POWER-VOLTAGE MONITORING WITH WATCHDOG TIMER MB3793-42/30 DE
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DS04-27402-2E
POWER-VOLTAGE MONITORING WITH WATCHDOG TIMER
MB3793-42/30
DESCRIPTION
MB3793 integrated circuit monitor power voltage; incorporates watchdog timer. reset signal output when power falls abruptly. When power recovers normally after resetting, power-on reset signal output microprocessor units (MPUs). internal watchdog timer with inputs system operation diagnosis provide fail-safe function various application systems. models with detection voltages available. There also mask option that detect voltages 0.1-V steps. model numbers MB3793-42 corresponding detected voltage. model number package code shown below.
8-PIN PLASTIC (DIP-8P-M01)
Model MB3793-42 MB3793-30
Package code 3793-A 3793-N
Detection voltage 8-PIN PLASTIC (FPT-8P-M02)
FEATURES
Precise detection power voltage fall: ±2.5% Detection voltage with hysteresis power dispersion: (reference) Internal dual-input watchdog timer Watchdog-timer halt function inhibition pin) Independently-set watchdog reset times Mask option detection voltage (4.9 0.1-V steps)
This device contains circuitry protect inputs against damage high static voltages electric fields. However, advised that normal precautions taken avoid application voltage higher than maximum rated voltages this high impedance circuit.
MB3793-42/30
ASSIGNMENT
(TOP VIEW)
RESET
(DIP-8P-M01) (FPT-8P-M02)
DESCRIPTION
Symbol RESET Description Outputs reset Sets monitoring time Sets power-on reset hold time Ground Symbol Description Power supply Inhibits watchdog timer function Inputs clock Inputs clock
MB3793-42/30
BLOCK DIAGRAM
30µA
blocks
RSFF2 Output buffer RESET Comp.
RSFF1
Comp. CTW(2) Watchdog timer Reference voltage generator
Pulse generator VREF 1.24
Pulse generator blocks
MB3793-42/30
BLOCK FUNCTIONS
Comp.
Comp. comparator with hysteresis compare reference voltage with voltage (VS) that result dividing power voltage (VCC) resistors When falls below 1.24 reset signal output. This function enables MB3793 detect abnormality within when power falls abruptly.
Comp.
Comp. comparator control reset signal (RESET) output compares threshold voltage with voltage setting power-on reset hold time. When voltage exceeds threshold voltage, resetting canceled.
Reset output buffer
Since reset (RESET) output buffer CMOS organization, pull-up resistor needed.
Pulse generator
pulse generator generates pulses when voltage clock pins changes High from level (positive-edge trigger) exceeds threshold voltage; sends clock signal watchdog timer.
Watchdog timer
watchdog timer monitor clock pulses. Short-circuit clock pins monitor single clock pulse.
Inhibition
inhibition (INH) forces watchdog timer on/off. When this High level, watchdog timer stopped.
Flip-flop circuit
flip-flop circuit RSFF1 controls charging discharging power-on reset hold time setting capacity (CTP). flip-flop circuit RSFF2 switches charging accelerator charging during resetting on/off. This circuit only functions during resetting does function power-on reset.
MB3793-42/30
STANDARD CONNECTION
RESET RESET MB3793 RESET
Microprocessor
Microprocessor
Equation time-setting capacitances (CTP CTW) time (ms) (µF) (ms) (µF) (µF) However, when about (ms) (µF) (ms) (µF)
Values Model MB3793-42 MB3793-30 1300 1500 1600 Remark
(Example) When 0.01 MB3793-42 [ms] [ms] [ms] MB3793-30 [ms] [ms] [ms]
MB3793-42/30
TIMING CHART
Basic operation (Positive clock pulse)
VCCL
tCKW
RESET
(3)(4)
(10)
(11)
(12)
(13) (14)
MB3793-42/30
Basic operation (Negative clock pulse)
VCCL
tCKW
RESET
(3)(4)
(10)
(11)
(12)
(13) (14)
MB3793-42/30
Single-clock input monitoring (Positive clock pulse)
RESET
MB3793-42/30
Inhibition operation (Positive clock pulse)
VCCL
tCKW
RESET
(3)(4)
(10)
(11)
(12)
(13) (14)
MB3793-42/30
Clock pulse input (Positive clock pulse)
MB3793 watchdog timer monitors Clock (CK1) Clock (CK2) pulses alternately. When pulse detected after detecting pulse, monitoring time setting capacity (CTW) switches charging from discharging. When consecutive pulses occur side this alternation before switching, second pulse ignored. above figure, pulses ignored.
OPERATION SEQUENCE
operation sequence explained using Timing Chart following item numbers correspond numbers Timing Chart When power voltage (VCC) reaches about (VCCL), reset signal output. When exceeds rising-edge detection voltage (VSH), charging power-on reset hold time setting capacitance (CTP) started. about MB3793-42 MB3793-30. When voltage setting power-on reset hold time exceeds threshold voltage (Vth), resetting canceled voltage RESET changes High level start charging watchdog-timer monitoring time setting capacitance (CTW). about MB3793-42 MB3793-30. power-on reset hold time (tPR) calculated following equation. (ms) (µF) Where, about 1300 MB3793-42 MB3793-30. When voltage setting monitoring time reaches High level (VH), switches discharging from charging. about 1.24 (reference value) both MB3793-42 MB3793-30. When clock pulses input during discharging after clock pulses input pin-positive-edge trigger, switches charging. clock pulse input does occur either clock pins during watchdog-timer monitoring time (tWD), voltage falls below level (VL), reset signal output, voltage RESET changes level. about 0.24 both MB3793-42 MB3793-30. calculated from following equation. (ms) (µF) (µF) Where, about 1500 MB3793-42 1600 MB3793-30. about MB3793-42 MB3793-30; much smaller than Hence, when calculation simplified follows: (ms) (µF)
MB3793-42/30
When voltage exceeds again result recharging resetting canceled watchdog timer restarts monitoring. watchdog timer reset time (tWR) calculated following equation. (ms) (µF) Where, about MB3793-42 MB3793-30. When falls below rising-edge detection voltage (VSL), voltage falls reset signal output, voltage RESET changes level. about MB3793-42 MB3793-30. When exceeds VSH, begins charging. (10) When voltage exceeds Vth, resetting canceled watchdog timer restarts. (11) When inhibition signal input (INH High level), watchdog timer halted forcibly. this case, monitoring continued ((8) (9)) without watchdog timer. watchdog timer does function unless this inhibition input canceled. (12) When inhibition input canceled (INH level), watchdog timer restarts. (13) When voltage falls below after power-off, reset signal output. Similar operation also performed negative clock-pulse input (Timing Chart Short-circuit clock pins monitor single clock. basic operation same clock pulses monitored every other pulse (Timing Chart
ABSOLUTE MAXIMUM RATINGS
+25°C)
Parameter Power voltage* Input voltage Reset output voltage (direct current) Allowable loss +85°C) Storage temperature RESET
Symbol VCK1 VCK2 VINH Tstg
LImits -0.3
Symbo
-0.3
+125
*The power voltage based ground voltage Note: Permanent device damage occur above ABSOLUTE MAXIMUM RATINGS exceeded. Functional operation should restricted conditions detailed operational sections this data sheet. Exposure absolute maximum rating conditions extended periods affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Limits Parameter Symbol Min. Typical Max. 1500 0.001 0.001 Unit
Reset (RESET) output current Power-on reset hold time setting capacity Watchdog-timer monitoring time setting capacity Watchdog timer monitoring time Operating ambient temperature
Note: These recommended operation conditions guarantee normal logic operation circuit. limits electrical characteristics guaranteed within these recommended conditions.
MB3793-42/30
ELECTRICAL CHARACTERISTICS
(VCC (MB3793-42), +3.3 (MB3793-30), +25°C)
Characteristics
Limits Parameter Symbol ICC1 MB3793-42 Power current MB3793-30 ICC2 MB3793-42 +25°C Detection voltage MB3793-30 +25°C Detection voltage hysteresis difference MB3793-42 VSHYS MB3793-30 VthCH Clock-input threshold voltage VthCL Clock-input hysteresis Inhibition-input threshold voltage Input current MB3793-42 Reset output voltage MB3793-30 Reset-output minimum power voltage VCCL IRESET IRESET 0.12 IRESET 3.10 IRESET 0.12 VCHYS VthIN IRESET (0.8) (0.4) -1.0 4.75 (1.8) (0.8) (1.4) (2.5) rising +85°C 2.92 3.07 3.22 2.97 3.07 3.17 falling +85°C 2.85 3.00 3.15 rising +85°C +25°C 4.15 2.90 4.30 3.00 4.45 3.10 4.20 4.30 4.40 Watchdog timer halt** +25°C falling +85°C 4.05 4.20 4.35 4.10 4.20 4.30 ICC2 ICC1 Watchdog timer halt** Watchdog timer operation* Test Conditions Min. Watchdog timer operation* Typical Max. Unit
clock input pins CK2, pulse input frequency pulse amplitude VCC. **Inhibition input High level.
MB3793-42/30
Characteristics
(VCC (MB3793-42), +3.3 (MB3793-30), +25°C)
Parameter MB3793-42 MB3793-30 MB3793-42 MB3793-30 MB3793-42 MB3793-42
Symbol
Test Conditions 0.01 50pF 50pF
Limits Min. Typical Max. 22.5
Unit
Power-on reset hold time
Watchdog timer monitoring time
Watchdog timer reset time
tCKW tTLH tTHL
Clock (CK1, CK2) input pulse duration Reset (RESET) output transition time* Rising Falling
*The voltage range testing reset output transition time.
WATCHDOG TIMER EXAMPLE
Monitoring Clocks
RESET RESET MB3793 RESET
Microprocessor
Microprocessor
MB3793-42/30
Monitoring Single Clock
RESET RESET MB3793
Microprocessor
Watchdog Timer Stopping
RESET MB3793 RESET Microprocessor HALT Microprocessor HALT RESET
MB3793-42/30
REFERENCE CHARACTERISTIC CURVES (FOR MB3793-42)
Power Current Power Voltage
Watchdog timer monitoring (VINH +25°C) +85°C
Detection Voltage Ambient Temperature
Power current: Watchdog timer stopping (VINH VCC) Reset (VCC VSH) Inhibited Detection voltage: (µA)
MB3793-42 Duty 0.01 VINH
+25°C)
+85°C
Power voltage:
Ambient temperature: (°C)
Reset Output Voltage Reset Output Current (P-MOS side)
Reset Output Voltage Reset Output Current (N-MOS side)
-40°C Reset output voltage: VRESET Reset output voltage: VRESET (mV) +25°C +85°C -40°C +25°C +85°C VRESET 4.800 4.750 4.707 58.6 IRESET
-40°C +25°C
VRESET
19.6 33.4
IRESET
+85°C
+25°C
+85°C
-40°C
Reset output current: IRESET (mA)
Reset output current: IRESET (mA)
MB3793-42/30
Reset-on Reset Time Ambient Temperature Reset Output Voltage Power Voltage
Pull-up resistance: +85°C Reset output voltage: VRESET +25°C Power-on reset time: (ms) Ambient temperature: (°C)
(when rising)
+85°C +25°C -40°C
Power voltage:
Watchdog Timer Reset Time Ambient Temperature (when monitoring)
+85°C Watchdog timer reset time: (ms) +25°C
Watchdog Timer Monitoring Time Ambient
+85°C +25°C Watchdog timer monitoring time: (ms) Ambient temperature: (°C)
Temperature
Ambient temperature: (°C)
MB3793-42/30
Power-on Reset Time Capacitance
Reset Time Capacitance
Power-on reset time: (ms)
-40°C
Reset Time: (ms) -40°C
+25°C +85°C 10-1 10-1 +25°C +85°C
10-4
10-3
10-2
10-1
10-2 10-4
10-3
10-2
10-1
Power-on reset time setting capacitance: (µF)
Power-on reset time setting capacitance: (µF)
Watchdog-Timer Monitoring Time Capacitance (under condition)
Watchdog-Timer Monitoring Time Capacitance
-40°C
Watchdog-timer monitoring time: (ms) +25°C
Watchdog-timer monitoring time: (ms)
+85°C
10-1
10-1 0.01
10-5
10-4
10-3
10-2
10-1
10-5
10-4
10-3
10-2
10-1
Watchdog-timer monitoring time setting capacitance: (µF)
Watchdog-timer monitoring time setting capacitance: (µF)
MB3793-42/30
PACKAGE DIMENSIONS
8-LEAD PLASTIC DUAL IN-LINE PACKAGE
+.016 .370 -.012 (9.40 +0.40 -0.30
15°MAX
INDEX
.244±.010 (6.20±0.25)
.300(7.62)
+.012 .039 (0.99 +0.30 +.014 .035 -.012 +0.35 (0.89 -0.30
+.012 .060 +0.30 (1.52
.010±.002 (0.25±0.05)
.172(4.36)MAX
.020(0.51) .100(2.54) .018±.003 (0.46±0.08)
.118(3.00)MIN
©1991 FUJITSU LIMITED D08006S-2C
Dimensions inches (millimeters)
MB3793-42/30
8-LEAD PLASTIC FLAT PACKAGE (CASE No.: FPT-8P-M02)
+.010 .199-.008 +0.25 (5.05-0.20) .061±.008
(1.55±0.20)
(MOUNTING HEIGHT) (STAND HEIGHT)
(0.15±0.10) .236±.016 (6.00±0.40) .154±.012 (3.90±0.30)
.006±.004
.197±.012 (5.00±0.30) .020±.008 (0.50±0.20) .008±.002 (0.20±0.05)
.016(0.40) .050(1.27) .017±.004
(0.42±0.10)
Details part .016(0.40)
.008(0.20) .004(0.10) .150(3.81) .007(0.18) .026(0.65) Dimensions inches (millimeters)
©1991 FUJITSU LIMITED F08004S-2C
MB3793-42/30
FUJITSU LIMITED
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 South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street Jose, 95134-1804, U.S.A. Tel: (408) 922-9000 Fax: (408) 432-9044/9045 Europe FUJITSU MIKROELEKTRONIK GmbH Siebenstein 6-10 63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122 Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE. LIMITED Bras Basah Road, Plaza Park, #06-04 #06-07 Singapore 189554 Tel: 336-1600 Fax: 336-1609
Rights Reserved. Circuit diagrams utilizing Fujitsu products included means illustrating typical semiconductor applications. Complete information sufficient construction purposes necessarily given. information contained this document been carefully checked believed reliable. However, Fujitsu assumes responsibility inaccuracies. information contained this document does convey license under copyrights, patent rights trademarks claimed owned Fujitsu. Fujitsu reserves right change products specifications without notice. part this publication copied reproduced form means, transferred third party without prior written consent Fujitsu. information contained this document intended with equipments which require extremely high reliability such aerospace equipments, undersea repeaters, nuclear control systems medical equipments life support.
F9603 FUJITSU LIMITED Printed Japan
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