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MIC1815 Microprocessor Reset Circuit MIC1815 Microprocessor Reset Circuit Description The MIC1815 is an inexpensive microprocessor supervisory circuit that monitor power supplies in microprocessor based systems. The function of these devices is to assert a reset if the power supply drops below a designated reset threshold level. Several different reset threshold levels are available to accomodate 10% or 20% drop in 3.3V powered systems. The MIC1815 has an active low RESET output. The reset output is guaranteed to remain asserted for a minimum of 100ms after VCC has risen above the designated reset threshold level. The MIC1815 comes in a 3-pin SOT-23 package. Pin Configuration Top View RESET 1 MIC1815 VCC 2 3 GND Typical Applications Features RESET * as 1.4V Remains Valid with VCC as Low * Precision Voltage Monitor for 10% or * Portable Equipment * Intelligent Instruments * Critical Microprocessor Power Monitoring * Printers/Computers * Controllers Reset Threshold Voltage (V) 2.88 2.55 Device Suffix -10 -20 * Available in 3-Pin SOT23 Package * 9A Supply Current * 100ms Minimum Reset Pulse Width * No External Components Required Typical Operating Circuit 20% drop in 3.3V Power Supplies Ordering Information Part MIC1815_U Package 3-Lead SOT23 Temp. Range -40C to +85C 8++ 8++ MIC1815 8++ P Place the device suffix of desired reset threshold voltage from table above in blank to complete the part number. 4-5-6 4-5-6 1 MIC1815 Microprocessor Reset Circuit Absolute Maximum Ratings Terminal Voltage VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V Input Current, VCC, . . . . . . . . . . . . . . . . . . . . . . . 20mA Output Current, RESET . . . . . . . . . . . . . . 20mA Rate of Rise, VCC . . . . . . . . . . . . . . . . . . . . . . 100V/s Operating Temperature Range MIC1815-U . . . . . . . . . . . . . . . . . . . . . . . . -40C to 85C Storage Temperature Range . . . . . . . . . . . . .-65C to 150C Lead Temperature (Soldering - 10 sec.) . . . . . . . . . . . 300C Power Dissipation (TA = +70C) . . . . . . . . . . . . . . . . 320mW Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability. Operating ranges define those limits between which the functionality of the device is guaranteed. Electrical Characteristics VCC = 3.3V, TA = Operating Temperature Range, unless otherwise noted. Parameter Operating Voltage Range, VCC Supply Current, ICC Reset Voltage Threshold, VTH Reset Timeout Period RESET Output Voltage, VOH RESET Output Voltage, VOL ISource = 800A VCC=VTH Min., ISink=1.2mA VCC>1.4V, ISink =50A MIC1815-10 MIC1815-20 2.80 2.47 100 VCC - 1.5V 0.4 0.3 Conditions TA = 0C to 70C TA = -40C to 85C Min 1.4 1.6 9 2.88 2.55 150 Typ Max 5.5 5.5 20 2.97 2.64 250 Units V A V ms V V 2 MIC1815 Microprocessor Reset Circuit Pin Functions Pin Name RESET VCC GND Pin No. 1 2 3 RESET goes low if VCC falls below the reset threshold and remains asserted for one reset timeout period (100ms min.) after VCC exceeds the reset threshold. Power supply input, 3.3V. IC Ground Pin. 3 MIC1815 Microprocessor Reset Circuit Block Diagram VCC (2) Reset Threshold (VTH) + RESET GENERATOR RESET (1) GND (3) Figure 1. MIC1815 Block Diagram 4 MIC1815 Microprocessor Reset Circuit Circuit Description Microprocessor Reset The RESET pin is asserted whenever VCC falls below the reset threshold voltage. The reset pin remains asserted for a period of 150ms after VCC has risen above the reset threshold voltage. The reset function ensures the microprocessor is properly reset and powers up into a known condition after a power failure. RESET will remain valid with VCC as low as 1.4V. VCC Transients The MIC1815 is relatively immune to negative-going VCC glitches below the reset threshold. Typically, a negative-going transient 125mV below the reset threshold with a duration of 50s or less will not cause an unwanted reset. 8++ 8JDH J 8JDH J 4-5-6 Figure 2. Reset Timing Diagram VCC VCC VCC P RESET 100K MIC1815 RESET RESET Valid to 0V A resistor can be added from the RESET pin to ground to ensure the RESET output remains low with V CC down to 0V. A 100K resistor connected from RESET to ground is recommended. The size of the resistor should be large enough to not load the RESET output and small enough to pull-down any stray leakage currents. Figure 3. RESET Valid to VCC = OV 5 MIC1815 Microprocessor Reset Circuit Alternate Source Cross Reference Guide Industry P/N DS1815-10 DS1815-20 MIC Direct Replacement MIC1815-10U MIC1815-20U 6 MIC1815 Microprocessor Reset Circuit Packaging Information U Package, 3-Pin SOT-23 Small-Outline Transistor Package 0.021 0.015 0.055 0.047 0.098 0.083 0.120 0.105 0.0059 0.040 0.031 0.0035 0-81/4 0.079 0.071 0.004 0.001 0.010 0.005 Dimensions are in inches. Device Marking Information Lot Code NDXX = MIC1815-10U NEXX = MIC1815-20U 7 MIC1815 Microprocessor Reset Circuit Packaging Information Tape and Reel Information 4.00.1 1.50.1 2.00.05 1.750.1 3.50.05 8.00.3 4.00.1 1.10.1 2.70.1 1.20.1 3.10.1 Dimensions are in millimeters. 8 |
Price & Availability of MIC1815
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