.8V, ISOURCE = 1mA TAMB = +25ºC, AS1976 only VCC = 5.5V, ISINK = 8mA VOL Output Voltage Swing Low 220 ISC tPD- Output Leakage Current Output Short-Circuit Current High-to-Low 4 Propagation Delay www.austriamicrosystems.com mV 70 200 300 AS1977 only, VOUT = 5.5V 0.001 Sourcing, VOUT = VEE, VCC = 5.5V 50 Sourcing, VOUT = VEE, VCC = 1.8V 6 Sinking, VOUT = VCC, VCC = 5.5V 70 Sinking, VOUT = VCC, VCC = 1.8V 5 VCC = 1.8V 10 VCC = 5.5V 12 Revision 1.01 500 650 TAMB = TMIN to TMAX, VCC = 1.8V, ISOURCE = 1mA ILEAK 200 300 TAMB = TMIN to TMAX, AS1976 only VCC = 5.5V, ISINK = 8mA TAMB = +25ºC, VCC = 1.8V, ISOURCE = 1mA pA 1 µA mA µs 4 - 17 AS1976/AS1977 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Table 4. AS1976/AS1977 Electrical Characteristics (Continued) Symbol Parameter Conditions Min Typ AS1976 only, VCC = 1.8V 13 AS1976 only, VCC = 5.5V 15 AS1977 only, VCC = 1.8V, RPULUP = 100kΩ 16 Max Units tPD+ Low-to-High 4 Propagation Delay AS1977 only, VCC = 3.6V, RPULUP = 100kΩ 18 tRISE Rise Time AS1976 only, CLOAD = 15pF 10 ns tFALL Fall Time CLOAD = 15pF 10 ns tON Power-Up Time 100 ns µs 1. VOS is defined as the center of the hysteresis band at the input. 2. The hysteresis-related trip points are defined as the edges of the hysteresis band, measured with respect to the center of the band (i.e., VOS) (see Figure 26 on page 11). 3. Guaranteed by design. 4. Specified with an input overdrive voltage (VOVERDRIVE) = 100mV, and load capacitance (CLOAD) = 15pF. VOVERDRIVE is defined above and beyond the offset voltage and hysteresis of the comparator input. A reference voltage error should also be added. www.austriamicrosystems.com Revision 1.01 5 - 17 AS1976/AS1977 Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s 7 Typical Operating Characteristics Figure 3. ICC vs. VCC and Temperature Figure 4. ICC vs. Temperature 500 300 400 275 300 Supply Current (nA) . Supply Current (nA) . VCC = 3V +85ºC +25ºC 200 -40ºC 100 0 250 225 VCC = 5V 200 175 150 1.5 2.5 3.5 4.5 5.5 -40 -15 Supply Voltage (V) 35 60 85 Figure 6. VOL vs. ISINK 50 600 Output Voltage Low (mV) . Supply Current (µA) . 10 Temperature (°C) Figure 5. ICC vs. Output Transition Frequency 40 VCC = 5V 30 20 VCC = 3V VCC = 1.8V 10 500 VCC = 3V 400 VCC = 1.8V VCC = 5V 300 200 100 0 0 1 10 100 1000 10000 100000 2 4 6 Output Transition Frequency (Hz) 8 10 12 14 16 Sink Current (mA) Figure 7. VOL vs. ISINK and Temperature Figure 8. VOH vs. ISOURCE 600 0.8 500 VCC-VOH (mV) . Output Voltage Low (mV) . VCC = 1.8V +25ºC 400 +85ºC 300 -40ºC 200 0.6 VCC = 1.8V VCC = 3V 0.4 VCC = 5V 0.2 100 0 0 2 4 6 8 10 12 14 16 0 10 15 20 Source Current (mA) Sink Current (mA) www.austriamicrosystems.com 5 Revision 1.01 6 - 17 AS1976/AS1977 Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s Figure 9. VOH vs. ISOURCE and Temperature Figure 10. Short Circuit Sink Current vs. Temperature 100 Sink Current (mA) . VCC-VOH (mV) . 0.8 0.6 +25ºC +85ºC 0.4 -40ºC 0.2 75 VCC = 5V 50 VCC = 3V 25 VCC = 1.8V 0 0 0 5 10 15 20 -40 -15 Source Current (mA) 35 60 85 60 85 Temperature (°C) Figure 11. Short Circuit Source Current vs. Temperature Figure 12. tPD+ vs. Temperature 25 80 20 60 VCC = 5V tPD+ (µs) . Source Current (mA) . 10 40 VCC = 3V VCC = 5V 15 VCC = 1.8V VCC = 3V 10 20 5 VCC = 1.8V 0 0 -40 -15 10 35 60 85 -40 -15 10 Temperature (°C) Temperature (°C) Figure 13. tPD- vs. Temperature Figure 14. tPD- vs. Capacitive Load 150 20 125 16 VCC = 5V VCC = 3V 100 tPD- (µs) . tPD- (µs) . 35 12 VCC = 1.8V 8 75 VCC = 1.8V 50 VCC = 3V 4 25 VCC = 5V 0 -40 -15 10 35 60 0 0.01 85 Temperature (°C) www.austriamicrosystems.com 0.1 1 10 100 1000 Capacitive Load (nF) Revision 1.01 7 - 17 AS1976/AS1977 Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s Figure 15. tPD+ vs. Capacitive Load Figure 16. tPD+ 5V In+ 100 50 2V/Div VCC = 1.8V Out VCC = 3V VCC = 5V 1 10 100 1000 4µs/Div Capacitive Load (nF) Figure 17. tPD- 5V 100mV/Div In+ Out 4µs/Div 2V/Div 100mV/Div 2V/Div Out In+ Figure 18. tPD+ 3V 4µs/Div 100mV/Div In+ Out Out 2V/Div Figure 20. tPD+ 1.8V In+ Figure 19. tPD- 3V 4µs/Div www.austriamicrosystems.com 100mV/Div 0.1 1V/Div tPD+ (µs) . 150 0 0.01 100mV/Div 200 4µs/Div Revision 1.01 8 - 17 AS1976/AS1977 Data Sheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s 20µs/Div 2V/Div VCC Out 2V/Div In+ 2V/Div Figure 24. Powerup/Powerdown Response 100mV/Div Figure 23. 1kHz Response @ 5V Out 1V/Div In+ Out 1V/Div In+ Out 4µs/Div 200µs/Div www.austriamicrosystems.com 100mV/Div Figure 22. 10kHz Response @ 1.8V 100mV/Div Figure 21. tPD- 1.8V 40µs/Div Revision 1.01 9 - 17 AS1976/AS1977 Data Sheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS1976/AS1977 are ultra low-current comparators and are guaranteed to operate with voltages as low as +1.8V. The common-mode input voltage range extends 200mV beyond the rail voltages, and internal hysteresis ensures clean output switching, even with slow input signals. The AS1976 push/pull output stage sinks and sources-current. The AS1977 open-drain output stage can be pulled beyond VCC to an absolute maximum of 3.6V > VEE. The AS1979/AS1977 are perfect for implementing wired-OR output logic functions. For all comparators, large internal output drivers allow rail-to-rail output swings with loads of up to 8mA. The output stage design minimizes supply-current surges during switching, eliminating most power supply transients. Input Stage The input common-mode voltage range extends from (VEE - 0.2V) to (VCC + 0.2V), and the comparators can operate at any differential input voltage within this range. The comparators have very low input bias current (±0.15nA, typ) if the input voltage is within the common-mode voltage range. Inputs are protected from over-voltage conditions by internal ESD protection diodes connected to the supply rails. As the input voltage exceeds the supply rails, these ESD protection diodes are forward biased and begin to conduct. Output Stage The break-before-make output stage is capable of rail-to-rail operation with loads up to 8mA. Many comparators consume orders of magnitude more current during switching than during steady-state operation. Even at loads of up to 8mA, changes in supply-current during an output transition are extremely small (see Figure 5 on page 6). As shown in Figure 5, the minimal supply current increases as the output switching frequency approaches 1kHz. This characteristic reduces the need for power-supply filter capacitors to reduce transients created by comparator switching currents. Because of the unique design of its output stage, the AS1976/AS1977 can dramatically increase battery life, even in high-speed applications. www.austriamicrosystems.com Revision 1.01 10 - 17 AS1976/AS1977 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9 Application Information The AS1976/AS1977 comparators are perfect for use with all 2-cell battery-powered applications. Figure 25 shows a typical application for the AS1977. Figure 25. AS1977 Typical Application Circuit VIN 5 4 VCC IN- AS1977 RPULLUP 1 OUT 3 2 IN+ VEE Internal Hysteresis The comparators were designed with 3mV of internal hysteresis to neutralize the effects of parasitic feedback, i.e., to prevent unwanted rapid changes between the two output states. The internal hysteresis in the AS1976/AS1977 creates two trip points: ! Rising Input Voltage (VTHR) – The comparator switches its output from low to high as VIN rises above this trip point. ! Falling Input Voltage (VTHF) – The comparator switches its output from high to low as VIN falls below this trip point. The area between the trip points is the hysteresis band (VHB) (see Figure 26). When the AS1976/AS1977 input voltages are equivalent, the hysteresis effectively causes one input to move quickly past the other, thus taking the input out of the region where oscillation occurs. In Figure 26 IN- has a fixed voltage applied and IN+ is varied. Note: If the inputs are reversed the output will be inverted. Figure 26. Threshold Hysteresis Band Thresholds IN+ VTHR IN- VHB Hysteresis Band VTHF OUT www.austriamicrosystems.com Revision 1.01 11 - 17 AS1976/AS1977 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Additional Hysteresis (AS1976) Additional hysteresis can be added to the AS1976 and AS1978 with three resistors and positive feedback (see Figure 27), however, this positive feedback method slows hysteresis response time. Figure 27. AS1976 Additional Hysteresis VCC R3 R1 VIN + – R2 VCC VEE OUT VREF Resistor Selection Example For the circuit shown in Figure 27, use the following steps to calculate values for R1, R2, and R3. 1. First select the value for R3. Leakage current at IN is less than 2nA, thus the current through R3 should be at least 0.2µA to minimize errors due to leakage current. The current through R3 at the trip point is: (VREF - VOUT)/R3 (EQ 1) Taking into consideration the two possible output states, solving for R3 yields two formulas: R3 = VREF/IR3 (EQ 2) R3 = (VCC - VREF)/IR3 (EQ 3) Use the smaller of the two resulting values for R3. For example, for VREF = 1.245V, VCC = 3.3V, and IR3 = 1µA, the two resistor values are 1.2MΩ and 2.0MΩ, therefore choose a 1.2MΩ standard resistor for R3. 2. Choose the required hysteresis band (VHB). For this example, choose 33mV. 3. Calculate R1 as: R1 = R3(VHB/VCC) (EQ 4) Substituting the R1 and VHB example values gives: R1 = 1.2MΩ(50mV/3.3V) = 12kΩ 4. Choose the trip point for VIN rising (VTHR) such that VTHR > VREF(R1 + R3)/R3. For this example, choose 3V. 5. Calculate R2 as: R2 = 1/[VTHR/(VREF x R1) - (1/R1) - (1/R3)] (EQ 5) Substituting the R1 and R3 example values gives: R2 = 1/[3.0V/(1.2V x 12kΩ) - (1/12kΩ) - (1/1.2MΩ)] = 8.05kΩ In this example, a standard 8.2kΩ resistor should be used for R2. 6. Verify the trip voltages and hysteresis as: www.austriamicrosystems.com VTHR = VREF x R1[(1/R1) + (1/R2) + (1/R3)] (EQ 6) VTHF = VTHR - (R1 x VCC/R3) (EQ 7) Hysteresis = VTHR - VTHF (EQ 8) Revision 1.01 12 - 17 AS1976/AS1977 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Additional Hysteresis (AS1977) Additional hysteresis can be added to the AS1977 and AS1979 with 4 resistors and positive feedback (see Figure 28). Figure 28. AS1977 Additional Hysteresis VCC R3 R4 R1 VIN + – R2 VCC OUT VEE VREF Resistor Selection Example For the circuit shown in Figure 28, use the following steps to calculate values for R1, R2, R3, and R4. 1. Select R3 according to one of these formulas: R3 = VREF/1µA (EQ 9) R3 = (VCC - VREF)/1µA - R4 (EQ 10) Use the smaller of the two resulting resistor values for R3. 2. Choose the hysteresis band required (VHB). 3. Calculate R1 as: R1 = (R3 + R4)(VHB/VCC) (EQ 11) 4. Choose the trip point for VIN rising (VTHR). 5. Calculate R2 as: R2 = 1/[VTHR/(VREF x R1) - (1/R1) - 1/R3] (EQ 12) 6. Verify the trip voltages and hysteresis as: VIN rising: VTHR = VREF[R1(1/R1 + 1/R2 + 1/R3)] (EQ 13) VIN falling: VTHF = VREF[R1(1/R1 + 1/R2 + 1/(R3+R4))] - [1/(R3+R4)]VCC (EQ 14) Hysteresis = VTHR - VTHF (EQ 15) Zero-Crossing Detector Figure 29 shows the AS1976 in a zero-crossing detector circuit. The inverting input (IN-) is connected to ground, and the non-inverting input (IN+) is connected to a 100mVp-p signal source. When the signal at IN- crosses 0V, the signal at OUT changes states. Figure 29. Zero Crossing Detector 100mVp-p 3 IN+ 4 + – 1 OUT IN5 AS1976 2 VCC www.austriamicrosystems.com VEE Revision 1.01 13 - 17 AS1976/AS1977 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Logic-Level Translation The AS1977 can be used as a 5V-to-3V logic translator. Figure 30 shows an application that converts 5V- to 3V-logic levels, and provides the full 5V logic-swing without creating overvoltage on the 3V logic inputs. Note: When the comparator is powered by a 5V supply, RPULUP for the open-drain output should be connected to the +3V supply voltage. For 3V-to-5V logic-level translations, connect the +3V supply voltage to VCC and the +5V supply voltage to RPULUP. Figure 30. AS1977 Logic-Level Translation Circuit +3/+5V 5 +3/+5V VCC RPullup 100kΩ 4 REF 100kΩ +5/+3V Logic In 1 AS1977 3 OUT +5/+3V Logic Out 2 IN+ VEE Logic-Level Translator Layout Considerations The AS1976/AS1977 requires proper layout and design techniques for optimum performance. ! ! ! ! Power-supply bypass capacitors are not typically required, although 100nF bypass capacitors should be placed close to the AS1976/AS1977 supply pins when supply impedance is high, leads are long, or for excessive noise on the supply lines. Minimize signal trace lengths to reduce stray capacitance. A ground plane should be used. Surface-mount components should be used whenever practical. www.austriamicrosystems.com Revision 1.01 14 - 17 AS1976/AS1977 Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10 Package Drawings and Markings The AS1976/AS1977 are available in a 5-pin SOT23 package. Figure 31. 5-pin SOT23 Package Symbol A A1 A2 b C D E E1 L e e1 α Min Max 0.90 1.45 0.00 0.15 0.90 1.30 0.30 0.50 0.09 0.20 2.80 3.05 2.60 3.00 1.50 1.75 0.30 0.55 0.95 REF 1.90 REF 0º 8º Notes: 1. 2. 3. 4. 5. Controlling dimension is millimeters. Foot length measured at intercept point between datum A and lead surface. Package outline exclusive of mold flash and metal burr. Package outline inclusive of solder plating. Meets JEDEC MO178. www.austriamicrosystems.com Revision 1.01 15 - 17 AS1976/AS1977 Data Sheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The devices are available as the standard products shown in Table 5. Table 5. Ordering Information Type Marking Description Output Type Delivery Form Package AS1976 ASI9 Ultra-Low Current 1.8V Comparator Push/Pull Tube 5-pin SOT23 AS1976-T ASI9 Ultra-Low Current 1.8V Comparator Push/Pull Tape and Reel 5-pin SOT23 AS1977 ASJA Ultra-Low Current 1.8V Comparator Open-Drain Tube 5-pin SOT23 AS1977-T ASJA Ultra-Low Current 1.8V Comparator Open-Drain Tape and Reel 5-pin SOT23 www.austriamicrosystems.com Revision 1.01 16 - 17 AS1976/AS1977 Data Sheet Copyrights Copyright © 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. 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Contact Information Headquarters austriamicrosystems AG A-8141 Schloss Premstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact www.austriamicrosystems.com Revision 1.01 17 - 17