User Guide

Operating Modes and Timing
T heprim ary s tates oftheSi4455 ares hown in Figu re7.T hes hu tdown s tatecom pletely s hu ts
down theradio,m inim izingcu rrent cons u m ption andis controlled u s ingtheSD N .Allother
s tates arecontrolledu s ingtheAPIcom m ands ST AR T _ R X,ST AR T _ T X and
CH AN G E _ ST AT E.Figu re8 s hows each oftheoperatingm odes with thetim erequ iredto
reach eitherRX orT X s tateas wellas thecu rrent cons u m ption ofeach s tate.T hetim es in
Figu re8arem eas u redfrom theris ingedgeofnSE L u ntilthechip is in thedes ireds tate.T his
inform ation is inclu dedforreferenceonly s incean au tom atics equ encerm ov es thechip from
ones tateto anotherand s o it is not neces s ary to m anu ally s tep throu gh each s tate.Figu re9
and Figu re10dem ons tratethis tim ingand thecu rrent cons u m ption foreach radio s tateas the
chip m ov es from s hu tdown ors tandby to T X and back.M os t applications willu tilizethe
s tandby m odes incethis prov ides thefas tes t trans ition res pons etim e,m aintains allregis ter
v alu es ,and res u lts in nearly thes am ecu rrent cons u m ption as s hu tdown.
Figure7.S tateM achineDiagram
Figure8.O peratingS tateR esponseT im eandCurrentConsum ption