TMP421-Q1 Datasheet, PDF (20/38 Pages) Texas Instruments – Remote and Local Temperature Sensor

TMP421-Q1, TMP422-Q1, TMP423-Q1
SBOS821 – NOVEMBER 2016
www.ti.com
N_ADJUST = 300 - ^{300 ´ 1.008}
h_eff
(3)
The η-correction value must be stored in two's-complement format, yielding an effective data range from –128 to
+127. The n-correction value can be written to and read from pointer address 21h. The η-correction value for the
second remote channel (TMP422-Q1 and TMP423-Q1) can be written and read from pointer address 22h. The η-
correction value for the third remote channel (TMP423-Q1 only) can be written to and read from pointer address
23h. The register power-on reset value is 00h, thus having no effect unless the register is written to.
8.5.10 Software Reset
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 can be reset by writing any value to the Software Reset
Register (pointer address FCh). This action restores the power-on reset state to all of the TMP421-Q1, TMP422-
Q1, and TMP423-Q1 registers as well as aborts any conversion in process. The TMP421-Q1, TMP422-Q1, and
TMP423-Q1 also support reset via the two-wire general call address (0000 0000). The General Call Reset
section contains more information.
BINARY
0111 1111
0000 1010
0000 1000
0000 0110
0000 0100
0000 0010
0000 0001
0000 0000
1111 1111
1111 1110
1111 1100
1111 1010
1111 1000
1111 0110
1000 0000
N_ADJUST
HEX
7F
0A
08
06
04
02
01
00
FF
FE
FC
FA
F8
F6
80
Table 5. η-Factor Range
DECIMAL
127
10
8
6
4
2
1
0
–1
–2
–4
–6
–8
–10
–128
η
1.747977
1.042759
1.035616
1.028571
1.021622
1.014765
1.011371
1.008
1.004651
1.001325
0.994737
0.988235
0.981818
0.975484
0.706542
8.5.11 General Call Reset
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 support reset via the two-wire General Call address 00h (0000
0000b). The TMP421-Q1, TMP422-Q1, and TMP423-Q1 acknowledge the General Call address and respond to
the second byte. If the second byte is 06h (0000 0110b), the TMP421-Q1, TMP422-Q1, and TMP423-Q1
execute a software reset. This software reset restores the power-on reset state to all TMP421-Q1, TMP422-Q1,
and TMP423-Q1 registers, and aborts any conversion in progress. The TMP421-Q1, TMP422-Q1, and TMP423-
Q1 take no action in response to other values in the second byte.
8.5.12 Identification Registers
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 allow for the two-wire bus controller to query the device for
manufacturer and device IDs to enable software identification of the device at the particular two-wire bus
address. The manufacturer ID is obtained by reading from pointer address FEh. The device ID is obtained by
reading from pointer address FFh. The TMP421-Q1, TMP422-Q1, and TMP423-Q1 each return 55h for the
manufacturer code. The TMP421-Q1 returns 21h for the device ID; the TMP422-Q1 returns 22h for the device
ID; and the TMP423-Q1 returns 23h for the device ID. These registers are read-only.
20
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