# MT41K256M16 DDR3L SDRAM Power Requirement

#### joniengr

##### Full Member level 5
Hi,

I am looking for the power requirement of this chip MT41K256M16. It is powered up by 1.35 V. How much current does this chip need at 1.35 V ?

What is typical and maximum current on termination resister voltage VTTDDR and VREFDDR ? I guess they both are 1.35 /2 = 0.675 V. How much the current on both ? Is is also possible to combine both VTTDDR and VREDDDR voltages ?

#### barry

Joniengr, you apparently have no concept of looking things up for yourself.

Do you know what a datasheet is? Because right there in the data sheet is an entire table defining current draw. In a previous post, you ask for help finding DC-DC converters when all you have to do is perform your own search instead of asking others to do it for you. Then, you have yet another post where you are asking us to give you a tutorial on RS-232 and serial communications.

I, for one, am done with engaging with your posts. Show at least SOME effort.

#### joniengr

##### Full Member level 5
Hi again, the datasheets of DDR3L SDRAM chips are bit complex to understand.

I have looked at the schematic of Xilinx ZC702 in which MT41J256M8HX DDR3 SDRAM is used. This chip is supposed to be powered up by VDD = VDDQ = 1.5V. The reason I refer this schematic is that I think it is relevant to my original question. I need some help in understanding the values of VTTREF_PS and VTTDDR_PS. I guess the values are 0.75 V. I will appreciate if someone please have a look and confirm the value of VTTREF_PS (VREFCA and VREFDQ) and VTTDDR_PS.

DDR3L SDRAM (1.35V) is a low voltage version of the DDR3 (1.5V) SDRAM.

I am working with DDR3L SDRAM which is MT41K256M16 a low voltage version of DDR3 SDRAM. According to datasheet VDD = VDDQ = 1.35V. This chip also have VTTDDR_PS and VTTREF_PS power supplies. I am wondering about the values of these two power supplies. If they are 1.35/2 = 0.675 V then is it possible to combine them and get them from one voltage source ?

I found on several places in the datasheet that VREFDQ = VDD/2 or VREFCA = VDD/2 but on page 30 it says VREF = VSS and VSS is Ground.

Similarly, on page 50 it says that "VTT is not applied directly to the device. VTT is a system supply for signal termination resistors. Minimum and maximum values are system-dependent". In he table above on same page it says that 0.5 × VDDQ.

I put my question again. If VTTREF and VTTDDR are equal to VDD/2 = VDDQ/2 then can I combine both power supplies ? How much is the current on each of the power rail VTTREF and VTTDDR ?

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#### KlausST

##### Super Moderator
Staff member
Hi,
Hi again, the datasheets of DDR3L SDRAM chips are bit complex to understand.
Maybe the datasheet is so complex, because there are no simple answers.
The "current" can be a very short peak less than a nanosecond ... this may be very high.
And it may be an average current over a millisecond. Both values will be very different.

Then there is some "idle" current or some "high traffic" current.

Then there may be low load or high load current ...capacitive, inductive, ohmic, complex.
And many more.

Klaus