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DIY Stompboxes => Building your own stompbox => Topic started by: JerS on October 08, 2015, 10:17:21 AM

Title: LT1054 - what happens if pin1 and 8 are connected?
Post by: JerS on October 08, 2015, 10:17:21 AM
I was wondering what the practical impact of connecting pin1 and 8 of an LT1054 being used as a voltage inverter is? This can happen in situations where one is replacing a MAX1044 with the oscilator boost function enabled with an LT1054. I see where folks recommend lifting pin 1 on the LT1054, but I am just wondering if this is absolutely necessary - and what are the negative effects of leaving it there.

Anyone have any experience with consequences?

The reason I ask is that I accidentally did just this, and did not notice any operational differences. I am not sure if some issue will crop up later or not. The datasheet doesn't really address this, though it does say that the volts on pin 1 can be equal to the max volts rating for VCC.

Let me know! Thanks!
Title: Re: LT1054 - what happens if pin1 and 8 are connected?
Post by: JerS on October 27, 2015, 07:07:27 PM
For anyone who is curious on this - I received a reply from Linear Technologies. They say there is no problem connecting pin 1 and 8 (same as when using a max1044 with oscillator boost enabled) while using the chip as a bipolar supply.

So there you have it - no need to clip pin 1 any more.

Peace
Title: Re: LT1054 - what happens if pin1 and 8 are connected?
Post by: midwayfair on October 28, 2015, 09:11:55 AM
while using the chip as a bipolar supply.

Bold, underline, and italics because that mean that this isn't necessarily true:

Quote
So there you have it - no need to clip pin 1 any more.

Most pedals use it as a voltage DOUBLER, not a bipolar supply.
Title: Re: LT1054 - what happens if pin1 and 8 are connected?
Post by: JerS on October 28, 2015, 11:47:43 AM
Good clarification. I should have included the actual reply from LT. Here it is:

(http://drive.google.com/uc?export=view&id=0B6oeC00sgURrdk15NDNuUW9nWmM)
Title: Re: LT1054 - what happens if pin1 and 8 are connected?
Post by: Frank_NH on October 28, 2015, 12:49:20 PM
Thanks JerS.  I have a bunch of LT1054 chips and was wondering the same thing.  I believe it should work equally well for voltage doubling configurations.  Here's the datasheet for reference:  http://cds.linear.com/docs/en/datasheet/1054lfh.pdf