M5295AP datasheet(6/8 Pages) MITSUBISHI

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ELECTRIC

MITSUBISHI

M5295AL/P/FP

MITSUBISHI<Dig.Ana.INTERFACE>

WATCHDOG TIMER

M5295AL

VDD

MCU/MPU

CLOCK

RST1

(RESET)

RST2

(HOLD)

Example of Backup Circuit with M5295AL

(2)Detection voltage 2(VTH2(L))adjustment

51.2k

18.8k

1.24V

APPLICATION EXAMPLE

OPERATION INSTRUCTIONS

1.When malfunction occurs due to noise or other related

trouble,connect capacitance of approximately 1000pF

between pin 5 and GND as well as pin 8 and GND to

stabilize operation.

2.To adjust detection voltage,add resistance of 15k

Ω

or less to both Vcc and GND via adjusting pins.

(Set detection voltage to no less than 3V.)

3.Set tWD and tRST(2) as shown below:

110µs

≤tWD≤1.1s

8.3µs

≤tRST(2)≤83ms

10k

Ω≤R1≤30kΩ

4.Input clock pulses to pin 1 via capacitor.To determine

capacitance,refer to "Relationship between Input Pulse

Width and Input Capacitance Cin".

RESET

OUTPUT

Backup switching voltage

VTH(L)

Switching voltage calculation formula

10K

Ω

3.5V

BACKUP POWER SUPPLY

Vcc

R3(k

Ω) R4(kΩ)

Detection voltage calculation formula

10.61

8.38

0.93

1.26

1.99

3.24

16.3

17.2

14.1

VTH2(L)=

R04

R03+R04

X1.24(V)

R03=R3//51.2k

Ω

R04=R4//18.8k

Ω

VTH2(L)(V)

4.6

3.5

∆VTH2(mV)

100

∆VTH2=

51.2k

R03

X100(mV)

To adjust detection voltage 2,determine external resistance

with the following equations:

a. VTH2(L)>4.6V(R3=10k

Ω)

b. VTH2(L)<4.6V(R4=5k

Ω)

R4=

18.8k

R3=

51.2k

R0=

VTH2(L)-1.24

8.37kX1.24

R0=

1.24

(VTH2(L)-1.24)3.95k

VTH2(L)=

R04

R03+R04

X1.24

R03=R3//51.2k

R04=R4//18.8k

(Note)Set backup switching voltage to be more

than or equal to backup supply voltage.

TO SYSTEM

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