Circuit arrangement and method for maintaining control of a peripheral device by a controller during a controller

A circuit arrangement comprising means for preventing a change of each of two preset states of a control member during resetting of a controller for setting the preset states of the control member, said means for preventing said change being connected between at least one terminal (P) of said controller (100) and at least one input of said control member (102) and including means for generating a second signal for controlling said control member according to a level of a first signal appearing at said at least one terminal (P) of said controller,

• wherein said circuit arrangement comprises a driver component (101) for generating said second signal, said driver component (101) having an output for said second signal connected with said at least one input of said control member (102) and said-driver component (101) having at least one input connected to said at least one terminal (P) of said controller;
• an RC-circuit forming a low pass filter, said RC-circuit being connected between said at least one terminal (P) and said at least one input of said driver component (101), and a feedback resistor (105) connecting said output of said driver component (101) to said at least one terminal (P) of said controller (100), wherein said feedback element has sufficiently high impedance so that said change each of said two preset states may be initiated by said controller, except during said resetting of said controller.

A method of preventing a change of each of two preset states of a control member during resetting of a controller or regulator for setting the preset states of the control member, said two preset states consisting of an active high state and an active low state of said control member, said method comprising the steps of:

• a) supplying a first signal to at least one terminal (P) of said controller (100);
• b) generating a second signal to control said control member (102) according to a level of said first signal by means of a driver stage (101);
• c) feeding back said second signal through a feedback element (105) to form a third signal;
• d) supplying said third signal to said at least one terminal (P) and to a low pass filter means to form a fourth signal;
• and
• e) supplying said fourth signal to said driver stage (101) together with said first signal;
• whereby said change of each of said two preset states of said control member may be initiated by said controller, except during said resetting of said controller.

A method of preventing a change of a preset state of a control member during resetting of a controller or regulator controlling the control member, said method comprising the steps of:

• a) supplying a first signal to at least one terminal (P) of said controller (100);
• b) generating a second signal to control said control member (102) according to a level of said first signal supplied to a logical component (302) via a first input of the logical component (302), said logical component comprising an OR gate;
• c) feeding back said second signal through a feedback element (105a ) to form a third signal;
• d) supplying said third signal to said at least one terminal (P) and to said logical component (302) together with said first signal;
• and
• e) passing a fourth signal to a second input of said logical component (302) through a high pass filter means, whereby said fourth signal acts as a switching signal.