RNA51953A,B

REJ03D0911-0100 Rev.1.00 Oct 10, 2008

Page 7 of 9

Notice for use

About the Power Supply Line

1. About bypass capacitor

Because the ripple and the spike of the high frequency noise and the low frequency are superimposed to the power

supply line, it is necessary to remove these.

and the GND line as shown in following figure 3.

Power-supply

Output

RNA51953

GND

+

Delay capacitor

Cd

Example of ripple

noise measures

Figure 3 Example of Ripple Noise Measures

Setting of Delay Capacity

Please use capacitor Cd for the delay within the range of 10

µF or less.

When a value that is bigger than this is set, the problem such as following (1), (2), and (3) becomes remarkable.

t

Output

tpd

Figure 4 Time Chart at Momentary Voltage-Decrease

(1) The difference at delay time becomes remarkable.

A long delay setting of tens of seconds is fundamentally possible. However, when set delay time is lengthened, the

range of the difference relatively grows, too. When a set value is assumed to be ‘tpd’, the difference occurs in the

range from 0.47

× tpd to 2.05 × tpd. For instance, 34 seconds can be calculated at 100 µF. However, it is likely to

vary within the ranges of 16-70 seconds.

(2) Difficulty to react to a momentary voltage decrease.

circuit constant C1 = 100

µF.

(Characteristic graph 1 is used and extrapolation in case of Cd = 100

µF.)

Therefore, it doesn't react to momentary voltage-decrease that is shorter than this.

(3) Original delay time is not obtained.

charge starts at that state. This phenomenon occurs at large capacitance. And, original delay time tpd is not

obtained.

Please refer to characteristic graph 2. (Delay time versus input pulse width)