DAC7822: Need Technical Support

Hi Khemraj,

1. At startup, both channels will be loaded with zero-scale data (all 0's)
2. When switching channels, the previous channel will maintain the same data as before.  It will be unaffected.
3. There is no need to clear the parallel input.  You switch the RS, WR, and LDAC pins to the "no operation" before changing the address.  During that state, you can change the parallel data with the other channels data without risk.
4. The DAC8822:www.ti.com/.../sbas390a.pdf
5.  Not sure what you mean - what register are you asking about?

thanks,

Paul

Hello Paul,

Thank you for your answer.

Can you please help to answer following queries:

1. DAC7822 and DAC882 are not footprint compatible part as DAC7822 is QFN package aand DAC8822 is TSOP package.

2. I am looking for DAC7822 software register configuration settings pdf file through which i can configure the internal register settings of DAC IC.

Your immediate response on this would be highly appreciated.

Regards,

Khemraj

Hi Khemraj,

I didn't understand what do you mean by software register configuration settings. For this device, there is no register maps to be configured for to work.

Device has parallel interface and selection of DAC depends on the state of DAC A/B pins.

DAC7822 and DAC8822 are offered on different packages, so these won't be footprint compatible.

Regards,

AK

Hello AK,

Thanks for your immediate reply. Can you please update me on following queries:

1. What is the status of this part? Is this in production or not?

2. Can you please let us know about the longitivity of this part that how many years this part will be supported?

Regards,

Khemraj

Hi,

DAC7822 is still in production.

As per the longevity of this part, it will be mentioned in the ti.com when this part will be not recommended for new designs.

You can go ahead with this part, if this part meets your design criteria, no need to worry.

Regards,

AK

Hi AK,

Thank you for the confirmation.

Can you please confirm DAC8822 and DAC8805 supports 10MSps data rate or not? If yes, we can consider these parts for our design.

Regards,

Khemraj

Hi Khemraj,

Basically DAC update rate consists for two parameter, digital interface timing and settling time of the DAC.

For DAC8820, in digital interface timing, we need to look for TDS and TLDAC. However, for our equation, we will disregard TLDAC as well.That time period is, again, overlapped by the DAC settling time, leaving only the data set up time to factor into the equation.

so with 500nS settling time and TDS of min 10 ns, total update rate can be 1/ ( 500nS +10nS) = 1.9Msps. Please note that datasheet specifies settling time for code jump from 0x0000 to 0xFFFF with 0.0015% error band. When code changes are small, settling time can be lower than 500nS.

Similarly you can calculate for DAC8805 as well. for DAC8805, settling to 0.1% is approx. 300ns and TDS is 10ns.

So update rate can be 1/310ns = 3.22Msps

What kind of waveform and frequency are you trying to generate here?

Regards,

AK

Hello Akhilesh,

Below is our requirement:

1. The application of the DAC is to generate the pulses to program the Hall Effect sensors.

2. Required rise/fall time  : 0.2ms typical

3. High/Low Time : 3ms

4. We need a DAC which can be used for update rate of 10MSPS.

Can you also please confirm whether we can achieve the update rate of DAC7822 or not? If yes, then can you also please suggest any 16-bit or 14-bit part number which can support the update rate of 10MSPS.

Waiting for your immediate response.

Regards,

Khemraj Suthar

Hello Akhilesh,

Below is our requirement:

1. The application of the DAC is to generate the pulses to program the Hall Effect sensors.

2. Required rise/fall time  : 0.2ms typical

3. High/Low Time : 3ms

4. We need a DAC which can be used for update rate of 10MSPS.

Can you also please confirm whether we can achieve the update rate of 10MSPS with DAC7822 or not? If yes, then can you also please suggest any 16-bit or 14-bit part number which can also support the update rate of 10MSPS.

Waiting for your immediate response.

Regards,

Khemraj Suthar