System Reset (with built-in watchdog timer) MM1142 MITSUMI System Reset (with built-in watchdog timer) Monolithic IC MM1142 Outline This IC was developed to drive low voltage batteries, and has a watchdog timer with built-in microcomputer reset voltage detection circuit and low battery detection circuit. A single reference voltage is used for low battery voltage detection and microcomputer reset voltage . detection, so detection voltage difference is uniform ( =. 0.2V). Further, there is a built-in watchdog timer for operation diagnosis, which prevents the system from running wild by generating an intermittent reset pulse during system mis-operation. Features 1. Accurate voltage drop detection voltage 1. Low battery detection 2.2V±3% 2. Power supply voltage detection 2.0V±3% 3. Detection voltage error 0.2V±20mV 1-2 4. Hysteresis both 50mV typ. 2. Watchdog function stop pin (can be made to function only as reset IC during VCC rise) 3. Low current consumption 150µA typ. Package SOP-8C (MM1142XF) Applications 1. 2V cordless telephones 2. Portable communication equipment 3. Various types of small, handy equipment Series Table Model VSLB VSLR TPR TWD TWR MM1142 2.2V 2.0V 100mS 100mS 2mS *C =0.02µF T TPR : TWD : TWR : VSLB: VSLR: Reset hold time during Vcc rise Timer monitoring time Reset time Battery check detection voltage Reset detection voltage System Reset (with built-in watchdog timer) MM1142 MITSUMI Pin Assignment TC 1 ---------------------------------------------- 8 1 7 2 6 3 5 4 SOP-8C 2 BC(RESET) 3 CK 4 GND 5 VCC 6 RCT VS 7 ---------------------------------------------- RESET 8 Pin Description Pin No. 1 Pin name TC Function TWD, TWR, TPR time setting pins. ----------------------------------------------------------------------------------- 2 BC(RESET) Battery check output pin (RESET low level output) for 3.4V 3 CK 4 GND 5 VCC 6 RCT 7 VS ----------------------------------------------------------------------------------- 8 RESET Block Diagram Clock input pin GND pin Power supply voltage input pin Watchdog timer stop pin Operation modes Operation OPEN, Stop connect to GND Detection voltage fine adjustment pin Reset output pin (low output) System Reset (with built-in watchdog timer) MM1142 MITSUMI Absolute Maximum Ratings (Ta=25°C) Item Power supply voltage Voltage applied to input pin Voltage applied to output pin Allowable loss Storage temperature Symbol VCC max. VIN VOUT Pd TSTG Rating -0.3~+7 -0.3~VCC+0.3 ( <= +7) -0.3~VCC+0.3 ( =< +7) 300 -40~+125 Units V V V mW °C Rating +1.9~+6.5 0~500 0~5.0 1.0< <0.2 1~10000 <100 100< 50< 0.0022~2.2 -20~+70 Units V µA mA V V mS µS µS µS µF °C Recommended Operating Conditions Item Power supply voltage RESET sync current BC sync current Clock input high level voltage Clock input low level voltage Clock monitoring time setting Clock rise and fall times Power supply voltage rise times Power supply voltage fall times TC pin capacitance Operating temperature Electrical Characteristics Item Consumption current RESET detection voltage Detection voltage temperature coefficient R Hysteresis voltage R BC detection voltage Detection voltage temperature coefficient B Hysteresis voltage B Detection voltage difference CK input threshold CK input current Output voltage RH Output voltage BH Output voltage RL Output voltage BL Output sync current R Output sync current B Output source current R CT charge current (Except where noted otherwise, Ta=25°C, VCC=2.6V) Symbol Measurement conditions Min. Typ. Max. Units ICC No load 200 280 µA VSLR VCC : High Low, RCT : GND, VTC=OPEN 2.00 ±3% V VSR T VHYSR VCC : Low High, RCT=GND, VTC=OPEN VSLB VCC : High Low, RLB=10kΩ VSB T VHYSB VSL VTH IIH IIL VOHR VOHB VOLR VOLB IOLR IOLB IOHR ICT1 ICT2 Minimum operating power supply voltage VCCL to ensure RESET ------------------------------------------------------------------------------- Symbol VCC IOLR IOLC VCKH VCKL TWD tRCK, tFCK tRVCC tFVCC CT TOP 25 ±0.01 ±0.05 %/°C 50 2.20 mV V 100 ±3% ±0.01 ±0.05 %/°C 25 50 100 0.175 0.200 0.225 0.4 0.6 1.2 VCK=2.6V 0 1 VCK=0.0V -15 -6 -2 IRESET=-1µA 2.0 2.2 RLB=10kΩ 2.0 2.2 IRESET=500µA, VCC=1.8V 0.3 0.5 IBC=5mA, VCC=1.8V 0.3 0.5 VRESET=0.5V, VCC=1.8V 500 700 VBC=0.5V, VCC=1.8V 5 7 VRESET=2.0V 2 4 VTC=0.5V during watchdog timer operation -0.300 -0.150 -0.075 VTC=0.5V during power ON reset operation -0.300 -0.150 -0.075 mV V V VCC : Low High, RLB=10kΩ VSL=VSLB-VSLR -------------------------------------------- -------------------------------------------- -------------------------------------------- -------------------------------------------- VRESET=0.4V, IRESET=0.05mA --------------------------------------------- --------------------------------------------- 0.8 1.0 µA V V V V µA mA µA µA V System Reset (with built-in watchdog timer) MM1142 MITSUMI Item Symbol VCC input pulse width TPI CK input pulse width TCKW CK CK input cycle TCK CK Watchdog timer monitoring time 1 Measurement conditions VCC Min. 2.6V TPI 1.8V TCKW or TCK Typ. Max. Units 20 µS 10 µS 50 µS TWD CT=0.022µF 50 100 150 mS TWR CT=0.022µF 1 2 3 mS TPR CT=0.022µF 50 100 150 mS * Watchdog timer reset time 2 * Reset hold time for power supply rise 3 * ------------------------------------------------------ RESET delay time tPDR VCC : High Low, RLR=100kΩ, CLR=15pF 10 µS BC delay time tPDB VCC : High Low, RLB=10kΩ, CLB=15pF 10 µS ------------------------------------------------------ tRR RLR=100kΩ, CLR=15pF 10 µS RESET fall time tFR RLR=100kΩ, CLR=15pF 2 µS BC rise time tRB RLB=10kΩ, CLB=15pF 10 µS BC fall time tFB RLB=10kΩ, CLB=15pF 2 µS RESET rise time ------------------------------------------------------ Notes: 1 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. 2 Reset time means reset pulse width. However, this does not apply to power ON reset. 3 Reset hold time is the time from when VCC exceeds detection voltage (VSHR) during power ON reset until reset release (RESET output high). 4 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. Example : When CT=0.22F ~ 4500 CT (µF) ~ 100mS TPR (mS) TPR ~ ~ 100mS TWD (mS) - 4500 CT (µF) TWD ~ 90 CT (µF) ~ 2mS TWR (mS) TWR 5 TWD can be varied by placing a resistor (1MΩ or more)between the RCT pin and VCC. 6 The voltage range when measuring output rise and fall time is 10~90%. 7 VCC rise time should be 100µS or more, and fall time should be 50µS or more. * * * * * * * ---------------------------------------------- System Reset (with built-in watchdog timer) MM1142 MITSUMI Measuring Circuit Timing Chart VCC VSHB VSLB VSHR VSLR 0.8V CK TCKW TCK CT RESET TPR TWR TWD BC RCT OPEN