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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. 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.
8-PIN PLASTIC DIP (DIP-8P-M01)
Model No. MB3793-42 MB3793-30
Package code 3793-A 3793-N
Detection voltage 4.2 V 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 A (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.
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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)
s
PIN DESCRIPTION
Symbol RESET CTW CTP GND Description Outputs reset Sets monitoring time Sets power-on reset hold time Ground Pin No. 5 6 7 8 Symbol VCC INH CK2 CK1 Description Power supply Inhibits watchdog timer function Inputs clock 2 Inputs clock 1
Pin No. 1 2 3 4
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BLOCK DIAGRAM
(5) VCC I1 3A I2 30A
To VCC of all blocks
CTP (3)
Q
S R1 280 to 760 k
RSFF2 Q Output buffer RESET (1) Comp. O + Q S R
RSFF1 Q R
INH (6)
Comp. S CTW(2) Watchdog timer Reference voltage generator + VS
Pulse generator 1 CK1 (8) VREF 1.24 V R1 240 k
Pulse generator 2 CK2 (7) To GND of all blocks (4) GND
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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 s 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.
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STANDARD CONNECTION
VCC
VCC RESET CTW RESET CTP MB3793 VCC RESET VCC
Microprocessor 1 CK1 CK GND
Microprocessor 2 CK GND
CTW
CTP
CK2 INH GND
Equation of time-setting capacitances (CTP and CTW) and set time tPR (ms) A x CTP (F) tWD (ms) B x CTW (F) + C x CTP (F) CTP However, when ---- about 10, CTW tWD (ms) B x CTW (F) tWR (ms) D x CTP (F)
Values of A, B, C, and D Model No. MB3793-42 MB3793-30 A 1300 750 B 1500 1600 C 3 4 D 100 55 Remark
(Example) When CTP = 0.1 F and CTW = 0.01 F, * MB3793-42 tPR 130 [ms] tWD 15 [ms] tWR 10 [ms] * MB3793-30 tPR 75 [ms] tWD 16 [ms] tWR 5.5 [ms]
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TIMING CHART
1. Basic operation (Positive clock pulse)
VCC
VSH VSL
VCCL
tCKW CK1
CK2
INH
CTP
Vth
VH CTW VL
RESET
tPR
tWD tWR
tPR
(1) (2)
(3)(4) (5)
(5)
(6) (7)
(8)
(9)
(10)
(11)
(12)
(13) (14)
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2. Basic operation (Negative clock pulse)
VSH VSL VCC VCCL
tCKW CK1
CK2
INH
Vth CTP
VH CTW VL
RESET
tPR
tWD tWR
tPR
(1) (2)
(3)(4) (5)
(5)
(6) (7)
(8)
(9)
(10)
(11)
(12)
(13) (14)
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3. Single-clock input monitoring (Positive clock pulse)
CK1 CK2
CTP Vth
VH CTW VL
RESET
tWR
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4. Inhibition operation (Positive clock pulse)
VSH VCC VSL VCCL
tCKW CK1
CK2
INH
Vth CTP
VH CTW VL
RESET
tPR
tWD tWR
tPR
(1) (2)
(3)(4) (5)
(5)
(6) (7)
(8)
(9) (10)
(11)
(12)
(13) (14)
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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.
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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 (F) 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 (F) + C x CTP (F) 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 (F)
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(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 (F) 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).
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ABSOLUTE MAXIMUM RATINGS
(Ta = +25C)
Parameter Power voltage* CK1 Input voltage CK2 INH Reset output voltage (direct current) Allowable loss (Ta +85C) Storage temperature RESET
Symbol VCC VCK1 VCK2 VINH IOL IOH PD Tstg
LImits -0.3 to +7
Symbo V
-0.3 to +7
V
-10 to +10 200 -55 to +125
mA mW C
*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.
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RECOMMENDED OPERATING CONDITIONS
Limits Parameter Symbol Min. Typical Max. +5 10 1 1500 +85 mA F F ms C IOL IOH CTP CTW tWD Ta -5 0.001 0.001 0.1 -40 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 of an LSI circuit. The limits of the AC and DC electrical characteristics are guaranteed within these recommended conditions.
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ELECTRICAL CHARACTERISTICS
(VCC = +5 V (MB3793-42), VCC = +3.3 V (MB3793-30), Ta = +25C)
1. DC Characteristics
Limits Parameter Symbol ICC1 MB3793-42 Power current MB3793-30 ICC2 VSL MB3793-42 Ta = +25C VSH Detection voltage VSL MB3793-30 Ta = +25C VSH Detection voltage hysteresis difference MB3793-42 VSHYS MB3793-30 VthCH Clock-input threshold voltage VthCL Clock-input hysteresis Inhibition-input threshold voltage Input current CK1 CK2 INH MB3793-42 VOL Reset output voltage VOH MB3793-30 VOL Reset-output minimum power voltage VCCL IRESET = +3 mA IRESET = +50 A 0.12 0.8 0.4 1.2 V V IRESET = -3 mA 2.8 3.10 V IRESET = +5 mA 0.12 0.4 V VCHYS VthIN IIH IIL VOH VCK = VCC VCK = 0 V IRESET = -5 mA (0.8) (0.4) 0.8 -1.0 4.5 1.3 0.6 1.5 0 0 4.75 (1.8) (0.8) 2.0 1.0 V V V A A V VSH - VSL 30 (1.4) 70 1.9 110 (2.5) mV V VCC rising Ta = -40 to +85C 2.92 50 3.07 100 3.22 150 mV 2.97 3.07 3.17 V VCC falling Ta = -40 to +85C 2.85 3.00 3.15 VCC rising Ta = -40 to +85C Ta = +25C 4.15 2.90 4.30 3.00 4.45 3.10 V 4.20 4.30 4.40 V Watchdog timer halt** Ta = +25C VCC falling Ta = -40 to +85C 4.05 4.20 4.35 4.10 24 4.20 45 4.30 V ICC2 ICC1 Watchdog timer halt** Watchdog timer operation* 25 25 45 45 Test Conditions Min. Watchdog timer operation* Typical 27 Max. 50 A Unit
A
*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.
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2. AC Characteristics
(VCC = +5 V (MB3793-42), VCC = +3.3 V (MB3793-30), Ta = +25C)
Parameter MB3793-42 MB3793-30 MB3793-42 MB3793-30 MB3793-42 MB3793-42
Symbol
Test Conditions CTP = 0.1 F CTW = 0.01 F CTP = 0.1 F CTP = 0.1 F CL = 50pF CL = 50pF
Limits Min. 80 30 7.5 8 5 2.0 500 Typical 130 75 15 16 10 5.5 Max. 180 120 22.5 24 15 9 500 500
Unit ms ms ms ms ms ms ns ns ns
Power-on reset hold time
tPR
Watchdog timer monitoring time
tWD
Watchdog timer reset time
tWR tCKW tTLH tTHL
Clock (CK1, CK2) input pulse duration Reset (RESET) output transition time* Rising Falling
*The voltage range is 10% to 90% at testing the reset output transition time.
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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 CK GND
Microprocessor 2 CK GND
CK2 (7) INH (6) GND (4)
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MB3793-42/30
2. Monitoring Single Clock
VCC (5) VCC RESET (1) (2) CTW RESET (3) CTP MB3793 VCC
Microprocessor CK1 (8) CK GND
CTW
CTP
CK2 (7) INH (6) GND (4)
3. Watchdog Timer Stopping
VCC
(5) VCC (6) INH (2) CTW RESET (3) CTP MB3793 VCC RESET VCC Microprocessor 1 CK1 (8) CK GND HALT Microprocessor 2 CK HALT GND RESET (1)
CTW
CTP
CK2 (7) GND (4)
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REFERENCE CHARACTERISTIC CURVES (FOR MB3793-42)
Power Current - Power Voltage
40 Watchdog timer monitoring (VINH = 0 V) 35 VSH (Ta = +25C) 30 4.4 MAX 4.5 Ta = -40 to +85C
Detection Voltage - Ambient Temperature
25 Power current: Watchdog timer stopping (VINH = VCC) 20 Reset (VCC < VSH) 15 Inhibited Detection voltage: VSH and VSL (V) ICC (A) 4.3 MAX TYP VSH
TYP 4.2 MIN VSL
10 MB3793-42 f = 1 kHz Duty 10% VL = 0 V VH = VCC CTW 0.01 F CTP 0.1 F VINH VCC
MIN 4.1 VSL (Ta = +25C)
Ta = -40 to +85C 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 (P-MOS side)
Reset Output Voltage - Reset Output Current (N-MOS side)
5.0 Ta = -40C 4.9 Reset output voltage: VRESET (V) Reset output voltage: VRESET (mV) Ta = +25C 4.8 4.7 4.6 4.5 Ta = +85C 4.4 4.3 4.2 4.1 4.0 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 Ta -40C +25C +85C VRESET 4.800 V 4.750 V 4.707 V RON 40 50 58.6 -5 mA IRESET
500
Ta -40C +25C
VRESET 98 mV 135 mV 167 mV
RON 19.6 27 33.4
IRESET
5 mA
400
+85C
Ta = +25C 300
Ta = +85C 200
100 Ta = -40C
0 0 1 2 3 4 5 6 7 8 9 10 Reset output current: IRESET (mA)
Reset output current: IRESET (mA)
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MB3793-42/30
Reset-on Reset Time - Ambient Temperature Reset Output Voltage - Power Voltage
7 Pull-up resistance: 100 k 6 260 240 Ta = -40 to +85C 220 Reset output voltage: VRESET (V) 5 200 Ta = +25C 4 Power-on reset time: tPR (ms) 180 MAX 160 140 120 100 80 MIN 3 4 5 6 7 60 40 20 0 -40 -20 0 20 40 60 80 100 Ambient temperature: Ta (C) TYP
(when VCC rising)
3 Ta = +85C 2 Ta = +25C 1 Ta = -40C 0 0 1 2
Power voltage: VCC (V)
Watchdog Timer Reset Time - Ambient Temperature (when monitoring)
26 24 Ta = -40 to +85C 22 20 18 Watchdog timer reset time: tWR (ms) Ta = +25C 16 MAX 14 12 10 8 6 MIN 4 2 0 -40 -20 0 20 40 60 80 100 TYP
Watchdog Timer Monitoring Time - Ambient
26 24 Ta = -40 to +85C 22 Ta = +25C 20 MAX Watchdog timer monitoring time: tWD (ms) 18 16 TYP 14 12 10 MIN 8 6 4 2 0 -40 -20 0 20 40 60 80 100 Ambient temperature: Ta (C)
Temperature
Ambient temperature: Ta (C)
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MB3793-42/30
Power-on Reset Time - CTP Capacitance
104
Reset Time - CTP Capacitance
103
103
Power-on reset time: tPR (ms)
102 Ta = -40C 10
1
102 Reset Time: tWR (ms) Ta = -40C 101
Ta = +25C 1 Ta = +85C 10-1 10-1 1 Ta = +25C Ta = +85C
10-4
10-3
10-2
10-1
1
101
102
10-2 10-4
10-3
10-2
10-1
1
101
102
Power-on reset time setting capacitance: CTP (F)
Power-on reset time setting capacitance: CTP (F)
Watchdog-Timer Monitoring Time - CTW Capacitance (under Ta condition)
Watchdog-Timer Monitoring Time - CTW Capacitance
104
103 Ta = -40C
103 CTP = 1 F 102 Watchdog-timer monitoring time: tWD (ms) Ta = +25C CTP = 0.1 F 10
1
102 Watchdog-timer monitoring time: tWD (ms)
10
1
Ta = +85C 1
1
10-1
10-1 CTP = 0.01 F
10-5
10-4
10-3
10-2
10-1
1
101
10-5
10-4
10-3
10-2
10-1
1
101
Watchdog-timer monitoring time setting capacitance: CTW (F)
Watchdog-timer monitoring time setting capacitance: CTW (F)
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PACKAGE DIMENSIONS
8-LEAD PLASTIC DUAL IN-LINE PACKAGE
+.016 .370 -.012 (9.40 +0.40 ) -0.30
15MAX
INDEX
.244.010 (6.200.25)
.300(7.62) TYP
+.012 .039 - 0 (0.99 +0.30 ) -0 +.014 .035 -.012 +0.35 (0.89 -0.30 )
+.012 .060 -0 +0.30 (1.52 -0 )
.010.002 (0.250.05)
.172(4.36)MAX
.020(0.51) MIN .100(2.54) TYP .018.003 (0.460.08)
.118(3.00)MIN
(c)1991 FUJITSU LIMITED D08006S-2C
Dimensions in inches (millimeters)
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MB3793-42/30
8-LEAD PLASTIC FLAT PACKAGE (CASE No.: FPT-8P-M02)
+.010 .199-.008 +0.25 (5.05-0.20) .061.008 (1.550.20)
(MOUNTING HEIGHT) (STAND OFF HEIGHT)
.006.004 (0.150.10)
.236.016 (6.000.40) .154.012 (3.900.30)
45
.197.012 (5.000.30)
.016(0.40) .050(1.27) TYP .017.004 (0.420.10) O.005(0.13)
.020.008 (0.500.20)
M
.008.002 (0.200.05)
"A"
Details of "A" part .016(0.40)
.008(0.20) .004(0.10) .150(3.81) REF .007(0.18) MAX .026(0.65) MAX Dimensions in inches (millimeters)
(c)1991 FUJITSU LIMITED F08004S-2C
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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 (c) FUJITSU LIMITED Printed in Japan
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