HT7022A

Rev. 1.10

5

April 20, 2004

Power-on Reset Circuit

With several external components, the HT7022A can be

used to perform a power-on reset function as shown:

Change of Detectable Voltage

If the required voltage is not found in the standard prod-

uct selection table, it is possible to change it by using ex-

ternal resistance dividers or diodes.

vider

Detectable voltage =

R+ R

R

AB

B

Hysteresis width =

R+ R

R

AB

B

Malfunction Analysis

The following circuit demonstrates the way a circuit ana-

lyzes malfunctions by monitoring the variation or spike

noise of power supply voltage.

Charge Monitoring Circuit

The following circuit shows a charged monitor for pro-

tection against battery deterioration by overcharging.

When the voltage of the battery is higher than the set de-

tectable voltage, the transistor turns on to bypass the

charge current, protecting the battery from overcharg-

ing.

H T 7 0 2 2 A

R

D

C

t

t

H T 7 0 2 2 A

H T 7 0 2 2 A

V f 1

V f 2

H T 7 0 2 2 A

H T 7 0 2 2 A

L o a d

B A T T

S o l a r

C e l l

T r