33972_09 Datasheet, PDF (9/32 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface with Suppressed Wake-up

TIMING DIAGRAMS
ELECTRICAL CHARACTERISTICS
TIMING DIAGRAMS
CS
SCLK
SI
0.2 V_DD
t _LEAD
0.7 V_DD
0.2 V_DD
t_SI(SU) t_SI(HOLD)
0.7 V_DD
0.2 V_DD
MSB IN
SO
t_SO(EN)
0.7 V_DD
0.2 V_DD
MSB OUT
t _VALID
Figure 4. SPI Timing Characteristics
t _LAG
LSB OUT
t_SO(DIS)
VPWR
VDD
WAKE
INT
CS
Wake-up From Interrupt
Timer Expire
SGn
Power-up
Normal Mode
Tri-state
Command
(Disable
Tri-state)
.
INT
Sleep
Command
Sleep Mode
Normal
Mode
Sleep Command Sleep Mode
Figure 5. Sleep Mode to Normal Mode Operation
Switch state change with
CS LOW generates INT
Wake-up From
Closed Switch
Normal
Mode
Sleep Command
Switch state change with
CS LOW generates INT
Latch switch status
CS
on falling edge of CS
SGn
SGn Bit in SPI Word
1
Switch
Status
Command
Rising edge of CS does not
clear INT because state change
occurred while CS was LOW
0
Switch
Status
Command
0
Switch
Status
Command
Switch closed “1”
1
Switch
Status
Command
Figure 6. Normal Mode Interrupt Operation
1
Switch
Status
Command
Switch open “0”
0
Switch
Status
Command
Analog Integrated Circuit Device Data
Freescale Semiconductor
33972
9