Si4020
CONTROL INTERFACE
Commands to the transmitters are sent serially. Data bits on pin SDI are shifted into the device upon the rising edge of the clock on
pin SCK whenever the chip select pin nSEL is low. When the nSEL signal is high, it initializes the serial interface. The number of bits
sent is an integer multiple of 8. All commands consist of a command code, followed by a varying number of parameter or data bits.
All data are sent MSB first (e.g. bit 15 for a 16-bit command). Bits having no influence (don’t care) are indicated with X. The Power
On Reset (POR) circuit sets default values in all control and command registers.
Timing Specification
Symbol
tCH
Parameter
Minimum value [ns]
Clock high time
25
25
10
10
25
5
tCL
Clock low time
tSS
Select setup time (nSEL falling edge to SCK rising edge)
Select hold time (SCK falling edge to nSEL rising edge)
Select high time
tSH
tSHI
tDS
Data setup time (SDI transition to SCK rising edge)
Data hold time (SCK rising edge to SDI transition)
Data delay time
tDH
5
tOD
10
25
tBL
Push-button input low time
Timing Diagram
tSHI
tSS
nSEL
tCH
tCL
tOD
tSH
SCK
tDS
tDH
BIT15
BIT14
BIT13
BIT8
BIT7
BIT1
BIT0
SDI
POR
WK-UP
nIRQ
nIRQ
12
SILICON [ SILICON ]
