FOR AUTOMOTIVE 125°C OPERATION WITH INTERRUPT TIME SETTING PIN CONVENIENCE TIMER

S-35720 Series

Seiko Instruments Inc.

11



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 12.

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 12 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

"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 one-shot loop time-out or handshake time-out is selected as the option.

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 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 as mentioned below while the RST

_______

pin is set to "L".

• When the product without a pull-up resistor is selected:

1.7

μA typ.

• When the product with a pull-up resistor is selected:

30

μA typ.

0.2 V or lower

RST pin input

Oscillation start signal

Oscillation circuit output

10 ms

within 500 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 13 When Power Supply Voltage is Raised at RST

_______

Pin = "L"