33975 Datasheet, PDF (10/32 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current

TIMING DIAGRAMS
TIMING DIAGRAMS
CS
0.2 VDD
t_lead
SCLK
0.7 VDD
0.2 VDD
t_SI(su) t_SI(hold)
SI
0.7 VDD
0.2 VDD
MSB in
SO
t_SO(en)
0.7 VDD
0.2 VDD
MSB out
t_valid
Figure 4. SPI Timing Characteristics
t_lag
LSB out
t_SO(dis)
VPWR
VDD
WAKE
INT
CS
SGn
Power-Up Tri-State
Sleep
Normal Mode Command Command
(Disable Tri-State)
Sleep Mode
Wake-Up From Interrupt
Timer Expire
Wake-Up From
Closed Switch
Normal
Mode
Sleep Command Sleep Mode
Normal
Mode
Sleep Command
Figure 5. Sleep Mode to Normal Mode Operation
INT
CS
Latch switch status
on falling edge of CS
Switch state change with
CS low generates INT
Switch state change with
CS low generates INT
SGn
SGn Bit in SPI Word
1
Switch
Status
Command
33975
10
0
Switch
Status
Command
0
Switch
Status
Command
Rising edge of CS does not
clear INT because state change
occurred while CS was low
Switch closed “1”
1
Switch
Status
Command
1
Switch
Status
Command
Switch open “0”
0
Switch
Status
Command
Figure 6. Normal Mode Interrupt Operation
Analog Integrated Circuit Device Data
Freescale Semiconductor