LC709004A Datasheet, PDF (10/13 Pages) ON Semiconductor – I/O-Expander for Microcontroller

LC709004A
Application Examples
(1) Example of a cascade configuration
Two or more LC709004A LSI chips can be cascaded to realize port expansion beyond 16 bits. Port expansion,
however, need to be made in units of 16 bits × n (n denotes the number of LSI chips).
Microcontroller (MCU)
Serial CS Output (CS)
Serial Clock Output (SCK)
Serial Data Output (SDO)
System Reset (RES)
Serial Data Input (SDI)
LC709004
CS
CLK
DIN DOUT
RES (LSI=1)
LC709004
CS
CLK
DIN DOUT
RES (LSI=2)
LC709004
CS
CLK
DIN DOUT
RES (LSI=n)
System Reset
Fig. 5
(2) Variable port power level example
When controlling the level of I/O ports according to the power voltage level of the peripheral equipment, the user
can connect the output from the power supply of the peripheral equipment directly to the power supply pins for the
I/O ports. The LC709004A dispenses with the need to add an external level shifter circuit.
Note the following when configuring the LC709004A in this way:
Note 5:
• VDDP1: The voltage level of VDDP1 must not be higher than that of VDD (VDDP1≤VDD).
• The input level of all ports (P00 to P17) is dependent on the VDD power source; it depends on none of the power
sources VDDP1.
* Be sure to check the electrical characteristics of the LC709004A.
5.0V
VDD
VDD
5.0V
Microcontroller (MCU)
VSS
5.0V selial
send/receive
P00 to P07 5.0V parallel data I/O
RES, CE,
CLK, DIN, DOUT
VDDP1
5.0V peripheral
3.3V
P10 to P13 3.3V parallel data I/O
LC709004A
3.3V peripheral
3.3V
P14 to P17 ^{Nch-open drain display} LED display
data output
VSS
Fig. 6
No.A0165-10/13