DDC264EVM: Change to common anode mode

Vitalii Bartosh

Part Number: DDC264EVM
Other Parts Discussed in Thread: DDC264,

Hello,

I'm working with diode-behavior device, which can work only in common anode configuration, In simple words - in its working mode we need to measure negative current. I saw such option in other read-out devices. So, is there any option or control register to chande operation mode to "common anode"?

over 1 year ago

0 ChienChun Yang over 1 year ago

TI__Mastermind 19815 points

Hi,

Knowing that you want to work with some diode-behavior device and in a common anode configuration.

Can I think/regard it as an array of diodes and each diode's anode are connected/common together and have separated cathodes?

Could you please take a look of the DDC264 datasheet, page 11 Figure 18 -

https://www.ti.com/lit/ds/symlink/ddc264.pdf?ts=1666289043000&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDDC264%253FkeyMatch%253DDDC264%2526tisearch%253Dsearch-everything%2526usecase%253DGPN

Is the Photodiode orientation in the Figure 18, the way you want to connect? And, when you say negative current, does that mean the input current flow direction will be opposite from the Figure 18, i.e. away from the input/inverting terminal?

Please take a look of datasheet page 26, highlighted below -

Thanks.

+1 Eduardo Bartolome over 1 year ago

TI__Expert 4620 points

Hi Vitalii,

The short answer is that there is no mode. The device can only measure currents flowing into the inputs, except for a very small 0.4% margin in the other direction. The usual recommendation we give to users to deal with this situation is described in this app note Basically you add an offset to the input to bring the "zero" to the full-scale of the device. Not ideal as you need to add one resistor per input...

Best regards,
Eduardo

0 Vitalii Bartosh over 1 year ago in reply to Eduardo Bartolome

Prodigy 40 points

Hi, Eduardo,

Thank you for answer. As I anyway planned to make a PCB for integration of my device with DDC264EVM and with small bias circuit, this solution is quite good. Thanks

Regards,
Vitalii

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DDC264EVM: Change to common anode mode