13

The two inputs CONTROL and

RESIN have a direct effect on the outputs. In this case, the RESIN input influences

both outputs, and the CONTROL input only the RESET output. The relationship can be seen in the truth table shown

in Figure 9.

CONTROL

RESIN

RESET

RESET

LL

false

H

L

LL

true

H

L

LH

false

H

L

L

H

true

L*

H*

HL

false

H

L

HL

true

H

L

HH

false

H

L

HH

true

H

H*

Figure 9.

Truth Table

With a Low level at the

RESIN Input

−

inactive state.

The input

RESIN can, for example, be used in order to activate the RESET procedure manually by means of a

switch. This input is also needed when several different supply voltages must be monitored in a single system (see

Section 5).

The CONTROL input is provided with a 1 M

Ω Pull-Down resistor. If the input CONTROL is left unconnected, it will

thus be held at a Low level. The reason for this Pull-Down resistor is to ensure compatibility with the bipolar version

TL770X. With the latter device, the input REF (Pin 1) had always to be connected to a 0.1

µF capacitor; if the

TL770X is replaced in an existing circuit with the TLC770X, then no circuit changes will be necessary.

Open circuit inputs should however be avoided, with the exception of the CONTROL input, in order to ensure

reliable operation of this component.

If the CMOS inputs are not connected as in Figure 10., undefined voltage levels can arise at these inputs and cause

uncontrolled states and lateral currents, which in turn can result in a considerable increase in the current

consumption.

Figure 10.

CMOS input

The reason for these undefined voltage levels at open circuit inputs is the leakage current of the circuit, and the high

insulation resistances (10

10

12

15

ΩΩ

and

) in the area of the inputs of these circuits. The result is that any

The dependence of the lateral current on the voltage level at input IN is shown in Figure 11.. For all other inputs, the

lateral current at the CONTROL input was measured in the same way. If a defined High or Low level is applied to