System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI System Reset (Built-in Watch Dog Timer) Monolithic IC MM1099 Outline The function of this IC series MM1099 is to accurately reset systems, a generating reset signal at the time of instantaneous supply voltage off or lowering in varied CPU and other logic system. Further, with the watch dog timer built-in it can diagnose the operation of the system, intermittently generating reset pulses when they operate erroneously to prevent runaway. Features 1. 2. 3. 4. 5. Built-in watch dog timer Low current consumption 130µA TYP. Low operating threshold voltage VCC=0.8V Watch dog stop function (RCT terminal) Long clock monitoring time TPR (POWER ON) : TWD (clock monitoring)=1 : 1 6. Fewer outer components Package DIP-8B (MM1099AD, MM1099BD) SOP-8C (MM1099AF, MM1099BF) SIP-8A (MM1099AS, MM1099BS) Applications 1. Reset circuit for microcomputers, CPU and MPU. 2. Reset circuit for logic circuitry. 3. Monitoring of microcomputer system, etc. Pin Assignmemt 8 1 7 2 6 3 5 4 1 TC 1 TC 2 N.C 2 N.C 3 CK 3 CK 4 GND 5 VCC 1 2 3 4 5 6 7 8 6 RCT SIP-8A 7 VS 4 GND 5 VCC 6 RCT 7 ----------------------------------------------------------- SOP-8C/DIP-8B 8 RESET VS ----------------------------------------------------------- 8 RESET System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Pin Description Pin No. Pin name 1 TC Function Variable terminals TWD, TWR and TPR The time for TWD, TWR and TPR to be TPR (mS) = 5000 CT (µF) TWD (mS) = 500 CT (µF) determined by the external capacitor. TWR(mS) = 100 2 N.C 3 CK 4 GND Ground terminal 5 VCC Voltage detection 6 RCT Watchdog timer stop pin Operation modes: Operation 7 VS 8 RESET CT (µF) Clock input terminal Inputs the clock from the logic system. MM1099A 3.2V MM1099B 4.2V OPEN, Stop connect to GND Detect voltage variable terminal Reset output pin (low output) Absolute Maximum Ratings Item Symbol Rating Units Power supply voltage VCC max. -0.3~+10 V CK pin input voltage VCK -0.3~VCC+0.3 ( <= +10) V VS pin input voltage VVS -0.3~VCC+0.3 ( <= +10) V Voltage applied to RCT pin VRCT -0.3~VCC+0.3 ( <= +10) V Voltage applied to RESET pin VOH -0.3~VCC+0.3 ( <= +10) V Allowable loss Pd 300 mW Storage temperature TSTG -40~+125 °C ---------------------------------------------------- Recommended Operating Conditions Item Symbol Rating Units Power supply voltage VCC +2.2~+7.0 V RESET sync current IOL 0~1.0 mA Clock monitoring time setting TWD 0.1~1000 mS Clock rise and fall times tFC, tRC <100 µS TC pin capacitance CT 0.0002~2 µF Operating temperature TOP -25~+75 °C ---------------------------------------------------- System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Electrical Characteristics (DC) Item Consumption current MM1099A MM1099B MM1099A Detection voltage (Except where noted otherwise, MM1099A : VCC=3.6V, Ta=25°C, MM1099B : VCC=5.0V) Symbol Measurement conditions ICC During watchdog timer operation VSL MM1099B MM1099A VSH MM1099B Detection voltage temperature coefficient Hysteresis voltage MM1099A MM1099B CK input threshold CK input current Output voltage (High) MM1099A R output sync current CT charge current Minimum operating power --------------------------------------------------- supply voltage to ensure RESET (100) (150) 130 VHYS 4.05 4.20 4.35 3.15 3.25 3.35 VS=OPEN, VCC µA V 4.15 4.30 4.45 %/°C ±0.01 VSH-VSL, VCC VTH IIH A : VCK=3.6V, B : VCK=5.0V IIL VCK=0V VOH I RESET =-1µA, VS=OPEN VOL1 195 3.10 3.20 3.30 VS=OPEN, VCC VS/ T MM1099B Output voltage (Low) Min. Typ. Max. Units ---------------------------------------------------- 25 50 100 50 100 150 0.8 1.2 2 0 1 -12 -6 -2 3.0 3.4 4.0 4.5 0.2 0.4 ---------------------------------------------------- 0.3 0.5 VOL2 I RESET =1.0mA, VS=0V IOL V RESET =1.0V, VS=0V ---------------------------------------------------- 1 V µA V ---------------------------------------------------- I RESET =0.5mA, VS=0V mV 2 V mA ICT1 VTC=1.0V during watchdog timer operation -0.16 -0.24 -0.48 µA ICT2 VTC=1.0V during power ON reset operation -0.16 -0.24 -0.48 µA ---------------------------------------------------- VCCL V RESET =0.4V ---------------------------------------------------- I RESET =0.1mA 0.8 1.0 V System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Electrical Characteristics (AC) Item VCC input pulse width Symbol MM1099A Measurement conditions VCC TPI MM1099B VCC CK input pulse width TCKW CK input cycle TCK Watchdog timer monitoring time 1 (Except where noted otherwise, MM1096A : VCC=3.6V, Ta=25°C MM1096B : VCC=5.0V) 3.6V Min. Typ. Max. Units 8 2.8V µS 5.0V 8 4.0V CK or 3 µS 20 µS TWD CT=0.02µF 50 100 150 mS TWR CT=0.02µF 1 2 3 mS 50 100 150 mS 2 10 µS 2.0 4.0 µS 0.2 1.0 µS * Reset time for watchdog timer 2 * Reset hold time for TPR power supply rise 3 * Output delay time from VCC 4 * Output rise time 5 * Output fall time 5 * TPD tR tF CT=0.02µF, VCC ---------------------------------------------------------------------- RESET pin, RL=10kΩ, CL=20pF ---------------------------------------------------------------------- RESET pin, RL=10kΩ, CL=20pF ---------------------------------------------------------------------- RESET pin, RL=10kΩ, CL=20pF Notes : 1 The "monitoring time" means the time interval from the last pulse of the clock pulses for timer clear (negative edge) to the output of the reset pulse. If the clock pulse is not input during this time interval, the reset output will be given. 2 The "reset time" is no other than the reset pulse width, except when resetting the POWER ON. 3 The "reset hold time" is the time interval from the time point when VCC exceeds the detect (VSH) at the time of Power On Reset (Power variation reset) to the reset release (RESET output "HIGH"). 4 The "output delay time" means the time interval from when the supply voltage comes lower than the detect voltage (VSL) to when comes the reset state (RESET output "Low"). 5 The voltage range is 10 to 90% when measuring the output rise and fall times. 6 By varying the capacitance of CT, we can vary the watch dog timer monitoring time (TWD), the reset time at the time of the watch dog timer (TWR), and the reset hold time at the time of power source rise (TPR). The variable time can be expressed by the following formulas: TPR (mS) .=. 5000 CT (µF) TWD (mS) .=. 5000 CT (µF) TWR (mS) .=. 100 CT (µF) Example : When CT=0.02µF . TPR =. 100mS TWD .=. 100mS TWR .=. 2mS * * * * * * ------------------------------------------------- ------------------------------------------------- System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Measuring Circuits Measuring Circuit 1 (DC) Measuring Circuit 1 Item Measuring Circuit 2 (AC) SW & Power Supply Table Symbol SW1 SW2 SW3 SW4 SW5 SW6 SW7 Consumption current Detection voltage CK input threshold CK input current Output voltage (High) Output voltage (Low) VCC VCK ----------------------------------------------- VCT I RESET VM, IM ICC OFF OFF OFF ON ON ON A 3.6V 3.6V 0V - ICC VSL OFF OFF ON ON ON ON A 3.6V 3V 0V 2V - VO1, CRT1 3V 3.6V 0V 2V - VO1, CRT1 1V - ICK, VCK VSH OFF OFF ON ON ON ON A VTH OFF OFF OFF ON ON ON A IIH OFF OFF OFF ON ON ON A 3.6V 3.6V 0V - ICK IIL OFF OFF OFF ON ON ON A 3.6V 0V 0V - ICK VOH ON OFF ON ON ON ON A 3.6V 3.6V 2V -1µA V O1 3.6V 0V 3V VOL1 ON ON ON ON ON ON A 3.6V 3.6V 2V 0.5mA V O1 VOL2 ON ON ON ON ON ON A 3.6V 3.6V 2V 1.0mA V O1 Output sink current IOL1 OFF ON ON ON ON ON B 3.6V 3.6V 2V - IO1 CT charge current 1 ITC1 OFF OFF OFF ON ON OFF A 3.6V - 1V - ITC CT charge current 2 ITC2 OFF OFF OFF ON ON OFF A 3.6V - IV - ITC VCCL ON OFF ON ON ON ON A 0V 2V 0V 0V - VO1, VCC Minimum operating power ------------------------------------------------------ supply voltage to ensure RESET Measuring Circuit 2 Item Symbol SW1 SW2 VCCA 3.6V T1 VCC VCK T2 T3 CK input pulse width TCKW A B - 3.6V TCK A B - 3.6V TWD A A - 3.6V - 3.6V TWR A A - 3.6V - 3.6V TPR B A A - 3.6V - 3.6V TPD C A - - 0V CRT1 Output rise time TR A A - 3.6V - 3.6V CRT1 Output fall time TF A A - 3.6V - 3.6V CRT1 monitoring time Reset time for watchdog timer Reset hold time for power supply rise Output delay time from VCC 3.6V 0V 0V 1.4V - CRT CRT1 B 2.8V - VCKA 1.4V C Watchdog timer VO=1V SW & Power Supply Table VCC input pulse width TP1 CK input cycle Notes T2 or 0V T2 1.4V 0V T2 T3 - CRT2 CRT1 CRT2 CRT1 CRT2 CRT1 CRT2 CRT1 CRT2 CRT1 CRT2 Notes T1=8µS T2=3µS T3=20µS System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Block Diagram MM1099A MM1099B RA RB ~ - 305k ~ - 350k ~ - 195k ~ - 150k Note 1. Cp = approx. 0.1µF Note 2. C ~ - 1000pF Note 3. The watchdog timer can be stopped by grounding the RCT pin. (Function as voltage detection circuit.) Note 4. TPR, TWD can be varied by pulling up the RCT pit to VCC using a resisteor. Timing Chart VCC VSH VSL 0.3V CK TCK CT TWD TPR RESET 1 2 3 4 5 5 TPR TWR 6 7 8 9 10 11 12 System Reset (Built-in Watch Dog Timer) MM1099 MITSUMI Description of Operation ------------------------------------------------------- 1. The RESET will become "Low" if VCC rises to about 0.8V. Approximately 1µA (Vcc=0.8V) of pull up current is output from RESET . . 2. Charging starts at the capacitor CT when VCC riset to VSH (MM1099A =. 3.25V, MM1099B =. 4.3V), when the output has been reset. 3. The output reset is released after a given interval TPR from when the CT Starts charging and to when it discharges (that is, the time from when CT voltage takes a given value 1 (.=. 1.4V) up until decreases to a given value 2 (.=. 0.2V). (RESET will become "High"). The RESET will output a pull up current, about 1µA (VCC=0.8V). The reset hold time TPR is expressed by the following formula: TPR (ms) .=. 5000 CT (µF) After the reset release CT restarts charging and the watch dog timer begins operating. Note that input of clock while POWER ON RESET time TPR will cause an erroneous operation. 4. If clock is input into CK terminal while CT is charging (negative edge trigger), CT changes from charging over to discharging. . 5. When the CT voltage decreases to a given threshold ( =. 0.2V), then discharging changes over to charging. Steps 4 and 5 will be repeated while normal clock is input from the logic system. 6. When the clock ceases and CT voltage reaches the RESET ON threshold (.=. 1.4V), the output enters into reset state (RESET becoming "Low"). The CT charging time TWD up until the reset is output (watch dog monitoring time) is expressed by the following formula: TWD (ms) .=. 5000 CT (µF) 7. The reset time at the time of watch dog time TWR is the discharging time while the CT voltage lowers down . to the reset off threshold ( =. 0.2V). The calculation formula: TWR (ms) .=. 100 CT (µF) After the reset off threshold is reached, the output reset is released and CT commences to charge. If thenceforth the clock is input normally, steps 4 and 5 will be repeated, and setps 6 and 7 repeated if the clock ceases. 8. When VCC lowers down to VSL (MM1099A .=. 3.2V, MM1099B .=. 4.2V), the reset is output. At the same time CT charged. 9. CT discharging starts when VCC rises up to VSH. If VCC lower instantaneously, charging starts after load discharging of CT if the time interval from when VCC comes lower than VSL up until when it rises to VSH or higher is equal or superior to the reference value of VCC input pulse width TPI. 10.The output reset is released TPR after VCC becomes VSH or higher, and the watch dog time will start. Then if VCC becomes VSL or lower, steps 8 to 10 will be repeated. 11.If power Off occurs, reset is output if VCC becomes VSL or lower. 12.When VCC comes down to 0V, the reset output will hold up until VCC becomes 0.8V. ---------------------------------------------------------------- ------------------------------------------------------- -------------------------------------------------------