LMH6517 input matching

Alex Savitskiy

Expert 1230 points

Other Parts Discussed in Thread: ADC16V130, LMH6517

Hello.

In our design we are using LMH6517 and ADC16V130 (First Nyquist zone).

The input schematic part of LMH6517 is the same as in AN–1942 "LMH6517 Evaluation Boards".

1) The middle point of transformer T4 isn't grounding by a capacitor. Is it correct ?

2) If i use only (A) channel of LMH6517, I must:

-> IPB+, IPB-, ENB connect to GND

- >14pin disconnected

My understanding is correct?

Thanks.

over 9 years ago

0 Loren Siebert 1 over 9 years ago

TI__Genius 13935 points

Hi Alex,

Yes, we recommend floating the balun center tap. It is not required. We get better HD2 performance with it floating.

INB+ and INB- are best left floating. If they are accidently enabled they will try to bias to 2.5V. It would be better to use a 0.01uF capacitor to ground. ENB is a logic pin, so it can be directly grounded.

Pin 14 must be connected to +5V. The internal ESD protection network requires that both power supply pins have power. With the ENB pin grounded the B channel will be disabled into a low power state so channel B will be off.

Best Regards,
Loren

0 Alex Savitskiy over 9 years ago in reply to Loren Siebert 1

Expert 1230 points

Hi Loren,

I am forgot to ask:
LMH6517 work in PARALLEL MODE [transparent mode].
Unused pins B0-B5 better connect to ground or to stay floating ?
Thanks.

0 Loren Siebert 1 over 9 years ago in reply to Alex Savitskiy

TI__Genius 13935 points

Hi Alex,

I like to ground unused digital pins.

Regards,
Loren

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LMH6517 input matching