Power Supply User Manual

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DS04-27401-7E

FUJITSU SEMICONDUCTOR

DATA SHEET

ASSP

Power Supply Monitor

with Watch-Dog Timer

MB3773

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DESCRIPTION

MB3773 generates the reset signal to protect an arbitrary system when the power-supply voltage momentarily is

intercepted or decreased. It is IC for the power-supply voltage watch and “Power on reset” is generated at the

normal return of the power supply. MB3773 sends the microprocessor the reset signal when decreasing more

than the voltage, which the power supply of the system specified, and the computer data is protected from an

accidental deletion.

In addition, the watchdog timer for the operation diagnosis of the system is built into, and various microprocessor

systems can provide the fail-safe function. If MB3773 does not receive the clock pulse from the processor for an

specified period, MB3773 generates the reset signal.

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FEATURES

• Precision voltage detection (VS = 4.2 V ± 2.5 %)

• Detection threshold voltage has hysteresis function

• Low voltage output for reset signal (V

CC = 0.8 V Typ)

• Precision reference voltage output (VR = 1.245 V ± 1.5%)

• With built-in watchdog timer of edge trigger input.

• External parts are few.(1 piece in capacity)

• The reset signal outputs the positive and negative both theories reason.

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PACKAGES

(DIP-8P-M01)

(FPT-8P-M01)

(SIP-8P-M03)

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.

Summary of content (29 pages)

PAGE 1
FUJITSU SEMICONDUCTOR DATA SHEET DS04-27401-7E ASSP Power Supply Monitor with Watch-Dog Timer MB3773 ■ DESCRIPTION MB3773 generates the reset signal to protect an arbitrary system when the power-supply voltage momentarily is intercepted or decreased. It is IC for the power-supply voltage watch and “Power on reset” is generated at the normal return of the power supply.
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MB3773 ■ PIN ASSIGNMENT (FRONT VIEW) CT 1 RESET 2 CK 3 GND 4 (TOP VIEW) CT 1 8 RESET RESET 2 7 VS CK 3 6 V REF V CC 5 GND 4 5 V CC V REF 6 VS 7 RESET 8 (DIP-8P-M01) (FPT-8P-M01) (SIP-8P-M03) 2
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MB3773 ■ BLOCK DIAGRAM VCC 5 Reference AMP. =: 1.24 V =: 1.24 V Reference Voltage Generator =: 100 =: 1.2 µA kΩ COMP.S + VS 7 + _ _ R _ COMP.O + + 6 VREF 4 GND =: 10 µA =: 10 µA Q _ S =: 40 kΩ Inhibit CK Watch Dog Timer 3 P.
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MB3773 ■ FUNCTIONAL DESCRIPTIONS Comp.S is comparator including hysteresis. it compare the reference voltage and the voltage of Vs, so that when the voltage of Vs terminal falls below approximately 1.23 V, reset signal outputs. Instantaneous breaks or drops in the power can be detected as abnormal conditions by the MB3773 within a 2 µs interval.
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MB3773 • MB3773 Basic Operation VCC VCC CT Logic Circuit TPR (ms) =: 1000 · CT (µF) TWD (ms) =: 100 · CT (µF) TWR (ms) =: 20 · CT (µF) RESET RESET CK RESET RESET CK Example : CT = 0.1 µF TRR (ms) =: 100 (ms) TWD (ms) =: 10 (ms) TWR (ms) =: 2 (ms) GND VCC VSH VSL 0.
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MB3773 ■ OPERATION SEQUENCE (1) When Vcc rises to about 0.8 V, RESET goes “Low” and RESET goes “High”. The pull-up current of approximately 1 µA (Vcc = 0.8 V) is output from RESET. (2) When Vcc rises to VSH ( =: 4.3V) , the charge with CT starts. At this time, the output is being reset. (3) When CT begins charging, RESET goes “High” and RESET goes “Low”. After TPR reset of the output is released.
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MB3773 ■ ABSOLUTE MAXIMUM RATINGS Rating Parameter Symbol Unit Min Max VCC − 0.3 + 18 V VS − 0.3 VCC + 0.3 ( ≤ +18) V VCK − 0.3 + 18 V RESET, RESET Supply voltage VOH − 0.3 VCC + 0.3 ( ≤ +18) V Power dissipation (Ta ≤ +85 °C) PD  200 mW TSTG − 55 + 125 °C Supply voltage Input voltage Storage temperature WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings.
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MB3773 ■ ELECTORICAL CHARACTERISTICS (1) DC Characteristics (VCC = 5 V, Ta = + 25 °C) Value Parameter Supply current Symbol ICC VSL Detection voltage VSH Hysteresis width VHYS Reference voltage VREF Min Typ Max Unit  600 900 µA VCC 4.10 4.20 4.30 Ta = − 40 °C to + 85 °C 4.05 4.20 4.35 VCC 4.20 4.30 4.40 Ta = − 40 °C to + 85 °C 4.15 4.30 4.45 50 100 150 1.227 1.245 1.263 1.215 1.245 1.
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MB3773 (2)AC Characteristics Parameter Symbol Condition 5V 8.0   µs 3.0   µs 20   µs CT = 0.1 µF 5 10 15 ms TWR CT = 0.1 µF 1 2 3 ms TPR CT = 0.1 µF, VCC 50 100 150 ms TPD1 RESET, RL = 2.2 kΩ, CL = 100 pF  2 10 TPD2 RESET, RL = 2.
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MB3773 ■ TYPICAL CHARACTERISTIC CURVES Supply current vs. Supply voltage Output voltage vs. Supply voltage (RESET terminal) 6.0 Ta = +85 °C Ta = +25 °C 0.65 Ta = −40 °C 0.55 CT = 0.1 µF 0.45 Ta = −40 °C Ta = +25 °C 0.35 Ta = +85 °C 0.25 0.15 0 2.0 4.0 6.0 Output voltage VRESET (V) Supply current ICC (mA) 0.75 Pull up 2.2 kΩ 5.0 Ta = −40 °C, +25 °C, +85 °C 4.0 3.0 2.0 1.0 0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 1.0 2.0 3.0 Output voltage VRESET (V) Pull up 2.2 kΩ 5.0 4.0 3.0 2.
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MB3773 High level output voltage vs. High level output current (RESET terminal) 5.0 CT = 0.1 µF Ta = +25 °C Ta = −40 °C 4.5 4.0 Ta = +85 °C −5 0 −10 High level output voltage VOH8 (V) High level output voltage VOH2 (V) High level output voltage vs. High level output current −15 (RESET terminal) 5.0 CT = 0.1 µF Ta = −40 °C 4.5 4.0 −5 0 Reference voltage vs. Supply voltage 1.255 CT = 0.1 µF 1.244 Ta = +85 °C Ta = −40 °C 1.240 CT = 0.1 µF 1.238 1.236 1.
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MB3773 (Continued) Reset time vs. Temperature Watchdog timer watching time vs. Temperature (At watch dog timer) 2 1 0 −40 −20 0 20 40 60 80 VCC = 5 V CT = 0.1 µF 14 Watch dog timer watching time TWD (ms) Reset time TWR (ms) 16 VCC = 5 V CT = 0.1 µF 3 12 10 8 6 4 0 100 −40 −20 0 20 40 60 80 100 Temperature Ta ( °C) Temperature Ta ( °C) CT terminal capacitance vs. Watchdog timer watching time CT terminal capacitance vs. Rising reset hold time CT terminal capacitance vs.
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MB3773 ■ APPLICATION CIRCUIT EXAMPLE 1: Monitoring 5V Supply Voltage and Watchdog Timer VCC (5V) MB3773 8 7 6 5 1 2 3 4 CT Logic circuit RESET RESET CK GND Notes : • Supply voltage is monitored using VS. • Detection voltage are VSH and VSL. EXAMPLE 2: 5V Supply Voltage Monitoring (external fine-tuning type) VCC (5V) MB3773 1 2 3 4 CT R1 8 7 6 5 R2 Logic circuit RESET RESET CK GND Notes : • Vs detection voltage can be adjusted externally.
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MB3773 EXAMPLE 3: With Forced Reset (with reset hold) (a) VCC MB3773 CT 1 2 3 4 Logic circuit 8 7 6 5 SW RESET RESET CK GND Note : Grounding pin 7 at the time of SW ON sets RESET (pin 8) to Low and RESET (pin 2) to High. (b) VCC MB3773 Cr 1 2 3 4 8 7 6 5 Logic circuit Tr 10 kΩ RESET RESET CK GND 10 kΩ RESIN Note : Feeding the signal to terminal RESIN and turning on Tr sets the RESET terminal to Low and the RESET terminal to High.
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MB3773 EXAMPLE 4: Monitoring Two Supply Voltages (with hysteresis, reset output and NMI) VCC2(12 V) VCC1 (5 V) Logic circuit MB3773 CT 1 2 3 4 RESET 8 7 6 5 RESET CK 30 kΩ R3 180 kΩ 10 kΩ R6 R4 NMI or port GND + _ + _ Comp. 1 1.2 kΩ R1 5.1 kΩ R2 Comp. 2 4.7 kΩ R5 Example : Comp. 1, Comp. 2 : MB4204, MB47393 Notes : • The 5 V supply voltage is monitored by the MB3773. • The 12 V supply voltage is monitored by the external circuit.
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MB3773 EXAMPLE 5: Monitoring Two Supply Voltages (with hysteresis and reset output) VCC2 (12 V) VCC1 (5 V) 20 kΩ R6 MB3773 CT 1 2 3 4 8 7 6 5 30 kΩ R3 Diode Logic circuit RESET RESET CK GND 180 kΩ R4 + _ + _ Comp. 1 1.2 kΩ R1 5.1 kΩ R2 Comp. 2 4.7 kΩ R5 Example : Comp. 1, Comp. 2 : MB4204, MB47393 Notes : • When either 5 V or 12 V supply voltage decreases below its detection voltage (VSL), the MB3773 RESET terminal is set to High and the MB3773 RESET terminal is set to Low.
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MB3773 EXAMPLE 6: Monitoring Low voltage and Overvoltage Monitoring (with hysteresis) VCC (5 V) 20 kΩ R6 MB3773 CT 1 2 3 4 8 7 6 5 RESET RESET CK GND Diode 30 kΩ R3 Logic circuit 180 kΩ R4 + _ _ 5.6 kΩ R6 + Comp. 1 1.2 kΩ R1 Comp. 2 4.7 kΩ R5 Example : Comp. 1, Comp. 2 : MB4204, MB47393 RESET 0 V1L V1H V2L V2H VCC Notes : • Comp. 1 and Comp. 2 are used to monitor for overvoltage while the MB3773 is used to monitor for low voltage.
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MB3773 EXAMPLE 7: Monitoring Supply Voltage Using Delayed Trigger VCC 5V VCC 4V MB3773 CT 1 2 3 4 8 7 6 5 Logic circuit C1 RESET RESET CK GND Note : Adding voltage such as shown in the figure to VCC increases the minimum input pulse width by 50 µs (C1 = 1000 pF).
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MB3773 EXAMPLE 8: Stopping Watch-dog Timer (Monitoring only supply voltage) These are example application circuits in which the MB3773 monitors supply voltage alone without resetting the microprocessor even if the latter, used in standby mode, stops sending the clock pulse to the MB3773. • The watch-dog timer is inhibited by clamping the CT terminal voltage to VREF. The supply voltage is constantly monitored even while the watch-dog timer is inhibited.
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MB3773 (Continued) (c) Using NPN transistor VCC (5 V) MB3773 1 2 3 4 Logic circuit 8 7 6 5 R1=1 MΩ RESET RESET CK HALT GND R2=1 kΩ CT (d) Using PNP transistor VCC (5 V) MB3773 1 2 3 4 Logic circuit 8 7 6 5 R1=51 kΩ RESET RESET CK HALT GND R2=1 kΩ CT 20
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MB3773 EXAMPLE 9: Reducing Reset Hold Time VCC ( = 5 V) VCC( = 5 V) MB3773 CT 1 2 3 4 8 7 6 5 MB3773 Logic circuit RESET RESET CK GND CT (a) TPR reduction method 1 2 3 4 8 7 6 5 Logic circuit RESET RESET CK GND (b) Standard usage Notes : • RESET is the only output that can be used. • Standard TPR, TWD and TWR value can be found using the following formulas.
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MB3773 EXAMPLE 10: Circuit for Monitoring Multiple Microprocessor FF1 S D1 Q1 FF2 S D2 Q2 VCC ( = 5 V) FF3 S D3 Q3 CK1 Q1 CK2 Q2 CK3 Q3 R R R R2 R1 * * * RESET RESET RESET RESET RESET RESET CK CK CK GND GND GND CT *: Microprocessor 1 2 8 7 3 4 6 5 MB3773 Figure 1 Notes : • connects from FF1 and FF2 outputs Q1 and Q2 to the NOR input. • Depending on timing, these connections may not be necessary. • Example : R1 = R2 = 2.2 kΩ CT = 0.
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MB3773 Description of Application Circuits Using one MB3773, this application circuit monitors multiple microprocessor in one system. Signals from each microprocessor are sent to FF1, FF2 and FF3 clock inputs. Figure 2 shows these timings. Each flip-flop operates using signals sent from microprocessor as its clock pulse. When even one signal stops, the relevant receiving flip-flop stops operating. As a result, cyclical pulses are not generated at output Q3.
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MB3773 EXAMPLE 11: Circuit for Limiting Upper Clock Input Frequency VCC (5 V) R2 1 2 3 4 CT 8 7 6 5 RESET RESET R1=10 kΩ CK GND Tr1 C2 Notes : • This is an example application to limit upper frequency fH of clock pulses sent from the microprocessor. If the CK cycle sent from the microprocessor exceeds fH, the circuit generates a reset signal. (The lower frequency has already been set using CT.
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MB3773 ■ NOTES ON USE • Take account of common impedance when designing the earth line on a printed wiring board. • Take measures against static electricity. - For semiconductors, use antistatic or conductive containers. - When storing or carrying a printed circuit board after chip mounting, put it in a conductive bag or container. - The work table, tools and measuring instruments must be grounded. - The worker must put on a grounding device containing 250 kΩ to 1 MΩ resistors in series.
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MB3773 ■ PACKAGE DIMENSIONS 8-pin plastic DIP (DIP-8P-M01) +0.40 9.40 –0.30 +.016 .370 –.012 6.20±0.25 (.244±.010) 1 PIN INDEX 0.51(.020)MIN 4.36(.172)MAX 0.25±0.05 (.010±.002) 3.00(.118)MIN 0.46±0.08 (.018±.003) +0.30 0.99 –0 +.012 .039 –0 +0.35 0.89 –0.30 +.014 .035 –.012 C +0.30 1.52 –0 +.012 .060 –0 7.62(.300) TYP 15°MAX 2.54(.100) TYP 1994 FUJITSU LIMITED D08006S-2C-3 Dimensions in mm (inches) . Note : The values in parentheses are reference values.
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MB3773 Note 1 : *1 : These dimensions include resin protrusion. Note 2 : *2 : These dimensions do not include resin protrusion. Note 3 : Pins width and pins thickness include plating thickness. Note 4 : Pins width do not include tie bar cutting remainder. 8-pin plastic FPT (FPT-8P-M01) +0.25 +.010 +0.03 *1 6.35 –0.20 .250 –.008 0.17 –0.04 +.001 8 .007 –.002 5 *2 5.30±0.30 7.80±0.40 (.209±.012) (.307±.016) INDEX Details of "A" part +0.25 2.00 –0.15 +.010 .079 –.006 1 1.27(.050) "A" 4 0.
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MB3773 (Continued) 8-pin plastic SIP (SIP-8P-M03) 3.26±0.25 (.128±.010) +0.15 19.65 –0.35 .774 +.006 –.014 INDEX-1 6.20±0.25 (.244±.010) 8.20±0.30 (.323±.012) INDEX-2 +0.30 0.99 –0 4.00±0.30 (.157±.012) +.012 .039 –0 2.54(.100) TYP C +0.30 1.52 –0 +.012 .060 –0 0.50±0.08 (.020±.003) 0.25±0.05 (.010±.002) 1994 FUJITSU LIMITED S08010S-3C-2 Dimensions in mm (inches) . Note : The values in parentheses are reference values.
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MB3773 FUJITSU LIMITED 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.