SBOS835C May 2017 – October 2019 TMP464
PRODUCTION DATA.
The Configuration Register sets the conversion rate, starts one-shot conversion of all enabled channels, enables conversion the temperature channels, controls the shutdown mode and reports when a conversion is in process. The Configuration Register is set by writing to pointer address 30h, and is read from pointer address 30h. Table 8 summarizes the bits of the Configuration Register.
CONFIGURATION REGISTER (READ = 30h, WRITE = 30h, POR = 0x0F9C) | |||
---|---|---|---|
BIT NUMBER | NAME | FUNCTION | POWER-ON-RESET VALUE |
15:12 | 0 | Reserved for future use; always reports 0 | 0000 |
11:8 | REN4:REN1 | 1 = enable respective remote channel 4 through 1 conversions | 1111 |
7 | LEN | 1 = enable local channel conversion | 1 |
6 | OS | 1 = start one-shot conversion on enabled channels | 0 |
5 | SD | 1 = enables device shutdown | 0 |
4:2 | CR2:CR0 | Conversion rate control bits; control conversion rates for all enabled channels from 16 seconds to continuous conversion | 111 |
1 | BUSY | 1 when the ADC is converting (read-only bit ignores writes) | 0 |
0 | Reserved | — | 0 |
The Remote Enable four through one (REN4:REN1, bits 11:8) bits enable conversions on the respective remote channels. The Local Enable (LEN, bit 7) bit enables conversions of the local temperature channel. If all LEN and REN are set to 1 (default), this enables the ADC to convert the local and all remote temperatures. If the LEN is set to 0, the local temperature conversion is skipped. Similarly if a REN is set to 0, that remote temperature conversion channel is skipped. The TMP464 device steps through each enabled channel in a round-robin fashion in the following order: LOC, REM1, REM2, REM4, LOC, REM1, and so on. All local and remote temperatures are converted by the internal ADC by default after power up. The configuration register LEN and REN bits can be configured to save power by reducing the total ADC conversion time for applications that do not require all of the four remote and local temperature information. Note writing all zeros to REN4:REN1 and LEN has the same effect as SD = 1 and OS = 0.
The shutdown bit (SD, bit 5) enables or disables the temperature-measurement circuitry. If SD = 0 (default), the TMP464 device converts continuously at the rate set in the conversion rate register. When SD is set to 1, the TMP464 device immediately stops the conversion in progress and instantly enters shutdown mode. When SD is set to 0 again, the TMP464 device resumes continuous conversions starting with the local temperature.
The BUSY bit = 1 if the ADC is making a conversion. This bit is set to 0 if the ADC is not converting.
After the TMP464 device is in shutdown mode, writing a 1 to the one-shot (OS, bit 6) bit starts a single ADC conversion of all the enabled temperature channels. This write operation starts one conversion and comparison cycle on either the four remote and one local sensor or any combination of sensors, depending on the LEN and REN values in the Configuration Register (read address 30h). The TMP464 device returns to shutdown mode when the cycle is complete. Table 9 details the interaction of the SD, OS, LEN, and REN bits.
WRITE | READ | FUNCTION | ||||
---|---|---|---|---|---|---|
REN[8:1], LEN | OS | SD | REN[8:1], LEN | OS | SD | |
All 0 | — | — | All 0 | 0 | 1 | Shutdown |
At least 1 enabled | — | 0 | Written value | 0 | 0 | Continuous conversion |
At least 1 enabled | 0 | 1 | Written value | 0 | 1 | Shutdown |
At least 1 enabled | 1 | 1 | Written value | 1 | 1 | One-shot conversion |
The conversion rate bits control the rate that the conversions occur (CR2:CR0, bits 4:2). The value of CR2:CR0 bits controls the idle time between conversions but not the conversion time itself, which allows the TMP464 device power dissipation to be balanced with the update rate of the temperature register. Table 10 describes the mapping for CR2:CR0 to the conversion rate or temperature register update rate.
CR2:CR0 | DECIMAL VALUE | FREQUENCY (Hz) | TIME (s) |
---|---|---|---|
000 | 0 | 0.0625 | 16 |
001 | 1 | 0.125 | 8 |
010 | 2 | 0.25 | 4 |
011 | 3 | 0.5 | 2 |
100 | 4 | 1 | 1 |
101 | 5 | 2 | 0.5 |
110 | 6 | 4 | 0.25 |
111 | 7 | Continuous conversion; depends on number of enabled channels; see Table 11 (default). |
NUMBER OF REMOTE CHANNELS ENABLED | CONVERSION TIME (ms) | ||
---|---|---|---|
LOCAL DISABLED | LOCAL ENABLED | ||
0 | 0 | 15.5 | |
1 | 15.8 | 31.3 | |
2 | 31.6 | 47.1 | |
3 | 47.4 | 62.9 | |
4 | 63.2 | 78.7 |
The remaining bits of the configuration register are reserved and must always be set to 0. The POR value for this register is 0x0F9C.