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| resources:demo:reference-designs:demo-ad5758-ao8z:demonstration_guide [10 Sep 2019 11:19] – [Navigation] Donal O''Sullivan | resources:demo:reference-designs:demo-ad5758-ao8z:demonstration_guide [29 Dec 2020 23:00] (current) – fix links Robin Getz |
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| - Set Desired Output to 20 mA and click **Apply to all**. This will set the remaining channels to the same state as channel 0. i.e. 20 mA output, DPC OFF. <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:apply-to-all-dpc_off-20ma.png?250|}}</WRAP> Observe that VDPC+ is fixed at 23.3 V even though the buffer output is at 0 V. | - Set Desired Output to 20 mA and click **Apply to all**. This will set the remaining channels to the same state as channel 0. i.e. 20 mA output, DPC OFF. <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:apply-to-all-dpc_off-20ma.png?250|}}</WRAP> Observe that VDPC+ is fixed at 23.3 V even though the buffer output is at 0 V. |
| - I<sub>FIELD</sub> should now be around 207 mA ± 10 mA (~5 W). I<sub>SYSTEM</sub> should be relatively unchanged. | - I<sub>FIELD</sub> should now be around 207 mA ± 10 mA (~5 W). I<sub>SYSTEM</sub> should be relatively unchanged. |
| - Click the **Status** button of any channel to see a graph of the internal die temperature rise of the [[adi>>https://www.analog.com/en/products/ad5758|AD5758]]. Notice how the temperature rises rapidly when DPC is disabled. \\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:die-temperature_rise_off-to-dpc_off.png?300|}}</WRAP> \\ <WRAP info round>When DPC mode is turned **off**, the DPC buck is programmed to output a fixed voltage of 23.3 V. Because the load resistance is low (1 Ω), there is a large voltage drop across the [[adi>>https://www.analog.com/en/products/ad5758|AD5758]] output buffer. There is 23.3V X 20mA = 466mW of power dissipated in the output buffer plus an additional 47 mW dissipation in the DPC buck regulator \\ (466 mW X (1-η)). Which translates to 513 mW of dissipation per channel in the module.</WRAP> | - Click the **Status** button of any channel to see a graph of the internal die temperature rise of the [[adi>AD5758]]. Notice how the temperature rises rapidly when DPC is disabled. \\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:die-temperature_rise_off-to-dpc_off.png?300|}}</WRAP> \\ <WRAP info round>When DPC mode is turned **off**, the DPC buck is programmed to output a fixed voltage of 23.3 V. Because the load resistance is low (1 Ω), there is a large voltage drop across the [[adi>AD5758]] output buffer. There is 23.3V X 20mA = 466mW of power dissipated in the output buffer plus an additional 47 mW dissipation in the DPC buck regulator \\ (466 mW X (1-η)). Which translates to 513 mW of dissipation per channel in the module.</WRAP> |
| - Now select CH0 **DPC ON**\\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:demo-ad5758-ao8z:13-08-2019_14-17-26.png?250|}}</WRAP> | - Now select CH0 **DPC ON**\\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:demo-ad5758-ao8z:13-08-2019_14-17-26.png?250|}}</WRAP> |
| - Click "**Apply to all**". \\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:13-08-2019_14-26-28.png?250|}}</WRAP>\\ Notice how VDPC+ is now at its minimum value of approximately 4.95 V and the die temperature begins to drop rapidly as DPC power saving take effect.\\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:die-temperature_fall_dpc_off-to-dpc_on-very-long.png?250|}}</WRAP> \\ <WRAP info round>When DPC mode is turned **on**, a high efficiency (η = 0.9) buck converter reduces the supply to the buffer to 2.5 V above the required output voltage or 4.95 V - whichever is higher, so there is now a small voltage drop of only 4.95 V across the [[adi>>https://www.analog.com/en/products/ad5758|AD5758]] output buffer<sup>1</sup>. This translates to 4.95V X 20mA = 99mW plus 99 mW X (1 - η) = 10 mW of heat dissipation in the output buffer of the [[adi>>https://www.analog.com/en/products/ad5758|AD5758]]. This is a power saving of 404 mW per channel.\\ <sup><fc #ff0000>1</fc></sup> <fc #ff0000>If VIOUT > 2.5 V, then the the DPC buck tracks the output to maintain a fixed 2.5 V headroom.</fc></WRAP> | - Click "**Apply to all**". \\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:13-08-2019_14-26-28.png?250|}}</WRAP>\\ Notice how VDPC+ is now at its minimum value of approximately 4.95 V and the die temperature begins to drop rapidly as DPC power saving take effect.\\ <WRAP>{{:resources:demo:reference-designs:demo-ad5758-ao8z:gui:die-temperature_fall_dpc_off-to-dpc_on-very-long.png?250|}}</WRAP> \\ <WRAP info round>When DPC mode is turned **on**, a high efficiency (η = 0.9) buck converter reduces the supply to the buffer to 2.5 V above the required output voltage or 4.95 V - whichever is higher, so there is now a small voltage drop of only 4.95 V across the [[adi>AD5758]] output buffer<sup>1</sup>. This translates to 4.95V X 20mA = 99mW plus 99 mW X (1 - η) = 10 mW of heat dissipation in the output buffer of the [[adi>AD5758]]. This is a power saving of 404 mW per channel.\\ <sup><fc #ff0000>1</fc></sup> <fc #ff0000>If VIOUT > 2.5 V, then the the DPC buck tracks the output to maintain a fixed 2.5 V headroom.</fc></WRAP> |
| - I<sub>FIELD</sub> should now be around 72 mA ± 5 mA (~ 1.7 W). I<sub>SYSTEM</sub> should be unchanged. | - I<sub>FIELD</sub> should now be around 72 mA ± 5 mA (~ 1.7 W). I<sub>SYSTEM</sub> should be unchanged. |
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| ==== Related Resources ==== | ==== Related Resources ==== |
| * [[adi>https://www.analog.com/en/products/ad5758.html|AD5758: Single-Channel, 16-Bit Current and Voltage Output DAC with Dynamic Power Control and HART Connectivity]] | * [[adi>AD5758]]: Single-Channel, 16-Bit Current and Voltage Output DAC with Dynamic Power Control and HART Connectivit |
| * [[adi>https://www.analog.com/en/products/adp1031.html|Three-Channel, Isolated Micropower Management Unit with Seven Digital Isolators ]] | * [[adi>adp1031]]: Three-Channel, Isolated Micropower Management Unit with Seven Digital Isolators |
| * Video: [[https://www.youtube.com/watch?v=3jvZrx5-yEY|ADI: Doubling Channel Density of Industrial Output Modules]] | * Video: [[https://www.youtube.com/watch?v=3jvZrx5-yEY|ADI: Doubling Channel Density of Industrial Output Modules]] |
| * Video [[https://www.youtube.com/watch?v=QbfdilQjfNY|Analog Devices: AD5758 DAC for EMC/EMI Robustness]] | * Video [[https://www.youtube.com/watch?v=QbfdilQjfNY|Analog Devices: AD5758 DAC for EMC/EMI Robustness]] |
