FM1233 Precision Reset Generator Circuit General Description Features The FM1233 features comprehensive reset generation for microcontroller/microprocessor based systems. If the system VCC voltage level is determined to be in an out-of-tolerance state, the device automatically generates a low-going reset signal. The reset signal is held in the active state (low) for a specified duration (minimum 140 ms) after the VCC returns to an in-tolerance state. ■ Automatic reset generation on power-up ■ Minimum 140 ms reset pulse — compatible with other similar 1233 class devices ■ Other reset pulse choices available: 32 - 256 ms ■ Choice of commercial and extended temperature ranges ■ Choice of Reset Thresholds: 4.63V, 4.38V, 4.00V, 3.08V, 2.93V, 2.63V The FM1233 also allows an external reset to be connected to the reset pin without adding aditional debounce logic or extra pins. ■ Package available: SOT-23 This device is fabricated using CMOS technology. This device is available in the SOT-23 package. Block Diagram VCC VCC Tolerance Detect & Reset Monitor Output Stage Reset_out (active low) External Reset Detection Temp. Compensated Reference Connection Diagram 1 1 = GND 2 = RESET' 3 = VCC FM1233 3 2 © 2000 Fairchild Semiconductor International FM1233 Rev. A 1 www.fairchildsemi.com FM1233 Precision Reset Generator Circuit August 2000 Reset Characteristics RESET THRESHOLD (V) Identifier(y) Fairchild Part Number 4.63 L FM1233Lz 4.38 M FM1233Mz 4.00 J FM1233Jz 3.08 T FM1233Tz 2.93 S FM1233Sz 2.63 R FM1233Rz RESET PULSE DURATION (mS) Identifier(z) Fairchild Part Number 32 E FM1233yE* 64 F FM1233yF* 128 H FM1233yH* 256 Blank FM1233y Note*: These choices are available upon special request only. Please work with Fairchild Marketing to determine availability. 2 FM1233 Rev. A www.fairchildsemi.com FM1233 Precision Reset Generator Circuit Each FM1233 device has the following Identifier (FM1233yz) (Top Mark on devices will be 10yz) Absolute Maximum Ratings Ambient Storage Temperature Operating Conditions –65°C to +150°C All Input or Output Voltages with Respect to Ground Ambient Operating Temperature Commercial Industrial -0.3V to 6.5V Lead Temperature (Soldering, 10 seconds) ESD Rating 0°C to +70°C -40°C to +85°C +300°C 2000V min. Electrical Characteristics Parameter Symbol VCC Range Temp Conditions Typ Max Units V Com 1.0 5.5V Ind 1.2 5.5 V 50 µA Supply Current ICC Com Reset Threshold VTH Com 100 µA 4.50 4.63 4.75 V 4.40 4.63 4.85 V 4.25 4.38 4.50 V 4.16 4.38 4.56 V ‘J’ Identifier 3.89 4.00 4.10 V 3.80 4.00 4.20 V ‘T’ Identifier 3.00 3.08 3.15 V 2.92 3.08 3.23 V 2.85 2.93 3.00 V 2.78 2.93 3.08 V 2.55 2.63 2.70 V 2.50 2.63 2.75 V ‘L’ Identifier Ind Com ‘M’ Identifier Ind Com Ind Com Ind Com ‘S’ Identifier Ind Com ‘R’ Identifier Ind nRESET Output Voltage High Min VOH All Isource = 150 mA nRESET Output Voltage Low VOL All Isink = 1.2mA Reset Timeout Period TRST All 0.8VCC V 0.4 175 V 240 375 ms Note: Production testing done at TA = +25°C, over temperature limits guaranteed by design only. 3 FM1233 Rev. A www.fairchildsemi.com FM1233 Precision Reset Generator Circuit Product Specifications The FM1233 features a highly accurate voltage reference against which the Vcc is compared. Once the Vcc is below the specified threshold, it will drive the RESET line and continue to hold it low until the VCC returns above the threshold and the time for the RESET pulse duration has expired. The FM1233 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. FM1233 Reset For a VCC value below 1.0V-1.3V, the FM1233 does not sink current on the RESET pin. This is not a problem in most systems since most common devices are not functional in this range. If it is desired for the FM1233 reset to be functional below the range above, it is suggested to use a 100KΩ pull-down resistor between RESET and VSS. Interfacing to Bidirectional reset pins FM1233 can be used with microprocessors with bidirectional reset pins. The microprocessors can still drive the reset line but when the microprocessor has released the reset line the FM1233 will continue to hold it for a duration no longer that 300 ms. Bi-Directional Reset The FM1233 allows for the connection of an external reset switch to be wired to the reset pin. The FM1233 has the feature of allowing an external reset pin to be connected without having to add debounce logic or an extra pin to the package. The FM1233 detects when an external source is pulling the reset line low. Once this occurs the FM1233 will pull the reset line low as well. When the external source stops driving the reset line the FM1233 will continue to hold the reset line low so as to prevent debounce. After a certain length of time the FM1233 will stop driving the reset line and it will return to its non-active (high) state. 4 FM1233 Rev. A www.fairchildsemi.com FM1233 Precision Reset Generator Circuit Connecting an External Reset to the FM1233 General Description Supply Current Vs. Temperature (FM1233R/S/T) 8 7 ICC (µA) 6 VCC = 5V 5 4 3 2 VCC = 3.3V 1 0 -60 -40 -20 0 20 40 60 80 100 Temperature (C) Power Up Reset Timeout (ms) Power up Reset Timeout Vs. Temperature FM1233(R/S/T) 300 280 260 240 220 200 -60 -40 -20 0 20 40 60 80 100 Temperature (C) Normalized Reset Threshold Vs. Temperature FM1233(R/S/T) Normalized Threshold 1.050 1.025 1.000 0.975 0.950 -60 -40 -20 0 -20 -40 60 80 100 Temperature (C) 5 FM1233 Rev. A www.fairchildsemi.com FM1233 Precision Reset Generator Circuit Typical Operating Characteristics FM1233 Precision Reset Generator Circuit 0.45~0.60 0.20 MIN Physical Dimensions inches (millimeters) unless otherwise noted 2.40 ±0.10 1.30 ±0.10 0.40 ±0.03 0.03~0.10 0.38 REF 0.40 ±0.03 +0.05 0.12 –0.023 0.96~1.14 2.90 ±0.10 0.97REF Dimensions in millimeters 0.95 ±0.03 0.95 ±0.03 1.90 ±0.03 0.508REF 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 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 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 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 Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. 6 FM1233 Rev. A www.fairchildsemi.com