DS2408 Maxim, DS2408 Datasheet - Page 6

• Manufacturer Part Number: DS2408
• Description: The DS2408 is an 8-channel, programmable I/O 1-Wire® chip
• Manufacturer: Maxim

APPLICATION
The DS2408 is a multipurpose device. Typical applications include port expander for microcontrollers,
remote multichannel sensor/actuator, communication and control unit of a microterminal, or as network
interface of a microcontroller. Typical application circuits and communication examples are found later
in this data sheet (Figures 17 to 22).
OVERVIEW
Figure 1 shows the relationships between the major function blocks of the DS2408. The device has two
main data components: 1) 64-bit lasered ROM, and 2) 64-bit register page of control and status registers.
Figure 2 shows the hierarchical structure of the 1-Wire protocol. The bus master must first provide one of
the eight ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Conditional
Search ROM, 5) Skip ROM, 6) Overdrive-Skip ROM, 7) Overdrive-Match ROM, or 8) Resume. Upon
completion of an Overdrive ROM command byte executed at standard speed, the device will enter
overdrive mode, where all subsequent communication occurs at a higher speed. The protocol required for
these ROM function commands is described in Figure 12. After a ROM function command is success-
fully executed, the control functions become accessible and the master may provide any one of the five
available commands. The protocol for these control commands is described in Figure 8. All data is read
and written least significant bit first.
Figure 1. DS2408 BLOCK DIAGRAM
V
I/O
GND
CC
GENERATOR
FUNCTION
CONTROL
REGISTER
FUNCTION
REGISTER
CONTROL
1-WIRE
CRC16
PAGE
PARASITE POWER
INTERNAL V
6 of 39
CC
LASERED ROM
FUNCTION
CONTROL
64-BIT
PORT
INTER-
PORT
FACE
RSTZ
P0
P1
P2
P3
P4
P5
P6
P7
DS2408