MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER GENERAL DESCRIPTION M62055FP is a 3V power supply featuring a watchdog timer function for a microcontroller system. It can be a power source of 3V ± 5% by utilizing the reference voltage and amplifier. It can also generate a reset pulse for the applied systems during power-on, moreover it includes the watchdog timer for a self diagnostics of the system, which can prevent system erroneous functions. PIN CONFIGURATION(TOP VIEW) WD TC FEATURES RESET • Power-on reset • Watchdock timer • High accuracy voltage source of 3V ±5% (max) • Overcurrent protection circuit • The voltage detection accuracy of ±5% (max) • Output power (Vo) cutoff function at erroneous conditions • Backward voltage protection circuits for inputs and outputs Vcc M62055FP GND CLM VDD VOC Outline 8P2S APPLICATION Handy information terminal equipment, CD-ROM, Portable audio equipment. BLOCK DIAGRAM CLM Vcc VO VD Vcc Vcc ; It indicates Vo, unless otherwise noted Vcc The input and output reversal conservation circuit VOLTAGE DETECTOR (CURRENT LIMITER) Note 56K START CIRCUIT 40K Vref =1.25v Vcc Reset priority Set priority R Q R Q S Q S Q Vref .=0.9v . Set priority RISE DELAY (300µsec) Vref .=1.25v . Vref .=1.5v . Reset priority Reset priority R Q S Q S Q R Q S Q R Q Vref .=1.5v . GND WD TC MITSUBISHI (1/6) RESET 970508 MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER Pin Functional description pin number symbol Functional description 1 GND Ground 2 WD Input for watchdock timer. 3 TC Setting up reset timer and watchdock timer. 4 RESET Reset signal output 5 VO Feedback to a power supply for a MCU. 6 VD Controlling the stability of an output voltage with a PNP transistor connected externally. 7 CLM Current limiting 8 Vcc Power supply voltage ABSOLUTE MAXIMUM RATINGS symbol Parameter Vcc supply voltage Output voltage VRM Reset pin Output current IRM VWDM Watchdock pin input voltage Ko Thermal derating Topr Operating temperature Tstg Storage temperature (Ta=25°C, Unless otherwise noted) conditions Ta ≥ 25°C MITSUBISHI (2/6) Ratings 13 10 10 3 4.0 - 20 ~ + 75 - 55 ~ + 150 Unit V V mA V mW/°C °C °C 970508 MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER ELECTRICAL CHARACTERISTICS (Vcc=5.0V,Ta=25°C, Unless otherwise noted) (1) DC CHARACTERISTICS symbol Parameter Test conditions Battery• back up• regulator VCC supply voltage ICC Circuitry current VO Output voltage IBmax Bias current Listing short-circuit bias current I BSC Reg-in Input voltage regulation Vcc=3.5V~13V Reg-lo Loading voltage regulation Io=10mA~100mA ∆Vo/∆T Output voltage thermal coefficient VTHCLM CLM threshold voltage Min Limits Typ 3.5 2.85 180 Max 13 650 3.0 10 1.5 0.02 950 3.15 1 0.02 200 25 0.25 220 Unit V µA V mA mA %/V mV %/T mV Reset, watch dock timer VTH1(H) VTH1(L) ∆VTH1 VOL(RST) Ileak VTH2(H) VTH2(L) IWD VTH(WD) Itco 2.68 2.58 Vo detection voltage Output voltage Output leakage current Reset Isink=4mA pin 2.28 0.95 Watchdock timer threshold voltage 2.82 2.72 0.1 0.2 2.96 2.86 2.4 1.0 2.52 1.05 1 VIN=3V WD input current 1.5 WD input threshold voltage TC output current 1 VIN=0.8V VIN=2.4V Itc1 Itc2 TC input current VCCMIN Vcc min operating voltage 0.4 5 2.0 In the output cutoff transmission mode 8.0 *1 2.0 V V V V µA V V µA V µA mA mA V Note *1; The Vcc minimum operating voltage at which the RESET output is Low (2) AC CHARACTERISTICS symbol tWD tRST(1) tRST(2) Parameter Watch dock timer Reset timer (1) Reset timer (2) (Vcc=5.0V,Ta=25°C, Unless otherwise noted) Test conditions C=0.1µF,R1=10KΩ C=0.1µF,R1=10KΩ CO=10µF, R1=10KΩ, IL=0 MITSUBISHI (3/6) Min 0.5 0.1 Limits Typ 1.2 0.7 Max Unit 1.7 mS mS 2.0 mS 970508 MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER FUNCTIONAL DESCRIPTION Tick deactivation VO+VCE(sat) Vcc 0 output cutoff VTH1(H) output cutoff VTH1(L) Vo 0 .=0.9V . .=0.9V . VTH2(H) TC 0 VTH2(L) RESET 0 TWD TRST(1) TRST(2) WD 0 1 3 2 1 4 6 5 7 9 8 : When Vo rises to 0.5 V, RESET becomes low. Then, charging to a capacitor C connected to TC will be started at the Vo of 2.82V(VTH1(H)). 2 : When VCC rises to 3V+VCE(sat), Vo becomes stable. 3 4 : When TC voltage rises to 1V(VTH2(L)) , RESET becomes high. When it rises to 2.4V (VTH2(H)) further, the capacitor C is switched to discharge and RESET becomes low. 5 : At the same time of a change-over to the discharge from the capacitor C, Vo is intercepted. Then,TC will be discharged completely at Vo of 2.72V(VTH1 (L)). 6 : Vo returns to 3V right after it has fallen down to 0.9 V. RESET repeats above operation till a normal clock signal is input to WD pin. 10 7 8 9 11 12 13 14 : In the case of a sudden power interruption, Vo falls down according to a decrease of VCC. When it falls down to 2.72V, the capacitor C is discharged and RESET will be low. In the case of a reversion from the power interruption, Vo rises according to a increase of VCC. When it rises to 2.82V, the charging to the capacitor C is started and RESET will be high right after TC voltage reaches 1V. 10 11 : In the case a clock signal for discharging the capacitor C is applied to pin WD before TC voltage reaches to 2.4V, a reset signal to RESET is canceled. 12 13 : In the case an abnormal clock signal is input, TC repeats charging / discharging alternately between 1 V and 2.4 V, so that RESET also repeats high / low till a normal clock signal is input. 14 : When Vo falls down to 2.72 V, RESET becomes Low. MITSUBISHI (4 / 6 ) 970508 MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER DESCRIPTION of TERMS tRST(1) Time from when TC begins to charge until it reaches to VTH2(L). tWD Time from when TC is VTH2(L) until it reaches to VTH2(H). tRST(2) Time from when TC is VTH2(H) until TC starts charging. 2. Pin 2 (WD pin) Input frequency, input pulse width, charge/discharge time . When input of 2 WD is normal, TC waveform 3 is as shown below. VTH2(H) = 2.4v XV 1. Pin 3 (TC pin) Charging and discharging time . Pin 3 VTH2(L) = 1.0v t1 When an error is occurred in WD input, TC waveform is as shown below. t2 Pin 2 output cutoff VTH1(H) VTH1(L) Vo 0 tWDIN .=0.9V . t1 = C • R1 • ln VTH2(H) TC 0 2 3-X R1 + 1 ) 1000 R1 - 2 1000 X( VTH2(L) tRST(1) t2 = 1000 • C • R1 • ln tRST(2) Inside delay time tWD -3 VO = 3.0V Conditions of an input to pin 2 (WD pin) R1 *1 (1) Input period should be tWD or less. tRST(1) = 0.406 • C • R1 + 300µs ( Pin discharge is completed before the arrival of VTH2(H) = 2.4 V ) 3 1 tWD = 1.2 • C • R1 (Charging time) 1.2 • C • R1 C *1 : Inside delay time (Typical values) <f (2) Input pulse width tWDIN should be t2 or less. The following formula can be obtained because tRST(2) is equal to the duration of Vo cutoff. 3 *3 tRST(2) = C • R • ln ( 0.9 ) Al C *2 + 300µs *2 = 40 • C + 300µs cutoff Tr *2 : Inside delay time (Typical values) *3 : R = Internal resistance MITSUBISHI (5 / 6 ) 970508 MITSUBISHI<Dig./Ana.INTERFACE> M62055FP 3V POWER SUPPLY with WATCHDOG TIMER 3. Relationship between the input pulse width and the low pass filter V0 R 3.0V VIN 1K VIN 0.0V t 3.0v WD t4 t3 WD 1.5v C + filter (External Element) t 2.4v 1.5V TC 2.4v 1.0v tWD t Addition of a low pass filter makes input waveform dull. An input pulse width and CR of a low pass filter is determined referring to the right figure. RESET t 1.5v If t3 is too long, the TC waveform changes as shown in the diagram above. t3 is set as follows; tWDIN (3 µs) or more and t 2 (charging time) or less. (t2 is a discharge time while an input is normal) t 3 = -C • R • ln VIN RESET is output in the case of t 4> t WD. APPLICATION VCC + 10µF CIN + 10µF CO VCC CLM VD VO TC RESET M62055FP GND WD RTC CTC RRST GND CLOCK RESET MCU/MPU VDD Note : hFE of the external PNP transistor, 100 to 300 is recommended. MITSUBISHI (6 / 6 ) 970508