19-5986; Rev 1; 12/11 EVALUATION KIT AVAILABLE MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator General Description Features The MAX44269 is an ultra-small and low-power dual comparator ideal for battery-powered applications such as cell phones, notebooks, and portable medical devices that have extremely aggressive board space and power constraints. The comparator is available in a miniature 1.3mm x 1.3mm, 9-bump WLP package, making it the industry’s smallest dual comparator. SUltra-Low Power Consumption 0.5µA per Comparator The IC can be powered from supply rails as low as 1.8V and up to 5.5V. It requires just 0.5µA of typical supply current per comparator. It has a rail-to-rail input structure and a unique output stage that limits supply current surges while switching. This design also minimizes overall power consumption under dynamic conditions. The IC has open-drain outputs, making it suitable for mixed voltage systems. The IC also features internal filtering to provide high RF immunity. It operates over a -40°C to +85°C temperature. S 6V Tolerant Inputs Independent of Supply Applications Smartphones Notebooks Two-Cell Battery-Powered Devices Battery-Operated Sensors Ultra-Low-Power Systems Portable Medical Mobile Accessories S Ultra-Small 1.3mm x 1.3mm WLP Package S Guaranteed Operation Down to VCC = 1.8V S Input Common-Mode Voltage Range Extends 200mV Beyond-the-Rails S Open-Drain Outputs S Internal Filters Enhance RF Immunity S Crowbar-Current-Free Switching S Internal Hysteresis for Clean Switching S No Output Phase Reversal for Overdriven Inputs Ordering Information appears at end of data sheet. For related parts and recommended products to use with this part, refer to www.maxim-ic.com/MAX44269.related. Typical Application Circuit VCC VCC VPULL MAX44269 VCC OUT1 VREF VPULL VCC OUT2 REMOTE KEY CONNECTOR GND ACCESSORY ID ����������������������������������������������������������������� Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator ABSOLUTE MAXIMUM RATINGS VCC to GND..............................................................-0.3V to +6V INA+, INA-, INB+, INB- to GND...............................-0.3V to +6V Continuous Input Current into Any Pin............................. Q20mA Maximum Power Dissipation (derate 11.9mW/NC at TA = +70NC).............................952mW Output Voltage to GND (OUT_)...............................-0.3V to +6V Output Current (OUT_)..................................................... Q50mA Output Short-Circuit Duration (OUT_)........................Continuous Operating Temperature Range........................... -40NC to +85NC Storage Temperature Range............................. -65NC to +150NC Junction Temperature......................................................+150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC PACKAGE THERMAL CHARACTERISTICS (Note 1) WLP Junction-to-Ambient Thermal Resistance (qJA)...........84°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. Stresses beyond those listed under “Absolute Maximum Ratings” 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 the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4 6 mV DC CHARACTERISTICS Input-Referred Hysteresis VHYS (VGND - 0.2V) P VCM P (VCC + 0.2V) (Note 3) Input Offset Voltage VOS VGND - 0.2V P VCM P VCC + 0.2V (Note 4) Input Bias Current Output-Voltage Swing Low IB VOL 0.15 0.2 VCC = 1.8V, ISINK = 1mA VCM Inferred from VOS test Output Short-Circuit Current ISC Sinking, VOUT = VCC VCC = 5.5V, VOUT = 5.5V 5 10 TA = +25NC Input Voltage Range ILEAK 0.15 -40NC P TA P +85NC TA = -40NC to +85NC VCC = 5V, ISINK = 6mA Output Leakage Current TA = +25NC TA = +25NC 105 -40NC P TA P +85NC nA 200 300 TA = +25NC 285 -40NC P TA P +85NC mV 350 mV 450 VGND - 0.2V VCC + 0.2V VCC = 1.8V 3 VCC = 5V 30 0.2 V mA nA ����������������������������������������������������������������� Maxim Integrated Products 2 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator ELECTRICAL CHARACTERISTICS (continued) (VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kI to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS AC CHARACTERISTICS Propagation Delay High to Low (Note 5) Propagation Delay Low to High (Note 5) Fall Time tPHL tPLH tF Input overdrive = Q100mV, VCC = 5V 5 Input overdrive = Q100mV, VCC = 1.8V 7 Input overdrive = Q20mV, VCC = 5V 8 Input overdrive = Q20mV, VCC = 1.8V 12 Input overdrive = Q100mV, VCC = 5V 34 Input overdrive = Q100mV, VCC = 1.8V 12 Input overdrive = Q20mV, VCC = 5V 35 Input overdrive = Q20mV, VCC = 1.8V 12 CLOAD = 15pF 0.2 Fs Fs Fs POWER SUPPLY Supply Voltage Range Power-Supply Rejection Ratio VCC PSRR Supply Current per Comparator ICC Power-Up Time tON Note Note Note Note Guaranteed from PSRR tests 1.8 VCC = 1.8V to 5.5V 60 5.5 80 dB VCC = 1.8V, TA = +25NC 0.4 0.75 VCC = 5V, TA = +25NC 0.5 0.85 VCC = 5V, -40NC P TA P +85NC V FA 1 1 ms 2: All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design. 3: Hysteresis is the input voltage difference between the two switching points. 4:VOS is the average of the positive and negative trip points minus VREF. 5: Overdrive is defined as the voltage above or below the switching points. ����������������������������������������������������������������� Maxim Integrated Products 3 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Typical Operating Characteristics (VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.) 0.6 TA = +25°C TA = -40°C 0.4 0.2 VOUT = HIGH TA = +25°C TA = -40°C 0.4 10 8 VCC = 5V 6 VCC = 2.7V 4 VCC = 1.8V 2 VOUT = LOW 0 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) INPUT FREQUENCY (Hz) INPUT OFFSET VOLTAGE vs. TEMPERATURE INPUT BIAS CURRENT vs. TEMPERATURE INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE -0.25 -0.30 VDD = 2.7V -0.35 -0.40 VDD = 1.8V -0.45 -0.50 VDD = 5V 0.14 0.12 0.10 VDD = 2.7V 0.08 VDD = 1.8V 0.06 -20 0 20 40 60 80 450 -20 0 20 40 60 80 VOUT = LOW TA = -40°C 30 25 15 TA = +85°C 10 10k PULLUP RESISTANCE (I) 100k 1 2 3 4 5 6 INPUT OFFSET VOLTAGE HISTOGRAM TA = +25°C 20 0 45 40 35 OCCURRENCE (%) 35 -1 MAX44269 toc08 40 SHORT-CIRCUIT CURRENT (mA) MAX44269 toc07 1k VDD = 0V INPUT COMMON-MODE VOLTAGE (V) 30 25 20 15 10 5 0 100 150 100 5 1 VDD = 5V 200 0 -40 SHORT-CIRCUIT CURRENT vs. SUPPLY VOLTAGE 10 VDD = 2.7V 250 50 OUTPUT-VOLTAGE LOW vs. PULLUP RESISTANCE 100 300 100 TEMPERATURE (°C) 1000 VDD = 1.8V 350 0.02 TEMPERATURE (°C) 10,000 400 0.04 100 10k 500 0 -40 1k MAX44269 toc06 0.16 100 MAX44269 toc09 -0.20 0.18 10 1 INPUT BIAS CURRENT (nA) -0.15 MAX44269 toc05 VDD = 5V -0.10 0.20 INPUT BIAS CURRENT (nA) -0.05 MAX44269 toc04 0 INPUT OFFSET VOLTAGE (mV) 0.8 0.2 0 OUTPUT VOLTAGE LOW (VOL - VEE) 1.0 0.6 12 SUPPLY CURRENT (µA) 0.8 TA = +85°C 1.2 SUPPLY CURRENT (µA) 1.0 14 MAX44269 toc02 TA = +85°C SUPPLY CURRENT (µA) 1.4 MAX44269 toc01 1.2 SUPPLY CURRENT vs. TRANSITION FREQUENCY (VOVERDRIVE = 20mV) SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX44269 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE 0 0 1 2 3 4 SUPPLY VOLTAGE (V) 5 6 -2 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 INPUT OFFSET VOLTAGE (mV) ����������������������������������������������������������������� Maxim Integrated Products 4 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Typical Operating Characteristics (continued) (VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.) 0.30 0.25 VCC = 5V 0.20 VCC = 2.7V 0.15 0.10 tPLH 60 40 -10 10 30 50 70 90 50 40 30 tPHL 110 1k 10k 1M 100k 0 10M 200 400 600 800 TEMPERATURE (°C) PULLUP RESISTANCE (I) CAPACITIVE LOAD (pF) PROPAGATION DELAY vs. TEMPERATURE (VOVERDRIVE = 100mV, VDD = 5V) PROPAGATION DELAY vs. INPUT OVERDRIVE (tPLH) PROPAGATION DELAY vs. INPUT OVERDRIVE (tPHL) 30 tPLH 25 20 15 tPHL 10 5 0 -40 -20 0 20 40 60 80 50 TA = +25°C TA = -40°C 40 30 TA = +85°C 20 10 8 0 0 0 200 400 600 800 1000 4.0 3.5 3.0 200 400 600 800 1000 INPUT OVERDRIVE VOLTAGE (mV) SMALL-SIGNAL TRANSIENT RESPONSE (VCC = 5V) SMALL-SIGNAL TRANSIENT RESPONSE (VCC = 1.8V) MAX44269 toc16 4.5 TA = +85°C 0 INPUT OVERDRIVE VOLTAGE (mV) INPUT REFERRED HYSTERESIS vs. TEMPERATURE TA = +25°C 4 2 100 TA = -40°C 6 10 TEMPERATURE (°C) 1000 MAX44269 toc15 35 12 PROPAGATION DELAY (µs) 40 60 PROPAGATION DELAY (µs) MAX44269 toc13 45 INPUT REFERRED HYSTERESIS (mV) 60 0 0 -30 70 10 VCC = 1.8V 0 -50 tPLH 80 20 tPHL 20 0.05 PROPAGATION DELAY (µs) 80 90 MAX44269 toc12 100 100 PROPAGATION DELAY (µs) 0.35 MAX44269 toc11 0.40 120 MAX44269 toc14 OUTPUT LEAKAGE CURRENT (nA) 0.45 PROPAGATION DELAY (µs) MAX44269 toc10 0.50 PROPAGATION DELAY vs. CAPACITIVE LOAD PROPAGATION DELAY vs. PULLUP RESISTANCE LEAKAGE CURRENT vs. TEMPERATURE MAX44269 toc18 MAX44269 toc17 VIN+ 20mV/div VIN+ 20mV/div 2.5 2.0 VOUT 1V/div 1.5 VOUT 2V/div 1.0 0.5 0 -40 -20 0 20 40 60 80 100 20µs/div 20µs/div TEMPERATURE (°C) ����������������������������������������������������������������� Maxim Integrated Products 5 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Typical Operating Characteristics (continued) (VCC = 5V, VGND = 0V, VIN- = VIN+ = 1.2V, RPULLUP = 100kΩ to VCC, TA = -40NC to +85NC. Typical values are at TA = +25NC, unless otherwise noted. All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.) LARGE-SIGNAL TRANSIENT RESPONSE (VCC = 5V) LARGE-SIGNAL TRANSIENT RESPONSE (VCC = 1.8V) MAX44269 toc20 MAX44269 toc19 VIN+ 100mV/div VIN+ 200mV/div VOUT 1V/div VOUT 2V/div 20µs/div 20µs/div NO OUTPUT PHASE REVERSAL POWER-UP RESPONSE MAX44269 toc22 MAX44269 toc21 VIN 200mV/div VIN -0.3V TO +6V VCC 2V/div VOUT VOUT 2V/div 800µs/div 20µs/div ����������������������������������������������������������������� Maxim Integrated Products 6 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Bump Configuration TOP VIEW 1 MAX44269 2 3 A INA- INA+ OUTA B GND N.C. VCC C INB- INB+ OUTB + WLP Bump Description PIN NAME FUNCTION A1 INA- Comparator A Inverting Input A2 INA+ Comparator A Noninverting Input A3 OUTA Comparator A Output B1 GND Negative Supply Voltage. Bypass to GND with a 1.0FF capacitor. B2 N.C. Not Connected B3 VCC Positive Supply Voltage. Bypass to GND with a 1.0FF capacitor. C1 INB- Comparator B Inverting Input C2 INB+ Comparator B Noninverting Input C3 OUTB Comparator B Output ����������������������������������������������������������������� Maxim Integrated Products 7 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Detailed Description The MAX44269 is a general-purpose dual comparator for battery-powered devices where area, power, and cost constraints are crucial. The IC can operate with a low 1.8V supply rail typically consuming 0.5µA quiescent current per comparator. This makes it ideal for mobile and very low-power applications. The IC’s common-mode input voltage range extends 200mV beyond-the-rails. An internal 4mV hysteresis ensures clean output switching, even with slow-moving input signals. Input Stage Structure The input common-mode voltage range extends from (VGND - 0.2V) to (VCC + 0.2V). The comparator operates at any different input voltage within these limits with low input bias current. Input bias current is typically 0.15nA if the input voltage is between the supply rails. The IC features a unique input ESD structure that can handle voltages from -0.3V to 6V independent of supply voltage. This allows for the device to be powered down with a signal still present on the input without damaging the part. This feature is useful in applications where one of the inputs has transient spikes that exceed the supply rails. Applications Information Hysteresis Many comparators oscillate in the linear region of operation because of noise or undesired parasitic feedback. This tends to occur when the voltage on one input is equal or very close to the voltage on the other input. The hysteresis in a comparator creates two trip points: one for the rising input voltage and one for the falling input voltage (Figure 1). The difference between the trip points is the hysteresis. When the comparator’s input voltages are equal and the output trips, the hysteresis effectively causes one comparator input to move quickly past the other. This takes the input out of the region where oscillation occurs. This provides clean output transitions for noisy, slow-moving input signals. The IC has an internal hysteresis of 4mV. Additional hysteresis can be generated with three resistors using positive feedback (Figure 2). VHYST VTL OUT Figure 1. Threshold Hysteresis Band (Not to Scale) VCC Open-Drain Output The IC features an open-drain output, enabling greater control of speed and power consumption in the circuit design. The output logic level is also independent from the input, allowing for simple level translation. R3 RF Immunity The IC has very high RF immunity due to on-chip filtering of RF sensitive nodes. This allows the IC to hold its output state even in the presence of high amounts of RF noise. This improved RF immunity makes the IC ideal for mobile wireless devices. VTH HYSTERESIS BAND IN- No Output Phase Reversal for Overdriven Inputs The IC’s design is optimized to prevent output phase reversal if both the inputs are within the input common mode voltage range. If one of the inputs is outside the input common-mode voltage range, then output phase reversal does not occur as long as the other input is kept within the valid input common-mode voltage range. This behavior is shown in the No Output Phase Reversal graph in the Typical Operating Characteristics section. THERSHOLDS IN+ R1 MAX44269 R2 VIN OUT R4 VREF GND Figure 2. Adding Hysteresis with External Resistors ����������������������������������������������������������������� Maxim Integrated Products 8 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Use the following procedure to calculate resistor values. 1) Select R3. Input bias current at IN_+ is less than15nA. To minimize errors caused by the input bias current, the current through R3 should be at least 1.5µA. Current through R3 at the trip point is (VREF - VOUT)/ R3. Considering the two possible output states in solving for R3 yields two formulas: R3 = VREF/IR3 and R3 = [(VCC - VREF)/IR3] - R1 Use the smaller of the two resulting resistor values. For example, for VCC = 5V, IR3 = -1.5µA, R1 = 200kI, and a VREF = 1.24V, the two resistor values are 827kI and 1.5MI. Therefore, for R3 choose the standard value of 825kI. 2)Choose the hysteresis band required (VHB). In this example, the VHB = 50mV. 3) Calculate R2 according to the following equation: VHB = (R1 + R3) R2 V CC + (VREF x R1) / R3 For this example, insert the value: 1 1 1 = V THR VREF xR2 + + R2 R3 R4 1 1 1 V= THF VREF x R2 + + R2 R1 + R3 R4 R2 x VCC − R1 + R3 The hysteresis network in Figure 2 can be simplified if the reference voltage is chosen to be at midrail and the trip points of the comparator are chosen to be symmetrical about the reference voltage. Use the circuit in Figure 3 if the reference voltage can be designed to be at the center of the hysteresis band. For the symmetrical case, follow the same steps outlined in the paragraph above to calculate the resistor values except that in this case, resistor R4 approaches infinity (open). So in the previous example with VREF = 2.5V, if VTHR = 2.525V and VTHF = 2.475V then using the above formulas, we get R1 = 200kI, R2 = 9.09kI and R3 = 825kI, R4 = not installed. Jack Detect 50mV = R2 (200kΩ + 0.825MΩ) = 9.67kΩ 5.3 For this example, choose standard value R2 = 9.76kI. 4) Choose the trip point for VIN rising (VTHR) in such a way that: VTHR > VREF 1 + 6) Verify the trip voltages and hysteresis as follows: VHB VCC VTHR is the threshold voltage at which the comparator switches its output from low to high, as VIN rises above the trip point. For this example, choose VTHR = 3V. The IC can be used to detect peripheral devices connected to a circuit. This includes a simple jackdetect scheme for cell phone applications. The Typical Application Circuit shows how the device can be used in conjunction with an external reference to detect a remote key connection and an accessory ID input. The opendrain output of the devices allows the output logic level to be controlled independent of the peripheral device’s load, making interfacing and controlling external devices as simple as monitoring a few digital inputs on a microcontroller or codec. VCC R3 5) Calculate R4 as follows: 1 V THR 1 1 − − VREF x R2 R2 R3 1 = = 6.93kΩ R4 1 1 3 − − 1.24 x 9.76 9.76 825 R4 = For this example, choose a standard value of 6.98kI. R1 MAX44269 R2 VIN OUT VREF GND Figure 3. Simplified External Hysteresis Network if VREF is at the Center of the Hysteresis Band ����������������������������������������������������������������� Maxim Integrated Products 9 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Logic-Level Translator Due to the open-drain output of the IC, the device can translate between two different logic levels (Figure 4). If the internal 4 mV hysteresis is not sufficient, then external resistors can be added to increase the hysteresis as shown in Figure 2 and Figure 3. Power-On Reset Circuit The IC can be used to make a power-on reset circuit as displayed in Figure 5. The positive input provides the ratiometric reference with respect to the power supply and is created by a simple resistive divider. Choose reasonably large values to minimize the power consumption in the resistive divider. The negative input provides the power-on delay time set by the time constant of the RC circuit formed by R2 and C1. This simple circuit can be used to power up the system in a known state after ensuring that the power supply is stable. Diode D1 provides a rapid reset in the event of unexpected power loss. VPULL VIN R3 x R4 V T_RISE = VCC R2R3 + R2R4 + R3R4 R4R5(R1 + R2 + R3) + R1R3R4 V T_FALL = VCC R4R5 (R1 + R2 + R3) + R1R3R4 + R2(R1R3 + R3R5 + R1R5) Using the basic time domain equations for the charging and discharging of an RC circuit, the logic-high time, logic-low time, and frequency can be calculated as: VCC MAX44269 Relaxation Oscillator The IC can also be used to make a simple relaxation oscillator (Figure 6). By adding the RC circuit R5 and C1, a standard Schmidt Trigger circuit referenced to a set voltage is converted into an astable multivibrator. As shown in Figure 7, IN- is a sawtooth waveform with capacitor C1 alternately charging and discharging through resistor R5. The external hysteresis network formed by R1 to R4 defines the trip voltages as: V T_FALL tLOW = R5C1 ln V T_RISE R1 OUT VREF VCC GND R3 VCC Figure 4. Logic-Level Translator R3 D1 R2 OUT R4 MAX44269 R1 MAX44269 R2 VCC VCC R1 GND RESET R5 R4 C1 C1 GND Figure 6. Relaxation Oscillator Figure 5. Power-On Reset Circuit ���������������������������������������������������������������� Maxim Integrated Products 10 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Since the comparator’s output is open drain, it goes to The frequency of the relaxation oscillator is: high impedance corresponding to logic-high. So, when 1 1 the output is at logic-high, the C1 capacitor charges f = = V T_FALL (VCC − VT_RISE ) through the resistor network formed by R1 to R5 as shown tHIGH + tLOW R5C11n in Figure 8. An accurate calculation of tHIGH would have V T_RISE (VCC − V T_FALL) involved applying thevenin’s theorem to compute the equivalent thevenin voltage (VTHEVENIN) and thevenin Simple PWM Generation Circuit resistance (RTHEVENIN) in series with the capacitor A pulse-width modulated (PWM) signal generator can be C1. tHIGH can then be computed using the basic time made utilizing both comparators in the IC (Figure 9). The domain equations for the charging RC circuit as: capacitor/feedback resistor combination on INA- deter VTHEVENIN − V T_RISE mines the switching frequency and the analog control tHIGH = R THEVENIN C1 ln voltage determines the pulse width. VTHEVENIN − V T_FALL R THEVENIN = [(R2 R4) + R3] R1 + R5 = VTHEVENIN VCC [(R2 R4) + R3] V x R4 + CC (R2 R4) + R3 + R1 R2 + R4 R1 x (R2 R4) + R3 + R1 The tHIGH calculation can be simplified by selecting the component values in such a way that R3 >> R1 and R5 >> R1. This ensures that the output of the comparator goes close to VCC when at logic-high (that is, VTHEVENIN ~ VCC and RTHEVENIN ~ R5). With this selection, tHIGH can be approximated as: VCC VCC R2 R1 R3 VTHEVENIN C1 C1 R4 Figure 8. Charging Network Corresponding to Logic-High Output R4 VCC VCC − V T_RISE tHIGH = R5C1 ln VCC − V T_FALL RTHEVENIN R5 VCC R2 R1 R3 INAR5 VT_FALL C1 WAVEFORM VT_RISE C1 VCC MAX44269 ANALOG CONTROL VOLTAGE R6 OUT OUT WAVEFORM GND Figure 7. Relaxation Oscillator Waveforms Figure 9. PWM Generator ���������������������������������������������������������������� Maxim Integrated Products 11 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Window Detector Circuit The IC is ideal for window detectors (undervoltage/overvoltage detectors). Figure 10 shows a window detector circuit for a single-cell Li+ battery with a 2.9V end-of-life charge, a peak charge of 4.2V, and a nominal value of 3.6V. Choose different thresholds by changing the values of R1, R2, and R3. OUTA provides an active-low undervoltage indication, and OUTB provides an active-low overvoltage indication. The open-drain outputs of both the comparators are wired OR to give an active-high power-good signal. Board Layout and Bypassing Use 1.0FF bypass capacitors from VCC to GND. To maximize performance, minimize stray inductance by putting this capacitor close to the VCC pin and reducing trace lengths. VIN R3 The design procedure is as follows: INA+ 1) Select R1. The input bias current into INB- is less than 15nA, so the current through R1 should exceed 1.5µA for the thresholds to be accurate. In this example, choose R1 = 825kI (1.24V/1.5µA). 2) Calculate R2 + R3. The overvoltage threshold should be 4.2V when VIN is rising. The design equation is as follows: V = R2 + R3 R1 x OTH − 1 V REF 4.2 = 825 x − 1 1.24 = 1969kΩ 3) Calculate R2. The undervoltage threshold should be 2.9V when VIN is falling. The design equation is as follows: R2 For this example, choose a 374kI standard value 1% resistor. 4) Calculate R3: MAX44269 INA- POWER GOOD INB+ OUTB REF 1.24V INB- GND R1 GND Figure 10. Window Detector Circuit Chip Information PROCESS: BiCMOS Ordering Information = ((825 + 1969) x (1.24 / 2.9)) − 825 VCC OUTA V R2 = (R1 + R2 + R3)x REF − R1 V UTH = 370kΩ 5V VOTH = 4.2V VUTH = 2.9V PART TEMP RANGE PINPACKAGE TOP MARK MAX44269EWL+T -40NC to +85NC 9 WLP +AJL +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. R3 = (R2 + R3) − R2 = 1969kΩ − 374kΩ =1.595MΩ For this example, choose a 1.58MI standard value 1% resistor. ���������������������������������������������������������������� Maxim Integrated Products 12 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 9 WLP W91B1-6 21-0430 Refer to Application Note 1891 ���������������������������������������������������������������� Maxim Integrated Products 13 MAX44269 1.3mm x 1.3mm, Low-Power Dual Comparator Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 9/11 Initial release 1 12/11 Revised Electrical Characteristics, Typical Operating Characteristics, and Figure 5. PAGES CHANGED — 3, 5, 6, 9, 10 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products 14 Maxim is a registered trademark of Maxim Integrated Products, Inc.