DS2408 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
DS2408 Datasheet PDF : 36 Pages
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PIN DESCRIPTION
PIN
NAME
1
N.C.
2
P0
3
VCC
4
I/O
5
GND
6
N.C.
7
P7
8
P6
9
P5
10
RSTZ
11
P4
12
P3
13
P2
14
P1
15
N.C.
16
N.C.
DS2408
DESCRIPTION
Not Connected
I/O Pin of Channel 0. Logic input/open-drain output with 100W maximum
on-resistance; 0V to 5.25V operating range. Power-on default is
indeterminate. If it is application-critical for the outputs to power up in the
"off" state, the user should attach an appropriate power-on-reset circuit or
supervisor IC to the RSTZ pin.
Optional Power Supply Input. Range 2.8V to 5.25V; must be tied to GND
if not used.
1-Wire Interface. Open-drain, requires external pullup resistor.
Ground
Not Connected
I/O Pin of Channel 7. Same characteristics as P0.
I/O Pin of Channel 6. Same characteristics as P0.
I/O Pin of Channel 5. Same characteristics as P0.
SW configurable PIO reset input ( RST ) or open-drain strobe output
( STRB ). When configured as RST , a LOW input sets all PIO outputs to
the "off" state by setting all bits in the PIO Output Latch State Register.
When configured as STRB , an output strobe will occur after a PIO write
(see Channel-Access Write command) or after a PIO Read (see Channel-
Access Read command). The power-on default function of this pin is
RST .
I/O pin of channel 4; same characteristics as P0
I/O pin of channel 3; same characteristics as P0
I/O pin of channel 2; same characteristics as P0
I/O pin of channel 1; same characteristics as P0
Not connected
Not connected
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.
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