ADS4249: Max output buffer current spec

Ella KIM

Part Number: ADS4249

Hello Team,

I wonder the maximum power consumption of IDRVDD. In ADS4249 datasheet, it specifies typical value only.

1. Could you let me know the maximum value? My customer needs this value to see if there's any possibility of overcurrent when they supply two ADS4249 using one 1A 1.8V LDO.

Customer wants to estimate the typical and maximum power consumption at 125 degC Tj (worst case) with LVPECL 245.76MHz. Let me know if more information is needed to estimate the power consumption.

2. There's a equation to get IDRVDD in datasheet. When it comes to 94 mA in datasheet above,

- CL would be zero because the condition specifies ' no load capacitance'

- DRVDD = 1.8V

- N*Favg = 50%*2.5MHz

CL would be zero then how to calculate the current consumption? Could you please check if there's any error on the calculation above?

Thank you a lot!

over 2 years ago

0 Rob Reeder over 2 years ago

TI__Mastermind 24530 points

Hi Ella,

We are looking into this for you.

Regards,

Rob

0 Ella KIM over 2 years ago in reply to Rob Reeder

TI__Expert 3942 points

Hi Rob,

Thank you for feedback. May I know when you can provide this information?

0 Rob Reeder over 2 years ago in reply to Ella KIM

TI__Mastermind 24530 points

Hi Kim,

We setup the ADS4249 evaluation board on the lab bench today and run the test pattern. We found the DRVDD current to be 107mA.

Keep in mind, that load capacitance (based on different trace lengths and pcb material types) will play a large factory in the equation and final calculation of the data output switching currents.

We are verifying the equation for you, but there will always be some variability in this measurement. This is why we didn't list a max limit here.

Regards,

Rob

0 Ella KIM over 2 years ago in reply to Rob Reeder

TI__Expert 3942 points

Hi Rob,

Could you help provide more detail on the lab bench?

Its condition is same as datasheet - +25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, fIN = 2.5MHz, no load capacitance ?

+1 Rob Reeder over 2 years ago in reply to Ella KIM

TI__Mastermind 24530 points

Hi Ella,

We set up the ADS4249 EVM again to test the max current consumption at 125 deg C Tj with LVPECL at 245.76 MHz and an analog input tone at 2.478 MHz.

The current draw increased about 1.2 mA after the part was heated to 125 deg C, from around 105.8 mA to 107 mA.

Regards,

Rob

0 Ella KIM over 2 years ago in reply to Rob Reeder

TI__Expert 3942 points

Appreciate for your feedback!

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ADS4249: Max output buffer current spec