Hello,
I am planning to add a DA14585 to an existing system, and have a few questions about bypassing the internal DC/DC:
1. The method in the FAQ refers to DA14580, does it work the same way for DA14580?
https://support.dialog-semiconductor.com/guide/faq-hardware-peripherals
2. Will the attached power circuit work? We may reduce supply voltage to 3.1V.
3. Is there any way to do a rough calculation for how this will affect efficiency, since the FAQ mentions it could be bad?
4. VDD is completely unnecessary, right? I know the datasheet says it is only for testing purposes, I just want to double check.
Thank you!
-Sam
Attachment:
Device:
嗨sampullman,
1) The method works the same at DA14580 and DA14585.
2)What is your implementation plan exactly? Yes it will work(Please check the datasheet).
3) You will have some effect to the efficiency(please the datasheet at DC-DC Efficiency vs Voltage Diagram page 133). For calculation use this formula:
(P=V x I)
Applied Voltage(for example 3.1V) x operation radio current= result1 in mW
result1/effiency of the dc-dc converter=result 2 in mW
The current that has to be apllied is: result2/applied voltage.
4)The Vdd is unnecessary.
BR,
STS_Dialog
Hello,
Thank you for the prompt reply!
What do you mean by "implementation plan"? We will use DA14585 with 64 or 128KB external flash in order to add BLE with a custom profile to our system. We will use the on-chip HCI stack, and may have a simple protocol over SPI or I2C to forward ADC readings to the main processor.
One last question: the existing dev boards don't seem to include decoupling capacitors near the power pins, do you think it would be better to include them?
-Sam
Hi,
Please check the AN-B-054 from application notes at the documents tab.
Thanks,
STS_Dialog.
Ok, thank you for your assistance!
Hello,
I would like to bypass the internal DC/DC and use an external 3v3 ldo as supply.
The attached schematic shows one of the possible bypassed DCDC schematic's when following the information from your website.
I will disable the DC/DC converter and will not use the XTAL32K.
However, to minimize the part count even further i would like to know if i can remove some capacitors from the schematic.
1) Can you advice if possible which capacitor may be removed?
Thanks
Hi VRBleeker,
As I can see in your schematic, you have referenced the boost mode configuration. According to the H/W group, it has no difference between boost and buck mode when the DC/DC is bypassed. So you can use the buck mode configuration like figure 2 in AN-B-054 document. The decoupling capacitors at the VDCDC_RF and VDCDC rails should be populated but their value can be reduced up to 100nF. The VBAT3V decoupling capacitor should remain at the same value and should be populated.
Thanks PM_dialog