AD9545 SPI Levels

Question

Hi all 
 
 We are designing a Hardware around the AD9545. We couldn't 100% figure out if the SPI can work with 3.3V Voltage Levels. In the manual on p. 30 VDDIOA is valid to be 3.3V for the CSB pin. Do these conditions also apply for the rest of the SPI Pins (SCLK, SDIO, SDO)? Or in short: can VDDIOA and VDDIOB be 3.3V in order to directly interface a MCU with 3.3V voltage levels? 
 
 On p. 167 it is stated: 
 "Physical layer: 3-wire and 4-wire supported and 1.5 V, 1.8 V, and 2.5 V operation supported", 
 which confuses us more, whether it will work with 3.3V voltage levels. 
 
 Thank you in advance

guushdi · Accepted Answer

Hi Petre 
 
 Thanks for the clarification and the fast reply. 
 
 guushdi)

pminc48 · Answer

HI, 
 The specifications table 28, page 30 in the AD9545 rev C data sheet states clearly the high level of SPI pins CSB, SCLK, SDO and SDIO depend on VDDIOA. The VDDIOA supply may be 1.8V, 2.5V or 3.3V. So if you need the AD9545 SPI to function with 3.3V logic, you need to use VDDIOA=3.3V. 
 Please note that the Mx pins and RESETB pin depend of VDDIOA or VDDIOB voltages. So if you use VDDIOA=3.3V to solve your SPI compatibility issues, make sure you know about the voltage levels of these pins, specially if you use them as inputs. The evaluation board has VDDIOA and VDDIOB connected together at 1.8V, but you can use then at different voltages. 
 I'll make a note to add 3.3V to the physical layer phrase you point to. 
 Petre

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AD9545 SPI Levels