EMC1201 View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
Manufacturer
EMC1201
SMSC -> Microchip
| EMC1201 Datasheet PDF : 0 Pages | |||
3.3
3.4
Single/Dual Single-Wire Temp Sensor in SOT23-5 Using SMSC BudgetBusTMSensor Interface
Datasheet
wire serial communication protocol between the computer host and its peripheral devices. Please refer
to the BBUS Specification for detailed information about the modes of operation.
Power Modes
The EMC1201 and EMC1202 have two basic modes of operation:
Standby Mode:
The host can initiate standby mode by actively pulling the BBUS low. When the Host places the device
in standby mode, the device immediately powers down to draw < 2uA of supply current. It will remain
in this state until it is awakened by the host. If the host pulls the BBUS line low while temperature data
is being clocked out, the device will not enter standby mode until completion of the data transfer. After
entering standby mode, the device will remain in this mode until it is forced into active mode by the
host. The transition from standby to active mode occurs when the host is no longer pulling the BBUS
low.
Active Mode:
The host initiates active mode by enabling a weak pull up on the BBUS. In this mode, the EMC1201
and EMC1202 continuously convert temperature data. During the time that the device is actively
converting a temperature, the BBUS is in tri-state mode, and the Host places a weak pull-up on the
bus to prevent it from floating. After a conversion is completed, the device automatically clocks out the
data from the most recent conversion to the host. When the data packet has been entirely clocked out,
the BBUS returns to tri-state mode, and the ADC begins converting the next temperature sample.
While BBUS is in tri-state mode, the host can command the device to standby mode.
Temperature Data Format
Temperature readings are coded in 2’s complement format with a -64ºC offset. This format spans from
–63.875ºC to +191.875ºC with 0.125ºC resolution. A temperature measurement outside this range is
reported as either –63.875ºC or +191.875ºC. The host must add 64ºC to calculate the actual
temperature. Table 3.1 shows example temperature readings and the value that will be reported on the
BBUS.
Table 3.1 Temperature Data Format
ACTUAL TEMP.
(ºC)
Diode Fault
-63.875
2’S COMPLEMENT
OF -64ºC OFFSET
100 0000 0000
100 0000 0001
HEX
400
401
-63.000
100 0000 1000
408
-1.000
101 1111 1000
5F8
0.000
110 0000 0000
600
+0.125
110 0000 0001
601
+1.000
110 0000 1000
608
As shown in Table 3.1, 400h is reserved for diode fault signaling which occurs when open or short
conditions are detected between the external DP and DN pins.
Revision 1.0 (06-14-06)
8
DATASHEET
SMSC EMC1201/EMC1202
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