MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER DESCRIPTION PIN CONFIGURATION (TOP VIEW) M5295A is a semiconductor integrated circuit which is designed for System Reset to detect +5V power supply. This IC keeps the operation microcomputer watching. When the system is abnormal,it generates Reset output until the system returns to normal states of the System. It is possible to vary the two detective voltage by connecting the resistor,so it is suitable to high quality and high performance system. FEATURES •Watch Dog Timer •Power on Reset Timer •Low circuit current 0.8mA(Typ,Vcc=5V) •Wide Range of power supply 8 ADJ2 7 RST2 6 Vcc 5 ADJ1 4 GND 3 RST1 2 TC 1 WD Outline 8P5(AL) APPLICATION WD 1 8 ADJ2 TC 2 7 RST2 RST1 3 6 Vcc GND 4 5 ADJ1 Microcomputer Systems RECOMMENDED OPERATING CONDITIONS Supply voltage...........................................4V to 15V Rated supply voltage............................................5V Outline 8P4(AP) 8P2S-A(AFP) BLOCK DIAGRAM 49.6k 51.2k - + F.F - F.F + - 20.4k + 18.8k W.D.T F.F 1.24V REFERENCE VOLTAGE GENERATOR CIRCUIT 20k 30k 1 2 3 4 5 6 7 8 WD TC RST1 GND ADJ1 Vcc RST2 ADJ2 MITSUBISHI ELECTRIC ( 1 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER ABSOLUTE MAXIMUM RATINGS (Ta=25°C,unless otherwise noted) Symbol Vcc VIN VOUT IOUT Pd K Topr Tstg Conditions Parameter Supply voltage Input voltage Output voltage Output current Power dissipation Thermal derating Operating temperature Ta≥25°C Storage temperature Ratings Unit 15 -10 to +10 15 10 V V V mA 800(SIP)/625(DIP)/440(FP) mW 8(SIP)/6.25(DIP)/4.4(FP) -20 to +75 -55 to +125 mW/°C °C °C ELECTRICAL CHARACTERISTICS (Ta=25°C,Vcc=5V,unless otherwise noted) (1)DC FEATURES Parameter Symbol IIH IIL VIH VIL WD input current WD input voltage Min. Limits Typ. VIN=5V 0.06 0.15 0.25 mA VIN=-5V 0.05 -0.1 -0.15 mA Pin WD Test conditions V 0.8 TC output current TC VIN=1.5V IIN TC input current TC VOUT=4.2V Threshold voltage of watch dog timer TC VVH3(L) VOL Output voltage ILEAK Output leak current VTH1 Vcc detective voltage(1) RST1 RST2 Vcc detective voltage(2) Vcc ∆VTH2 µA -1 mA 3.7 4 4.3 V 1.7 2 2.3 V 0.1 0.5 V 5 µA VOUT=15V Vcc V 3.3 IOUT=1mA VTH2(H) VTH2(L) Unit 2 WD IOUT VVH3(H) Max. 4.05 4.25 4.45 V 4.5 4.7 4.9 V 4.45 4.6 4.75 V 0.05 0.1 0.2 V V5 ADJ1 voltage ADJ1 1.17 1.46 1.75 V V8 ADJ2 voltage ADJ2 1.07 1.34 1.61 V RST1 on voltage RST1 Vcc=1.2V,RL=4.7k 0.5 V Vcc=1.2V,RL=4.7k 0.5 V 0.8 1.5 V Limits Typ. Max. RST1 RST2 Icc RST2 on voltage Circuit current RST2 Vcc (2)AC FEATURES Symbol tWD Parameter Watch dog timer tRST(1) Reset timer (1) tRST(2) Reset timer (2) Pin Test conditions C=0.1µF,R1=10kΩ 0.5 C=0.1µF,R1=10kΩ 0.2 Input pulse watch td1 td2 Transmittal delay time s 1.1 1.7 ms 1.1 ms 220 µs 0.5•C•R1 RST1 RST1 Unit 1.1•C•R1 RST1 R1=10kΩ C=0.1µF,R1=10kΩ tWD IN Min. WD 0.5 s s 830•C 40 83 µs 3 RST1 20 µs RST2 10 µs MITSUBISHI ELECTRIC ( 2 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER OPERATING EXPLANETION Vcc VTH2(H) VTH1 VTH2(L) VTH1 0V VTH3(H) VTH3(L) TC 0V VIN 0V RST1 0V RST2 0V tRST(1) 12 3 tWD tRST(2) 4 6 5 1 The Vcc rises up to 0.8V,then Reset1 and 2 generate Low output,and Rising up to 4.25V,charge of C1 begins. 2 The Vcc rises up to 4.7V,then Reset2 generates high. 3 , 4 The voltage at TC pin is 2V,then Reset2 generates high,when 4V,C1 is discharged and Reset1 generates Low. 5 The voltage at TC pin falls to 2V,then Reset1 generates high unless normal clock signal is entered to WD pin,Reset1 repeats this operation. Before the voltage at TC pin reaches 4V,if normal 7 6 , clock signal is entered to WD pin,Low Reset1 is canceled. 7 8 9 10 11 8 , 9 In the case of entrance of abnormal signal input, as the waveform of TC pin repeats charge and discharge of Reset1 alternatively from 2V to 4V,the Reset1 repeats high and low output operation. 10 The Vcc falls to 4.6V,then Reset2 generates Low, this detective voltage has a 100mV hysteresis. 11 When Vcc goes down to 4.25V(VTH1),the status of TC pin is switched to discharge.When the potentional at TC pin is detected being VTH3(H) or VTH3(L),the status of Reset1 becomes "low". MITSUBISHI ELECTRIC ( 3/ 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER 2.Pin 1 (WD Pin) Input Frequency, Input Pulse Width,Charge Time and Discharge Time TERMINOLOGY tRST1:Time required for TC pin potential to rise from 0V VTH3(L) when Vcc is being applied. tWD: Time required for TC pin potential to rise from VTH3(L) to VTH3(H). tRST2:Time required for TC pin potential to go down from VTH3(H) to VTH3(L). When input to WD pin 1 is normal,TC pin 2 output waveform is as shown below: (Vcc=5V) 4V Pin 2 xV 1.Pin 2 (TC Pin) Charge Time and Discharge Time 2V t1 t2 When input to WD pin is abnormal,TC pin output waveform is as shown below: 4 •Vcc 5 TC 0V Input 2 •Vcc 5 tWD tWDIN t1=C•R1•in tRST(1) 3 (charge time) 5-x tRST(2) tRST(1)=0.51•C•R1 tWD=1.1•C•R1(charge time) 4• R1 tRST(2)=1000•C•in 1000 2• R1 1000 t2=1000•C•in R1 1000 2• +1 R1 1000 x-5 (discharge time) -3 -1 (discharge time) -3 Vcc R1 2 C PIN 1 (WD PIN)INPUT REQUIREMENTS (1)Connect capacitor between WD pin and voltage input. (Refer to Section 3.) (2)Input cycle:No more than tWD (Discharge should start before voltage at WD pin reaches 4V.) 1 < f 1.1•C•R1 (3)Input pulse width tWDIN:No more than t2 Resistance R1:10kΩ≤R1≤30kΩ When R1 is 10kΩ,tRST(2) is 830•C. C=103 100µs C=104 1ms t t1 Vcc=5V R1=10kΩ 50µs 0.5 ms t2 4 3 2 DISCHARGE VOLTAGE x(V) MITSUBISHI ELECTRIC ( 4 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER 3.Relationship between Input Pulse Width and Input Capacitance Cin Vin VIN When input to pin 1 is 1.5V or more,TC pin discharges electricity. Determine pulse width and input capacitance Cin with reference to the diagram shown on the right. VIN 1 Cin Vin WD 1 1.5V t t3 4V TC 2 30k t t4 tWD 2V t Q1 20k RST1 3 Q1 is off when voltage at pin 1 is 1.5V or less. t Cin:10.000pF,t3=0.6ms Cin:1000pF,t3=0.6µs Cin:100pF,t3=6µs t3=Cin•5X10 4 •In Vin 1.5 RST1 is output when t4 is longer than tWD. When t3 is too long,TC pin output waveform frequency changes as shown above.Set t3 to be sufficiently long to turn on Q1[tWDIN(3µs)or more] but not to exceed t2(Discharge time). (t2:Discharge time during normal input) VTH1(V) R1(kΩ) 4.Vcc Detection Voltage Adjustment (1)Detection voltage 1(VTH1)adjustment. R2(kΩ) 13 10 0.92 10 10 1.25 7 10 1.96 5 10 3.17 4 10.90 5 3.5 8.59 5 Detection voltage calculation formula VTH1= R01+R02 X1.24(V) R02 4.25 6 49.6k R1 R2 RL + 5 R01=R1//49.6kΩ R02=R2//20.4kΩ 20.4k 3 To adjust detection voltage 1,determine external resistance with the following equation: a. VTH>4.25V(R1=10kΩ) 1.24V R2= 4 1 1 R0 1 20.4k R0= 8.322kX1.24 VTH1-1.24 b. VTH1<4.25V(R2=5kΩ) R1= MITSUBISHI ELECTRIC 1 1 R0 R0= 1 49.6k (VTH1-1.24)4.016k 1.24 ( 5 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER (2)Detection voltage 2(VTH2(L))adjustment VTH2(L)(V) R3(kΩ) R4(kΩ) ∆VTH2(mV) 13 10 0.93 16.3 10 10 1.26 16.3 7 10 1.99 16.3 5 10 3.24 16.3 100 4 10.61 5 17.2 3.5 8.38 5 14.1 6 51.2k R3 RL + 5 R4 7 18.8k 4.6 R4= R3= 1 1 R0 X100(mV) R0= 8.37kX1.24 VTH2(L)-1.24 1 18.8k 1 1 R0 M5295AL CLOCK R03 51.2k ∆VTH2= b. VTH2(L)<4.6V(R4=5kΩ) APPLICATION EXAMPLE 3 R03=R3//51.2kΩ R04=R4//18.8kΩ a. VTH2(L)>4.6V(R3=10kΩ) 4 2 VTH2(L)= R03+R04 X1.24(V) R04 To adjust detection voltage 2,determine external resistance with the following equations: 1.24V 1 Detection voltage calculation formula 4 5 RST1 (RESET) 6 7 R0= (VTH2(L)-1.24)3.95k 1 51.2k 1.24 8 RST2 (HOLD) MCU/MPU VDD Example of Backup Circuit with M5295AL OPERATION INSTRUCTIONS BACKUP POWER SUPPLY 1.When malfunction occurs due to noise or other related trouble,connect capacitance of approximately 1000pF between pin 5 and GND as well as pin 8 and GND to stabilize operation. 2.To adjust detection voltage,add resistance of 15kΩ or less to both Vcc and GND via adjusting pins. (Set detection voltage to no less than 3V.) 3.Set tWD and tRST(2) as shown below: 110µs≤tWD≤1.1s 8.3µs≤tRST(2)≤83ms 10kΩ≤R1≤30kΩ 4.Input clock pulses to pin 1 via capacitor.To determine capacitance,refer to "Relationship between Input Pulse Width and Input Capacitance Cin". M5295AL 3.5V 10KΩ 1 2 MITSUBISHI ELECTRIC 3 4 5 6 7 8 R4 R3 Vcc Backup switching voltage TO SYSTEM VTH(L) Switching voltage calculation formula RESET OUTPUT VTH2(L)= R03+R04 X1.24 R04 R03=R3//51.2k R04=R4//18.8k (Note)Set backup switching voltage to be more than or equal to backup supply voltage. ( 6 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER TYPICAL CHARACTERISTICS THERMAL DERATING (MAXIMUM RATING) DETECTION VOLTAGE VS. SUPPLY VOLTAGE 4.9 1000 M5295AL 4.8 800 VTH2(H) 4.7 M5295AP 4.6 600 M5295AFP VTH2(L) 4.5 400 4.4 VTH1 4.3 200 4.2 0 0 25 50 75 100 125 4.1 -40 -20 0 AMBIENT TEMPERATURE Ta(°C) AMBIENT TEMPERATURE Ta(°C) INTERRUPTION OUTPUT VOLTAGE VS. CIRCUIT CURRENT CIRCUIT CURRENT VS. SUPPLY VOLTAGE 4.0 1.6 1.4 RL=4.7kΩ 3.5 Vcc=5V 1.2 3.0 1.0 2.5 0.8 2.0 0.6 1.5 0.4 1.0 0.2 0.5 0 -40 -20 0 20 40 60 80 100 120 RST1 High RST2 High (Icc FLUCTUATION CAUSED BY CIRCUIT OPERATION) 0 0 2 CRITICAL OPERATION VOLTAGE CHARACTERISTICS 100 7 5 3 2 0.7 0.6 10 0.5 0.4 0.3 0.2 8 10 12 14 16 6 4 SUPPLY VOLTAGE Vcc(V) AMBIENT TEMPERATURE Ta(°C) 0.8 20 40 60 80 100 120 RL=2.2kΩ 1 RL=22kΩ RL=100kΩ DELAY TIME VS.DELAY CAPACITY CHARACTERISTICS Vcc=5V tWD(R1=10kΩ) 7 5 3 2 tRST2 7 5 3 2 0.1 7 5 3 2 0.1 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 SUPPLY VOLTAGE Vcc(V) 0.01 2 0.01 3 57 0.1 2 3 57 1 2 3 57 10 2 3 57 100 DELAY CAPACITY C(µF) MITSUBISHI ELECTRIC ( 7 / 8 ) MITSUBISHI<Dig.Ana.INTERFACE> M5295AL/P/FP WATCHDOG TIMER OUTPUT SATURATION VOLTAGE VS. AMBIENT TEMPERATURE OUTPUT SATURATION VOLTAGE VS. LOAD CURRENT 0.4 1.6 Vcc=5V RL=4.7kΩ 1.4 Vcc=5V 0.3 1.2 1.0 0.2 0.8 0.6 0.1 0.4 0.2 0 -40 -20 0 0.1 20 40 60 80 100 120 0 2 3 5 7 1 2 3 5 7 10 2 3 5 7 AMBIENT TEMPERATURE Ta(°C) LOAD CURRENT IOUT(mA) WATCHDOG TIMER THRESHOLD VOLTAGE VS. AMBIENT TEMPERATURE PIN TC INPUT CURRENT VS. AMBIENT TEMPERATURE 8 7 8 Vcc=5V 7 6 5 VTH3(H) 4 4 3 3 VTH3(L) 2 2 1 1 0 -40 -20 0 0 -40 -20 20 40 60 80 100 120 0 20 40 60 80 100 120 AMBIENT TEMPERATURE Ta(°C) AMBIENT TEMPERATURE Ta(°C) WATCHDOG TIMER VS. AMBIENT TEMPERATURE RESET TIMER(2) VS. AMBIENT TEMPERATURE 1.6 1.2 Vcc=5V 6 5 1.4 100 320 Vcc=5V C=0.1µF R1=10kΩ 280 240 1.0 200 0.8 160 0.6 120 0.4 80 0.2 40 0 -40 -20 0 Vcc=5V C=0.1µF 0 -40 -20 20 40 60 80 100 120 0 20 40 60 80 100 120 AMBIENT TEMPERATURE Ta(°C) AMBIENT TEMPERATURE Ta(°C) MITSUBISHI ELECTRIC ( 8 / 8 )