Johnny_YU
Member level 2
Hi, all
in my circuit, there are:
1. one CC2541, a SOC for BLE. it runs with a 32M and a 32.768K crystal oscillator;
2. one EEPROM(400K speed);
3. one OPA379;
4. one NTC (Temperature Sensor)
i use OPA to amplify the voltage signal associate with NTC, then use CC2541 to convert that voltage signal to digital ,save the data in EEPROM and send the data to other equipment through BLE.
i use a 3.7V Li-battery and a LDO to provide 3V for all the devices in my circuit.
My problem:
1. CC2541 has two DVDD input and five AVDD input, if i have to isolate AVDD and DVDD, should i use a ferrite bead?
2. if CC2541 without BLE module, should i choose 32M as the highest targeted noise frequency? Could you give me more info about how to decide the targeted noise frequency systematically?
3. i'm confused about using inductor to isolate AVDD and DVDD. is there any difference between using power input as AVDD directly,then add a inductor between DVDD, or using power input as DVDD directly, then add a inductor between AVDD?
4. if add a conductor and capacitor before IC power supply, the IC output voltage will be delay, am I right? if i'm right ,does that mean DVDD should be connect to power input?
5. if add a bead or inductor for OPA ,would it get a better performance?
i'd like to make a good power system, but i have a lot to learn, please give me some advise, thank you!
in my circuit, there are:
1. one CC2541, a SOC for BLE. it runs with a 32M and a 32.768K crystal oscillator;
2. one EEPROM(400K speed);
3. one OPA379;
4. one NTC (Temperature Sensor)
i use OPA to amplify the voltage signal associate with NTC, then use CC2541 to convert that voltage signal to digital ,save the data in EEPROM and send the data to other equipment through BLE.
i use a 3.7V Li-battery and a LDO to provide 3V for all the devices in my circuit.
My problem:
1. CC2541 has two DVDD input and five AVDD input, if i have to isolate AVDD and DVDD, should i use a ferrite bead?
2. if CC2541 without BLE module, should i choose 32M as the highest targeted noise frequency? Could you give me more info about how to decide the targeted noise frequency systematically?
3. i'm confused about using inductor to isolate AVDD and DVDD. is there any difference between using power input as AVDD directly,then add a inductor between DVDD, or using power input as DVDD directly, then add a inductor between AVDD?
4. if add a conductor and capacitor before IC power supply, the IC output voltage will be delay, am I right? if i'm right ,does that mean DVDD should be connect to power input?
5. if add a bead or inductor for OPA ,would it get a better performance?
i'd like to make a good power system, but i have a lot to learn, please give me some advise, thank you!