FM1233E 3-Pin µC Supervisor Circuit General Description Features The FM1233E is a supervisor circuit that monitors a microprocessor power supply or other system voltage and issues a reset pulse when a fault condition exists. Several different threshold voltages are offered to accommodate 3V systems with different tolerances. ■ Precision monitoring of 3.3V and lower voltage microprocessor systems ■ VTH values of 2.88V, 2.72V ■ Automatic restart of microprocessor after power failure ■ 140ms (min) power-on RESET delay (typ.: 256ms) The device features a precision temperature-compensated voltage reference and comparator. When VCC falls to the threshold voltage, a RESET pulse is issued, holding the output in the active state. When power rises above VTH, the reset remains for approximately 250 ms to allow the system clock and other circuits to stabilize. The reset output of FM1233E is of open-drain active low type. ■ ■ ■ ■ Internal 5kΩ pull-up resistor Other reset choices available: 32 to 128ms Operating Temperature -40°C to +105°C SOT23-3 package Typical Operating Circuit VCC 3 Controller FM1233E 1 2 RESET GND Connection Diagram GND 1 FM1233E 3 VCC RESET 2 SOT23-3 Package ©2003 Fairchild Semiconductor Corporation FM1233E Rev. D 1 www.fairchildsemi.com FM1233E 3-Pin µC Supervisor Circuit February 2003 Voltage on any pin relative to GND VCC RESET Input Current Output Current (RESET) Continuous Power Dissipation (TA = 70°C) SOT23 (derate 4mW above 70°C) Operating Temperature Range Storage Temperature Range Lead Temperature (soldering, 10s) -0.3V to +6.0V -0.3V to (VCC + 0.3V) 20mA 20mA 300mW -40°C to +105°C -65°C to +150°C +300°C These are stress ratings only, and functional operation is not implied for these levels or beyond. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. Electrical Characteristics (VCC = 3.3V; TA = -40°C to +105°C unless otherwise noted) (Note 1) Parameter Symbol Conditions Operating Voltage VCC Supply Current ICC VCC < 3.3V Min Typ Max Units 1.2 3.3 5.5 V 3 6 µA Reset Threshold VTH FM1233EC 2.70 2.88 2.97 V Reset Threshold VTH FM1233ED 2.58 2.72 2.86 V Reset Output Voltage VOL FM1233E 0.4 V Reset Timeout Period tRST FM1233E 560 ms ISINK = 5mA VCC = VTH(min) 140 256 Note 1: Testing at production is done at 25°C only. Limits over temperature are guaranteed by design. 2 FM1233E Rev. D www.fairchildsemi.com FM1233E 3-Pin µC Supervisor Circuit Absolute Maximum Ratings FM1233E 3-Pin µC Supervisor Circuit Typical Operating Characteristics Supply Current Vs. Temperature 10 8 8 6 6 ICC (µA) 10 4 4 VCC = 3.3V 2 0 2 -55C +25C +110C 0 Temperature (C) Power up Reset timeout (ms) Power up Reset Timeout Vs. Temperature 600 600 500 500 400 400 300 300 200 200 100 -40C +25C +105C 100 Temperature (C) 3 FM1233E Rev. D www.fairchildsemi.com Pin Number Name 1 GND 2 RESET 3 VCC Function GROUND RESET remains LOW while VCC is below VTH, and for at least 140ms after VCC rises above VTH. Circuit Timing (Ex: FM1233E) VCC 3.3V VTH 1V GND RESET 3.3V VTH 1V GND 140ms When operating properly with 3V VCC (for example), RESET will also be about 3V. When VCC starts to fall, RESET will follow it down as shown. When VCC drops below VTH, RESET drops to ground (“issues a RESET”) and stays there unless VCC also falls below its minimum operating voltage, approx. 1V. At this point, the supervisor loses control, and its output may rise, only to again follow VCC down to the ground. When VCC begins to rise, RESET follows it until 1.0V or so is reached, whereupon the device regains control, RESET is pulled to ground, etc. When VCC rises above VTH, RESET comes out of RESET 140 ms later. If it is required that a lower value than GND + 1.0V is needed on RESET signal during VCC ≤ 1V, a 100K resistor may be used on the device output to GND. 4 FM1233E Rev. D www.fairchildsemi.com FM1233E 3-Pin µC Supervisor Circuit Pin Descriptions FM1233E 3-Pin µC Supervisor Circuit General Description The FM1233E features a highly accurate voltage reference to which VCC is compared. Once VCC is below the specified threshold, it will drive the RESET line and continue to hold it low until VCC returns above the threshold and the time for the RESET pulse duration has expired. The FM1233E is immune to short negative going transients on the VCC line. The placement of a 0.1µF bypass capacitor as close as possible to the VCC pin provides additional transient immunity. For a VCC value below 1.0V, the FM1233E does not sink very much current on the RESET pin. This is not a problem in most systems since common devices are not functional in this range. If it is desired for the FM1233E reset to be functional below this range, use a 100KΩ pull-down resistor between RESET and VSS. 5 FM1233E Rev. D www.fairchildsemi.com Part Number Top Marking RESET Threshold (V) Output Type Package Type Packing Method FM1233ECS3X 3EC 2.88 Open-Drain, active LOW 3-Pin, SOT23 3000 units in T&R FM1233EDS3X 3ED 2.72 Open-Drain, active LOW 3-Pin, SOT23 3000 units in T&R Note 3: Devices listed above feature 250ms typical reset pulse width. Consult Fairchild Sales for other reset pulse width options. 6 FM1233E Rev. D www.fairchildsemi.com FM1233E 3-Pin µC Supervisor Circuit Ordering Information FM1233E 3-Pin µC Supervisor Circuit Physical Dimensions inches (millimeters) unless otherwise noted 0.021 0.015 0.055 0.047 0.098 0.083 0.120 0.105 0.0059 0.0035 0.040 0.031 0.079 0.071 0-8° 0.010 0.005 0.004 0.001 0.76 2.29 PKG CL 0.76 0.95 LAND PATTERN RECOMMENDATION SOT-23 Package Dimensions FS Pkg Code AU 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 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 to the user. Fairchild Semiconductor Americas Customer Response Center Tel. 1-888-522-5372 Fairchild Semiconductor Europe Fax: +44 (0) 1793-856858 Deutsch Tel: +49 (0) 8141-6102-0 English Tel: +44 (0) 1793-856856 Français Tel: +33 (0) 1-6930-3696 Italiano Tel: +39 (0) 2-249111-1 Fairchild Semiconductor Hong Kong 8/F, Room 808, Empire Centre 68 Mody Road, Tsimshatsui East Kowloon. Hong Kong Tel; +852-2722-8338 Fax: +852-2722-8383 7 FM1233E Rev. D 2. A critical component is 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. Fairchild Semiconductor Japan Ltd. 4F, Natsume Bldg. 2-18-6, Yushima, Bunkyo-ku Tokyo, 113-0034 Japan Tel: 81-3-3818-8840 Fax: 81-3-3818-8841 www.fairchildsemi.com