MIC1810 Microprocessor Reset Circuit MIC1810 Microprocessor Reset Circuit Description Pin Configuration The MIC1810 is an inexpensive microprocessor supervisory circuits 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 5%, 10%, or 15% drop in 5V powered systems. The MIC1810 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 MIC1810 comes in a 3-pin SOT-23 package. Typical Applications · Portable Equipment · Intelligent Instruments · Critical Microprocessor Power Monitoring · Printers/Computers · Controllers Reset Threshold Voltage (V) 4.62 4.37 4.12 Device Suffix -5 -10 -15 Top View RESET 1 MIC1810 3 GND VCC 2 Features RESET Remains Valid with VCC as Low · as 1.4V · Precision Voltage Monitor for 5%, 10%, or 15% drop in 5V Power Supplies · Available in 3-Pin SOT23 Package · 9µA Supply Current (typical) · 100ms Minimum Reset Pulse Width · No External Components Required Typical Operating Circuit VCC Ordering Information Part MIC1810_U Package 3-Lead SOT23 Temp. Range -40°C to +85°C Place the device suffix of desired reset threshold voltage from table above in blank to complete the part number. VCC VCC MIC1810 µP RESET RESET 1 MIC1810 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/µs Operating Temperature Range MIC1810-U . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C Storage Temperature Range . . . . . . . . . . . . .-65°C to 150°C Lead Temperature (Soldering - 10 sec.) . . . . . . . . . . . 300°C Power Dissipation (TA = +70°C) . . . . . . . . . . . . . . . . 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 = 5V, TA = Operating Temperature Range, unless otherwise noted. Parameter Operating Voltage Range, VCC Conditions TA = 0°C to 70°C TA = -40°C to 85°C Min Max Units 5.5 5.5 V 9 20 µA 4.50 4.25 4.00 4.62 4.37 4.12 4.75 4.50 4.24 V 100 150 250 ms Supply Current, ICC Reset Voltage Threshold, VTH MIC1810-5 MIC1810-10 MIC1810-15 Reset Timeout Period RESET Output Voltage, VOH ISource = 800µA RESET Output Voltage, VOL VCC=VTH Min., ISink=3.2mA VCC>1.4V, ISink =50µA 2 Typ 1.4 1.6 VCC - 1.5V V 0.4 0.3 V MIC1810 Microprocessor Reset Circuit Pin Functions Pin Name Pin No. RESET 1 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. VCC 2 Power supply input, 5V. GND 3 IC Ground Pin. 3 MIC1810 Microprocessor Reset Circuit Block Diagram + VCC (2) Reset RESET - GENERATOR Threshold (VTH) GND (3) Figure 1. MIC1810 Block Diagram 4 RESET (1) MIC1810 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 MIC1810 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 50µs or less will not cause an unwanted reset. VCC Vthr Vthr t1 t1 RESET Figure 2. Reset Timing Diagram VCC VCC VCC MIC1810 µP RESET RESET 100K 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 100KΩ 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 MIC1810 Microprocessor Reset Circuit Alternate Source Cross Reference Guide Industry P/N 6 MIC Direct Replacement DS1810R-5 MIC1810-5U DS1810R-10 DS1810R-15 MIC1810-10U MIC1810-15U MIC1810 Microprocessor Reset Circuit Packaging Information U Package, 3-Pin SOT-23 Small-Outline Transistor Package 0.021 0.015 0.055 0.098 0.047 0.083 0.120 0.105 0.0059 0.0035 0.040 0-8¼ 0.031 0.079 0.071 0.004 0.001 0.010 0.005 Dimensions are in inches. Device Marking Information Lot Code XXXX = MIC1810-5U XXXX = MIC1810-10U XXXX = MIC1810-15U 7 MIC1810 Microprocessor Reset Circuit Packaging Information Tape and Reel Information 4.0±0.1 ¯1.5±0.1 1.75±0.1 2.0±0.05 3.5±0.05 8.0±0.3 4.0±0.1 2.7±0.1 1.2±0.1 3.1±0.1 Dimensions are in millimeters. 8 ¯1.1±0.1