System Reset (with built-in watchdog timer) MM1075 MITSUMI System Reset (with built-in watchdog timer) Monolithic IC MM1075 Outline This IC functions in a variety of CPU systems and other logic systems to generate a reset signal and reset the system accurately during momentary interruption or lowering of power supply voltage. It also has a built-in watchdog timer for operation diagnosis. This prevents the system from running wild by generating an intermittent reset pulse during system mis-operation. Features 1. 2. 3. 4. 5. 6. 7. Built-in watchdog timer Low minimum operating voltage VCC=0.8V typ. Both positive and negative logic reset output can be extracted Accurate detection of drop in power supply voltage Detection voltage has hysteresis Few external parts 1 capacitor Timer monitoring time can be varied by using an external resistor Package DIP-8A (MM1075XD) SOP-8A (MM1075XF) Applications Microcomputer system monitoring, etc. Absolute Maximum Ratings (Ta=25°C) Item Symbol Rating Units Storage temperature TSTG -40~+125 °C Operating temperature TOPR -20~+70 °C Power supply voltage VCC max. -0.3~+10 V Voltage applied to VS & CK pins VVS &VCK -0.3~+10 V Voltage applied to RESET, RESET pin VOH -0.3~+10 V Allowable loss Pd 400 mW -------------------------------------------------------------- System Reset (with built-in watchdog timer) MM1075 MITSUMI Electrical Characteristics (DC) (Except where noted otherwise, Ta=25°C, VCC=5V) Measurement Item Symbol Consumption current ICC 1 VSL 1 VS=OPEN, VCC VSH 1 VS=OPEN, VCC VS/ T 1 Hysteresis voltage VHYS 1 CK input threshold VTH 1 IIH 1 VCK=5V IIL 1 VCK=0V VOH1 1 I RESET =-5µA, VS=OPEN Detection voltage Detection voltage temperature coefficient CK input current Output voltage (High) Output voltage (Low) Output sink current circuit ---------------------------------------------------------------------------- Minimum operating power supply voltage to ensure RESET 0.7 1.0 4.05 4.20 4.35 4.15 4.30 4.45 VSH-VSL, VCC ---------------------------------------------------------------- ---------------------------------------------------------------- I RESET =-5µA, VS=0V VOL1 1 I RESET =3mA, VS=0V V 50 100 150 mV 0.8 1.2 2 V 0 1 -20 -10 -3 4.5 4.8 4.5 4.8 ---------------------------------------------------------------- ---------------------------------------------------------------- µA V 0.2 0.4 VOL2 1 I RESET =10mA, VS=0V 0.3 0.5 VOL3 1 IRESET=0.5mA, VS=OPEN 0.2 0.4 VOL4 1 IRESET=1mA, VS=OPEN 0.3 0.5 ---------------------------------------------------------------- mA %/°C ±0.01 1 V IOL1 1 V RESET =1.0V, VS=0V 10 16 IOL2 1 VRESET=1.0V, VS=OPEN 1 2 ICT1 1 -0.8 -1.2 -2.4 µA ICT2 1 -0.8 -1.2 -2.4 µA 0.8 1.0 V 0.8 1.0 V * voltage to ensure RESET Min. Typ. Max. Units During watchdog timer operation VOH2 CT charge current 1 Minimum operating power supply Measurement conditions VTC=1.0V, RCT=OPEN during watchdog timer operation VTV=1.0V during power ON reset operation mA ---------------------------------------------------------------- VCCL1 1 V RESET =0.4V ---------------------------------------------------------------- I RESET =0.2mA VCCL2 1 VRESET=VCC-0.1V RL2 (between Pin 2 and GND) System Reset (with built-in watchdog timer) MM1075 MITSUMI Electrical Characteristics (AC) (Except where noted otherwise, Ta=25°C, VCC=5V) Item Symbol Measurement circuit VCC input pulse width TP1 2 VCC CK input pulse width CK input cycle Watchdog timer monitoring time 2 Reset time for watchdog timer 3 Reset hold time for power supply rise 4 TCKW TCK 2 2 CK TWD 2 CT=0.1µF RCT=OPEN 50 100 150 mS TWR 2 CT=0.1µF 1 2 3 mS TPR 2 50 100 150 mS Output delay time from VCC 5 TPD1 2 2 10 * * * * Output rise time 6 * Output fall time 6 * TPD2 2 tR1 2 tR2 2 tF1 2 tF2 2 Measurement conditions 5V 4V or CT=0.1µF, VCC RESET pin RL1=2.2kΩ, CL1=100pF RESET pin R1, 2=10kΩ, CL2=20pF RESET pin RL1=2.2kΩ, CL1=100pF RESET pin RL2=10kΩ, CL2=20pF RESET pin RL1=2.2kΩ, CL1=100pF RESET pin RL2=10kΩ, CL2=20pF Min. Typ. Max. Units 8 µS 3 20 µS µS µS 3 10 1.0 1.5 µS 1.0 1.5 µS 0.1 0.5 µS 0.5 1.0 µS Notes: 1 ICT1 changes according to RCT pin (Pin 6) pull up resistance. 2 Monitoring time is the time from the last pulse (negative edge) of the timer clear clock pulse until reset pulse output. In other words, reset output is output if a clock pulse is not input during this time. Also, monitoring time can be varied by pulling up the RCT pin to VCC with a resistor (RCT). Monitoring time adjustments are shown in Graph 1. 3 Reset time means reset pulse width. However, this does not apply to power ON reset. 4 Reset hold time is the time from when VCC exceeds detection voltage (VSH) during power ON reset until reset release (RESET output high, RESET output low). 5 Output delay time is the time from when power supply voltage drops below detection voltage (VSI) until reset (RESET output low, RESET output high). 6 Voltage range when measuring output rise and fall is 10~90%. 7 Watchdog timer monitoring time (TWD), watchdog timer reset time (TWR) and reset hold time (TPR) during power supply rise can be changed by varying CT capacitance. The times are expressed by the following formulae. The recommended range for CT is 0.001~10µF. * * * * * -------------------------------------------------------------- -------------------------------------------------------------- * * ~ 1000 CT (µF) TPR (mS) ~ 1000 CT (µF) TWD (mS) ~ TWR (mS) - 20 CT (µF) Example : When CT=0.1µF (RCT pin OPEN) ~ 100mS TPR ~ 100mS TWD ~ 2mS TWR - System Reset (with built-in watchdog timer) MM1075 MITSUMI (mS) 100 80 TWD 60 40 20 0 50k 100k 1M 10M 100M ∞ (Ω) RCT Graph 1 RCT & Monitoring Time Note : The above graph shows data for when CT=0.1µF. TWD is proportionate to CT. Refer to the calculation formula for TWD above. Block Diagram Note 1 : CP=0.1µF approx. ~1000pF Note 2 : CNote 3 : The watchdog timer can be stopped by connecting the RCT pin to GND. (Then it functions as a voltage detection circuit.) Note 4 : TPR and TWD can be varied by pulling up the RCT pin to VCC with a resistor. The recommended range for RCT is 100kΩ~RCT pin OPEN. System Reset (with built-in watchdog timer) MM1075 MITSUMI Timing Chart VCC VSH VSL CK TCK CT TWD TPR RESET TWR RESET Pin Assignment 8 1 7 2 6 3 5 4 1 TC 2 RESET 3 CK 4 GND 5 VCC 6 RCT VS 7 ----------------------------------------------------------------------------- RESET 8 Pin Description Pin No. Pin Name Function 1 TC 2 RESET 3 CK 4 GND 5 VCC 4.2V detection voltage 6 RCT Watchdog timer stop pin Operation modes : Operation 7 VS TWD, TWR, TPR variable pins.(TWD, TWR and TPR times are determined by the external capacitor.) Reset output pin (High output) Clock input pin (inputs clock from logic system) Detection voltage variable pin Adjustment modes : Lower --------------------------------------------------------------- 8 RESET Reset output pin (Low output) OPEN, Stop connect to GND pull up resistance, Raise pull down System Reset (with built-in watchdog timer) MM1075 MITSUMI Measuring Circuits Measuring Circuit 1 Measuring Circuit 2 Measuring Circuit 2-1 Item SW & Power Supply Table Symbol SW1 SW2 SW3 SW4 SW5 SW6 SW7 VCC Consumption current Detection voltage CK input threshold CK input current Output voltage (High) ------------------------------------------------------------- VCK VCT I RESET IRESET VM, IM Notes ICC OFF OFF OFF ON B B ON 5V 0V - - ICC 5V VSL OFF OFF ON ON B B ON 5V 4V 3V 3V - - VO1, CRT1 VSH OFF OFF ON ON B B ON 4V 5V 3V 3V - - VO1, CRT1 VTH OFF OFF OFF ON B B ON 5V 0V 3V 1V - - ICK IIH OFF OFF OFF ON B B ON 5V 5V 0V - - ICK IIL OFF OFF OFF ON B B ON 5V 0V 0V - - ICK ON OFF ON B B ON 5V 5V 3V -5µA - VO1 VOH1 VOH2 OFF ON VOL1 ON ON ON C B ON 5V 5V 3V - -5µA VO2 ON ON ON ON B B ON 5V 5V 3V 3mA - VO1 ON Output voltage VOL2 ON ON ON B B ON 5V 5V 3V 10mA - VO1 (Low) VOL3 OFF OFF ON ON C B ON 5V 5V 3V - 0.5mA VO2 VOL4 OFF OFF ON ON C B ON 5V 5V 3V - 1mA VO2 IOL1 OFF ON ON ON B C ON 5V 5V 3V - - I O1 VOO=1V IOL2 OFF OFF ON ON B A ON 5V 5V 3V - - I O2 VOO=1V CT charge current 1 ITC1 OFF OFF OFF ON B B OFF 5V - 1V - - ITC CT charge current 2 ITC2 OFF OFF ON ON B B OFF 5V - 1V - - ITC VCCL1 ON OFF ON ON B B ON 0V 2V 0V 0V - VO1, VCC ON A B ON 0V 2V 0V 0V - VO2, VCC Output sink current Minimum operating power supply ---------------------------------------------------------- voltage to ensure RESET Minimum operating power supply voltage to ensure RESET VCCL2 OFF ON ON - System Reset (with built-in watchdog timer) MM1075 MITSUMI Measuring Circuit 2-2 Item SW & Power Supply Table Symbol SW1 SW2 5V T1 VCC T2 1.4V T3 VCK CRT Notes - CRT1, 2, 3 T1=8µS - CRT1, 2, 3 T2=3µS - CRT1, 2, 3 T3=20µS B CK input pulse width TCKW A B - 5V TCK A B - 5V TWD A A - 5V - 5V CRT1, 2, 3 TWR A A - 5V - 5V CRT1, 2, 3 TPR B A A - 5V - 5V CRT1, 2, 3 TPD1 C A - - 0V CRT1, 3 TPD2 C A - - 0V CRT2, 3 TR1 A A - 5V - 5V CRT1 TR2 A A - 5V - 5V CRT2 TP1 A A - 5V - 5V CRT1 TP2 A A - 5V - 5V CRT2 CK input cycle Watchdog timer monitoring time Reset time for watchdog timer Reset hold time for power supply rise Output delay time from VCC Output rise time Output fall time 4V 5V 0V 5V 0V Detection Voltage Adjustment 1 - VCKA C VCC input pulse width TPI VCCA 0V 1.4V T2 or 0V T2 1.4V T2 T3 0V (lowering detection voltage) Graph 1. Detection voltage change using MM1075 external resistor Detection voltage (Vs) (V) 5.0 VSH value 4.5 VSL value 100 200 300 400 500 600 Vs pin external resistance (R2) (kΩ) Detection voltage can be changed by connecting resistor R2 externally to MM1075 VS pin. Determine R2 according to graph 1 when changing VS. System Reset (with built-in watchdog timer) MM1075 MITSUMI Detection Voltage Adjustment 2 (raising detection voltage) Graph 2. Detection voltage change using MM1075 external resistor VSH value Detection voltage (VS) (V) 4.0 VSL value 3.5 3.0 100 200 300 400 500 600 Vs pin external resistance (R1) (kΩ) Detection voltage can be changed by connecting resistor R1 externally to MM1075 VS pin. Determine R1 according to graph 2 when changing VS. Characteristics 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Output voltage-Power supply voltage (RESET pin) 7.0 Clock pulse input time 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Power supply current ICC (mA) Power supply current ICC (mA) Power supply current-Power supply voltage PULL UP resistance 10kΩ 6.0 5.0 Ta=20°C, 25°C, 75°C 4.0 3.0 2.0 1.0 Power supply voltage VCC (V) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Power supply voltage VCC (V) Output voltage-Power supply voltage (RESET pin) PULL UP resistance 2.2kΩ 6.0 5.0 4.0 3.0 2.0 1.0 ----------------------------------------------------------------- Ta=-25°C Ta=25°C Ta=75°C 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Power supply voltage VCC (V) Detection voltage (V) Output voltage VRESET (V) 7.0 Detection voltage (VSL, VSH) temperature (RESET, RESET pins) 4.50 4.40 VSH 4.30 4.20 VSL 4.10 4.00 3.90 -40-20 0 20 40 60 80 100 Ambient temperature Ta (°C) System Reset (with built-in watchdog timer) MM1075 Output saturation voltage-Output sink current (RESET pin) Output saturation voltage VOL (mV) ------------------------------------------------------------------------ 500 400 300 200 100 Ta=25°C °C Ta=75 °C Ta=-25 0.2 0.4 0.6 0.8 1.0 1.4 1.6 1.8 Output saturation voltage-Output sink current (RESET pin) ----------------------------------------------------------------- Output saturation voltage VOL (mV) MITSUMI 500 400 300 100 4.8 4.6 4.4 4.2 4.0 3.8 -2 -4 -6 -8-10-12-14 -16-18 2 4 6 8 10 12 14 16 18 Output sink current IOL (mA) ----------------------------------------------------------- 5.0 4.8 4.6 4.4 4.2 4.0 3.8 -2 -4 -6 -8-10-12-14 -16 -18 High level output current IOM (µA) 160 VCC=5V (Cr=0.1µF) 140 120 100 80 60 40 -40-20 0 20 40 60 80 100 Ambient temperature Ta (°C) High level output current IOM (µA) Watchdog timer monitoring time temperature Watchdog timer monitoring time temperature TWD (mS) Reset hold time temperature during power supply rise TPR (mS) Reset hold time temperature during power supply rise Ta=-25°C High level output voltage-High level output current (RESET pin) High level output voltage VOM (V) High level output voltage VOM (V) 5.0 Ta=25°C 200 Output sink current IOL (mA) High level output voltage-High level output current (RESET pin) Ta=75°C VCC=5V (Cr=0.1µF) 160 140 120 100 80 60 40 -40 -20 0 20 40 60 80 100 Ambient temperature Ta (°C ) System Reset (with built-in watchdog timer) MM1075 MITSUMI Reset time temperature (for watchdog timer) Watchdog timer monitoring time temperature VCC=5V (Cr=0.1µF) VCC=5V (Cr=0.1µF) Reset time TWR (mS) 3.5 3.0 100 2.5 6PIN 5MΩ PULL UP 2.0 1.5 10 1.0 6PIN 100kΩ PULL UP 0.5 -40 -20 0 20 40 60 80 100 -40 -20 0 Ambient temperature Ta (°C) Ambient temperature Ta (°C) CT value for reset hold time during power supply rise CT value for reset time (for watchdog timer) 105 103 Reset time TWR (mS) Hold time TPR (mS) 20 40 60 80 100 104 103 102 101 100 102 101 100 10-1 10-2 10-3 10-2 10-1 100 101 10-3 10-2 10-1 100 101 CT capacitance (µF) CT value for watchdog timer monitoring time Type of timer time adjustment CT value for watchdog timer monitoring time Timer monitoring time TWD (mS) Timer monitoring time TWD (mS) CT capacitance (µF) 105 104 103 102 101 100 10-3 10-2 10-1 100 101 CT capacitance (µF) 104 Connect R between Rct and VCC 103 102 101 100 R= OPEN 2.2MΩ 1kΩ 470kΩ 200kΩ 10-1 10-3 10-2 10-1 100 101 CT capacitance (µF)