MM1142

MITSUMI System Reset (with built-in watchdog timer) MM1142 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 MM1142 TPR : TWD : TWR : VSLB: VSLR: VSLB 2.2V VSLR 2.0V TPR 100mS TWD 100mS TWR 2mS Reset hold time during Vcc rise Timer monitoring time Reset time Battery check detection voltage Reset detection voltage *C =0.02µF T MITSUMI System Reset (with built-in watchdog timer) MM1142 Pin Assignment 1 8 7 6 5 2 3 4 1 2 3 4 5 6 SOP-8C 7 8 TC ---------------------------------------------- BC(RESET) CK GND VCC RCT VS ---------------------------------------------- RESET Pin Description Pin No. 1 2 3 4 5 6 7 8 Pin name TC ----------------------------------------------------------------------------------- Function TWD, TWR, TPR time setting pins. 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) BC(RESET) Battery check output pin (RESET low level output) for 3.4V CK GND VCC RCT VS ----------------------------------------------------------------------------------- RESET Block Diagram MITSUMI System Reset (with built-in watchdog timer) MM1142 Absolute Maximum Ratings (Ta=25°C) 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 Item Power supply voltage Voltage applied to input pin Voltage applied to output pin Allowable loss Storage temperature 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 Symbol VCC IOLR IOLC VCKH VCKL TWD tRCK, tFCK tRVCC tFVCC CT TOP Rating +1.9~+6.5 0~500 0~5.0 1.0<