1) Is the transponder schematic above correct for a 3.6V-powered and RFID-powered configuration?
2) Is the voltage stated correct for a 3.6V-powered and RFID-powered configuration for the RFID transponder?
a) 2.6V - 3.1V (3.6V powered)
b) 1 - 1.5V (RFID powered)
Your supply voltage correction has been received. I will make the correction.
Your question: Is this the intended purpose for your application?
Answer: We don't have an application for the current product, but we want to understand how this tamper alarm works.
I calculated the Vout for 1.8V and 2.2 V. Is this calculation correct? If yes, the Vout is too low to do anything meaningful.
Vout = Ivdd X 1k
Ivdd = Iinternal +Iout
The typical, permanent current consumption will be ~120 µA for 1.8V and ~340 µA for 2.2V.
For VDD = 1.8 V, Idd = 0.00012A
For VDD = 2,2 V, Idd = 0.00034A
For VDD = 1.8 V, Vout = 0.00012 X 1kohm
Vout = 0.12V
For VDD = 2.2 V, Vout = 0.00034 X 1kohm
Vout = 0.34V
Hello @pragashsangaran
When externally supplied, VDD pad requires a voltage between 1.8V and 2.2V; for a higher value, a series resistance would be required. For proper calculation, please refer to AN10940 FAQs on UCODE G2i, Chapter 3/Chapter 4.
OUT pad is a digital output that can be used for tamper loop, a small external circuit or as indicator; these configurations require VDD pin to be externally suppled. If you populate R35, it will introduce a connection that could activate the "tamper indicator" bit, as per Tag Tamper Alarm feature (please see AN10940 FAQs on UCODE G2i, Chapter 16). Is this the intended purpose for your application?
Expected voltage level on OUT pin is described in AN10940 FAQs on UCODE G2i, Chapter 13. A solution that powers a device connected to OUT pin requires an external supply on VDD pin.
I will recommend you taking a look at the AN11237 UCODE G2iM+ demo board documentation, Fig 3 and Fig 5 for some reference connections.
Regards,
Eduardo.
Hi,
In order to use the OUT pin functionalities, such as digital output/switch or powering an external circuit, an external supply is required. Also, as mentioned in AN10940 FAQs on UCODE G2i, Chapter 16 "How is the Tag Tamper Alarm used?" this feature is based on a galvanic connection between VDD and OUT; something important to remark is that the tamper feature and the external supply mode cannot be used at the same time.
Regarding the calculations, please consider that the voltage level available on the OUT pin is defined by the voltage level on VDD reduced by the voltage drop on the internal series resistor. You can find a few examples on AN10940 FAQs on UCODE G2i, Chapter 5.3.
Regards,
Eduardo.
EduardoZamora, thank you so much. After many attempts to ask the same questions again and again, I finally feel like I im getting the correct answers to my questions. I really hope we can resolve my question in this ticket.
I also want to know if it is the Vout of the RFID-powered configuration (without VDD). Can you please let me know as well?
im not using a tamper indicator. I hope we can justify the use of SL3S1013FTB0,115 vs a Schottky diode. If a Schottky diode can provide higher Vout without a supply voltage, I'd rather go for a Schottky diode.
Hi,
Vout depends on the voltage present on VDD pin (after proper dimensioning of the series resistor between VDD and RFN according to AN10940 FAQs on UCODE G2i, Chapter 5), reduced by the voltage drop on the internal series resistor between VDD and OUT (~1kΩ). Some calculation examples can be found in Chapter 5.3.
Regarding the state of OUT pin, please refer to Chapter 8 to 10 for more information on how to control this pin.
Regards,
Eduardo.
Hi EduardoZamora,
We are not going to use Tamper Alarm, so we can ignore this. The R35 is there just in case.
For us, Vout is very important because it needs to turn the product ON. You are saying VDD needs to be present in order to get Vout. However, I have two major concerns about using this part.
- The calculated Vout is too low.
For VDD = 1.8 V, Vout = 0.12V
For VDD = 2.2 V, Vout = 0.34V.
This Vout will not help at all to turn things on . Even if we think about boosting this voltage, there aren't many options available to raise it further.
Is my calculation correct? Please see one of my previous replies for full calculations.
- In the presence of VDD, can Vout be present regardless of the RFID signal? We want Vout to be present only when the antenna receives an RFID signal. Is this true?
hi EduardoZamora,
im getting more confused and am unable to follow the calculation you pointed out. I feel the Ohm's law calculation is wrong.
This is what the document says:
VSupply with 2.5V connected via 2kΩ to VDD will give a typical, permanent supply current of ~250μA, a VDD voltage of ~1.99V and an output voltage Vout ~1.68V for 100μA load on OUT
− If no current is pulled from OUT: ~ 240μA supply current and ~ 1.73V on OUT
• VSupply with 3.3V connected via 5.1kΩ to VDD will give a typical, permanent supply current of ~255μA, a VDD voltage of ~2V and an output voltage Vout ~1.68V for 100μA load on OUT
− If no current is pulled from OUT: ~ 245μA supply current and ~ 1.73V on OUT
At 2.5V supply, Idd = 250μA
At 3.3V supply, Idd = 255μA
but my calculation says 3.3V , Idd = 647uA and 2.5V, Idd = 1250uA.
im so confused about how Vout is calculated. Another unanswered question is: I want Vout to be present only when the antenna/chip detects the RFID signal. If there is a direct 1 kohm resistor between VDD and OUT, OUT will always have voltage in it, correct? thats not what i want and it will not work for my application. Please confirm this.