33993 Datasheet, PDF (8/28 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface

ELECTRICAL CHARACTERISTICS
TIMING DIAGRAMS
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. 33993 SPI Timing Characteristics
t_lag
LSB out
t_SO(dis)
V_PWR
V_DD
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
.
Switch state change with
Switch state change with
INT
CS low generates INT
CS low generates INT
Latch switch status
CS
on falling edge of CS
SGn
SGn Bit in SPI Word
1
Switch
Status
Command
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
Figure 6. Normal Mode Interrupt Operation
Switch open “0”
0
Switch
Status
Command
33993
8
Analog Integrated Circuit Device Data
Freescale Semiconductor