Minimizing current in hibernate mode of PSoC3

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Anonymous
Not applicable

I have started to using low power modes of PSoC 3 and i'm wondering how to minimize current consumption in hibernate mode.

   

I am using CY8C3866LTI-068ES3 device, i have made blank project - without any components, i have changed some parameters such as:

   
        
  • disabled pll,
  •     
  • master clock changed to IMO (3MHz),
  •     
  • completly disable debugging port.
  •    
   

On my PCB i have 3.3V connected to: Vdda, Vcca, Vddio0,  Vddio1,  Vddio2,  Vddio3,  Vddd,  Vccd

   

The ground is connected to: Vbat, Vb, Vssb, Vssd, Ex_Pad

   

All other pins are unconnected.

   

The only two lines in my code are:

   

CyPmSaveClocks(); //Save Clock configuration before entering Hibernate
CyPmHibernate(); // put the device into hibernate mode

   

When i measure current taken by PSoC 3 (after starting this program) it's about 100 uA - when in datasheet it says that it supouse to be about 200nA.

   

I'm wondering where such big difference comes from?

   

What can i change to minimize current consumption?

   

I was testing with forcing some pins to be outputs in high impedance, some to inputs and etc. - but any such move leads to bigger current.

   

I have also tried "Hibernate_WakeupWithPICU" (application note and example) - but the minimum current is the same (over 100uA).

   

I have attached example project which takes 100uA.

   

Thanks in advance for any help/hints.

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7 Replies
Anonymous
Not applicable

 Hi,

   

Can you give us more information on the test setup? Are you using the Cypress DVk. Or is it a custom board. How are you measuring the current? Is it the board current or PSoC current that you are measuring?

   

-Udayan

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Anonymous
Not applicable

 Hi,

   

Can you give us more information on the test setup? Are you using the Cypress DVk. Or is it a custom board. How are you measuring the current? Is it the board current or PSoC current that you are measuring?

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Anonymous
Not applicable

 Hi,

   

Can you give us more information on the test setup? Are you using the Cypress DVk. Or is it a custom board. How are you measuring the current? Is it the board current or PSoC current that you are measuring?

   

-Udayan

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Anonymous
Not applicable

Thanks for reply.

   

So this is my custom board and i'm measuring board current. 

   

But as i wrote, on my board there are just few capacitors between GND and VCC and all other pins are uconnected - they are floating. When i remove Cypress chip, the current is 0 - as it supouse to be.
 

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Anonymous
Not applicable

Hello,

   

I understand from your first commment that the VCCA terminal on PSoC is connected to VDDD/VDDA terminal as well. If this is the case what you are doing is wrong. 

   
        
  •      
            
    • PSoC3 has two internal 1.8V regulators that provide the digital (Vccd) and analog (Vcca) supplies for the internal core logic.
    •      
  •     
  •      
            
    • The output pins of the regulators (Vccd and Vcca) have very specific capacitor requirements that are listed in the data sheet.
    •      
  •    
   

Hence you may have to connect VCCA and VCCD terminal to an appropriate capacitor. There is a possibility that the chip may not work because of excess voltage applied at VCCA. 

   

-Udayan

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Anonymous
Not applicable

Yep, You are right!

   
        
  • the one (Vcca) was was my mistake during writing that post. On PCB Vcaa is connected to 1uF capacitor - (not to 3.3V - as i wrote before)
  •     
  • but Vccd is connected to 3.3V  - so this can be the reason of these extra 100uAmps. (device is still working properly)
  •    
   

Thank You for finding it, i will change my design and PCB and try again soon.

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Anonymous
Not applicable

Hello Vac,

   

After making the changes, let us know if it works.

   

Thanks,

   

Udayan

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