WAKE-UP TIMER IC

PIN-SELECTABLE WAKE-UP TIMER IC

S-35720 Series

10



Power-on Detection Circuit

In order for the power-on detection circuit to operate normally, raise the power supply voltage of the IC from 0.2 V or lower

so that it reaches 1.8 V of the operation power supply voltage minimum value within 10 ms, as shown in Figure 9.

Within 10 ms

1.8 V

(Operation power

supply voltage min.)

0 V

*1

0.2 V or lower

*1. 0 V means that there is no potential difference between the VDD pin and the VSS pin of the S-35720 Series.

Figure 9 How to Raise the Power Supply Voltage

If the power supply voltage of the S-35720 Series cannot be raised under the above conditions, the power-on detection

circuit may not operate normally and an oscillation may not start. In such case, perform the operations shown in

"1. When power supply voltage is raised at RST

_______

pin = "L" " and "2. When power supply voltage is raised at

RST

_______

pin = "H" ".

1. When power supply voltage is raised at RST

_______

pin = "L"

Set the RST

_______

pin to "L" until the power supply voltage reaches 1.8 V or higher. While the RST

_______

pin is set to "L", the

oscillation start signal becomes "H", and the crystal oscillation circuit normally oscillates. If the RST

_______

pin is set to "H"

after the power supply voltage reaches 1.8 V, the oscillation start signal becomes "L" within 500 ms, and the

oscillation status is maintained.

The current consumption increases by 30

μA typ. while the RST

_______

pin is set to "L".

0.2 V or lower

RST pin input

Oscillation start signal

10 ms

1.8 V

(Operation power supply voltage min.)

*1. 0 V means that there is no potential difference between the VDD pin and the VSS pin of the S-35720 Series.

Figure 10 When Power Supply Voltage is Raised at RST

_______

Pin = "L"