MB3771 Power Supply Monitor Description The Cypress MB3771 is designed to monitor the voltage level of one or two power supplies (+5 V and an arbitrary voltage) in a microprocessor circuit, memory board in large-size computer, for example. If the circuits power supply deviates more than a specified amount, then the MB3771 generates a reset signal to the microprocessor. Thus, the computer data is protected from accidental erasure. Using the MB3771 requires few external components. To monitor only a +5 V supply, the MB3771 requires the connection of one external capacitor. The level of an arbitrary detection voltage is determined by two external resistors. The MB3771 is available in an 8-pin Dual In-Line, Single In-Line Package or space saving Flat Package. Features Precision voltage detection (V = 4.2 V 2.5 %) SA User selectable threshold level with hysteresis (V = 1.23 V 1.5 %) SB Monitors the voltage of one or two power supplies (5 V and an arbitrary voltage, >1.23 V) Usable as over voltage detector Low voltage output for reset signal (V = 0.8 V Typ) CC Minimal number of external components (one capacitor Min) Low power dissipation (I = 0.35 mA Typ, V = 5 V) CC CC Detection threshold voltage has hysteresis function Reference voltage is connectable. One type of package (SOP-8pin : 1 type) Application Industrial Equipment Arcade Amusement etc. Cypress Semiconductor Corporation 198 Champion Court San Jose, CA 95134-1709 408-943-2600 Document Number: 002-08511 Rev. *D Revised June 28, 2017 MB3771 Contents Description ............................................................................. 1 (VCC = 5 V) .................................................................... 11 Features .................................................................................. 1 8.7 5 V Power Supply Monitor with Non-inverted Application ............................................................................. 1 RESET ............................................................................ 11 Contents ................................................................................. 2 8.8 Supply Voltage Monitoring with Delayed Trigger ..... 11 1. Pin Assignment ................................................................. 3 8.9 Dual (Positive/Negative) Power Supply Voltage 2. Block Diagram ................................................................... 3 Monitoring (VCC = 5 V, VEE = Negative Power Supply). 12 3. Functional Descriptions .................................................... 4 8.10 Reference Voltage Generation and Voltage Sagging 4. Function Explanation ........................................................ 4 Detection ........................................................................ 12 5. Absolute Maximum Ratings ............................................. 5 8.11 Low Voltage and Over Voltage Detection 6. Recommended Operating Conditions ............................. 5 (VCC = 5 V) .................................................................... 14 7. Electrical Characteristics .................................................. 6 8.12 Detection of Abnormal State of Power Supply System 7.1 DC Characteristics ..................................................... 6 (VCC = 5 V) .................................................................... 14 7.2 AC Characteristics ...................................................... 7 8.13 Back-up Power Supply System (VCC = 5 V) ......... 15 8. Application Circuit ............................................................. 8 9. Typical Characteristics ................................................... 17 8.1 5V Power Supply Monitor ........................................... 8 10. Notes on Use .................................................................. 19 8.2 5V Power Supply Voltage Monitor 11. Ordering Information ..................................................... 19 (Externally Fine-Tuned Type) ........................................... 8 12. RoHS Compliance Information ..................................... 19 8.3 Arbitrary Voltage Supply Monitor ................................ 9 13. Package Dimensions ..................................................... 20 8.4 5 V and 12 V Power Supply Monitor (2 types of power Document History ................................................................ 21 supply monitor VCC1 = 5 V, VCC2 =12 V) ..................... 10 Sales, Solutions, and Legal Information ...........................22 8.5 5 V and 12 V Power Supply Monitor (RESET signal is generated by 5 V, VCC1 = 5 V, VCC2 = 12 V) ............... 10 8.6 5 V Power Supply Monitor with forced RESET input Document Number: 002-08511 Rev. *D Page 2 of 22