SS8017 Datasheet, PDF (12/16 Pages) Silicon Standard Corp. – Two Remote Temperature Sensors with SMBus Serial Interface and System Reset

SS8017
Table 4. Command-Byte Bit Assignments
REGISTER
RRTE2
RRTE1
RSL
RCL
RCRA
RRHI2
RRLS2
RRHI1
RRLS1
WCA
WCRW
WRHA2
WRLN2
WRHA1
WRLN1
OSHT
TCRIT1
TCRIT2
COMMAND
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
35h
36h
POR STATE
FUNCTION
0000 0000b Read 2nd remote temperature: returns latest temperature
0000 0000b Read 1st remote temperature: returns latest temperature
N/A
Read status byte (flags, busy signal)
0000 0000b Read configuration byte
0000 0010b Read conversion rate byte
0111 1111b (127) Read 2nd remote THIGH limit
1100 1001b(-55) Read 2nd remote TLOW limit
0111 1111b (127) Read 1st remote THIGH limit
1100 1001b (-55) Read 1st remote TLOW limit
N/A
Write configuration byte
N/A
Write conversion rate byte
N/A
Write 2nd remote THIGH limit
N/A
Write 2nd remote TLOW limit
N/A
Write 1st remote THIGH limit
N/A
Write 1st remote TLOW limit
N/A
One-shot command (use send-byte format)
0110 1100b (108) Critical temperature for 1^st remote temperaure sensor
0101 1000b (88) Critical temperature for 2^nd remote temperaure sensor
The Alert Response can activate several different slave
devices simultaneously, similar to the SMBus General
Call. If more than one slave attempts to respond, bus
arbitration rules apply, and the device with the lower
address code wins. The losing device does
not generate an acknowledge and continues to hold
the ALERT line low until serviced (implies that the
host interrupt input is level sensitive). Successful
reading of the alert response address clears the inter-
rupt latch.
Command Byte Functions
The 8-bit command byte register (Table 4) is the mas-
ter index that points to the various other registers
within the SS8017. The register's POR state is 0000
0000, so that a Receive Byte transmission (a protocol
that lacks the command byte) that occurs immediately
after POR returns the current local temperature data.
The one-shot command immediately forces a new con-
version cycle to begin. In software standby mode
( RUN /STOP bit = high), a new conversion is begun,
after which the device returns to standby mode. If a
conversion is in progress when a one-shot command is
received in auto-convert mode (RUN/STOP bit = low)
between conversions, a new conversion begins, the
conversion rate timer is reset, and the next automatic
conversion takes place after a full delay elapses.
Configuration Byte Functions
The configuration byte register contents are listed in
table 5. Bit 7 (MASK) is used to mask ALERT inter-
rupt. Bit 6 (RUN /STOP) is to put the device in software
standby mode. Setting bit 5 (DET_FAN) with logic 1
can activate the detection of fan failure. Logic 1 in bit 4
(EN_TH_SHUT) makes thermal shutdown function valid
and logic 0 disables this function and keep TH_SHUT
pin low. Bit 3~0 forms thermal shutdown fault queue.
The number of faults these bits decided are listed in
table 6.
Thermal Status Byte Functions
The thermal status byte register (02h) (Table 6) indi-
cates which (if any) temperature thresholds have been
exceeded. This byte also indicates whether or not the
ADC is converting and whether there is an open circuit
in the remote diode DXPx-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 successful read of the status, unless
the fault persists. Note that the ALERT interrupt latch
is not automatically cleared when the status flag bit is
cleared.
When reading the status byte, you must check for in-
ternal bus collisions caused by asynchronous ADC
timing, or else disable the ADC prior to reading the
status byte (via the RUN /STOP bit in the configuration
byte). In one-shot mode, read the status byte only after
the conversion is complete, which is 150ms max after
the one-shot conversion is commanded.
Rev.2.01 6/06/2003
www.SiliconStandard.com
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