19-0291; Rev 1; 3/07 Hex/Quad, Power-Supply Supervisory Circuits The MAX6887/MAX6888 multivoltage supply supervisors provide several voltage-detector inputs, one watchdog input, and three outputs. Each voltage-detector input offers a factory-set undervoltage and overvoltage threshold. Manual reset and margin disable inputs offer additional flexibility. The MAX6887 offers six voltage-detector inputs, while the MAX6888 offers four inputs. Output RESET asserts when any input voltage drops below its respective undervoltage threshold or manual reset MR is asserted. Output OV asserts when any input voltage exceeds its respective overvoltage threshold. Monitor standard supply voltages listed in the Selector Guide. The MAX6887/MAX6888 offer a watchdog timer with an initial and normal timeout periods of 102.4s and 1.6s, respectively. Watchdog output WDO asserts when the watchdog timer expires. Connect WDO to manual reset input MR to generate resets when the watchdog timer expires. RESET, OV, and WDO are active-low, opendrain outputs. The MAX6887/MAX6888 are available in a 5mm x 5mm x 0.8mm, 16-pin thin QFN package and operate over the extended -40°C to +85°C temperature range. Applications Multivoltage Systems Telecom Networking Servers/Workstations/Storage Systems Features ♦ Hex/Quad Voltage Detectors ♦ Undervoltage and Overvoltage Thresholds ♦ 1% Threshold Accuracy ♦ Margining Disable and Manual Reset Input ♦ Watchdog Timer ♦ Open-Drain RESET, OV, and WDO Outputs ♦ 180ms (min) Reset Timeout Period ♦ Few External Components ♦ Small 5mm x 5mm, 16-Pin Thin QFN Packages Ordering Information PART TEMP RANGE PINPACKAGE PKG CODE MAX6887_ETE -40°C to +85°C 16 Thin QFN T1655-2 MAX6888_ETE -40°C to +85°C 16 Thin QFN T1655-2 Note: Insert the desired letter from the Selector Guide into the blank to complete the part number. Pin Configurations and Typical Operating Circuit appear at end of data sheet. Selector Guide NOMINAL INPUT VOLTAGE (V)* NOMINAL INPUT VOLTAGE (V)* IN4 IN5 IN6 TOL (%) 2.5 1.8 Adj Adj 5 MAX6887IETE 5.0 3.3 2.5 1.8 Adj Adj 10 2.5 Adj Adj Adj 5 MAX6887JETE 5.0 3.3 2.5 Adj Adj Adj 10 3.3 1.8 Adj Adj Adj 5 MAX6887KETE 5.0 3.3 1.8 Adj Adj Adj 10 2.5 1.8 1.5 Adj Adj 5 MAX6887LETE 3.3 2.5 1.8 1.5 Adj Adj 10 3.3 2.5 1.8 Adj Adj Adj 5 MAX6887METE 3.3 2.5 1.8 Adj Adj Adj 10 3.3 2.5 1.5 Adj Adj Adj 5 MAX6887NETE 3.3 2.5 1.5 Adj Adj Adj 10 MAX6887GETE 3.3 2.5 Adj Adj Adj Adj 5 MAX6887OETE 3.3 2.5 Adj Adj Adj Adj 10 MAX6887HETE 3.3 1.8 Adj Adj Adj Adj 5 MAX6887PETE 3.3 1.8 Adj Adj Adj Adj 10 MAX6887QETE Adj Adj Adj Adj Adj 5 MAX6887RETE Adj Adj Adj Adj Adj Adj 10 PART IN1 IN2 IN3 MAX6887AETE 5.0 3.3 MAX6887BETE 5.0 3.3 MAX6887CETE 5.0 MAX6887DETE 3.3 MAX6887EETE MAX6887FETE Adj PART IN1 IN2 IN3 IN4 IN5 IN6 TOL (%) *See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds. Selector Guides continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX6887/MAX6888 General Description MAX6887/MAX6888 Hex/Quad, Power-Supply Supervisory Circuits ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) IN1–IN6, VCC, RESET, OV, WDO .............................-0.3V to +6V WDI, MR, MARGIN ...................................................-0.3V to +6V BP .............................................................................-0.3V to +3V Input/Output Current (all pins)..........................................±20mA Continuous Power Dissipation (TA = +70°C) 16-Pin 5mm x 5mm Thin QFN (derate 20.8mW/°C above +70°C) ..............................1667mW Maximum Junction Temperature .....................................+150°C Operating Temperature Range ...........................-40°C to +85°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 (VIN1–VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL Operating Voltage Range (Note 3) Supply Current Threshold Accuracy (See the Selector Guide) CONDITIONS Voltage on either one of IN1–IN4 or VCC to guarantee the part is fully operational ICC VTH MIN TYP 2.7 VIN1 = 5.8V, IN2–IN6 = GND, no load 0.9 MAX UNITS 5.8 V 1.2 mA IN1–IN6, IN_ falling, TA = +25°C to +85°C -1 +1 IN1–IN6, IN_ falling, TA = -40°C to +85°C -1.5 +1.5 % VTH Threshold Hysteresis VTH-HYST 0.3 % VTH Threshold Tempco ∆VTH/°C 10 ppm/°C IN_ Input Impedance RIN IN_ Input Leakage Current IIN Power-Up Delay tD-PO For VIN_ < highest VIN1–IN4 and VIN_ < VCC (not ADJ), thresholds are not set as adjustable IN5, IN6 (MAX6887 only) IN1–IN4 set as adjustable thresholds 200 -150 VCC ≥ 2.5V IN_ to RESET or OV Delay tD-R RESET Timeout Period tRP OV Timeout Period tOP RESET, OV, and WDO Output Low VOL ISINK = 4mA, output asserted RESET, OV, and WDO Output Open-Drain Leakage Current ILKG Output high impedance 2 130 IN_ falling/rising, 100mV overdrive 300 kΩ +150 nA 2.5 ms 220 ms 20 180 200 µs 25 -1 _______________________________________________________________________________________ µs 0.4 V +1 µA Hex/Quad, Power-Supply Supervisory Circuits (VIN1–VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP VIL MR, MARGIN, WDI Input Voltage MR Input Pulse Width UNITS 0.6 VIH 1.4 tMR 1 V µs MR Glitch Rejection 100 MR to RESET or OV Delay tD-MR MR to Internal BP Pullup Current IMARGIN WDI Pulldown Current ns 200 IMR MARGIN to Internal BP Pullup Current IWDI ns VMR = 1.4V 5 10 15 µA VMARGIN = 1.4V 5 10 15 µA 5 10 15 µA VWDI = 0.6V WDI Input Pulse Width 50 Watchdog Timeout Period Note 1: Note 2: Note 3: Note 4: MAX ns tWDI Initial 92.16 102.4 112.64 tWD Normal 1.44 1.6 1.76 s 100% production tested at TA = +25°C and TA = +85°C. Specifications at TA = -40°C are guaranteed by design. Device may be supplied from any one of IN1–IN4 or VCC. The internal supply voltage, measured at VCC, equals the maximum of IN1–IN4. Versions Q and R require that power be applied through VCC. Typical Operating Characteristics (VIN1–VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA = +25°C, unless otherwise noted.) VCC SUPPLY CURRENT vs. VCC SUPPLY VOLTAGE 0.85 0.80 TA = +25°C TA = -40°C 0.75 0.95 TA = +85°C 0.90 0.85 0.80 TA = +25°C 2.6 3.6 4.6 SUPPLY VOLTAGE (V) 5.6 205 200 195 185 0.70 0.70 210 190 TA = -40°C 0.75 215 TIMEOUT PERIOD (ms) 0.90 220 MAX6887 toc02 TA = +85°C SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 0.95 1.00 MAX6887 toc01 1.00 RESET TIMEOUT PERIOD vs. TEMPERATURE MAX6887 toc03 IN1–IN4 SUPPLY CURRENT vs. IN1–IN4 SUPPLY VOLTAGE 180 2.6 3.6 4.6 SUPPLY VOLTAGE (V) 5.6 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX6887/MAX6888 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN1–VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA = +25°C, unless otherwise noted.) 27 26 25 24 23 1.650 1.625 1.600 1.575 1.550 22 21 1.525 20 1.500 -40 -15 10 35 60 85 1.005 MAX6887 toc06 1.675 TIMEOUT PERIOD (s) 1.004 1.003 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995 -40 -15 10 35 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) MAXIMUM IN_ TRANSIENT vs. IN_THRESHOLD OVERDRIVE OUTPUT-VOLTAGE LOW vs. SINK CURRENT MR TO RESET OUTPUT PROPAGATION DELAY vs. TEMPERATURE 150 125 100 PO_ ASSERTION OCCURS ABOVE THIS LINE 75 50 25 350 300 250 200 150 100 2.75 50 0 10 100 1000 IN_ THRESHOLD OVERDRIVE (mV) 2.50 2.25 2.00 1.75 1.50 1.25 0 1 MAX6887 toc09 3.00 PROPAGATION DELAY (µs) 175 400 OUTPUT-VOLTAGE LOW (mV) MAX6887 toc07 200 MAX8667 toc08 PROPAGATION DELAY (µs) 28 MAX6887 toc05 100mV OVERDRIVE 29 NORMALIZED IN_ THRESHOLD vs. TEMPERATURE 1.700 MAX6887 toc04 30 WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE NORMALIZED IN_ THRESHOLD IN_ TO RESET OR OV PROPAGATION DELAY vs. TEMPERATURE MAXIMUM TRANSIENT DURATION (µs) MAX6887/MAX6888 Hex/Quad, Power-Supply Supervisory Circuits 1.00 0 2 4 6 8 10 12 14 SINK CURRENT (mA) -40 -15 10 35 60 85 TEMPERATURE (°C) Pin Description PIN NAME MAX6887 MAX6888 1 1 RESET 2 2 WDO 3 3 OV 4 4 GND 4 FUNCTION Open-Drain, Active-Low Reset Output. RESET asserts when any input voltage falls below its undervoltage threshold or when MR is pulled low. RESET remains low for 200ms after all assertion-causing conditions are cleared. An external pullup resister is required. Open-Drain, Active-Low Watchdog Timer Output. Logic output for the watchdog timer function. WDO goes low when WDI is not strobed high-to-low or low-to-high within the watchdog timeout period. Open-Drain Active-Low Overvoltage Output. OV asserts when any input voltage exceeds its overvoltage threshold. OV remains low for 25µs after all overvoltage conditions are cleared. An external pullup resistor is required. Ground _______________________________________________________________________________________ Hex/Quad, Power-Supply Supervisory Circuits PIN MAX6887 MAX6888 5 5 NAME FUNCTION MR Manual Reset Input. Pull MR low to assert RESET. Connect MR to WDO to generate resets when the watchdog timer expires. Leave MR unconnected or connect to DBP if unused. MR is internally pulled up to BP through a 10µA current source. 6 6 MARGIN Margin Input. When MARGIN is pulled low, RESET is held in its existing state independent of subsequent changes in monitored input voltages or the watchdog timer expiration. MARGIN is internally pulled up to BP through a 10µA current source. Leave MARGIN unconnected or connect to BP if unused. MARGIN overrides MR if both are asserted at the same time. 7 7 WDI Watchdog Timer Input. Logic input for the watchdog timer function. If WDI is not strobed with a valid low-to-high or high-to-low transition within the selected watchdog timeout period, WDO asserts. WDI is internally pulled down to GND through a 10µA current sink. 8 8 I.C. Internal Connection. Leave unconnected. 9 9 VCC Internal Power-Supply Voltage. Bypass VCC to GND with a 1µF ceramic capacitor as close to the device as possible. VCC supplies power to the internal circuitry. VCC is internally powered from the highest of the monitored IN1–IN4 voltages. Do not use VCC to supply power to external circuitry. To externally supply VCC, see the Powering the MAX6887/MAX6888 section. 10 10 BP Bypass Voltage. The internally generated voltage at BP supplies power to internal logic and output RESET. Connect a 1µF capacitor from BP to GND as close to the device as possible. Do not use BP to supply power to external circuitry. IN6 Input Voltage Detector 6. IN6 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. IN6 cannot power the device. For improved noise immunity, bypass IN6 to GND with a 0.1µF capacitor installed as close to the device as possible. IN5 Input Voltage Detector 5. IN5 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. IN5 cannot power the device. For improved noise immunity, bypass IN5 to GND with a 0.1µF capacitor installed as close to the device as possible. IN4 Input Voltage Detector 4. IN4 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4 or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity, bypass IN4 to GND with a 0.1µF capacitor installed as close to the device as possible. IN3 Input Voltage Detector 3. IN3 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4 or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity, bypass IN3 to GND with a 0.1µF capacitor installed as close to the device as possible. IN2 Input Voltage Detector 2. IN2 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4 or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity, bypass IN2 to GND with a 0.1µF capacitor installed as close to the device as possible. 11 12 13 14 15 — — 13 14 15 16 16 IN1 Input Voltage Detector 1. IN1 monitors both undervoltage and overvoltage conditions. See the thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4 or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity, bypass IN1 to GND with a 0.1µF capacitor installed as close to the device as possible. — 11, 12 N.C. No Connection. Not internally connected. — — EP Exposed Paddle. Internally connected to GND. Connect EP to GND or leave unconnected. _______________________________________________________________________________________ 5 MAX6887/MAX6888 Pin Description (continued) Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888 Functional Diagram WDI *IN_ DETECTOR IN1 MARGIN MR IN2 IN2 DETECTOR IN3 IN3 DETECTOR IN4 IN4 DETECTOR IN5 (N.C.) IN6 (N.C.) IN5 DETECTOR RESET TIMING BLOCK OV OV TIMING BLOCK (VIRTUAL DIODES) IN6 DETECTOR LOGIC ARRAY RESET WDO WDO TIMING BLOCK VCC REFERENCE 1µF 2.55V LDO MAX6887 MAX6888 BP 1µF ( ) MAX6888 ONLY GND *FOR ADJUSTABLE INPUTS REFER TO THE ADJUSTABLE THRESHOLD INPUTS SECTION. 6 _______________________________________________________________________________________ Hex/Quad, Power-Supply Supervisory Circuits The MAX6887/MAX6888 provide several supply-detector inputs, one watchdog input, and three outputs for powersupply monitoring applications. The MAX6887 offers six voltage-detector inputs, while the MAX6888 offers four. Each voltage-detector input offers both an undervoltage and overvoltage threshold. The undervoltage and overvoltage thresholds are factory-set for monitoring standard supply voltages (see the Selector Guide). Inputs in the Selector Guide that contain “Adj” allow an external voltage-divider to be connected to set a user-defined threshold. RESET goes low when any input voltage drops below its undervoltage threshold or when MR is brought low. RESET stays low for 200ms after all assertion-causing conditions have been cleared. OV goes low when an input voltage rises above its overvoltage threshold. OV typically stays low for 25µs (typ) after all inputs fall back under their overvoltage thresholds. The MAX6887/MAX6888 offer a watchdog timer with initial and normal timeout periods of 102.4s and 1.6s, respectively. WDO goes low when the watchdog timer expires and deasserts when WDI transitions from lowto-high or high-to-low. The MAX6887/MAX6888 generate a supply voltage at BP for the internal logic circuitry. Bypass BP to GND with a 1µF ceramic capacitor installed as close to the device as possible. The nominal BP output voltage is +2.55V. Do not use BP to provide power to external circuitry. Inputs The MAX6887 offers six voltage-detector inputs, while the MAX6888 offers four voltage-detector inputs. Each voltage-detector input offers an undervoltage and overvoltage threshold set at the factory to monitor standard supply voltages (see the Selector Guide). The 5% and 10% tolerances are based on maximum and minimum threshold values. Actual thresholds for the MAX6887/MAX6888 are shown in Tables 1 and 2. Inputs in the Selector Guide listing “Adj” allow an external voltage-divider to be connected to set a userdefined threshold. Adjustable Threshold Inputs Inputs listed in the Selector Guide containing “Adj” for inputs allow external resistor voltage-dividers to be connected at the voltage-detector inputs. These inputs monitor any voltage supply higher than 0.6V (see Figure 1). Use the following equation to set a voltage- Powering the MAX6887/MAX6888 The MAX6887/MAX6888 derive power from the voltagedetector inputs IN1–IN4 or through an externally supplied VCC. A virtual diode-ORing scheme selects the positive input that supplies power to the device (see the Functional Diagram). The highest input voltage on IN1–IN4 supplies power to the device. One of IN1–IN4 must be at least 2.7V to ensure proper operation. Internal hysteresis ensures that the supply input that initially powered the device continues to power the device when multiple input voltages are within 50mV of each other. VCC powers the analog circuitry and is the bypass connection for the MAX6887/MAX6888 internal supply. Bypass V CC to GND with a 1µF ceramic capacitor installed as close to the device as possible. The internal supply voltage, measured at VCC, equals the maximum of IN1–IN4. If VCC is externally supplied, VCC must be at least 200mV higher than any voltage applied to IN1–IN4 and VCC must be brought up first. VCC always powers the device when all IN_ are factory set as “Adj.” Do not use the internally generated VCC to provide power to external circuitry. VIN MAX6887 MAX6888 R1 IN_ R2 *VREFUV *VREFOV *VREFOV AND VREFUV ARE REFERENCED TO 0.6V ACCORDING TO THE DEVICE'S TOLERANCE Figure 1. Adjusting the Monitored Threshold _______________________________________________________________________________________ 7 MAX6887/MAX6888 Detailed Description MAX6887/MAX6888 Hex/Quad, Power-Supply Supervisory Circuits detector input (IN1–IN6) to monitor a user-defined supply voltage: ⎛ R2 ⎞ 0.6V = VMON × ⎜ ⎟ ⎝ R1+ R2 ⎠ where VMON is the desired voltage to be monitored. Use the following procedure to design the proper voltage-divider and calculate thresholds: 1) Pick a value for R2. Use the equation above with the desired supply voltage to be monitored and solve for R1. Use high-value resistors R1 and R2 to minimize current consumption due to low leakage currents. 2) To find the actual undervoltage and overvoltage thresholds, use the following equations: ⎛V ⎞ VACTUALUV = VMON × ⎜ REFUV ⎟ ⎝ 0.6V ⎠ ⎛V ⎞ VACTUALOV = VMON × ⎜ REFOV ⎟ ⎝ 0.6V ⎠ VREFUV and VREFOV are the undervoltage and overvoltage thresholds listed in Tables 1 and 2 that allow adjustable thresholds. Their values are based on tolerances of ±7.5% and ±12.5% from a 0.6V reference. See the Selector Guide to find which thresholds in Tables 1 and 2 are adjustable. Manual Reset (MR) Many µP-based products require manual reset capability to allow an operator or external logic circuitry to initiate a reset. The manual reset input (MR) can be connected directly to a switch without an external pullup resistor or debouncing network. MR is internally pulled up to BP. Leave unconnected if not used. MR is internally pulled up to BP through a 10µA current source. MR is designed to reject fast, falling transients (typically 100ns pulses) and MR must be held low for a minimum of 1µs to assert RESET. Connect a 0.1µF capacitor from MR to ground to provide additional noise immunity. After MR transitions from low to high, RESET remains asserted for the duration of its time delay. Margin Output Disable (MARGIN) MARGIN allows system-level testing while power supplies exceed the normal operating ranges. Drive MARGIN low to hold RESET, OV, and WDO in their Table 1. MAX6887 Threshold Options PART UV THRESHOLDS (V) OV THRESHOLDS (V) IN1 IN2 IN3 IN4 IN5 IN6 IN1 IN2 IN3 IN4 IN5 IN6 MAX6887AETE 4.620 3.060 2.310 1.670 0.557 0.557 5.360 3.540 2.680 1.930 0.643 0.643 MAX6887BETE 4.620 3.060 2.310 0.557 0.557 0.557 5.360 3.540 2.680 0.643 0.643 0.643 MAX6887CETE 4.620 3.060 1.670 0.557 0.557 0.557 5.360 3.540 1.930 0.643 0.643 0.643 MAX6887DETE 3.060 2.310 1.670 1.390 0.557 0.557 3.540 2.680 1.930 1.610 0.643 0.643 MAX6887EETE 3.060 2.310 1.670 0.557 0.557 0.557 3.540 2.680 1.930 0.643 0.643 0.643 MAX6887FETE 3.060 2.310 1.390 0.557 0.557 0.557 3.540 2.680 1.610 0.643 0.643 0.643 MAX6887GETE 3.060 2.310 0.557 0.557 0.557 0.557 3.540 2.680 0.643 0.643 0.643 0.643 MAX6887HETE 3.060 1.670 0.557 0.557 0.557 0.557 3.540 1.930 0.643 0.643 0.643 0.643 MAX6887QETE 0.557 0.557 0.557 0.557 0.557 0.557 0.643 0.643 0.643 0.643 0.643 0.643 MAX6887IETE 4.380 2.880 2.190 1.580 0.527 0.527 5.620 3.700 2.810 2.020 0.673 0.673 MAX6887JETE 4.380 2.880 2.190 0.527 0.557 0.557 5.620 3.700 2.810 0.673 0.673 0.673 MAX6887KETE 4.380 2.880 1.580 0.527 0.557 0.557 5.620 3.700 2.020 0.673 0.673 0.673 MAX6887LETE 2.880 2.190 1.580 1.310 0.557 0.557 3.700 2.810 2.020 1.680 0.673 0.673 MAX6887METE 2.880 2.190 1.580 0.527 0.557 0.557 3.700 2.810 2.020 0.673 0.673 0.673 MAX6887NETE 2.880 2.190 1.310 0.527 0.557 0.557 3.700 2.810 1.680 0.673 0.673 0.673 MAX6887OETE 2.880 2.190 0.527 0.527 0.557 0.557 3.700 2.810 0.673 0.673 0.673 0.673 MAX6887PETE 2.880 1.580 0.527 0.527 0.557 0.557 3.700 2.020 0.673 0.673 0.673 0.673 MAX6887RETE 0.527 0.527 0.527 0.527 0.527 0.527 0.673 0.673 0.673 0.673 0.673 0.673 8 _______________________________________________________________________________________ Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888 Table 2. MAX6888 Threshold Options PART UV THRESHOLDS (V) OV THRESHOLDS (V) IN1 IN2 IN3 IN4 IN1 IN2 IN3 IN4 MAX6888AETE 4.620 3.060 2.310 1.670 5.360 3.540 2.680 1.930 MAX6888BETE 4.620 3.060 2.310 0.557 5.360 3.540 2.680 0.643 MAX6888CETE 4.620 3.060 1.670 0.557 5.360 3.540 1.930 0.643 MAX6888DETE 3.060 2.310 1.670 1.390 3.540 2.680 1.930 1.610 MAX6888EETE 3.060 2.310 1.670 0.557 3.540 2.680 1.930 0.643 MAX6888FETE 3.060 2.310 1.390 0.557 3.540 2.680 1.610 0.643 MAX6888GETE 3.060 2.310 0.557 0.557 3.540 2.680 0.643 0.643 MAX6888HETE 3.060 1.670 0.557 0.557 3.540 1.930 0.643 0.643 MAX6888QETE 0.527 0.527 0.527 0.527 0.673 0.673 0.673 0.673 MAX6888IETE 4.380 2.880 2.190 1.580 5.620 3.700 2.810 2.020 MAX6888JETE 4.380 2.880 2.190 0.527 5.620 3.700 2.810 0.673 MAX6888KETE 4.380 2.880 1.580 0.527 5.620 3.700 2.020 0.673 MAX6888LETE 2.880 2.190 1.580 1.310 3.700 2.810 2.020 1.680 MAX6888METE 2.880 2.190 1.580 0.527 3.700 2.810 2.020 0.673 MAX6888NETE 2.880 2.190 1.310 0.527 3.700 2.810 1.680 0.673 MAX6888OETE 2.880 2.190 0.527 0.527 3.700 2.810 0.673 0.673 MAX6888PETE 2.880 1.580 0.527 0.527 3.700 2.020 0.673 0.673 MAX6888RETE 0.557 0.557 0.557 0.557 0.643 0.643 0.643 0.643 existing state while system-level testing occurs. Leave MARGIN unconnected or connect to BP if unused. An internal 10µA current source pulls MARGIN to BP. MARGIN overrides MR if both are asserted at the same time. The state of RESET, OV, and WDO does not change while MARGIN = GND. RESET, OV, and WDO Outputs The MAX6887/MAX6888 feature three active-low opendrain outputs: RESET, OV, and WDO. After power-up or overvoltage/undervoltage conditions, RESET and OV remain in their active states until their timeout periods expire and no undervoltage/overvoltage conditions are present (see Figure 2). OV asserts when any monitored input is above its overvoltage threshold and remains asserted until all inputs are below their thresholds and its respective 25µs timeout period expires. Connect OV to MR to bring RESET low during an overvoltage condition. OV requires a pullup resistor (unless connected to MR). RESET asserts when any monitored input is below its undervoltage threshold or MR is asserted. RESET remains asserted for 200ms after all assertion-causing conditions have been cleared. Configure RESET to assert when the watchdog timer expires by connecting WDO to MR. RESET requires a pullup resistor. WDO asserts when the watchdog timer expires. See the Configuring the Watchdog Timer section for a complete description. WDO requires a pullup resistor. Configuring the Watchdog Timer A watchdog timer monitors microprocessor (µP) software execution for a stalled condition and resets the µP if it stalls. Connect the watchdog timer output WDO to the reset input or a nonmaskable interrupt of the µP. The watchdog timer features independent initial and normal watchdog timeout periods of 102.4s and 1.6s, respectively. _______________________________________________________________________________________ 9 MAX6887/MAX6888 Hex/Quad, Power-Supply Supervisory Circuits OVERVOLTAGE THRESHOLD VIN PRIMARY THRESHOLD OV tOP RESET tRP Figure 2. Output Timing Diagram 2.5V . 2.5V VCC OR IN1–IN4 VCC OR IN1–IN4 WDO WDO RESET RESET WDI WDI tD-PO tRP *tWDI tWD *tWDI tD-PO tRP *tWDI WDO CONNECTED TO MR WDO NOT CONNECTED TO MR *tWDI IS THE INITIAL WATCHDOG TIMER PERIOD Figure 3. Watchdog, Reset, and Power-Up Timing Diagram 10 ______________________________________________________________________________________ tWD tRP *tDWI Hex/Quad, Power-Supply Supervisory Circuits Selector Guide (continued) NOMINAL INPUT VOLTAGE (V)* PART TOLERANCE (%) IN1 IN2 IN3 IN4 MAX6888AETE 5.0 3.3 2.5 1.8 5 MAX6888BETE 5.0 3.3 2.5 Adj 5 MAX6888CETE 5.0 3.3 1.8 Adj 5 MAX6888DETE 3.3 2.5 1.8 1.5 5 MAX6888EETE 3.3 2.5 1.8 Adj 5 MAX6888FETE 3.3 2.5 1.5 Adj 5 MAX6888GETE 3.3 2.5 Adj Adj 5 MAX6888HETE 3.3 1.8 Adj Adj 5 MAX6888QETE Adj Adj Adj Adj 5 MAX6888IETE 5.0 3.3 2.5 1.8 10 MAX6888JETE 5.0 3.3 2.5 Adj 10 MAX6888KETE 5.0 3.3 1.8 Adj 10 MAX6888LETE 3.3 2.5 1.8 1.5 10 MAX6888METE 3.3 2.5 1.8 Adj 10 Layout and Bypassing MAX6888NETE 3.3 2.5 1.5 Adj 10 For better noise immunity, bypass each of the voltagedetector inputs to GND with 0.1µF capacitors installed as close to the device as possible. Bypass VCC and BP to GND with 1µF capacitors installed as close to the device as possible. VCC (when not externally supplied) and BP are internally generated voltages and should not be used to supply power to external circuitry. MAX6888OETE 3.3 2.5 Adj Adj 10 MAX6888PETE 3.3 1.8 Adj Adj 10 MAX6888RETE Adj Adj Adj Adj 10 Applications Information *See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds. Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 11 MAX6887/MAX6888 At power-up, WDO goes high after tD-PO (see Figure 3). The initial watchdog timeout period (tWDI) applies immediately after WDO is high. The initial watchdog timeout period allows the µP to perform its initialization process. A normal watchdog timeout period (tWD) applies whenever WDI transitions from high to low after the initial watchdog timeout period occurs. WDI monitors the toggling output of the µP, indicating normal processor behavior. If WDI does not toggle during the normal watchdog timeout period (t WD ), indicating that the processor has stopped operating or is stuck in an infinite execution loop, WDO goes low. WDO stays low until the next transition on WDI. An initial watchdog timeout period (tWDI) starts when WDO goes high. If WDO is connected to MR, the WDO will assert for a short duration (~5µs), long enough to assert the RESET output. Asserting RESET clears the watchdog timer and WDO goes high. The reset output will remain asserted for its timeout period after a watchdog fault. The watchdog timer stays cleared as long as RESET is low. Hex/Quad, Power-Supply Supervisory Circuits IN6 BP VCC N.C. N.C. BP VCC 12 11 10 9 12 11 10 9 IN4 13 IN3 14 8 I.C. IN4 13 7 WDI IN3 14 IN1 16 *EXPOSED PAD 2 3 4 1 2 3 4 GND MR RESET 5 GND IN2 15 OV RESET 1 MARGIN WDO *EXPOSED PAD 6 OV IN2 15 IN1 16 8 I.C. 7 WDI 6 MARGIN 5 MR MAX6888 MAX6887 WDO TOP VIEW IN5 MAX6887/MAX6888 Pin Configurations THIN QFN THIN QFN *EXPOSED PAD CONNECTED TO GND. *EXPOSED PAD CONNECTED TO GND. Typical Operating Circuit 12V 12V DC-DC 1 5V DC-DC 2 3.3V DC-DC 3 2.5V DC-DC 4 1.8V 1.5V 1.2V IN1 IN2 IN3 IN4 IN5* IN6* VCC OV LOGIC INPUT WDO LOGIC INPUT VCC µP BP MAX6887 MAX6888 MARGIN RESET RESET LOGIC OUTPUT WDI GND MR GND *MAX6887 ONLY 12 ______________________________________________________________________________________ Hex/Quad, Power-Supply Supervisory Circuits QFN THIN.EPS ______________________________________________________________________________________ 13 MAX6887/MAX6888 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) MAX6887/MAX6888 Hex/Quad, Power-Supply Supervisory Circuits Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) Revision History Pages changed at Rev 1: 1, 5, 14 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. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.