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Altera_Forum
Honored Contributor I
961 Views

MAX7000AE consumes high power on a Max3000A design

Hi, 

 

I am using a MAX3000A (EPM3032AT44-10) in a design running at fairly low speed (~1MHz). Since the Max3000 is obsolete now, I have migrated my design to the pin compatible type MAX7000AE (EPM7032AEAT44-10) 

 

The power consuption of the Max3000 was neglectable so far. A few milliamps on the 3.3V rail. 

 

First I programed the new MAX7000 with the binaries that were produced for the MAX3000. The MAX7000 seems to work fine and the device consumes the same small power figure as the MAX3000.  

Then I changed the device type to the new MAX7000 device and compiled a fresh binary. When I program the device with this binary the power consumption goes up to 90mA - that's a factor of 10 more than before! Also here the design seems to work fine. But due to the high power consumption my power supply is overloaded. 

 

I wonder why that happens!?! 

 

The Max7000 devices have extra I/O pins where the Max3000 had GND pins. These extra IOs are not used in my design and with a setting, I can tie them to ground or set them to inputs. Both settings do not have an effect on the power consumption. 

 

I am using Quartus 13.0sp1 - the last version that supported the Max3000 devices. 

 

Any ideas? 

 

Andi
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Altera_Forum
Honored Contributor I
17 Views

just wanted to add that the unused IO pins are connected to GND because I have kept the PCB layout. 

 

Meanwhile my assumption is that the unused IOs are (somehow) driving HIGH but are tied to ground externally. At least that would explain the high current consumption. But how can I avoid this? I have enabled the global setting to configure unused ports as inputs. But maybe that does not have an effect. Do I have to declare the unused pins in my design and connect them to LOW or declare them as inputs?  

 

Anybody got a clue?
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