Design requirements to achieve <1uA sleep current for the WirelessUSB radio

Question: How does a design achieve <1uA sleep current for the WirelessUSB radio?

 

Answer:

To achieve <1uA for the WirelessUSB radios (CYWUSB6934/5) do the following:

  Pull all inputs appropriately:

 

   SCK = Gnd
   nSS = Vcc
   nPD = Gnd
   nReset = Vcc
   MOSI = Gnd
   Vcc = Vcc
   Gnd = Gnd

  Initialize Radio Registers:

     
  1.    Bring nPD high
  2.  
  3.    Bring nReset low
  4.  
  5.    Bring nReset high (this initializes the radio register defaults properly
  6.  
  7.    Write Reg 0x06 = 0x0B (change DIO/DIOVAL to outputs to avoid floating input)
  8.  
  9.    Write Reg 0x20 = 0x44 (change PACTL to output, to avoid floating input)
  10.  
  11.    Bring nPD low (should now see <1uA current draw on Vcc for the radio)

 

General note:  A /PD pin event will not affect the contents of the registers.  The X13OUT pin will be driven low while the /PD pin is asserted.