NCT214
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12
Table 13. LIST OF REGISTERS
Read Address (Hex)
Write Address (Hex)
Name
Power-On Default
Not Applicable
Not Applicable
Address Pointer
Undefined
00
Not Applicable
Local Temperature Value
0000 0000 (0x00)
01
Not Applicable
External Temperature Value High Byte
0000 0000 (0x00)
02
Not Applicable
Status
Undefined
03
09
Configuration
0000 0000 (0x00)
04
0A
Conversion Rate
0000 1000 (0x08)
05
0B
Local Temperature High Limit
0101 0101 (0x55) (85癈)
06
0C
Local Temperature Low Limit
0000 0000 (0x00) (0癈)
07
0D
External Temperature High Limit High Byte
0101 0101 (0x55) (85癈)
08
0E
External Temperature Low Limit High Byte
0000 0000 (0x00) (0癈)
Not Applicable
0F (Note 1)
One-shot
10
Not Applicable
External Temperature Value Low Byte
0000 0000
11
11
External Temperature Offset High Byte
0000 0000
12
12
External Temperature Offset Low Byte
0000 0000
13
13
External Temperature High Limit Low Byte
0000 0000
14
14
External Temperature Low Limit Low Byte
0000 0000
19
19
External THERM
Limit
0101 0101 (0x55) (85癈)
20
20
Local THERM
Limit
0101 0101 (0x55) (85癈)
21
21
THERM
Hysteresis
0000 1010 (0x0A) (10癈)
22
22
Consecutive ALERT
0000 0001 (0x01)
FE
Not Applicable
Manufacturer ID
0100 0001 (0x41)
1.  Writing to Address 0x0F causes the NCT214 to perform a single measurement. It is not a data register, and it does not matter what data is
written to it.
Serial Bus Interface
Control of the NCT214 is carried out via the serial bus.
The NCT214 is connected to this bus as a slave device, under
the control of a master device.
The NCT214 has an SMBus/I
2
C timeout feature. When
this is enabled, the SMBus/I
2
C times out after typically
25 ms of no activity. However, this feature is not enabled by
default.   Bit 7   of   the   consecutive   alert   register
(Address = 0x22) should be set to enable it.
Addressing the Device
In general, every SMBus/I
2
C device has a 7-bit device
address, except for some devices that have extended 10-bit
addresses. When the master device sends a device address
over the bus, the slave device with that address responds.
The NCT214 has two address pins, ADD0 and ADD1, to
allow selection of the device address, so that several
NCT214s can be used on the same bus, and/or to avoid
conflict with other devices.
Although only two address pins are provided, these are
threestate, and can be grounded, left unconnected, or tied to
V
DD
, so that a total of nine different addresses are possible,
as shown in Table 14. It should be noted that the state of the
address pins is only sampled at powerup, so changing them
after powerup has no effect.
Table 14. DEVICE ADDRESSES
ADD0
ADD1
Device Address
0
0
001 1000
0
NC
001 1001
0
1
001 1010
NC
0
010 1001
NC
NC
010 1010
NC
1
010 1011
1
0
100 1100
1
NC
100 1101
1
1
100 1110
The serial bus protocol operates as follows:
1. The master initiates a data transfer by establishing
a start condition, defined as a high-to-low
transition on SDATA, the serial data line, while
SCLK, the serial clock line, remains high. This
indicates that an address/data stream follows. All
slave peripherals connected to the serial bus
respond to the start condition and shift in the next
eight bits, consisting of a 7-bit address (MSB first)
plus an R/W
bit, which determines the direction of