HIGH-PRECISION VOLTAGE DETECTOR
S-807 Series
Advantage over the S-805 Series
The S-807 Series, in comparison with conventional reset ICs such as the S-805 Series, offers greater detection voltage precision
(twice that of conventional units) and lower current consumption (half that of conventional units). These characteristics result in
the following advantages over conventional units.
1. Advantages of greater detection voltage precision
1.1 Detecting lithium battery service life
The discharge characteristics of lithium batteries are
shown in Figure 4. When using the S-805 Series,
the service life can be detected over t1. When
using the S-807 Series, it can be detected over t2.
This improvement in detection precision of the S-
807 Series means that batteries can be used over
more of their service life.
V
S-807
S-805
t2
t1
Figure 4
1.2 Detecting a power voltage at two points
It is usual for the CPU to detect the power voltage
at two points, one to caution and the other to reset.
The service life of battery may also be detected at
two points, one to caution and the other to request
immediate replacement.
Two voltage values to be detected (No. 1 and No.
2) do not cross and the voltage can be detected
correctly.
t
V
No. 2
No. 1
Must be close
t
Figure 5
1.3 Voltage drop when modifying detection voltage
If no voltage to be detected is suitable, the voltage
can be set higher in Nch open-drain output
products by using a resistor divider. (Example :
when detecting 6V or 9V.)
When 8V is detected using the S-8054HN (a
4V±5% device), the -Vdet tolerance becomes
2×4.00×±0.05=0.8V (R1=R2). In constrast, the S-
80740AN (a 4V±2.4% device) can hold down the
tolerance to 2×4.00×±0.024=0.384V (R1=R2).
R1
S-807
XXAN/SN
R2
Nch open-drain
output product
Figure 6
Seiko Instruments Inc.
5
SII [ SEIKO INSTRUMENTS INC ]
