www.fairchildsemi.com FM811/812 Microprocessor Reset Circuits Description • Feature • Precision Voltage Monitor for 3V, 3.3V or 5V Power Supplies • 6µA Supply Current • 140ms Minimum Reset Pulse Width • RESET Remains Valid with VCC as Low as 1.4V • Active Low Manual Reset Input • No External Components • 4-Pin SOT-143 Package The FM811/FM812 is a low cost microprocessor supervisory circuit that asserts a reset if the power supply drops below a designated threshold or the manual reset pin is forced low. Several different reset thresholds are available to accommodate systems operating at 3V, 3.3V or 5V. The FM811 has an active low RESET output, while the FM812 offers an active high RESET output. The reset output is guaranteed to remain asserted for a minimum of 140ms after VCC has risen above the designated reset threshold. The FM811/FM812 is available in a 4-pin SOT-143. Applications • • • • • Critical Microprocessor Power Monitoring Portable Equipment Intelligent Instruments Computers & Printers Controllers Typical Applications VCC MR VCC VCC FM811 FM812 µP RESET (RESET) RESET INPUT ( ) = FM812 PRELIMINARY INFORMATION describes products that are in the design stage. Specifications may change in any manner whatever without notice. Contact Fairchild Semiconductor for current information. REV. 1.5.1 7/15/02 Preliminary Information Features FM811/812 Pin Assignments Top View 4 1 GND VCC GND 1 FM811 Preliminary Information VCC 3 MR FM812 3 2 RESET 4 MR RESET 2 Pin Definitions Pin Number Pin Name FM811 FM812 Description GND 1 1 RESET 2 N/A RESET goes low if VCC falls below the reset threshold and remains asserted for one reset time-out period (140ms min.) after VCC exceeds the reset threshold. RESET N/A 2 RESET goes high if VCC falls below the reset threshold and remains asserted for one reset time-out period (140ms min.) after VCC exceeds the reset threshold. MR 3 3 Manual reset input. Shorting this pin to GND forces a reset. The reset will remain asserted as long as MR is held low and for one reset time-out period (140ms min.) after MR goes high. This input cannot be driven by a CMOS or TTL logic. Push-button switch is recommended to be used with this pin. Float if unused. VCC 4 4 Power supply input, 3V, 3.3V, or 5V Ground Pin Internal Block Diagram VCC 4 Reset Threshold (V) MR + – Reset Generator 2 RESET (FM811) RESET (FM812) 3 1 GND 2 REV. 1.5.1 7/15/02 FM811/812 Absolute Maximum Ratings Parameter Terminal Voltage Input Current Output Current Rate of Rise Operating Temperature Range Symbol Ratings Units VCC -0.3 to 6.0 V MR -0.3 to (VCC + 0.3) V VCC, MR 20 mA RESET, RESET 20 mA VCC 100 V/µs TA ˚C ˚C Lead Temperature Range 300 ˚C Power Dissipation (TA = +70˚C) 320 mW 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 for FM81_L/M/J, VCC = 3.3V for FM81_S/T, VCC = 3V for FM81_R, TA = Operating Temperature Range, unless otherwise noted. Parameter Operating Voltage Range Supply Current, ICC Reset Voltage Threshold, VTH Conditions TA = 0˚C to 70˚C TA = -40˚C to 85˚C FM811L/M/J, FM812L/M/J VCC < 3.6V, FM811R/S/T, FM812R/S/T FM811L, FM812L FM811M, FM812M FM811J, FM812J FM811T, FM812T FM811S, FM812S FM811R, FM812R Min. 1.4 1.6 4.40 4.18 3.90 2.97 2.79 2.49 140 VCC - 1.5 0.8 x VCC Reset Time-out Period, tR RESET Output Voltage, VOH ISOURCE = 800µA, FM811L/M/J ISOURCE = 500µA, FM811R/S/T RESET Output Voltage, VOL VCC= VTH Min., ISINK = 3.2mA, FM811L/M/J VCC= VTH Min., ISINK = 1.2mA, FM811R/S/T VCC > 1.4V, ISINK = 50µA, TA= 0˚C to 70˚C VCC > 1.6V, ISINK = 50µA, TA= -40˚C to 85˚C 0.8 x VCC RESET Output Voltage, VOH 1.8V < VCC < VTH Min., ISOURCE = 150µA RESET Output Voltage, VOL ISINK = 3.2mA, FM810L/M/J ISINK = 1.2mA, FM810R/S/T 10 MR Minimum Pulse Width MR to Reset Delay MR Input Threshold, VIH VCC > VTH Max., FM81_L/M/J 2.3 FM81_R/S/T 0.7 x VCC MR Input Threshold, VIL VCC > VTH Max., FM81_L/M/J FM81_R/S/T MR Pull-Up Resistance 10 MR Glitch Immunity REV. 1.5.1 7/15/02 Typ. 9 6 4.63 4.38 4.00 3.08 2.93 2.63 240 Max. 5.5 5.5 15 10 4.86 4.52 4.18 3.19 3.00 2.70 560 Units V 0.4 0.3 0.3 0.3 V 0.4 0.35 V ms V V V µs µs V 0.5 20 100 µA 0.8 0.25xVCC 30 kΩ ns 3 Preliminary Information -40 to +85 -65 to +150 Storage Temperature Range FM811/812 Circuit Description Microprocessor Reset Interfacing to Bidirectional Reset Pins The RESET pin is asserted whenever VCC falls below the reset threshold voltage or if MR (manual reset) is forced low. The reset pin remains asserted for a period of 40ms after VCC has risen above the reset threshold voltage or MR has returned high. 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. The FM811/ FM812 can interface with µPs with bidirectional reset pins by connecting a 4.7kΩ resistor in series with the FM811/ FM812 output and the µP reset pin. Preliminary Information VCC VTH RESET Valid to 0V A resistor can be added from the RESET pin to ground to ensure the RESET output remains low with VCC 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. MR VCC tR tR RESET VCC Transients The FM811/ FM812 are relatively immune to negative-going VCC glitches below the reset threshold. Typically, a negativegoing transient 125mV below the reset threshold with a duration of 50ms (25ms for FM81_R/S/T) or less will not cause an unwanted reset. VCC VCC FM811 µP RESET RESET 100k Manual Reset Function Momentarily connecting the Manual Reset input pin (MR) to GND forces a reset. Typically a Push-button switch is used in most of the applications to force a manual reset. See Typical Applications diagram. The reset will remain asserted as long as MR is held low and for one reset time-out period (140ms min.) after MR goes high. Note that this input cannot be driven by a CMOS or TTL logic. This pin should be left floating if manual reset feature is unused. 4 REV. 1.5.1 7/15/02 FM811/812 Packaging Information 4-Pin SOT-143 0.079 0.071 0.098 0.083 0.055 0.047 Dimensions are in inches 0.021 0.015 0.037 0.030 0.040 0.031 0.080 0.070 Preliminary Information 0.120 0.105 0.0059 0.0035 0.010 0.005 0.004 0.001 Tape and Reel Information 4.0 ± 0.1 2.0 ± 0.05 O1.5 ± 0.1 1.75 ± 0.1 3.5 ± 0.05 8.0 ± 0.3 4.0 ± 0.1 O1.1 ± 0.1 2.7 ± 0.1 1.2 ± 0.1 Dimensions are in millimeters 3.1 ± 0.1 REV. 1.5.1 7/15/02 5 FM811/812 Preliminary Information Ordering Information Part Number Top Marking* RESET Threshold (V) Output Type Package Packing Method FM811LUX KLYY 4.63 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM811MUX KMYY 4.38 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM811JUX KJYY 4.00 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM811TUX KTYY 3.08 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM811SUX KSYY 2.93 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM811RUX KRYY 2.63 Push-Pull, active LOW 4-Pin, SOT143 3000 units in T&R FM812LUX LLYY 4.63 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R FM812MUX LMYY 4.38 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R FM812JUX LJYY 4.00 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R FM812TUX LTYY 3.08 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R FM812SUX LSYY 2.93 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R FM812RUX LRYY 2.63 Push-Pull, active HIGH 4-Pin, SOT143 3000 units in T&R * YY = Lot Code DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 7/15/02 0.0m 004 Stock#DS30000811 2002 Fairchild Semiconductor Corporation