88C57-AF5-R datasheet(9/16 Pages) UTC

9 / 16 page

88CXX

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

www.unisonic.com.tw

QW-R502-040,A

OPERATION

1. Basic operation: CMOS active low output

(1) When power supply voltage VDD is greater than the release voltage +VDET, the Nch transistor is OFF and the

Pch transistor ON, causing VDD (high) to appear at the output.

(2) When power supply voltage VDD goes below +VDET, the output maintains the power supply voltage level, as

long as VDD remains above the detection voltage -VDET. When VDD does fall below -VDET (A in Figure 7), the Nch

transistor goes ON the Pch transistor goes OFF, and VSS appears at the output.

(3) When VDD falls below the minimum operating voltage, the output becomes undefined. However, output will

revert to VDD if a pull-up has been employed.

(4) VSS will again be output when VDD rises above the minimum operating voltage. VSS will continue to be output

even when VDD surpasses -VDET, as long as it does not exceed the release voltage +VDET.

(5) When VDD rises above +VDET (B in Figure 7), the Nch transistor goes OFF the Pch transistor goes ON, and VDD

appears at the output. Then VDD at the OUT terminal appears with delay time (td) due to delay circuit.

*Parasitic diode

VREF

OUT

Delay

circuit

Nch

Pch

Figure 6

Hysteresis

width(VHYS)

Release voltage (+VDET)

Detection voltage (-VDET)

Min.operating voltage

Vss

OUT terminal output

VDD

Vss

Figure 7

(1)

(2)

(3)

(4)

(5)

VDD

Vss

VDD

2. Delay circuit

The delay circuit outputs the signal delayed from the release voltage (+VDET) point of the power voltage VDD

rising. The output signal is not delayed when the VDD goes down the detection voltage (-VDET) or less. (See Figure 7).

The delay time (td) is determined by the time constant of the built-in constant current (approx. 100nA in the case

of products with detection voltage of 1.5V or more, approx. 570nA in the case of products with detection voltage of

1.4V or less) and the attached external capacitor (CD), and calculated from the following formula.

td (ms) = Delay factor×CD (nF)

Delay factor: (25℃)

Products with detection voltage of 1.4V or less: Min.0.57, Typ.0.77, Max.0.96

Products with detection voltage of 1.5V or more: Min.3.8, Typ. 5.1, Max.6.4

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