DS2482X-100+T Maxim Integrated Products, DS2482X-100+T Datasheet - Page 21

• Manufacturer Part Number: DS2482X-100+T
• Description: IC MASTER I2C-1WIRE 1CH 9-WLP
• Manufacturer: Maxim Integrated Products

Specifications of DS2482X-100+T

• Controller Type: I²C Bus Controller
• Interface: I²C
• Voltage - Supply: 2.9 V ~ 5.5 V
• Current - Supply: 750µA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 9-WLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SDA is an open-drain output on the DS2482-100 that
requires a pullup resistor to realize high-logic levels.
Because the DS2482-100 uses SCL only as input (no
clock stretching), the master can drive SCL either
through an open-drain/-collector output with a pullup
resistor or a push-pull output.
According to the I
be able to sink at least 3mA at a V
condition determines the minimum value of the pullup
resistor as:
With an operating voltage of 5.5V, the minimum value
for the pullup resistor is 1.7kΩ. The “MINIMUM R
in Figure 11 shows how the minimum pullup resistor
changes with the operating voltage.
For I
sured from 30% to 70% of the pullup voltage. The maxi-
mum bus capacitance, C
1-Wire Triplet (To Perform a Search ROM Function on the 1-Wire Line)
Case A: 1-Wire Idle (1WB = 0), No Busy Polling
The idle time is needed for the 1-Wire function to complete. Then access the device in read mode to get the
result from the 1-Wire Triplet command.
Case B: 1-Wire Idle (1WB = 0), Busy Polling Until the 1-Wire Command is Completed
When 1WB has changed from 1 to 0, the Status Register holds the valid result of the 1-Wire Triplet command.
Case C: 1-Wire Busy (1WB = 1)
The master should stop and restart as soon as the DS2482-100 does not acknowledge the command code.
S
S
S
2
C systems, the rise time and fall time are mea-
AD,0
AD,0
AD,0
R
Applications Information
P(MIN)
SDA and SCL Pullup Resistors
2
______________________________________________________________________________________
A
A
A
C specification, a slave device must
= (V
Pullup Resistor R
1WT
1WT
1WT
B
CC
, is 400pF. The maximum rise
- 0.4V)/3mA
A\
A
A
OL
<byte>
<byte>
of 0.4V. This DC
P
Single-Channel 1-Wire Master
P
Sr
A
A
S
Sizing
I 2 C Communication Examples (continued)
P
” line
AD,1
AD,1
P
(Idle)
A
A
time must not exceed 1000ns at standard speed and
300ns at fast speed. Assuming maximum rise time, the
maximum resistor value at any given capacitance C
calculated as:
For a bus capacitance of 400pF, the maximum pullup
resistor values are 2.95kΩ at standard speed and 885Ω
at fast speed. A value between 1.7kΩ and 2.95kΩ
meets all requirements at standard speed.
Because an 885Ω pullup resistor, as would be required
to meet the rise time specification at fast speed and
400pF bus capacitance, is lower than R
different approach is necessary. The “MAX LOAD AT
MIN R
first calculating the minimum pullup resistor at any
given operating voltage (“MINIMUM R
calculating the respective bus capacitance that yields a
300ns rise time.
Only for pullup voltages of 3V and lower can the maximum
permissible bus capacitance of 400pF be maintained. A
REPEAT UNTIL THE 1WB BIT
HAS CHANGED TO 0.
R
<byte>
<byte>
PMAXS
R
P
PMAXF
FAST MODE” line in Figure 11 is generated by
= 1000ns/[C
A\
A
= 300ns/[C
<byte>
P
B
x ln(7/3)] (standard speed)
B
A\
x ln(7/3)] (fast speed)
P
P
P(MIN)
” line) and then
at 5.5V, a
B
21
is