Applications of VD (Voltage Detectors) | NEXTY Electronics, a trading company for electronic components and semiconductors

As the name suggests, a VD (voltage detector) is a product that monitors voltage.
They are also called voltage detectors, voltage monitoring ICs, reset ICs, etc.
Last time, we introduced the main uses of VDs (voltage detectors), their circuit elements, and the features of each type.
This time, we will introduce applications using external VD (voltage detector) components.

Application of the reset IC with external components

①High voltage POWER SUPPLIES monitoring

I want to use a reset IC to monitor a high-voltage POWER SUPPLIES, but the input voltage rating of the IC will be exceeded.
⇒This can be achieved by using external resistors R1 and R2.

*Note ①:
The input voltage will drop by the IC's current consumption x R1, so it is not good to make the resistance value too large (e.g., 100kΩ or less).

In addition, the through current at the time of detection and release
VIN dropped ⇒ detected again
Detection ⇒ Release through current...
This may cause " hiccups."

The hiccup phenomenon can be prevented by inserting Cin between the resistor and the VIN TERMINALS.

*Note ②: Leak current occurs due to external resistors (VIN/(R1+R2)).

*Note ③: The relative accuracy of resistors R1 and R2 will cause large variations.

②Increase the hysteresis width

I want to set the hysteresis width larger.
⇒This can be achieved by using external resistors R1 and R2.
As the release voltage increases, the hysteresis width also increases (the detection voltage does not change).

Detection voltage = Vdet

Release voltage = Vdet + Vhys

Hysteresis width = Vhys

Detection voltage = Vdet

Release voltage = (1+R1/R2) × (Vdet + Vhys)

Hysteresis width = (R1/R2) × Vdet + (1+R1/R2) × Vhys

*The hysteresis width cannot be reduced by using an external circuit.

*As with Application ➀, it is not good to make the resistance value of R1 too large.

③ Higher accuracy of release delay time

To shorten the time from POWER SUPPLIES on to device startup completion, the release delay time needs to be made more accurate than the IC's specified value.
⇒ Improved accuracy of release delay time with external resistor RD2 *This may not be applicable depending on the product.

・ The built-in resistor RD varies by about ±50%

RD2<<RD, RD is not used and CAPACITORS is charged with RD2.

・ External resistors are available with high accuracy of ±2% or less, including temperature characteristics.