ENERGY HARVESTING POWERED BY ULTRA-LOW POWER AND ULTRA-LOW VOLTAGE OPERATION BOOST CHARGE PUMP FOR STEP-UP DC-DC CONVERTER STARTUP

S-8880A Series

11

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external parts, and the output load.

Generally, an output smoothing capacitor with a large capacitance and an output load are connected to the output pin of

the step-up DC-DC converter. Therefore, to start up the step-up DC-DC converter thus connected, it is necessary to





0.1

Discharge start voltage of S-8880A Series (Unit: V)

Capacitance of startup capacitor (Unit:

μF)

Capacitance of power smoothing capacitor for step-up DC-DC converter (Unit:

μF)

Current consumption of step-up DC-DC converter (Unit: mA)

Minimum operation voltage of step-up DC-DC converter (Unit: V)

Step-up DC-DC converter startup time

≅ Soft start time (Unit: ms)

If the Schottky diode (SD1) has a large reverse current or if a pull-down resistor is added to the OUT pin of the S-8880A

Moreover, if SD1 is added between the OUT pin of the S-8880A Series and the power supply pin (VDD) of the step-up

Caution 1. The S-8880A Series can start up the step-up DC-DC converter more reliably as the discharge start

note that the time from when the power is input until the step-up DC-DC converter starts becomes

longer in this case.

> 2.0 V, the minimum operation

OUT pin of the S-8880A Series) rises from 0.37 V to 0.39 V (Refer to Table 10).

4. Do not connect a load other than a capacitance to the CPOUT pin. Note that the discharge operation

may not be performed if a resistance, etc. is connected.

Table 10

1.8 V, 2.0 V

0.37 V min.

Ta =

−30°C to +60°C

1.8 V to 2.4 V

0.39 V min.

Ta =

−40°C to +85°C

Caution The above connection diagram and constant will not guarantee successful operation. Perform

thorough evaluation using the actual application to set the constant.