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| U5020M Digital Window Watchdog Timer Description The digital window watchdog timer, U5020M, is a CMOS integrated circuit. In applications where safety is critical, it is especially important to monitor the microcontroller. Normal microcontroller operation is indicated by a cyclically transmitted trigger signal, which is received by a window watchdog timer within a defined time window. A missing or a wrong trigger signal makes the watchdog timer reset the microcontroller. The IC is tailored for microcontrollers which can work in both full-power and sleep mode. With an additional voltage monitoring (power-on reset and supply voltage drop reset), the U5020M offers a complete monitoring solution for microsystems in automotive and industrial applications. Features D Low current consumption: IDD < 100 mA D RC-oscillator D Internal reset during power-up and supply voltage drops (POR) D "Short" trigger window for active mode "long" trigger window for sleep mode D Cyclical wake-up of microcontroller in sleep mode D Trigger input D Six wake-up inputs D Reset output D Enable output Block Diagram C R1 VDD C1 Reset 10 Input ts 16 mC Trigger 11 OSC Input signal conditioning POR State machine 9 Enable Power-on reset POR Test logic External switching circuitry OSC 15 RC Oscillator OSC VDD 10 nF 13 95 10387 Mode 12 Wake up 3-8 14 GND 2 Test 1 Test Figure 1. Block diagram with external circuit Ordering Information Extended Type Number U5020M-FP Package SO16 Remarks Rev. A5, 10-Apr-01 1 (8) U5020M Pin Description Pin 1 2 TM TM 1 2 16 ts 15 Osc 14 GND 13 VDD 12 Mode 10 Wake-up 6 Wake-up 7 Wake-up 8 95 10635 Symbol TM TM Function Test must not be connected Test must be connected to GND Wake-up 3 Wake-up 4 3 to 8 Wake-up Wake-up inputs (pull-down resistor) There are six digitally debounced wake-up inputs. During the long trigger mode each signal slope at the inputs initiates a reset pulse at Pin 10. 9 Ena Enable output (push-pull) It is used for the control of peripheral components. It is activated after the processor triggers three times correctly. Reset output (open drain) Resets the processor in the case of a trigger error or if a wake-up pulse occurs during the long watchdog period. Trigger input (pull-up resistor) It is connected to the microprocessor's trigger signal. Mode input (pull-up resistor) The processor's mode signal initiates the switchover between the long and the short watchdog time. Supply voltage Ground, reference voltage RC oscillator Time switch input Programming pin to select different time durations for the long watchdog time. Wake-up 5 Reset 11 Trig 10 Reset 11 9 Ena 12 Mode Trig Figure 2. Pin connections 13 14 15 16 VDD GND Osc ts Functional Description Supply, Pin 13 The U5020M requires a stabilized supply voltage VDD = 5 V " 5% to comply with its electrical characteristic. An external buffer capacitor of C = 10 nF may be connected between Pin 13 and GND. f+1 t where t + 1.35 ) 1.57 R1 (C 1 ) 0.01) R 1 in kW, C1 in nF and t in ms The clock frequency determines all time periods of the logic part as shown in the last section of the data sheet (timing). With an appropriate selection of components, the clock frequency, f, is nearly independent of the supply voltage as shown in figure 3. Frequency tolerance Dfmax = 10% with R1 " 1%, C1 = " 5%. RC-Oscillator, Pin 15 The clock frequency, f, can be adjusted with the components R1 and C1 according to the formula: 2 (8) Rev. A5, 10-Apr-01 U5020M 1000.00 100.00 t (ms) 10.00 4.5 V 5.0 V 5.5 V C1 = 500 pF 1.00 1 10 100 1000 95 10636 R1 (kW) Figure 3. Period t vs. R1, @ C1 = 500 pF Pin 13 V DD Reset Out to t1 t6 Pin 10 Mode Figure 4. Power-up reset and mode switchover Pin 12 95 10637 Supply Voltage Monitoring, Pin 10 The integrated power-on reset (POR) circuitry sets the internal logic to a defined basic status and generates a reset pulse at the reset output, Pin 10, during ramp-up of the supply voltage and in the case of voltage drops of the supply. A hysteresis in the POR threshold prevents the circuit from oscillating. During ramp-up of the supply voltage the reset output stays active for time, to, in order to bring the microcontroller in its defined reset status (see figure 4). Pin 10 has an open-drain output. and the time, t1, starts again. Micro and watchdog are synchronized with the switchover mode time, t1, each time a reset pulse is generated. Microcontroller in Active Mode Monitoring with the "Short" Trigger Window After the switch-over mode the watchdog works in the short watchdog mode and expects a trigger pulse from the microcontroller within the defined time window, t3, (enable time). The watchdog generates a reset pulse which resets the microcontroller if D the trigger pulse duration is too long, D the trigger pulse is within the disable time, t2 D there is no trigger pulse Figure 5 shows the pulse diagram with a missing trigger pulse. Switch-over Mode Time, Pin 12 The switch-over mode time enables the synchronous operation of micro and watchdog. After the power-up reset time the watchdog has to be switched to its monitoring mode by the micro with a "low" signal transmitted to the mode pin (Pin 12) within the time out period, t1,. If the low signal does not occur within time, t1, (see figure 4) the watchdog generates a reset pulse, t6, Rev. A5, 10-Apr-01 3 (8) U5020M V DD Reset Out Pin 13 to t1 Pin 10 t2 Mode t3 Pin 12 Pin 11 Trigger Figure 5. Pulse diagram with no trigger pulse during the short watchdog time 95 10638 Figure 6 shows a correct trigger sequence. The positive edge of the trigger signal starts a new monitoring cycle with the disable time, t2. To ensure a correct operation of the microcontroller, the watchdog needs to be triggered three times correctly before it sets its enable output. This feature is used to activate or deactivate safety-critical components which have to be switched to a certain condition (emergency status) in the case of a microcontroller malfunction. As soon as there is an incorrect trigger sequence, the enable signal is reset and it takes again a sequence of three correct triggers before enable is reset. Microcontroller in Sleep Mode Monitoring with the "Long" Trigger Window The long watchdog mode allows cyclical wake-up of the microcontroller during sleep mode. As in short watchdog mode, there is a disable time, t4, and an enable time, t5, in which a trigger signal is accepted. The watchdog can be switched from the short trigger window to the long trigger window with a "high" potential at the mode pin (Pin 12). In contrast to the short watchdog mode, the time periods are now much longer and the enable output remains inactive so that other components can be switched off to effect a further decrease in current consumption. As soon as a wake-up signal at one of the 6 wake up inputs (Pins 3 to 8) is detected, the long watchdog mode ends, a reset pulse wakes-up the sleeping microcontroller and the normal monitoring cycle starts with the mode switch-over time. By means of a low or high potential at Pin 16 (time switch), two values for the long watchdog time can be selected. Pin 13 VDD t0 Reset Out t1 Pin 10 t3 t2 t2 Pin 12 Pin 11 Mode Trigger t trig Enable 95 10639 Pin 9 Figure 6. Pulse diagram of a correct trigger sequence during the short watchdog time 4 (8) Rev. A5, 10-Apr-01 U5020M Figure 7 shows the switch-over from the short to the long watchdog mode. The wake-up signal during the enable time, t5, activates a reset pulse, t6. The watchdog can be switched back from the long to the short watchdog mode with a low potential at the mode pin (Pin 12). t6 Reset out t1 Pin 10 Wake-up Pins 3 to 8 t4 Mode t5 Pin 12 t2 Trigger Pin 11 Enable 95 10640 Pin 9 Figure 7. Pulse diagram of the long watchdog time Application Hint In order to prevent the IC from an undesired reset output signal which may be caused by transcients on the supply under certain conditions, a pc board connection from Pin 2 to GND is strongly recommended. Absolute Maximum Ratings AAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAAAAAA AAAAAAAAAAAAAAAA AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA A AA AAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAAAAAA AAAAAAAAAAAAAAAA AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA A AA AAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAAAAAA AAAAAAAAAAAAAAAA AA Supply voltage Output current Input voltage VDD VIN Tstg 6.5 V V IOUT Parameters Symbol Value Unit mA C C "2 -0.5 V to VDD + 0.5 V -40 to +85 -55 to +150 Ambient temperature range Storage temperature range Tamb Thermal Resistance Junction ambient AAAA A AA AAAA AAAAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAAAAAA AAAAAAAAAAAAAAAA AA SO16 RthJA 160 K/W Rev. A5, 10-Apr-01 5 (8) Parameters Symbol Value Unit AA A A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AA A A AA A A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAAA AAAAAAAA AAAAAAAA A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AA A A AA A A A A AA A A AAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAAA AAAAAAAA AAAAAAAA A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AA A A A AA A A A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAA A A AA A AAA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A AA A A AAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A AAAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAA AAA AAA AAA AA AAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAA A A AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A AAAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAA AAA AAA AAA AA AAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAA A A AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A AA A A AAAAA AAAAAAAAA AA AAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAA AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAA AAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A AAAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAA AAA AAA AA AAAAAAAA A A AA A AAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAA AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAA A A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAA AAAAAAAAA AAAAAAAA A A AA A A AA A A A AAAA A A AA A A A A AA A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA A A A AA A A AAAAAAAAAAAAAAA AAAAAAAA AAAAAAAA AAAAAAAAAAAA AAAAAAAA AAAAAAAA A A AA A A VDD = 5 V; Tamb = -40C to +85C; reference point is ground (Pin14); figure 4, unless otherwise specified Electrical Characteristics U5020M 6 (8) Reset-out time Long enable time Long disable time Long enable time Long disable time Short enable time Short disable time Time-out period Power-up reset time Max. trigger pulse period Debounce period Debounce period Timing Lower output voltage ("0") IOUT = -1 mA Max. output current Output Pin 10 Lower output voltage ("0") IOUT = -1 mA Upper output voltage ("1") Max. output current Output Pin 9 Input current Input voltage range Lower threshold ("0") Upper threshold ("1") Inputs Power-on reset Power-on reset Power-on reset Current consumption Supply voltage Parameters Input switch = high (1) Pin 16 Input switch = high (1) Pin 16 Input switch = low (0) Pin 16 Input switch = low (0) Pin 16 Wake-up 1-6, Pins 3 to 8 Trig, Mode, Pins 11 and 12 IOUT = 1 mA Depending on pin Hysteresis Threshold Logic functions R1 = 66 kW Test Conditions / Pins Pins 3 to 8, 11, 12 and 16 Pin 13 Pin 13 Pin 13 Pin 13 Pin 13 Symbol VPOR IOUT VOH IOUT Vhys VDD VDD VOL VOL VIN VIH VIL IDD I IN t6 t5 t4 t5 t4 t3 t2 t1 to Min. -20 4.5 4.0 4.5 96 3 2 2 1 30002 71970 1200 1112 Typ. 400 124 130 201 100 3.8 40 45 -0.4AAAA VDD + 0.2 Rev. A5, 10-Apr-01 Max. 128 100 0.5 0.5 1.0 5.5 20 4 Unit mA mA mV mA mA cyc cyc cyc cyc cyc cyc cyc cyc cyc cyc cyc cyc V V V V V V V V V U5020M Package Information Package SO16 Dimensions in mm 10.0 9.85 5.2 4.8 3.7 1.4 0.4 1.27 8.89 16 9 0.25 0.10 0.2 3.8 6.15 5.85 technical drawings according to DIN specifications 13036 1 8 Rev. A5, 10-Apr-01 7 (8) U5020M Ozone Depleting Substances Policy Statement It is the policy of Atmel Germany GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances (ODSs). The Montreal Protocol (1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. Atmel Germany GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2. Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency (EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively. Atmel Germany GmbH can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances. We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use Atmel Wireless & Microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. Data sheets can also be retrieved from the Internet: http://www.atmel-wm.com Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423 8 (8) Rev. A5, 10-Apr-01 |
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