Rainbow Electronics MAX6654 - Manual (Page 13)

MAX6654
1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
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Status Byte Functions
The status byte register (Table 7) indicates which (if
any) temperature thresholds have been exceeded. This
byte also indicates whether the ADC is converting and
whether there is an open circuit in the remote diode
DXP–DXN path. After POR, the normal state of all the
flag bits is zero, assuming none of the alarm conditions
are present. The status byte is cleared by any success-
ful read of the status byte, unless the fault persists.
Note that the ALERT interrupt latch is not automatically
cleared when the status flag bit indicating the ALERT is
cleared. The fault condition must be eliminated before
the ALERT can be cleared.
When reading the status byte, check for internal bus
collisions caused by asynchronous ADC timing, or else
disable the ADC prior to reading the status byte
(through the RUN/STOP bit in the configuration byte). In
one-shot mode, read the status byte only after the con-
version is complete, which is 150ms max after the one-
shot conversion is commanded.
BIT NAME POR STATE FUNCTION
7 (MSB) MASK1 0 Masks ALERT interrupts if high.
6 RUN/STOP 0 Standby mode control bit; if high, standby mode is initiated.
5 ETA 0 If high, lower temperature range will be extended from 0 °C to -64°C.
4 PRCM 0 If high, parasitic resistance cancellation mode is enabled.
3 SPNP 0 Set high for operation with CPU.
2 to 0 RFU 0 Reserved.
Table 6. Configuration-Byte Bit Assignments
REGISTER ADDRESS POR STATE FUNCTION
RLTS 00h 0000 0000 Read Internal Temperature
RRTE 01h 0000 0000 Read External Temperature
RSL 02h 0000 0000 Read Status Byte
RCL 03h 0000 0000 Read Configuration Byte
RCRA 04h 0000 0010 Read Conversion Rate Byte
RLHN 05h 0111 1111 Read Internal High Limit
RLLI 06h 1100 1001 Read Internal Low Limit
RRHI 07h 0111 1111 Read External High Limit
RRLS 08h 1100 1001 Read External Low Limit
WCA 09h N/A Write Configuration Byte
WCRW 0Ah N/A Write Conversion Rate Byte
WLHO 0Bh N/A Write Internal High Limit
WLLM 0Ch N/A Write Internal Low Limit
WRHA 0Dh N/A Write External High Limit
WRLN 0Eh N/A Write External Low Limit
OSHT 0Fh N/A One-Shot
RRET 10h 0000 0000 Read External Extended Temperature
RLET 11h 0000 0000 Read Internal Extended Temperature
N/A FEh 4D Read Device ID
N/A FFh 08 Read Device Revision
Table 5. Command-Byte Bit Assignments