M62055FP View Datasheet(PDF) - Renesas Electronics

Part Name

Description

Manufacturer

M62055FP

3 V Power Supply with Watchdog Timer

Renesas Electronics 

M62055FP

3. Relationship between the Input Pulse Width and the Low Pass Filter

VO

3.0V

0.0V

R

1k

VIN

C

Filter

(External element)

WD

–

+

1.5V

Figure 4

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 figure 5.

t3 = –C ⋅ R ⋅ ln

1.5V

VIN

RESET is output in the case of t4 > tWD.

VIN

3.0V

t3

t4

WD 1.5V

2.4V

TC 1.0V

tWD

t

t

2.4V

t

RESET

t

Figure 5

If t3 is too long, the TC waveform changes as shown in figure5.

t3 is set as follows:

tWDIN (3 µs) or more and t2 (charging time) or less. (t2 is a discharge time while an input is normal)

Rev.2.00 Mar 10, 2006 page 7 of 9

Share Link: