UPD72042BGT NEC [NEC], UPD72042BGT Datasheet - Page 27

• Manufacturer Part Number: UPD72042BGT
• Description: LSI DEVICE FOR Inter Equipment Bus (IEBus) PROTOCOL CONTROL
• Manufacturer: NEC [NEC]

3.3 CONNECTION TO A MICROCOMPUTER
(1) Three-wire serial I/O
(2) Two-wire serial I/O
Notes 1. When only the PD72042B is to be controlled from a microcomputer via a serial I/O interface, the CS
2. When an interrupt is detected by polling (in FLG register read), IRQ may be left open. When high-volume
3. Required when the microcomputer’s N-ch open-drain output is used. The SIO pin of the PD72042B
pin must be tied low (by connecting it to GND).
or high-speed data transfer is required, however, the system described above is recommended to ensure
reliable data transfer.
is a CMOS I/O pin.
180
180
180
180
120
120
120
120
5 V
5 V
6 MHz
6 MHz
Data Sheet S13990EJ3V0DS
V
AV
TEST
BUS+
BUS–
XI
XO
GND
V
AV
TEST
BUS+
BUS–
XI
XO
GND
DD
DD
DD
PD72042B
DD
PD72042B
IRQ
CS
RESET
IRQ
RESET
CS
SCK
SEL
Note 1
Note 2
C/D
SCK
SO
SEL
Note 1
Note 2
C/D
SIO
SI
SO
Low
voltage
detection
circuit
Low
voltage
detection
circuit
5 V
5 V
Note 3
Output port
Output port
SCK
SO
SI
INT
Output port
Output port
SCK
SIO
INT
Microcomputer
Microcomputer
75XL series
78K series
75XL series
78K series
PD72042B
27