FUJITSU SEMICONDUCTOR DATA SHEET DS04-27403-2E ASSP For Power Supply Applications BIPOLAR Power Voltage Monitoring IC with Watchdog Timer MB3793-37A ■ DESCRIPTION The MB3793 is an integrated circuit to monitor power voltage; it incorporates a watchdog timer. 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 fall-safe function for various applicaiton systems. There is also a mask option that can detect voltages of 4.9 to 2.4 V in 0.1-V steps. The model number is MB3793-37A corresponding to the detected voltage. The model number and package code are as shown below. Model No. Package code Detection voltage MB3793-37A 3793AF 3.7 V ■ FEATURES • • • • • • Precise detection of power voltage fall: ±2.5% Detection voltage with hysteresis Low power dispersion: ICC = 30 µA (reference) Internal dual-input watchdog timer Watchdog-timer halt function (by inhibition pin) Independently-set wacthdog and reset times ■ PACKAGE 8-pin, Plastic SOP 8-pin, Plastic SOL (FPT-8P-M01) (FPT-8P-M02) MB3793-37A ■ PIN ASSIGNMENT (Top view) RESET 1 8 CK1 CTW 2 7 CK2 CTP 3 6 INH GND 4 5 VCC (FPT-8P-M01) (FPT-8P-M02) ■ PIN DESCRIPTION 2 Pin no. Symbol 1 RESET 2 Descriptions Pin no. Symbol Descriptions Outputs reset pin 5 VCC Power supply pin CTW Watchdog timer monitor time setting pin 6 INH Inhibit pin 3 CTP Power-on reset hold time setting pin 7 CK2 Inputs clock 2 pin 4 GND Ground pin 8 CK1 Inputs clock 1 pin MB3793-37A ■ BLOCK DIAGRAM To VCC of all blocks . 3 µA I1 = . 5 VCC I2 .=. 30 µA CTP 3 . R1 = . 494 kΩ Logic circuit RESET 1 Output circuit INH 6 Comp.S CTW 2 Watchdog timer Reference voltage generator − VS + Pulse generator 1 . 1.24 V VREF = . CK1 8 R2 .=. 240 kΩ Pulse generator 2 CK2 7 To GND of all blocks 4 GND 3 MB3793-37A ■ BLOCK DESCRIPTION 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 ans abnomality within 1 µs when the power is cut or falls abruptly. 2. Output circuit The output circuit contains a RESET output control comparator that compares the voltage at the CTP pin to the threshold voltage to release the RESET output if the CTP pin voltage exceeds the threshold value. Since the reset (RESET) output buffer has CMOS organization, no pull-up resistor is needed. 3. 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. 4. Watchdog timer The watchdog timer can monitor two clock pulses. Short-circuit the CK1 and CK2 clock pins to monitor a single clock pulse. 5. Inhibition pin The inhibition (INH) pin forces the watchdog timer on/off. When this pin is High level, the watchdog timer is stopped. 6. Logic circuit The logic circuit contains flip-flops. Flip-flop RSFF1 controls the charging and discharging of the power-on reset time setting capacitor (CTP). Flip-flop RSFF2 turns on/off the circuit that accelerates charging of the power-on reset time setting capacitor (CTP) at a reset. The RSFF2 operates only at a reset; it does not operate at a power-on reset when the power is turned on. 4 MB3793-37A ■ ABSOLUTE MAXIMUM RATINGS (Ta = +25°C) Parameter Symbol Conditions VCC — CK1 VCK1 — CK2 VCK2 — INH IINH — RESET IOL IOH Power supply voltage* Input voltage Reset output current Allowable loss Storage temperature Rating Unit Min. Max. –0.3 +7 V –0.3 +7 V — –10 +10 mA PD Ta ≤ +85°C — 200 mW Tstg — –55 +125 °C * : The power supply voltage is based on the ground voltage (0 V). WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. ■ RECOMMENDED OPERATING CONDITIONS Parameter Symbol Conditions Power supply voltage VCC Reset (RESET) output current Value Unit Min. Typ. Max. — 1.2 — 6.0 V 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 Operating temperature Ta — –40 — +85 °C * : The watchdog timer monitor time range depends on the rating of the setting capacitor. WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device's electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within their recommended operating condition ranges. Operation outside these ranges may adversely affect reliability and could result in device failure. No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representatives beforehand. 5 MB3793-37A ■ ELECTRICAL CHARACTERISTICS 1. DC Characteristics (VCC = +5 V, Ta = +25°C) Parameter Symbol Power supply current ICC1 After exit from reset VSL VCC falling VSH VCC rising Detection voltage Detection voltage hysteresis difference Clock-input threshold voltage Clock-input hysteresis Inhibition-input voltage Input current (CK1, CK2, INH) Reset output voltage Reset-output minimum power voltage Value Conditions Ta = +25°C Ta = –40°C to +85°C Ta = +25°C Ta = –40°C to +85°C Min. Typ. Max. — 30 50 3.60 3.70 3.80 (3.55)* 3.70 (3.85)* 3.69 3.79 3.89 (3.64)* 3.79 (3.94)* Unit µA V V VSHYS VSH – VSL 40 85 130 mV VCIH CK rising (1.4)* 1.9 2.5 V VCIL CK falling 0.8 1.3 (1.8)* V V VCHTS — (0.4)* 0.6 (0.8)* VIIH — 3.5 — — VIIL — — 0 0.8 V IIH VCK = 5 V — 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 VCCL IRESET = +50 µA — 0.8 1.2 V * : The values enclosed in parentheses ( ) are setting assurance values. 2. AC Characteristics (VCC = +5 V, Ta = +25°C) Parameter Symbol Conditions Value Min. Max. 130 180 ms — — µs Power-on reset hold time tPR CTP = 0.1 µF VCC input pulse width tPI CTP = 0.1 µF (110)* VCC delay time tPD CTP = 0.1 µF — 20 (100)*2 µs Watchdog timer reset time tWD CTW = 0.01 µF, CTP = 0.1 µF 7.5 15 22.5 ms Watchdog timer reset time tWR CTP = 0.1 µF 5 10 15 ms Clock input pulse width tCKW — 500 — — ns Clock input pulse cycle tCKT — 20 — — µs Reset (RESET) output transition time*1 80 2 Rising tr*1 CL = 50 pF — — 500 ns Falling tf*2 CL = 50 pF — — 500 ns *1:The voltage range is 10% to 90% at testing the reset output transition time. *2:The values enclosed in parentheses ( ) are setting assurance values. 6 Unit Typ. MB3793-37A ■ DIAGRAM 1. Basic operation (Positive clock pulse) VSH VSL VCC tCKW CK1 tCKT CK2 INH Vth CTP VH CTW VL RESET tWD tPR (1) (2) (3) (4)(5) (5) tPR tWR (6) (7) (8) (9) (10) (11) (12) (13) 7 MB3793-37A 2. Basic operation (Negative clock pulse) VSH VSL VCC tCKW CK1 tCKT CK2 INH Vth CTP VH CTW VL RESET tPR (1) (2) 8 tWD (3) (4)(5) (5) tPR tWR (6) (7) (8) (9) (10) (11) (12) (13) MB3793-37A 3. Single-clock input monitoring (Positive clock pulse) tCKW CK1 CK2 tCKT Vth CTP VH CTW VL RESET Note: tWD tWR The MB3793 can monitor only one clock. The MB3793 checks the clock signal at every other input pulse. Therefore, set watchdog timer monitor time tWD to the time that allows the MB3793 to monitor the period twice as long as the input clock pulse. 9 MB3793-37A 4. Inhibition operation (Positive clock pulse) VSH VSL VCC tCKW CK1 CK2 INH Vth CTP VH CTW VL RESET tPR (1) (2) 10 tWD (3) (4)(5) (5) tPR tWR (6) (7) (11) (8) (9) (10) (12) (13) MB3793-37A 5. Clock pulse input supplementation (Positive clock pulse) *1 CK1 *2 CK2 VH CTW VL Note: The MB3793 watchdog timer monitors Clock1 (CK1) and Clock2 (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, pulse *1 and *2 are ignored. ■ OPERATION SEQUENCE 1. Positive clock pulse input See “1. Basic operation (positive clock pulse)” under “■ DIAGRAM.” 2. Negative clock pulse input See “2. Basic operation (negative clock pulse)” under “■ DIAGRAM.” The MB3793 operates in the same way whether it inputs positive or negative pulses. 3. Clock monitoring To use the MB3793 while monitoring only one clock, connect clock pins CK1 and CK2. Although the MB3793 operates basically in the same way as when monitoring two clocks, it monitors the clock signal at every other input pulse. See “3. Single-clock input monitoring (positive clock pulse)” under “■ DIAGRAM.” 4. Description of Operations The numbers given to the following items correspond to numbers (1) to (13) used in “■ DIAGRAM.” (1) The MB3793 outputs a reset signal when the supply voltage (VCC) reaches about 0.8 V (VCCL) (2) If VCC reaches or exceeds the rise-time detected voltage VSH, the MB3793 starts charging the power-on reset hold time setting capacitor CTP. At this time, the output remains in a reset state. The VSH value is about 3.79 V. (3) When CTP has been charged for a certain period of time TPR (until the CTP pin voltage exceeds the threshold voltage (Vth) after the start of charging), the MB3793 cancels the reset (setting the RESET pin to “H” level from “L” level). 11 MB3793-37A The Vth value is about 3.6 V with VCC = 5.0 V The power-on reset hold timer monitor time tPR is set with the following equation: tPR (ms) .=. A × CTP (µF) The value of A is about 1300 with VCC = 5.0 V. The MB3793 also starts charging the watchdog timer monitor time setting capacitor (CTW). (4) When the voltage at the watchdog timer monitor time setting pin CTW reaches the “H” level threshold voltage VH, the CTW switches from the charge state to the discharge state. The value of VH is always about 1.24 V regardless of the detected voltage. (5) If the CK2 pin inputs a clock pulse (positive edge trigger) when the CTW is being discharged in the CK1-CK2 order or simultaneously, the CTW switches from the discharge state to the charge state. The MB3793 repeats operations (4) and (5) as long as the CK1/CK2 pin inputs clock pulses with the system logic circuit operating normally. (6) If no clock pulse is fed to the CK1 or CK2 pin within the watchdog timer monitor time tWD due to some problem with the system logic circuit, the CTW pin is set to the “L” level threshold voltage VL or less and the MB3793 outputs a reset signal (setting the RESET pin to “L” level from “H” level). The value of VL is always about 0.24 V regardless of the detected voltage. The watchdog timer monitor time tWD is set with the following equation: tWD (ms) .=. B × CTW (µF) The value of B is hardly affected by the supply voltage; it is about 1500 with VCC = 5.0 V. (7) When a certain period of time tWR has passed (until the CTP pin voltage reaches or exceeds Vth again after recharging the CTP), the MB3793 cancels the reset signal and starts operating the watchdog timer. The watchdog timer monitor reset time tWR is set with the following equation: tWR (ms) .=. D x CTP (µF) The value of D is about 100 with VCC = 5.0 V. The MB3793 repeats operations (4) and (5) as long as the CK1/CK2 pin inputs clock pulses. If no clock pulse is input, the MB3793 repeats operations (6) and (7). (8) If VCC is lowered to the fall-time detected voltage (VSL) or less, the CTP pin voltage decreases and the MB3793 outputs a reset signal (setting the RESET pin to “L” level from “H” level). The value of VSL is 3.7 V (9) When VCC reaches or exceeds VSH again, the MB3793 starts charging the CTP. (10) When the CTP pin voltage reaches or exceeds Vth, the MB3793 cancels the reset and restarts operating the watchdog timer. It repeats operations (4) and (5) as long as the CK1/CK2 pin inputs clock pulses. (11) Making the inhibit pin active (setting the INH pin to “H” from “L”) forces the watchdog timer to stop operation. This stops only the watchdog timer, leaving the MB3793 monitoring VCC (operations (8) to (10)). The watchdog timer remains inactive unless the inhibit input is canceled. (12) Canceling the inhibit input (setting the INH pin to “L” from “H”) restarts the watchdog timer. (13) The reset signal is output when the power supply is turned off to set VCC to VSL or less. 12 MB3793-37A ■ TYPICAL CHARACTERISTICS Power supply current-Power supply voltage Detection voltage-Ambient temperature 40 4.0 Ta = −40°C to +85°C 35 Power supply current: ICC (µA) 25 Watchdog timer monitoring (VINH = 0 V) 20 15 10 MB3793-37A VINH f = 1 kHz Duty = 10% VL = 0 V VH = VCC VCC Detection voltage: VSH and VSL (V) VSH (Ta = +25°C) 30 3.9 MAX MAX 3.8 TYP 3.7 MIN 3.6 VSL (Ta = +25°C) CTP CTW 0.01 µF 0.1 µF (Ta = −40°C to +85°C) −40 −20 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 20 40 60 80 100 Power supply voltage: VCC (V) Ambient temperature: Ta (°C) Reset output voltage-Reset output current (P-MOS side) Reset output voltage-Reset output current (N-MOS side) Ta = −40°C 4.9 Ta = +25°C 4.8 4.7 4.6 4.5 4.4 4.3 4.2 Ta VRESET RON IRESET −40°C 98 mV 19.6 Ω +25°C 135 mV 27 Ω +5 mA +85°C 167 mV 33.4 Ω 500 Ta = +85°C Ta VRESET RON IRESET −40°C 4.800 V 40 Ω +25°C 4.750 V 50 Ω −5 mA +85°C 4.707 V 58.6 Ω Reset output voltage: VRESET (mV) 5.0 Reset output voltage: VRESET (V) VSL MIN 3.5 0 VSH TYP 400 Ta = +25°C 300 Ta = +85°C 200 100 Ta = −40°C 4.1 4.0 0 −1 −2 −3 −4 −5 −6 −7 −8 −9 −10 Reset output current: IRESET (mA) 0 0 1 2 3 4 5 6 7 8 9 10 Reset output current: IRESET (mA) (Continued) 13 MB3793-37A Reset-on reset time-Ambient temperature (when VCC rising) Reset output voltage-Power supply voltage 260 7 Pull-up resistance: 100 kΩ 240 220 5 Power-on reset time: tPR (ms) Reset output voltage: VRESET (V) 6 4 3 Ta = +85°C 2 Ta = +25°C 1 Ta = −40°C 0 0 1 2 3 4 5 6 Ta = −40°C to +85°C 200 Ta = +25°C 180 MAX 160 140 120 TYP 100 80 MIN 60 7 40 Power supply voltage: VCC (V) 20 0 −40 −20 0 20 40 60 80 100 Ambient temperature: Ta (°C) Watchdog timer reset time-Ambient temperature (when monitoring) 26 26 24 24 Ta = −40°C to +85°C Watchdog timer monitoring time: tWD (ms) 22 Watchdog timer reset time: tWR (ms) Watchdog timer monitoring time-Ambient temperature 20 18 16 Ta = +25°C 14 MAX 12 TYP 10 8 6 MIN 4 MAX 22 20 Ta = +25°C 18 16 TYP 14 12 10 8 MIN 6 4 2 0 Ta = −40°C to +85°C 2 −40 −20 0 0 20 40 60 80 100 Ambient temperature: Ta (°C) −40 −20 0 20 40 60 80 100 Ambient temperature: Ta (°C) (Continued) 14 MB3793-37A (Continued) Reset time-CTP capacitance 103 104 103 10 Reset time: tWR (ms) Power-on reset time: tPR (ms) Power-on reset time-CTP capacitance Ta = −40°C 2 Ta = +25°C 101 Ta = +85°C 1 10 −1 10−4 10−3 10−2 10−1 102 Ta = −40°C 10 1 1 Ta = +25°C Ta = +85°C −1 10 101 1 102 Power-on reset time setting capacitance: CTP (µF) 10−2 10−4 10−3 10−2 10−1 1 101 102 Power-on reset time setting capacitance: CTP (µF) Watchdog-timer monitoring time: tWD (ms) Watchdog-timer monitoring time-CTW capacitance 103 Ta = −40°C 102 Ta = +25°C 1 10 1 Ta = +85°C −1 10 10−5 10−4 10−3 10−2 10−1 1 101 Watchdog-timer monitoring time setting capacitance: CTW (µF) 15 MB3793-37A ■ APPLICATION EXAMPLE 1. Supply voltage monitor and watchdog timer (1-clock monitor) VCC 5 VCC 2 CTW RESET 1 M B 3 7 9 3 RESET CTW* 3 CTP CTP* CK1 8 VCC Microprocessor CK 6 INH GND 4 CK2 7 GND GND * : Use a capacitor with less leakage current. The MB3793 monitors the clock (CK1/2) at every other input pulse. 2. Supply voltage monitor and watchdog timer stop VCC 6 INH 5 VCC RESET 1 RESET M B 3 7 9 3 2 CTW CK1 8 VCC Microprocessor 1 CK HALT GND CTW* CTP* 3 CTP GND CK2 7 4 GND * : Use a capacitor with less leakage current. 16 RESET VCC Microprocessor 2 CK HALT GND MB3793-37A ■ TYPICAL APPLICATION VCC 5 VCC 2 CTW RESET 1 RESET MB3793 CTW* CTP* 3 CTP VCC Microprocessor 1 CK1 8 GND VCC Microprocessor 2 CK CK GND 6 INH RESET GND CK2 7 4 GND * : Use a capacitor with less leakage current. 1. Equation of time-setting capacitances (CTP and CTW) and set time . tPR [ms] =. A × CTP [µF] . tWD [ms] =. B × CTW [µF] + C × CTP [µF] . However, when CTP ≤ about 10, tWD [ms] =. B × CTW [µF] CTW . tWR [ms] =. D × CTP [µF] Values of A, B, C, and D A B C D Remark 1300 1500 0 100 VCC = 5.0 V 2. (Example) when CTP = 0.1 µF and CTW = 0.01 µF tPR time (msec) tWD tWR . =. 130 . =. 15 . =. 10 17 MB3793-37A ■ ORDERING INFORMATION Part number 18 Package MB3793-37PF 8-pin Plastic SOP (FPT-8P-M01) MB3793-37PNF 8-pin Plastic SOL (FPT-8P-M02) Remarks MB3793-37A ■ PACKAGE DIMENSIONS 8-pin Plastic SOP (FPT-8P-M01) +0.25 2.25(.089)MAX (Mounting height) +.010 6.35 –0.20 .250 –.008 0.05(.002)MIN (STAND OFF) 5.30±0.30 (.209±.012) INDEX 1.27(.050) TYP 0.45±0.10 (.018±.004) 3.81(.150)REF +0.40 6.80 –0.20 7.80±0.40 (.307±.016) +.016 .268 –.008 +0.05 Ø0.13(.005) M 0.15 –0.02 +.002 .006 –.001 0.50±0.20 (.020±.008) Details of "A" part 0.20(.008) 0.50(.020) "A" 0.18(.007)MAX 0.10(.004) C 1994 FUJITSU LIMITED F08002S-4C-4 0.68(.027)MAX Dimensions in mm (inches) (Continued) 19 MB3793-37A (Continued) 8-pin Plastic SOL (FPT-8P-M02) +0.25 +.010 5.05 –0.20 .199 –.008 1.55±0.20(.061±.008) (Mounting height) 0.15±0.10 (STAND OFF) (.006±.004) 3.90±0.30 (.154±.012) 6.00±0.40 (.236±.016) 5.00±0.30 (.197±.012) 45° 0.40(.016) 1.27(.050)TYP 0.42±0.10 (.017±.004) Ø0.13(.005) M 0.20±0.05 (.008±.002) 0.50±.020 (.020±.008) Details of "A" part 0.40(.016) "A" 3.81(.150)REF 0.10(.004) 0.20(.008) 0.18(.007)MAX 0.65(.026)MAX C 20 1994 FUJITSU LIMITED F08004S-2C-4 Dimensions in mm (inches) MB3793-37A 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 211-8588, Japan Tel: 81(44) 754-3763 Fax: 81(44) 754-3329 http://www.fujitsu.co.jp/ North and South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street San Jose, CA 95134-1804, USA Tel: (408) 922-9000 Fax: (408) 922-9179 Customer Response Center Mon. - Fri.: 7 am - 5 pm (PST) Tel: (800) 866-8608 Fax: (408) 922-9179 http://www.fujitsumicro.com/ Europe FUJITSU MIKROELEKTRONIK GmbH Am Siebenstein 6-10 D-63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122 http://www.fujitsu-ede.com/ Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE LTD #05-08, 151 Lorong Chuan New Tech Park Singapore 556741 Tel: (65) 281-0770 Fax: (65) 281-0220 All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU sales representatives before ordering. The information and circuit diagrams in this document are presented as examples of semiconductor device applications, and are not intended to be incorporated in devices for actual use. Also, FUJITSU is unable to assume responsibility for infringement of any patent rights or other rights of third parties arising from the use of this information or circuit diagrams. FUJITSU semiconductor devices are intended for use in standard applications (computers, office automation and other office equipment, industrial, communications, and measurement equipment, personal or household devices, etc.). CAUTION: Customers considering the use of our products in special applications where failure or abnormal operation may directly affect human lives or cause physical injury or property damage, or where extremely high levels of reliability are demanded (such as aerospace systems, atomic energy controls, sea floor repeaters, vehicle operating controls, medical devices for life support, etc.) are requested to consult with FUJITSU sales representatives before such use. The company will not be responsible for damages arising from such use without prior approval. Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under the Foreign Exchange and Foreign Trade Law of Japan, the prior authorization by Japanese government will be required for export of those products from Japan. http://www.fmap.com.sg/ F9901 FUJITSU LIMITED Printed in Japan 21