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External component connection check

IP.com Disclosure Number: IPCOM000018457D
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jul-23
Document File: 2 page(s) / 345K

Publishing Venue

Siemens

Related People

Bernacchia Giuseppe: AUTHOR [+3]

Abstract

In testing circuits with an external current generator and external feedback resistors of a typical regulator may appear problems when the high side power is turned on. In switching regulators at the start-up of the system the output voltage reaches the maximum value power VCC if the controller doesn’t have feedback of the output voltage. This is dangerous for the connected device because it couldn’t sustain this voltage. Until now, there is no voltage regulator system that checks whether the feedback resistors are connected properly.

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Bauelemente

When the EN voltage is high both operational ampli-fiers start to work. The output voltages become im-mediately high and remain high until VR1 or VR2reach  respectively  Voff1  and Voff2. The resistorvoltages VR1 and VR2 are shown in figure 3 withR1>R2. Their slopes are:

External component connectioncheck

Idee: Bernacchia Giuseppe, IT–Padova;

Chiozzi Giorgio, IT–Padova;Galvano Maurizio, IT–Padova

In testing circuits with an external current generatorand external feedback resistors of a typical regulatormay appear problems when the high side power isturned on. In switching regulators at the start-up ofthe system the output voltage reaches the maximumvalue  power  VCC  if  the  controller doesn’t havefeedback of the output voltage. This is dangerous forthe connected device because it couldn’t sustain thisvoltage.  Until  now,  there  is  no voltage regulatorsystem that checks whether the feedback resistors areconnected properly.

That’s why  the  circuit  arrangement  in  figure  1  issuggested.

Fig. 1: suggested circuit arrangement

1  R

I

R

I

R

C

R

2  R

D

=

load

out

2

D

=

load

out

1

+

1

2  and

1

2

C

R

+

where Cout is the output capacitance and Iload is theconstant current that flows in the inductor.

Fig. 3: resistor voltages

● Block 2 is a logic circuit that provides to disablethe current supply and the operational amplifi-ers  if  the  check  was  successful. Moreover itprovides to enable the control of the switchingregulator (figure 4).

Fig. 4: Bloc...