19-2534; Rev 4; 3/09 High-Voltage, Low-Current Voltage Monitors in SOT Packages Features o Wide Supply Voltage Range, 4V to 28V o Internal 2.25V ±2.5% Reference o Low Current (3.5µA, typ at 12V) o Open-Drain n-Channel Output (28V Compliant) o Internal Threshold Hysteresis Options (0.5%, 5%, 8.3%) o Two IN-to-OUT Timeout Period Options (50µs, 150ms) o Internal Undervoltage Lockout o Immune to Short Voltage Transients o Small SOT23 Packages o Few External Components o Fully Specified from -40°C to +125°C Ordering Information PART TEMP RANGE MAX6457UKD_ _-T -40°C to +125°C 5 SOT23 MAX6458UKD_ _-T -40°C to +125°C 5 SOT23 MAX6459UT_-T -40°C to +125°C 6 SOT23 MAX6460UT-T -40°C to +125°C 6 SOT23 Note: The MAX6457/MAX6458/MAX6459 are available with factory-trimmed internal hysteresis options. The MAX6457 and MAX6458 offer two fixed timing options. Select the desired hysteresis and timing options using Table 1 or the Selector Guide at the end of the data sheet, and enter the corresponding letters and numbers in the part number by replacing “_ _” or “_”. These devices are offered in tape-and-reel only and must be ordered in 2500-piece increments. Devices are available in both leaded and lead(Pb)-free/RoHScompliant packaging. Specify lead(Pb)-free by replacing “-T” with “+T” when ordering. Pin Configurations appear at end of data sheet. Typical Operating Circuit Applications Undervoltage Monitoring/Shutdown Overvoltage Monitoring/Protection Window Voltage Detection Circuitry Multicell Battery-Stack Powered Equipment Notebooks, eBooks Automotive Industrial Telecom Networking PIN-PACKAGE BATTERY CHARGER +21V (NOMINAL) IN OUT DC-DC CONVERTER SHDN VCC MAX6457 R1 5-CELL Li+ BATTERY STACK IN+ RPULLUP LOAD OUT R2 GND CLEAR ________________________________________________________________ Maxim Integrated Products 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. 1 MAX6457–MAX6460 General Description The MAX6457–MAX6460 high supply voltage, low-power voltage monitors operate over a 4V to 28V supply voltage range. Each device includes a precision bandgap reference, one or two low-offset voltage comparators, internal threshold hysteresis, power-good or reset timeout options, and one or two high-voltage open-drain outputs. Two external resistors (three for window detection) set the trip threshold voltages. The MAX6457 is a single voltage monitor for undervoltage or overvoltage detection. A logic-based clear input either latches the output for overvoltage applications or allows the device to operate in transparent mode. The MAX6458 includes two comparators (one overvoltage and one undervoltage) for window detection and a single output to indicate if the monitored input is within an adjustable voltage window. The MAX6459 includes dual overvoltage/ undervoltage comparators with two independent comparator outputs. Use the MAX6459 as a window comparator with separate undervoltage and overvoltage outputs or as two independent, single voltage monitors. The MAX6460 includes a single comparator and an internal reference, and can also accept an external reference. The inverting and noninverting inputs of the comparator are externally accessible to support positive or negative voltage monitors and to configure the device for activehigh or active-low output logic. The MAX6457/MAX6458 offer fixed timing options as a voltage detector with a 50µs typical delay or as a reset circuit with a 90ms minimum reset timeout delay. The monitored input must be above the adjusted trip threshold (or within the adjusted voltage window for the MAX6458) for the selected timeout period before the output changes state. The MAX6459/MAX6460 offer only a fixed 50µs timeout period. Internal threshold hysteresis options (0.5%, 5%, and 8.3% for the MAX6457/MAX6458/MAX6459, and 0.5% for the MAX6460) reduce output chatter in noisesensitive applications. Each device is available in a small SOT23 package and specified over the extended temperature range of -40°C to +125°C. MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages ABSOLUTE MAXIMUM RATINGS VCC, OUT, OUTA, OUTB, CLEAR to GND ..........-0.3V to +30.0V IN+, IN- to GND..........................................-0.3V to (VCC + 0.3V) REF to GND..............-0.3V to the lower of +6V and (VCC + 0.3V) Input Currents (VCC, IN+, IN-) ............................................20mA Sink Current (OUT, OUTA, OUTB) ......................................20mA Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1 mW/°C above +70°C)............571mW 6-Pin SOT23 (derate 8.7 mW/°C above +70°C)............696mW Junction Temperature ......................................................+150°C Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 = 4V to 28V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage Range VCC Supply Current ICC CONDITIONS (Note 2) MIN 2 5 7.5 TA = -40°C to +85°C, VCC ≥ 4V VIN rising TA = +85°C to +125°C, VCC ≥ 4V 1.195 TA = -40°C to +85°C 1.180 1.255 TA = +85°C to +125°C 1.155 1.255 TA = -40°C to +85°C 1.133 1.194 1.111 1.194 TA = -40°C to +85°C 1.093 1.151 TA = +85°C to +125°C 1.071 1.151 5 MAX64_ _U_D_C 8.3 VIN (Note 2) IN Leakage Current IIN VIN = 1.25V, VCC = +28V tTP MAX645_UKD0_ MAX6459UT_ MAX6460UT MAX6457 and MAX6458 only, D3 option 2 V %VTH+ 0 VCC V -55 +55 nA 50 90 VCC rising from GND to VCC ≥ 4V in less than 1µs (Note 3) 150 µs 210 2 VIL VIH µA 0.5 MAX64_ _U_D_B IN Operating Voltage Range CLEAR Input Logic Voltage (MAX6457) 12.5 1.255 1.255 MAX64_ _U_D_A Startup Time 6.5 1.228 1.170 VIN MAX645_U_D_B falling TA = +85°C to +125°C MAX645_U_D_C OUT Timeout Period V 3.5 Threshold Voltage Threshold Voltage Hysteresis UNITS 28 VCC = 12V, no load MAX645_U_D_A VTH- MAX VCC = 5V, no load VCC = 24V, no load VTH+ TYP 4 ms 0.4 2 _______________________________________________________________________________________ ms V High-Voltage, Low-Current Voltage Monitors in SOT Packages MAX6457–MAX6460 ELECTRICAL CHARACTERISTICS (continued) (VCC = 4V to 28V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER Output Voltage Low SYMBOL VOL Output Leakage Current Output Short-Circuit Sink ILKG ISC CONDITIONS MIN TYP MAX VCC ≥ 1.5V, ISINK = 250µA, OUT asserted, TA = -40°C to +85°C 0.4 VCC ≥ 4.0V, ISINK = 1mA, OUT asserted, TA = -40°C to +125°C 0.4 UNITS V VCC = 5V, VOUT = 28V (Note 4) 500 OUT asserted, OUT = VCC 10 nA mA MAX6460 Reference Short-Circuit Current Reference Output Voltage REF = GND VREF 7 2.183 2.25 2.303 TA = +85°C to +125°C 2.171 2.25 2.303 Sourcing: 0 ≤ IREF ≤ 100µA, sinking: 0 ≤ |IREF| ≤ 300nA Load Regulation Input Offset Voltage mA TA = -40°C to +85°C VOFFSET 50 -4.5 Input Hysteresis µV/µA +4.5 6 Input Bias Current IBIAS Input Offset Current VIN+ = 1.4V, VIN- = 1V -25 IOFFSET Common-Mode Voltage Range CMVR Common-Mode Rejection Ratio CMRR Comparator Power-Supply Rejection Ratio PSRR 2 VIN+ = VIN- = 1.4V mV mV +25 0 V nA pA 1.4 V 80 dB 80 dB Note 1: Devices are production tested at TA = +25°C. Overtemperature limits are guaranteed by design. Note 2: IN voltage monitoring requires that VCC ≥ 4V, but OUT remains asserted in the correct undervoltage lockout state for VCC down to 1.5V. Note 3: Startup time is the time required for the internal regulator and reference to reach specified accuracy after the monitor is powered up from GND. Note 4: The open-drain output can be pulled up to a voltage greater than VCC but cannot exceed +28V. _______________________________________________________________________________________ 3 Typical Operating Characteristics (GND = 0, RPULLUP = 10kΩ, and TA = +25°C, unless otherwise noted.) TA = +25°C 6 4 TA = -40°C 2 1.21 VTH- (FALLING) 1.19 1.17 1.15 10 16 22 28 VTH- (FALLING) TEMPERATURE (°C) OUTPUT LOW VOLTAGE vs. OUTPUT SINK CURRENT 100,000 10,000 TA = +125°C VTH+ (RISING) 1000 VOL (mV) 1.19 1.17 1.15 1.15 -40 -25 -10 5 20 35 50 65 80 95 110 125 MAX6457-60 toc04 TRIP THRESHOLD VOLTAGE (V) 1.21 1.17 TEMPERATURE (°C) TRIP THRESHOLD VOLTAGE vs. TEMPERATURE (8.3% HYSTERESIS) 1.23 VTH+ (RISING) 1.19 -40 -25 -10 5 20 35 50 65 80 95 110 125 VCC (V) 1.25 1.21 1.11 1.11 4 1.23 1.13 1.13 0 MAX6457-60 toc03 1.23 1.25 MAX6457-60 toc05 TA = +125°C VTH+ (RISING) TRIP THRESHOLD VOLTAGE (V) 8 MAX6457-60 toc02 10 1.25 TRIP THRESHOLD VOLTAGE (V) MAX6457-60 toc01 12 TRIP THRESHOLD VOLTAGE vs. TEMPERATURE (5% HYSTERESIS) TRIP THRESHOLD VOLTAGE vs. TEMPERATURE (0.5% HYSTERESIS) SUPPLY CURRENT vs. SUPPLY VOLTAGE ICC (µA) MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages TA = +25°C 100 TA = -40°C 10 VTH- (FALLING) 1.13 1 1.11 0.1 VCC = 12V -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 4 0.01 0.1 1 10 100 ISINK (mA) _______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages 100 tTP (ms) MAX6457UKD3 12 VCC = 5V 10 11 1 MAX6457UKD0 10 VCC = 24V 0.1 1800 TA = +125°C 1600 1400 1200 1000 800 600 TA = +25°C 400 9 TA = -40°C 200 0.01 8 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 4 8 12 TEMPERATURE (°C) MAXIMUM TRANSIENT DURATION vs. INPUT OVERDRIVE 24 28 10 MAX6457-60 toc10 250 20 INPUT LEAKAGE CURRENT vs. TEMPERATURE MAX6457-60 toc09 300 16 VCC (V) TEMPERATURE (°C) VIN = 1.25V 8 200 6 IIN (nA) MAXIMUM TRANSIENT DURATION (µs) ISC (mA) 13 2000 OUTPUT FALL TIME (ns) VCC = 12V MAX6457-60 toc07 14 1000 MAX6457-60 toc06 15 OUTPUT FALL TIME vs. SUPPLY VOLTAGE TIMEOUT PERIOD vs. TEMPERATURE MAX6457-60 toc08 OUTPUT SHORT-CIRCUIT SINK CURRENT vs. TEMPERATURE 150 100 4 2 OUT ASSERTED LOW ABOVE THIS LINE 50 0 0 -2 1 10 100 INPUT OVERDRIVE (VTH- - VIN+) (mV) 1000 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX6457–MAX6460 Typical Operating Characteristics (continued) (GND = 0, RPULLUP = 10kΩ, and TA = +25°C, unless otherwise noted.) MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages Pin Description PIN MAX6457 MAX6458 MAX6459 MAX6460 NAME FUNCTION MAX6457: Open-Drain Monitor Output. OUT requires an external pullup resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low when VIN+ drops below VTH- and goes high after the timeout period (tTP) when VIN+ exceeds VTH+. 1 1 — 1 OUT MAX6458: Open-Drain Monitor Output. OUT requires an external pullup resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low when VIN+ drops below VTH- or when VIN- exceeds VTH+. OUT goes high after the timeout period (tTP) when VIN+ exceeds VTH+ and VINdrops below VTH-. MAX6460: Open-Drain Monitor Output. OUT requires an external pullup resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low when VIN+ drops below VIN-. OUT goes high when VIN+ is above VIN-. — 1 — OUTA — — 5 — OUTB Open-Drain Monitor B Overvoltage Output. OUTB requires an external pullup resistor. OUTB goes low when VIN- exceeds VTH+ and goes high when VIN- drops below VTH-. OUTB also goes low when VCC drops below 4V. 2 2 2 2 GND Ground 3 3 3 3 IN+ Adjustable Undervoltage Monitor Threshold Input. Noninverting input for MAX6460. — 4 4 4 IN- Adjustable Overvoltage Monitor Threshold Input. Inverting input for MAX6460. 4 6 — Open-Drain Monitor A Undervoltage Output. OUTA requires an external pullup resistor. OUTA goes low when VIN+ drops below VTH- and goes high when VIN+ exceeds VTH+. OUTA also goes low for VCC between 1.5V and 4V. — — — CLEAR Clear Input. For VIN+ > VTH+, drive CLEAR high to latch OUT high. Connect CLEAR to GND to make the latch transparent. CLEAR must be low when powering up the device. Connect CLEAR to GND when not used. — — — 5 REF Reference. Internal 2.25V reference output. Connect REF to IN+ through a voltage divider for active-low output. Connect REF to IN- through a voltage divider for active-high output. REF can source up to 100µA and sink up to 300nA. Leave REF floating when not used. REF output is stable with capacitive loads from 0 to 50pF or greater than 1µF. 5 5 6 6 VCC Supply Voltage _______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages VCC VCC IN+ MAX6458 UV MAX6457 TIMEOUT OPTION IN+ TIMEOUT OPTION LATCH OUT HYSTERESIS OPTION OUT INOV HYSTERESIS OPTION 1.228V CLEAR 1.228V "UV": UNDERVOLTAGE "OV": OVERVOLTAGE GND GND Figure 2. MAX6458 Functional Diagram Figure 1. MAX6457 Functional Diagram VCC VCC IN+ MAX6459 OUTA UV IN+ OUT IN- INOUTB OV REF MAX6460 HYSTERESIS OPTION 2.25V 1.228V "UV": UNDERVOLTAGE "OV": OVERVOLTAGE GND GND Figure 3. MAX6459 Functional Diagram Figure 4. MAX6460 Functional Diagram _______________________________________________________________________________________ 7 MAX6457–MAX6460 Functional Diagrams MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages Detailed Description ⎛ R4 ⎞ VREFD = VREF ⎜ ⎟ ⎝ R 3 + R4 ⎠ Each of the MAX6457–MAX6460 high-voltage (4V to 28V), low-power voltage monitors include a precision bandgap reference, one or two low-offset-voltage comparators, internal threshold hysteresis, internal timeout period, and one or two high-voltage open-drain outputs. Programming the Trip Voltage (VTRIP) Two external resistors set the trip voltage, VTRIP (Figure 5). VTRIP is the point at which the applied voltage (typically VCC) toggles OUT. The MAX6457/MAX6458/MAX6459/ MAX6460’s high input impedance allows large-value resistors without compromising trip-voltage accuracy. To minimize current consumption, select a value for R2 between 10kΩ and 1MΩ, then calculate R1 as follows: ⎛V ⎞ R1 = R2 ⎜ TRIP - 1⎟ ⎝ VTH ⎠ ⎛V ⎞ R1= R2 ⎜ TRIP − 1⎟ ⎝ VREFD ⎠ where VREF = reference output voltage (2.25V, typ), VREFD = divided reference, VTRIP = desired trip threshold in (in volts). For an active-low power-good output, connect the resistor divider R1 and R2 to the inverting input and the reference-divider network to the noninverting input. Alternatively, connect an external reference less than 1.4V to either input. VTRIP VCC VCC RPULLUP R1 VCC RPULLUP R1 MAX6457– MAX6460 IN+ R2 OUT (OUTA FOR MAX6459) IN+ OUT (OUTA) REF VREFD GND VTRIP = VTH MAX6460 R3 OUT OUT R2 INGND R4 R1 + R2 R2 Figure 5a. Programming the Trip Voltage Figure 5b. Programming the MAX6460 Trip Voltage where VTRIP = desired trip voltage (in volts), VTH = threshold trip voltage (VTH+ for overvoltage detection or VTH- for undervoltage detection). Use the MAX6460 voltage reference (REF) to set the trip threshold by connecting IN+ or IN- through a voltage divider (within the inputs common-mode voltage range) to REF. Do not connect REF directly to IN+ or IN- since this violates the input common-mode voltage range. Small leakage currents into the comparators inputs allows use of large value resistors to prevent loading the reference and affecting its accuracy. Figure 5b shows an active-high power-good output. Use the following equation to determine the resistor values when connecting REF to IN-: 8 VHYST VTH+ VIN+ VTH- VCC VOUT 0 tTP tTP Figure 6. Input and Output Waveforms (Noninverting Input Varied) _______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages MAX6457–MAX6460 >VTH+ IN+ <VTH- VCC CLEAR 0 VCC OUT tTP tTP tTP 0 Figure 7. Timing Diagram (MAX6457) Hysteresis Hysteresis adds noise immunity to the voltage monitors and prevents oscillation due to repeated triggering when VIN is near the threshold trip voltage. The hysteresis in a comparator creates two trip points: one for the rising input voltage (VTH+) and one for the falling input voltage (VTH-). These thresholds are shown in Figure 6. The internal hysteresis options of the MAX6457/ MAX6458/MAX6459 are designed to eliminate the need for adding an external hysteresis circuit. Timeout Period The timeout period (tTP) for the MAX6457 is the time from when the input (IN+) crosses the rising input threshold (VTH+) to when the output goes high (see Figures 6 and 7). For the MAX6458, the monitored voltage must be in the “window” before the timeout starts. The MAX6459 and MAX6460 do not offer the extended timeout option (150ms). The extended timeout period is suitable for overvoltage protection applications requiring transient immunity to avoid false output assertion due to noise spikes. Latched-Output Operation The MAX6457 features a digital latch input (CLEAR) to latch any overvoltage event. If the voltage on IN+ (VIN+) is below the internal threshold (VTH-), or if VCC is below BATTERY CHARGER +21V IN OUT DC-DC CONVERTER SHDN VCC MAX6457– MAX6460 R1 5-CELL Li+ BATTERY STACK IN+ R2 RPULLUP LOAD OUT (OUTA FOR MAX6459) GND Figure 8. Undervoltage Lockout Typical Application Circuit 4V, OUT remains low regardless of the state of CLEAR. Drive CLEAR high to latch OUT high when VIN+ exceeds VTH+. When CLEAR is high, OUT does not deassert if VIN+ drops back below VIN-. Toggle CLEAR to deassert OUT. Drive CLEAR low to make the latch transparent (Figure 7). CLEAR must be low when powering up the MAX6457. To initiate self-clear at power-up, add a 100kΩ pullup resistor from CLEAR to VCC and a 1µF capacitor from CLEAR to GND to hold CLEAR low. Connect CLEAR to GND when not used. See Figure 9. _______________________________________________________________________________________ 9 MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages FUSE VSUPPLY VSUPPLY R1 VCC VCC LOAD IN+ 100kΩ MAX6457– MAX6460 R2 CLEAR RPULLUP LOAD OUT (OUTA FOR MAX6459) GND Figure 9. Overvoltage Shutdown Circuit (with External Pass MOSFET) Applications Information Undervoltage Lockout Figure 8 shows the typical application circuit for detecting an undervoltage event of a 5-cell Li+ battery stack. Connect OUT of the MAX6457/MAX6458/MAX6460 (OUTA of the MAX6459) to the shutdown input of the DCDC converter to cut off power to the load in case of an undervoltage event. Select R1 and R2 to set the trip voltage (see the Programming the Trip Voltage (VTRIP) section). When the voltage of the battery stack decreases so that VIN+ drops below VTH- of the MAX6457–MAX6460, then OUT (OUTA) goes low and disables the power supply to the load. When the battery charger restores the voltage of the 5-cell stack so that VIN+ > VTH+, OUT (OUTA) goes high and the power supply resumes driving the load. GND Figure 10. Overvoltage Shutdown Circuit (with SCR Fuse) Window Detection The MAX6458/MAX6459 include undervoltage and overvoltage comparators for window detection (Figures 2 and 3). The circuit in Figure 11 shows the typical configuration for this application. For the MAX6458, OUT asserts high when VCC is within the selected “window.” When VCC falls below the lower limit of the window (VTRIPLOW) or exceeds the upper limit (VTRIPHIGH), OUT asserts low. The MAX6459 features two independent open-drain outputs: OUTA (for undervoltage events) and OUTB (for overvoltage events). When VCC is within the selected window, OUTA and OUTB assert high. When VCC falls below V TRIPLOW , OUTA asserts low while OUTB VCC Overvoltage Shutdown The MAX6457–MAX6460 are ideal for overvoltage shutdown applications. Figure 9 shows a typical circuit for this application using a pass P-channel MOSFET. The MAX6457–MAX6460 are powered directly from the system voltage supply. Select R1 and R2 to set the trip voltage (see the Programming the Trip Voltage (V TRIP) section). When the supply voltage remains below the selected threshold, a low logic level on OUT (OUTB for MAX6459) turns on the p-channel MOSFET. In the case of an overvoltage event, OUT (OUTB) asserts high, turns off the MOSFET, and shuts down the power to the load. Figure 10 shows a similar application using a fuse and a silicon-controlled rectifier (SCR). An overvoltage event turns on the SCR and shorts the supply to ground. The surge of current through the short circuit blows the fuse and terminates the current to the load. Select R3 so that the gate of the SCR is properly biased when OUT (OUTB) goes high impedance. 10 SCR OUT (OUTA FOR MAX6459) IN+ R2 1µF R3 MAX6457– MAX6460 R1 VCC VCC RPULLUP OUT MAX6458 ONLY R1 OUT VCC IN+ MAX6458 MAX6459 R2 RPULLUP INR3 RPULLUP OUTA OUTA OUTB MAX6459 ONLY OUTB GND Figure 11. Window Detection ______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages ⎛R ⎞ VTRIPLOW = VTH- ⎜ TOTAL ⎟ ⎝ R2 + R3 ⎠ ⎛R ⎞ VTRIPHIGH = VTH+ ⎜ TOTAL ⎟ ⎝ R3 ⎠ where RTOTAL = R1 + R2 + R3. Use the following steps to determine the values for R1, R2, and R3. 1) Choose a value for RTOTAL, the sum of R1, R2, and R3. Because the MAX6458/MAX6459 have very high input impedance, RTOTAL can be up to 5MΩ. 2) Calculate R3 based on R TOTAL and the desired upper trip point: V × RTOTAL R3 = TH+ VTRIPHIGH 3) Calculate R2 based on RTOTAL, R3, and the desired lower trip point: Example Calculations for Window Detection The following is an example for calculating R1, R2, and R3 of Figure 11 for window detection. Select the upper and lower trip points (VTRIPHIGH and VTRIPLOW). VCC = 21V VTRIPHIGH = 23.1V VTRIPLOW = 18.9V For 5% hysteresis, VTH+ = 1.228 and VTH- = 1.167. 1) Choose RTOTAL = 4.2MΩ = R1 + R2 + R3 2) Calculate R3 R3 = VTH+ × RTOTAL (1.228V) (4.2MΩ) = VTRIPHIGH 23.1V = 223.273kΩ 3) Calculate R2 VOUT (UP TO 28V) VCC (4V TO 28V) VCC RPULLUP V × RTOTAL R2 = TH- R3 VTRIPLOW MAX6457– MAX6460 OUT/ OUTA/ OUTB OUT/ OUTA/ OUTB 4) Calculate R1 based on RTOTAL, R3, and R2: R1 = RTOTAL - R2 - R3 GND Figure 13. Interfacing to Voltages Other than VCC VCC VCC VMON VCC VCC INRPULLUP RPULLUP R1 MAX6457– MAX6460 IN+ R2 OUT (OUTA FOR MAX6459) MAX6460 OUT OUT (OUTA) OUT REF R1 IN+ GND GND R2 VNEG Figure 12. Monitoring Voltages Other than VCC Figure 14. Monitoring Negative Voltages ______________________________________________________________________________________ 11 MAX6457–MAX6460 remains high. When VCC exceeds VTRIPHIGH, OUTB asserts low while OUTA remains high. VTRIPLOW and VTRIPHIGH are given by the following equations: MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages Table 1. Factory-Trimmed Internal Hysteresis and Timeout Period Options PART SUFFIX TIMEOUT OPTION HYSTERESIS OPTION (%) 0A 50µs 0.5 MAX6457UKD_ _ -T MAX6458UKD_ _ -T MAX6459UT_ -T MAX6460UT-T 0B 50µs 5 0C 50µs 8.3 3A 150ms 0.5 3B 150ms 5 3C 150ms 8.3 A 50µs 0.5 B 50µs 5 C 50µs 8.3 N/A 50µs 0.5 Selector Guide TIMEOUT PERIOD PIN COUNT LATCHED OUTPUT NUMBER OF OUTPUTS HYSTERESIS (%VTH+) MAX6457UKD0A-T 5 ✓ 1 0.5 MAX6457UKD3A-T 5 ✓ 1 0.5 MAX6457UKD0B-T 5 ✓ 1 5 50µs AANL 1 MAX6457UKD3B-T 5 ✓ 1 5 150ms AANO 1 MAX6457UKD0C-T 5 ✓ 1 8.3 50µs AANM 1 MAX6457UKD3C-T 5 ✓ 1 8.3 150ms ADZZ 1 MAX6458UKD0A-T 5 — 1 0.5 50µs AANP 2 MAX6458UKD3A-T 5 — 1 0.5 150ms AANS 2 MAX6458UKD0B-T 5 — 1 5 50µs AANQ 2 MAX6458UKD3B-T 5 — 1 5 150ms AEAB 2 MAX6458UKD0C-T 5 — 1 8.3 50µs AANR 2 MAX6458UKD3C-T 5 — 1 8.3 150ms AANT 2 MAX6459UTA-T 6 — 2 0.5 50µs ABML 2 MAX6459UTB-T 6 — 2 5 50µs ABEJ 2 MAX6459UTC-T 6 — 2 8.3 50µs ABMM 2 MAX6460UT-T 6 — 1 0.5 50µs ABEG 1 PART 12 TOP MARK COMPARATORS 50µs AEAA 1 150ms AANN 1 ______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages Interfacing to Voltages Other than VCC The open-drain outputs of the MAX6457–MAX6460 allow the output voltage to be selected independent of VCC. For systems requiring an output voltage other than VCC, connect the pullup resistor between OUT, OUTA, or OUTB and any desired voltage up to 28V (see Figure 13). VTH- × RTOTAL - R3 VTRIPLOW (1.167V) (4.2MΩ) - 223.273kΩ 18.9V = 36.06kΩ = Monitoring Negative Voltages 4) Calculate R1 Figure 14 shows the typical application circuit for monitoring negative voltages (VNEG) using the MAX6460. Select a value for R1 between 25kΩ and 1MΩ. Use the following equation to select R2: R1 = RTOTAL - R2 - R3 = 4.2MΩ - 223.273kΩ - 36.06kΩ = 3.94067MΩ R2 = R1 × Monitoring Voltages Other than VCC The MAX6457–MAX6460 can monitor voltages other than V CC (Figure 12). Calculate V TRIP as shown in the Programming the Trip Voltage (VTRIP) section. The monitored voltage (VMON) is independent of VCC. VIN+ must be within the specified operating range: 0 to VCC. -VNEG VREF where VREF = 2.25V and VNEG < 0. VIN+ must always be within the specified operating range: 0 to VCC. Pin Configurations TOP VIEW OUT 1 GND 2 5 VCC MAX6457 IN+ 3 OUT 1 GND 2 4 CLEAR OUTA 1 GND 2 MAX6459 IN+ 3 SOT23 VCC 4 IN- 6 VCC 5 REF 4 IN- MAX6458 IN+ 3 SOT23 5 SOT23 6 VCC OUT 1 5 OUTB GND 2 4 IN- MAX6460 IN+ 3 SOT23 ______________________________________________________________________________________ 13 MAX6457–MAX6460 R2 = MAX6457–MAX6460 High-Voltage, Low-Current Voltage Monitors in SOT Packages Package Information Chip Information TRANSISTOR COUNT: 785 PROCESS: BiCMOS 14 For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 5 SOT23 U5-1 21-0057 6 SOT23 U5-1 21-0058 ______________________________________________________________________________________ High-Voltage, Low-Current Voltage Monitors in SOT Packages REVISION NUMBER REVISION DATE 0 7/02 Initial release 1 6/03 Updated the Pin Description and Detailed Description sections. 2 12/05 Added lead-free notation to Ordering Information. 3 1/07 Updated the Pin Description and Figures 5a, 9, 12. 4 3/09 Updated the Programming the Trip Voltage (VTRIP) section. DESCRIPTION PAGES CHANGED — 6, 8 1 6, 8, 10, 11, 13-16 8 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX6457–MAX6460 Revision History