FUJITSU SEMICONDUCTOR DATA SHEET DS04-27402-2E ASSP POWER-VOLTAGE MONITORING IC WITH WATCHDOG TIMER MB3793-42/30 DESCRIPTION The MB3793 is an integrated circuit to monitor power voltage; it incorporates a watchdog timer. 8-PIN PLASTIC DIP (DIP-8P-M01) A reset signal is output when the power is cut or falls abruptly. When the power recovers normally after resetting, a power-on reset signal is output to microprocessor units (MPUs). An internal watchdog timer with two inputs for system operation diagnosis can provide a fail-safe function for various application systems. Two models with detection voltages of 4.2 and 3.0 V are available. There is also a mask option that can detect voltages of 4.9 to 3.0 V in 0.1-V steps. The model numbers are MB3793-42 or -30 corresponding to the detected voltage. The model number and package code are as shown below. Model No. Package code Detection voltage MB3793-42 3793-A 4.2 V MB3793-30 3793-N 3.0 V 8-PIN PLASTIC SOL (FPT-8P-M02) FEATURES • Precise detection of power voltage fall: ±2.5% • Detection voltage with hysteresis • Low power dispersion: ICC = 27 µA (reference) • Internal dual-input watchdog timer • Watchdog-timer halt function (by inhibition pin) • Independently-set watchdog and reset times • Mask option for detection voltage (4.9 to 3.0 V, 0.1-V steps) This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields. However, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. 1 MB3793-42/30 ■ PIN ASSIGNMENT (TOP VIEW) RESET 1 8 CK1 CTW 2 7 CK2 CTP 3 6 INH GND 4 5 VCC (DIP-8P-M01) (FPT-8P-M02) ■ 2 PIN DESCRIPTION Pin No. Symbol 1 RESET 2 Description Pin No. Symbol Description Outputs reset 5 VCC Power supply CTW Sets monitoring time 6 INH Inhibits watchdog timer function 3 CTP Sets power-on reset hold time 7 CK2 Inputs clock 2 4 GND Ground 8 CK1 Inputs clock 1 MB3793-42/30 ■ BLOCK DIAGRAM (5) VCC To VCC of all blocks I1 ≈ 3µA I2 ≈ 30µA Q CTP (3) S RSFF2 Output buffer RESET (1) Q R + Q S - RSFF1 R1 ≈ 280 to 760 kΩ Comp. O Q R INH (6) Comp. S CTW(2) Watchdog timer Reference voltage generator - VS + Pulse generator 1 VREF ≈ 1.24 V CK1 (8) R1 ≈ 240 kΩ Pulse generator 2 CK2 (7) To GND of all blocks (4) GND 3 MB3793-42/30 ■ BLOCK FUNCTIONS 1. Comp. S Comp. S is a comparator with hysteresis to compare the reference voltage with a voltage (VS) that is the result of dividing the power voltage (VCC) by resistors 1 and 2. When VS falls below 1.24 V, a reset signal is output. This function enables the MB3793 to detect an abnormality within 1 µs when the power is cut or falls abruptly. 2. Comp. O Comp. O is a comparator to control the reset signal (RESET) output and compares the threshold voltage with the voltage at the CTP pin for setting the power-on reset hold time. When the voltage at the CTP pin exceeds the threshold voltage, resetting is canceled. 3. Reset output buffer Since the reset (RESET) output buffer has CMOS organization, no pull-up resistor is needed. 4. Pulse generator The pulse generator generates pulses when the voltage at the CK1 and CK2 clock pins changes to High from Low level (positive-edge trigger) and exceeds the threshold voltage; it sends the clock signal to the watchdog timer. 5. Watchdog timer The watchdog timer can monitor two clock pulses. Short-circuit the CK1 and CK2 clock pins to monitor a single clock pulse. 6. Inhibition pin The inhibition (INH) pin forces the watchdog timer on/off. When this pin is High level, the watchdog timer is stopped. 7. Flip-flop circuit The flip-flop circuit RSFF1 controls charging and discharging of the power-on reset hold time setting capacity (CTP). The flip-flop circuit RSFF2 switches the charging accelerator for charging CTP during resetting on/off. This circuit only functions during resetting and does not function at power-on reset. 4 MB3793-42/30 ■ STANDARD CONNECTION VCC VCC RESET CTW RESET CTP CTW MB3793 CK1 VCC RESET VCC Microprocessor 1 Microprocessor 2 CK CK CTP GND GND CK2 INH GND Equation of time-setting capacitances (CTP and CTW) and set time tPR (ms) ≈ A x CTP (µF) tWD (ms) ≈ B x CTW (µF) + C x CTP (µF) CTP However, when —— ≤ about 10, CTW tWD (ms) ≈ B x CTW (µF) tWR (ms) ≈ D x CTP (µF) Values of A, B, C, and D A B C D MB3793-42 Model No. 1300 1500 3 100 Remark MB3793-30 750 1600 4 55 (Example) When CTP = 0.1 µF and CTW = 0.01 µF, • MB3793-42 • MB3793-30 tPR ≈ 130 [ms] tPR ≈ 75 [ms] tWD ≈ 15 [ms] tWD ≈ 16 [ms] tWR ≈ 10 [ms] tWR ≈ 5.5 [ms] 5 MB3793-42/30 ■ TIMING CHART 1. Basic operation (Positive clock pulse) VCC VSH VSL VCCL tCKW CK1 CK2 INH CTP Vth VH CTW VL tPR RESET tPR tWR (1) (2) 6 tWD (3)(4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) MB3793-42/30 2. Basic operation (Negative clock pulse) VSH VSL VCC VCCL tCKW CK1 CK2 INH Vth CTP VH CTW VL tPR RESET tWD tPR tWR (1) (2) (3)(4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) 7 MB3793-42/30 3. Single-clock input monitoring (Positive clock pulse) CK1 CK2 CTP Vth VH CTW VL RESET 8 tWR MB3793-42/30 4. Inhibition operation (Positive clock pulse) VSH VCC VSL VCCL tCKW CK1 CK2 INH Vth CTP VH CTW VL tPR RESET tWD tPR tWR (1) (2) (3)(4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) 9 MB3793-42/30 5. Clock pulse input (Positive clock pulse) a CK1 b CK2 VH CTW VL The MB3793 watchdog timer monitors Clock 1 (CK1) and Clock 2 (CK2) pulses alternately. When a CK2 pulse is detected after detecting a CK1 pulse, the monitoring time setting capacity (CTW) switches to charging from discharging. When two consecutive pulses occur on one side of this alternation before switching, the second pulse is ignored. In the above figure, pulses a and b are ignored. ■ OPERATION SEQUENCE The operation sequence is explained by using Timing Chart 1. The following item numbers correspond to the numbers in Timing Chart 1. (1) When the power voltage (VCC) reaches about 0.8 V (VCCL), a reset signal is output. (2) When VCC exceeds the rising-edge detection voltage (VSH), charging of power-on reset hold time setting capacitance (CTP) is started. VSH is about 4.3 V in the MB3793-42 and 3. 07 V in the MB3793-30. (3) When the voltage at the CTP pin setting the power-on reset hold time exceeds the threshold voltage (Vth), resetting is canceled and the voltage at the RESET pin changes to High level to start charging of the watchdog-timer monitoring time setting capacitance (CTW). Vth is about 3.6 V in the MB3793-42 and 2.4 V in the MB3793-30. The power-on reset hold time (tPR) can be calculated by the following equation. tPR (ms) ≈ A x CTP (µF) Where, A is about 1300 in the MB3793-42 and 750 in the MB3793-30. (4) When the voltage at the CTW pin setting the monitoring time reaches High level (VH), CTW switches to discharging from charging. VH is about 1.24 V (reference value) in both the MB3793-42 and MB3793-30. (5) When clock pulses are input to the CK2 pin during CTW discharging after clock pulses are input to the CK1 pin—positive-edge trigger, CTW switches to charging. (6) If clock pulse input does not occur at either the CK1 or CK2 clock pins during the watchdog-timer monitoring time (tWD), the CTW voltage falls below Low level (VL), a reset signal is output, and the voltage at the RESET pin changes to Low level. VL is about 0.24 V in both the MB3793-42 and MB3793-30. tWD can be calculated from the following equation. tWD (ms) ≈ B x CTW (µF) + C x CTP (µF) Where, B is about 1500 in the MB3793-42 and 1600 in the MB3793-30. C is about 3 in the MB3793-42 and 4 in the MB3793-30; it is much smaller than B. CTP Hence, when —— ≤ 10, the calculation can be simplified as follows: CTW tWD (ms) ≈ B x CTW (µF) 10 MB3793-42/30 (7) When the voltage of the CTP pin exceeds Vth again as a result of recharging CTP, resetting is canceled and the watchdog timer restarts monitoring. The watchdog timer reset time (tWR) can be calculated by the following equation. tWR (ms) ≈ D x CTP (µF) Where, D is about 100 in the MB3793-42 and 55 in the MB3793-30. (8) When VCC falls below the rising-edge detection voltage (VSL), the voltage of the CTP pin falls and a reset signal is output, and the voltage at the RESET pin changes to Low level. VSL is about 4.2 V in the MB3793-42 and 3.0 V in the MB3793-30. (9) When VCC exceeds VSH, CTP begins charging. (10) When the voltage of the CTP pin exceeds Vth, resetting is canceled and the watchdog timer restarts. (11) When an inhibition signal is input (INH pin is High level), the watchdog timer is halted forcibly. In this case, VCC monitoring is continued ((8) - (9)) without the watchdog timer. The watchdog timer does not function unless this inhibition input is canceled. (12) When the inhibition input is canceled (INH pin is Low level), the watchdog timer restarts. (13) When the VCC voltage falls below VSL after power-off, a reset signal is output. Similar operation is also performed for negative clock-pulse input (Timing Chart 2). Short-circuit the clock pins CK1 and CK2 to monitor a single clock. The basic operation is the same but the clock pulses are monitored at every other pulse (Timing Chart 3). ■ ABSOLUTE MAXIMUM RATINGS (Ta = +25°C) Parameter Power voltage* Input voltage Reset output voltage (direct current) Symbol LImits Symbo VCC -0.3 to +7 V -0.3 to +7 V CK1 VCK1 CK2 VCK2 INH VINH RESET IOL IOH -10 to +10 mA PD 200 mW Tstg -55 to +125 °C Allowable loss (Ta ≤ +85°C) Storage temperature *The power voltage is based on the ground voltage (0 V). Note: Permanent device damage may occur if the above ABSOLUTE MAXIMUM RATINGS are exceeded. Functional operation should be restricted to the conditions as detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ■ RECOMMENDED OPERATING CONDITIONS Limits Parameter Symbol Unit Min. Typical Max. Reset (RESET) output current IOL IOH -5 - +5 mA Power-on reset hold time setting capacity CTP 0.001 - 10 µF Watchdog-timer monitoring time setting capacity CTW 0.001 - 1 µF Watchdog timer monitoring time tWD 0.1 - 1500 ms Operating ambient temperature Ta -40 - +85 °C Note: These recommended operation conditions guarantee normal logic operation of an LSI circuit. The limits of the AC and DC electrical characteristics are guaranteed within these recommended conditions. 11 MB3793-42/30 ■ ELECTRICAL CHARACTERISTICS 1. DC Characteristics (VCC = +5 V (MB3793-42), VCC = +3.3 V (MB3793-30), Ta = +25°C) Limits Parameter Symbol Test Conditions Unit Min. Typical Max. ICC1 Watchdog timer operation* - 27 50 ICC2 Watchdog timer halt** - 25 45 ICC1 Watchdog timer operation* - 25 45 ICC2 Watchdog timer halt** - 24 45 Ta = +25°C 4.10 4.20 4.30 VSL VCC falling Ta = -40 to +85°C 4.05 4.20 4.35 Ta = +25°C 4.20 4.30 4.40 Ta = -40 to +85°C 4.15 4.30 4.45 Ta = +25°C 2.90 3.00 3.10 Ta = -40 to +85°C 2.85 3.00 3.15 Ta = +25°C 2.97 3.07 3.17 Ta = -40 to +85°C 2.92 3.07 3.22 50 100 150 mV 30 70 110 mV MB3793-42 Power current MB3793-30 µA µA V MB3793-42 VSH VCC rising Detection voltage VSL V VCC falling V MB3793-30 VSH Detection voltage hysteresis difference VCC rising V MB3793-42 VSHYS VSH - VSL MB3793-30 VthCH - (1.4) 1.9 (2.5) V VthCL - (0.8) 1.3 (1.8) V Clock-input hysteresis VCHYS - (0.4) 0.6 (0.8) V Inhibition-input threshold voltage VthIN - 0.8 1.5 2.0 V Clock-input threshold voltage Input current CK1 CK2 INH IIH VCK = VCC - 0 1.0 µA IIL VCK = 0 V -1.0 0 - µA VOH IRESET = -5 mA 4.5 4.75 - V VOL IRESET = +5 mA - 0.12 0.4 V VOH IRESET = -3 mA 2.8 3.10 - V VOL IRESET = +3 mA - 0.12 0.4 V VCCL IRESET = +50 µA - 0.8 1.2 V MB3793-42 Reset output voltage MB3793-30 Reset-output minimum power voltage *At clock input pins CK1 and CK2, the pulse input frequency is 1 kHz and the pulse amplitude is 0 V to VCC. **Inhibition input is at High level. 12 MB3793-42/30 2. AC Characteristics (VCC = +5 V (MB3793-42), VCC = +3.3 V (MB3793-30), Ta = +25°C) Parameter Power-on reset hold time Watchdog timer monitoring time Watchdog timer reset time Symbol MB3793-42 tPR MB3793-30 MB3793-42 tWD MB3793-30 MB3793-42 tWR MB3793-42 Clock (CK1, CK2) input pulse duration Reset (RESET) output transition time* Limits Test Conditions Typical Max. 80 130 180 ms 30 75 120 ms 7.5 15 22.5 ms 8 16 24 ms 5 10 15 ms 2.0 5.5 9 ms 500 - - ns CTP = 0.1 µF CTW = 0.01 µF CTP = 0.1 µF CTP = 0.1 µF - tCKW Unit Min. Rising tTLH CL = 50pF - - 500 ns Falling tTHL CL = 50pF - - 500 ns *The voltage range is 10% to 90% at testing the reset output transition time. ■ WATCHDOG TIMER USE EXAMPLE 1. Monitoring Two Clocks VCC (5) VCC RESET (1) (2) CTW RESET (3) CTP MB3793 CK1 (8) CTW CTP VCC RESET VCC Microprocessor 1 Microprocessor 2 CK CK GND GND CK2 (7) INH (6) GND (4) 13 MB3793-42/30 2. Monitoring Single Clock VCC (5) VCC RESET (1) (2) CTW RESET (3) CTP CTW VCC Microprocessor MB3793 CK1 (8) CK CTP GND CK2 (7) INH (6) GND (4) 3. Watchdog Timer Stopping VCC (5) VCC RESET (1) (6) INH (2) CTW RESET (3) CTP CTW Microprocessor 1 MB3793 CK1 (8) CK HALT GND CTP CK2 (7) GND (4) 14 VCC RESET VCC Microprocessor 2 CK HALT GND MB3793-42/30 REFERENCE CHARACTERISTIC CURVES (FOR MB3793-42) Power Current - Power Voltage Detection Voltage - Ambient Temperature 40 4.5 Watchdog timer monitoring (VINH = 0 V) Ta = -40 to +85°C 35 VSH (Ta = +25°C) 30 4.4 MAX Detection voltage: VSH and VSL (V) Watchdog timer stopping (VINH = VCC) ICC (µA) Power current: 25 20 Reset (VCC < VSH) Inhibited 15 10 MAX 4.3 TYP VSH TYP 4.2 MIN VSL MB3793-42 f = 1 kHz VINH Duty ≈ 10% VCC MIN 4.1 VL = 0 V VH = VCC VSL (Ta = +25°C) CTW CTP 0.01 µF 0.1 µF Ta = -40 to +85°C 4.0 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 -40 -20 0 20 40 60 80 100 Power voltage: VCC (V) Ambient temperature: Ta (°C) Reset Output Voltage - Reset Output Current Reset Output Voltage - Reset Output Current (P-MOS side) (N-MOS side) 5.0 500 Ta = -40°C 4.9 Ta = +25°C Reset output voltage: VRESET (mV) Reset output voltage: VRESET (V) ■ 4.8 4.7 4.6 400 Ta VRESET RON -40°C 98 mV 19.6 Ω +25°C 135 mV 27 Ω +85°C 167 mV 33.4 Ω IRESET 5 mA Ta = +25°C 300 4.5 Ta = +85°C Ta = +85°C 4.4 200 4.3 4.2 4.1 Ta VRESET RON -40°C 4.800 V 40 Ω +25°C 4.750 V 50 Ω +85°C 4.707 V 58.6 Ω IRESET 100 -5 mA Ta = -40°C 4.0 0 0 -1 -2 -3 -4 -5 -6 -7 Reset output current: IRESET (mA) -8 -9 -10 0 1 2 3 4 5 6 7 8 9 10 Reset output current: IRESET (mA) 15 MB3793-42/30 Reset-on Reset Time - Ambient Temperature Reset Output Voltage - Power Voltage (when VCC rising) 7 260 Pull-up resistance: 100 kΩ 240 6 Ta = -40 to +85°C 5 200 Ta = +25°C 180 4 Power-on reset time: tPR (ms) Reset output voltage: VRESET (V) 220 3 Ta = +85°C 2 Ta = +25°C MAX 160 140 TYP 120 100 1 80 Ta = -40°C MIN 0 0 1 2 3 4 5 6 60 7 40 Power voltage: VCC (V) 20 0 -40 -20 0 20 40 60 80 100 Ambient temperature: Ta (°C) Watchdog Timer Reset Time - Ambient Temperature Watchdog Timer Monitoring Time - Ambient (when monitoring) 26 Temperature 26 24 24 Ta = -40 to +85°C Ta = -40 to +85°C 22 22 20 20 18 18 Ta = +25°C Watchdog timer monitoring time: tWD (ms) Watchdog timer reset time: tWR (ms) MAX Ta = +25°C 16 MAX 14 12 16 TYP 14 12 TYP 10 10 MIN 8 8 6 6 MIN 4 4 2 2 0 -40 -20 0 20 40 60 80 Ambient temperature: Ta (°C) 16 100 0 -40 -20 0 20 40 60 Ambient temperature: Ta (°C) 80 100 MB3793-42/30 Power-on Reset Time - CTP Capacitance Reset Time - CTP Capacitance 103 103 102 102 Reset Time: tWR (ms) Power-on reset time: tPR (ms) 104 Ta = -40°C 1 10 Ta = -40°C 101 Ta = +25°C 1 1 Ta = +25°C Ta = +85°C Ta = +85°C 10-1 10-1 10-4 10-3 10-2 10-1 101 1 10-2 10-4 102 10-3 10-2 10-1 1 101 102 Power-on reset time setting capacitance: CTP (µF) Power-on reset time setting capacitance: CTP (µF) Watchdog-Timer Monitoring Time - CTW Capacitance Watchdog-Timer Monitoring Time - CTW Capacitance (under Ta condition) 104 103 103 Ta = -40°C CTP = 1 µF 102 Watchdog-timer monitoring time: tWD (ms) Watchdog-timer monitoring time: tWD (ms) 102 Ta = +25°C 10 1 Ta = +85°C CTP = 0.1 µF 1 10 1 1 10-1 10-1 CTP = 0.01 µF 10-5 10-4 10-3 10-2 10-1 1 101 Watchdog-timer monitoring time setting capacitance: CTW (µF) 10-5 10-4 10-3 10-2 10-1 1 101 Watchdog-timer monitoring time setting capacitance: CTW (µF) 17 MB3793-42/30 ■ PACKAGE DIMENSIONS 8-LEAD PLASTIC DUAL IN-LINE PACKAGE +.016 .370 –.012 (9.40 +0.40 ) –0.30 INDEX +.012 .039 – 0 (0.99 +0.30 ) –0 +.014 .035 –.012 +0.35 (0.89 –0.30 ) 15°MAX .244±.010 (6.20±0.25) .300(7.62) TYP +.012 .060 –0 +0.30 (1.52 –0 ) .010±.002 (0.25±0.05) .172(4.36)MAX .020(0.51) MIN .100(2.54) TYP 1991 FUJITSU LIMITED D08006S-2C 18 .118(3.00)MIN .018±.003 (0.46±0.08) Dimensions in inches (millimeters) MB3793-42/30 8-LEAD PLASTIC FLAT PACKAGE (CASE No.: FPT-8P-M02) +.010 .199–.008 .061±.008 (1.55±0.20) +0.25 (5.05–0.20) (MOUNTING HEIGHT) .006±.004 (0.15±0.10) .236±.016 (6.00±0.40) 45° .154±.012 (3.90±0.30) .016(0.40) .017±.004 .050(1.27) TYP (0.42±0.10) Ø.005(0.13) M (STAND OFF HEIGHT) .197±.012 (5.00±0.30) .020±.008 (0.50±0.20) .008±.002 (0.20±0.05) Details of “A” part .016(0.40) “A” .008(0.20) .004(0.10) .150(3.81) REF 1991 FUJITSU LIMITED F08004S-2C .007(0.18) MAX .026(0.65) MAX Dimensions in inches (millimeters) 19 MB3793-42/30 FUJITSU LIMITED For further information please contact: Japan FUJITSU LIMITED Corporate Global Business Support Division Electronic Devices KAWASAKI PLANT, 4-1-1, Kamikodanaka Nakahara-ku, Kawasaki-shi Kanagawa 211-88, Japan Tel: (044) 754-3753 Fax: (044) 754-3329 North and South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street San Jose, CA 95134-1804, U.S.A. Tel: (408) 922-9000 Fax: (408) 432-9044/9045 Europe FUJITSU MIKROELEKTRONIK GmbH Am Siebenstein 6-10 63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122 Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE. LIMITED No. 51 Bras Basah Road, Plaza By The Park, #06-04 to #06-07 Singapore 189554 Tel: 336-1600 Fax: 336-1609 All Rights Reserved. Circuit diagrams utilizing Fujitsu products are included as a means of illustrating typical semiconductor applications. Complete information sufficient for construction purposes is not necessarily given. The information contained in this document has been carefully checked and is believed to be reliable. However, Fujitsu assumes no responsibility for inaccuracies. The information contained in this document does not convey any license under the copyrights, patent rights or trademarks claimed and owned by Fujitsu. Fujitsu reserves the right to change products or specifications without notice. No part of this publication may be copied or reproduced in any form or by any means, or transferred to any third party without prior written consent of Fujitsu. The information contained in this document are not intended for use with equipments which require extremely high reliability such as aerospace equipments, undersea repeaters, nuclear control systems or medical equipments for life support. F9603 FUJITSU LIMITED Printed in Japan 20