SA56004X Datasheet, PDF (16/23 Pages) NXP Semiconductors – 1 Degrees Celcious accurate, SMBus-compatible, 8-pin, remote/local digital temperature sensor with over temperature alarms

Philips Semiconductors
±1 °C accurate, SMBus-compatible, 8-pin, remote/local
digital temperature sensor with over temperature alarms
Product data sheet
SA56004X
T_CRIT output
The T_CRIT output is LOW when any temperature reading is
greater than the preset limit in the corresponding critical temperature
setpoint register. When one of the T_CRIT setpoint temperatures is
exceeded, the appropriate status register bit, 1 (RCRIT) or 0
(LCRIT), is set.
After every local and remote temperature conversion the Status
register flags and the T_CRIT output are updated. Figure 15 is a
timing diagram showing the relationship of T_CRIT output, Status
bit 1 (RCRIT) and the remote critical temperature setpoint (RCS),
and critical temperature hysteresis (TH) with remote temperature
changes. Note that the T_CRIT output is de-activated only after the
remote temperature is below the remote temperature setpoint, RCS
minus the Hysteresis, TH. In the interrupt mode only, the Status
register flags are reset after the Status register is read.
RCS
RCS - TH
Remote Temperature
Status Bit 1, RCRIT
T_CRIT Output
A
BC
SL02058
Figure 15. T_CRIT temperature response timing diagram
Event A: T_CRIT goes LOW and Status bit 1, RCRIT is set HIGH
when Remote Temperature exceeds RCS, Remote T_CRIT
Setpoint.
Event B: Remote Temperature goes below RCS-TH. T_CRIT is
deactivated, but Status Register remains unchanged.
Event C: The Status Register Bit 1, RCRIT is reset by a read of the
Status Register (in the interrupt mode).
Fault Queue
To suppress erroneous ALERT or T_CRIT triggering, the SA56004X
implements a Fault Queue for both local and remote channel. The
Fault Queue insures a temperature measurement is genuinely
beyond a HIGH, LOW or T_CRIT setpoint by not triggering until
three consecutive out-of-limit measurements have been made. The
fault queue defaults off upon POR and may be activated by setting
bit 0 in the Configuration register (address 09h) to ‘1’.
RCS
RCS -TH
Remote HIGH
Setpoint
Remote
Temperature
Remote LOW
Setpoint
ALERT Output
T_CRIT Output
Events A
B
C
DE F G
H
I
SL02059
NOTE: All events indicate the completion of a conversion.
Figure 16. Fault Queue Remote High and Low and T_CRIT,
T_CRIT Hysteresis setpoint response (Comparator mode)
At Event A: The remote temperature has exceeded the Remote
HIGH setpoint.
At Event B: Three consecutive over limit measurements have been
made exceeding the Remote HIGH setpoint; the ALERT output is
activated (goes LOW).
By now, the remote temp has exceeded the Remote T_CRIT
setpoint (RCS).
At Event C: Three consecutive over limit measurements have been
made exceeding RCS; the T_CRIT output is activated (goes LOW).
At Event D: The remote temperature falls below the RCS–TH
setpoint.
At Event E: The ALERT output is de-activated (goes HIGH) after a
below_high_limit temperature measurement is completed.
At Event F: Three consecutive measurements have been made
with the remote temperature below the RCS–TH threshold; the
T_CRIT output is de-activated (goes HIGH).
At Event G: The remote temp falls below the Remote LOW setpoint.
At Event H: Three consecutive measurements are made with the
temp below the Remote LOW setpoint; ALERT output is activated
(goes LOW).
At Event I: The ALERT output is de-activated (goes HIGH) after a
above_low_limit temperature measurement is completed.
2004 Oct 06
16