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MITSUBISHI
M62055FP
3V POWER SUPPLY with WATCHDOG TIMER GENERAL DESCRIPTION
M62055FP is a 3V power supply featuring a watchdog timer function for a microcontroller system. It can be a power source of 3V 5% by utilizing the reference voltage and amplifier. It can also generate a reset pulse for the applied systems during power-on, moreover it includes the watchdog timer for a self diagnostics of the system, which can prevent system erroneous functions. PIN CONFIGURATION(TOP VIEW)
GND WD TC
Vcc CLM VDD VOC
M62055FP
FEATURES
* Power-on reset * Watchdock timer * High accuracy voltage source of 3V 5% (max) * Overcurrent protection circuit * The voltage detection accuracy of 5% (max) * Output power (Vo) cutoff function at erroneous conditions * Backward voltage protection circuits for inputs and outputs
RESET
Outline 8P2S
APPLICATION
Handy information terminal equipment, CD-ROM, Portable audio equipment.
BLOCK DIAGRAM
Vcc
CLM
Vcc Vcc
VD
Vcc
VO
Note
; It indicates Vo, unless otherwise noted
VOLTAGE DETECTOR (CURRENT LIMITER)
The input and output reversal conservation circuit
START CIRCUIT
56K
40K Vref =1.25v
Vcc
Set priority
R S Q Q
Reset priority
R S Q Q
.Vref =0.9v . Set priority
RISE DELAY (300sec) S Q Q
. Vref =1.25v .
.Vref =1.5v .
Reset priority
R S Q Q
Reset priority
S R Q Q
R
.Vref =1.5v .
GND
WD
TC
RESET
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M62055FP
3V POWER SUPPLY with WATCHDOG TIMER Pin Functional description
pin number 1 2 3 4 5 6 7 8 symbol GND WD TC RESET VO VD CLM Vcc Ground Input for watchdock timer. Setting up reset timer and watchdock timer. Reset signal output Feedback to a power supply for a MCU. Controlling the stability of an output voltage with a PNP transistor connected externally. Current limiting Power supply voltage Functional description
ABSOLUTE MAXIMUM RATINGS
symbol Parameter Vcc supply voltage Output voltage VRM Reset pin Output current IRM VWDM Watchdock pin input voltage Ko Thermal derating Topr Operating temperature Tstg Storage temperature
(Ta=25C, Unless otherwise noted) conditions Ratings 13 10 10 3 4.0 - 20 ~ + 75 - 55 ~ + 150 Unit V V mA V mW/C C C
Ta 25C
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M62055FP
3V POWER SUPPLY with WATCHDOG TIMER
ELECTRICAL CHARACTERISTICS
(1) DC CHARACTERISTICS symbol Parameter
(Vcc=5.0V,Ta=25C, Unless otherwise noted)
Test conditions
Min 3.5 2.85
Limits Typ
Max 13
Unit
Battery* back up* regulator VCC supply voltage ICC Circuitry current VO Output voltage IBmax Bias current Listing short-circuit bias current I BSC Reg-in Input voltage regulation Vcc=3.5V~13V Reg-lo Loading voltage regulation Io=10mA~100mA
Vo/T
Output voltage thermal coefficient
650 3.0 10 1.5 0.02 1 0.02 200 2.82 2.72 0.1 0.2 2.4 1.0 1.5
950 3.15
0.25 25 220 2.96 2.86 0.4 5 2.52 1.05 1 1
VTHCLM VTH1(H) VTH1(L) VTH1 VOL(RST) Ileak VTH2(H) VTH2(L) IWD VTH(WD) Itco Itc1 Itc2 VCCMIN
CLM threshold voltage
180 2.68 2.58
V A V mA mA %/V mV %/T mV V V V V A V V A V A mA mA V
Reset, watch dock timer Vo detection voltage
Output voltage
Output leakage current
Reset Isink=4mA pin 2.28 0.95 VIN=3V VIN=0.8V VIN=2.4V
In the output cutoff transmission mode
Watchdock timer threshold voltage WD input current
WD input threshold voltage
TC output current TC input current
Vcc min operating voltage
2.0 8.0 2.0
*1
Note *1; The Vcc minimum operating voltage at which the RESET output is Low
(2) AC CHARACTERISTICS symbol tWD tRST(1) tRST(2) Parameter Watch dock timer Reset timer (1) Reset timer (2)
(Vcc=5.0V,Ta=25C, Unless otherwise noted)
Test conditions C=0.1F,R1=10K C=0.1F,R1=10K
CO=10F, R1=10K, IL=0
Min 0.5 0.1
Limits Typ 1.2 0.7
Max 1.7 2.0
Unit mS mS mS
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M62055FP
3V POWER SUPPLY with WATCHDOG TIMER FUNCTIONAL DESCRIPTION
Tick deactivation
VO+VCE(sat)
Vcc 0
output cutoff
VTH1(H)
output cutoff
Vo 0
VTH1(L)
. =0.9V . . =0.9V .
VTH2(H)
TC 0
VTH2(L)
RESET 0 TRST(1)
TWD TRST(2)
WD 0
13 2
46 5
79 8
10
11
12
13
14
: When Vo rises to 0.5 V, RESET becomes low. Then, charging to a capacitor C connected to TC will be started at the Vo of 2.82V(VTH1(H)). 2 : When VCC rises to 3V+VCE(sat), Vo becomes stable. 3 4 : When TC voltage rises to 1V(VTH2(L)) , RESET becomes high. When it rises to 2.4V (VTH2(H)) further, the capacitor C is switched to discharge and RESET becomes low. 5 : At the same time of a change-over to the discharge from the capacitor C, Vo is intercepted. Then,TC will be discharged completely at Vo of 2.72V(VTH1 (L)). 6 : Vo returns to 3V right after it has fallen down to 0.9 V. RESET repeats above operation till a normal clock signal is input to WD pin.
1
78 9
: In the case of a sudden power interruption, Vo falls down according to a decrease of VCC. When it falls down to 2.72V, the capacitor C is discharged and RESET will be low. In the case of a reversion from the power interruption, Vo rises according to a increase of VCC. When it rises to 2.82V, the charging to the capacitor C is started and RESET will be high right after TC voltage reaches 1V.
10 11 : In the case a clock signal for discharging the capacitor C is applied to pin WD before TC voltage reaches to 2.4V, a reset signal to RESET is canceled. 12 13 : In the case an abnormal clock signal is input, TC repeats charging / discharging alternately between 1 V and 2.4 V, so that RESET also repeats high / low till a normal clock signal is input. 14 : When Vo falls down to 2.72 V, RESET becomes Low.
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M62055FP
3V POWER SUPPLY with WATCHDOG TIMER DESCRIPTION of TERMS
tRST(1) Time from when TC begins to charge until it reaches to VTH2(L). Time from when TC is VTH2(L) until it reaches to VTH2(H). Time from when TC is VTH2(H) until TC starts charging.
XV
2. Pin 2 (WD pin) Input frequency, input pulse width, charge/discharge time .
When input of 2 WD is normal, TC waveform 3 is as shown below.
VTH2(H) = 2.4v
tWD tRST(2)
1. Pin 3 (TC pin) Charging and discharging time .
When an error is occurred in WD input, TC waveform is as shown below. output cutoff
VTH1(H)
Pin 3
VTH2(L) = 1.0v
t1 t2
Pin 2
Vo 0
VTH2(H)
VTH1(L)
. =0.9V .
tWDIN
t1 = C * R1 * ln
2 3-X X( R1 + 1) 1000 R1 - 2 1000 -3
TC 0
VTH2(L)
tRST(1) tWD
tRST(2)
t2 = 1000 * C * R1 * ln
Inside delay time
VO = 3.0V Conditions of an input to pin 2 (WD pin) R1 (1) Input period should be tWD or less.
( Pin discharge is completed before the arrival of VTH2(H) = 2.4 V )
tRST(1) = 0.406 * C * R1 + 300s tWD = 1.2 * C * R1
(Charging time)
*1
3 C
1 1.2 * C * R1
*1 : Inside delay time (Typical values)
(2) Input pulse width tWDIN should be t2 or less.
The following formula can be obtained because tRST(2) is equal to the duration of Vo cutoff.
tRST(2) = C * R * ln ( 0.9 )
Al
*2
*3
3
+ 300s
*2
C
= 40 * C + 300s
*2 : Inside delay time (Typical values) *3 : R = Internal resistance
cutoff Tr
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M62055FP
3V POWER SUPPLY with WATCHDOG TIMER 3. Relationship between the input pulse width and the low pass filter
V0 3.0V R 1K
VIN
VIN
0.0V C
WD +
3.0v WD 1.5v
t t3 t4
filter
(External Element)
t 1.5V TC 2.4v 1.0v tWD t 2.4v
Addition of a low pass filter makes input waveform dull. An input pulse width and CR of a low pass filter is determined referring to the right figure. t 3 = -C * R * ln VIN
1.5v
RESET t
RESET is output in the case of t 4> t WD.
If t3 is too long, the TC waveform changes as shown in the diagram above. t3 is set as follows; tWDIN (3 s) or more and t 2 (charging time) or less. (t2 is a discharge time while an input is normal)
APPLICATION
VCC
+ 10F CIN VCC CLM VD VO
+ 10F CO
M62055FP
GND
WD
TC
RESET RTC
CTC RRST
GND
CLOCK
RESET VDD
MCU/MPU
Note : hFE of the external PNP transistor, 100 to 300 is recommended.
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