SA56004X Datasheet, PDF (14/23 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
Programmable offset register (remote only)
Table 12. Remote Temperature Offset registers
(RTOHB and RTOLB)
High Byte (Read/Write address 11h)
Bit D7 D6 D5 D4 D3 D2 D1 D0
Value Sign 64 32 16 8
4
2
1
POR default RTOHB = RTOLB = 00h.
Low Byte (Read/Write address 12h)
Bit D7 D6 D5 D4 D3 D2 D1 D0
Value 0.5 0.25 0.125 0
0
0
0
0
POR default RTOLB = 00h.
ALERT mode register
Table 13. ALERT mode register (AM)
(Read and Write address BFh)
Bit D7 D6 D5 D4 D3 D2 D1
D0
Value 0 0 0 0 0 0 0 ALERT mode
D7-D1: is not defined and defaults to ‘0’.
D0: The ALERT output is in Interrupt mode when this bit is LOW.
The ALERT output is in comparator mode when this bit is HIGH.
Other registers
The Manufacturers ID register has a default value A1h (1010 0001)
and a read address FEh.
The Die Revision Code register has a default value 00h
(0000 0000) and read address FFh. This register will increment by 1
every time there is a revision to the die.
One-shot register
The one-shot register is used to initiate a single conversion and
comparison cycle when the device is in the standby mode; upon
completion of the single conversion cycle the device returns to the
standby mode. It is not a data register; it is the write operation that
causes the one-shot conversion. The data written to this register is
not stored; a FF value will always be read from this register. To
initiate an one-shot operation, send a standard write command with
the command byte of 0Fh (One-Shot Write Address).
INTERRUPTION LOGIC
FUNCTIONAL DESCRIPTION
ALERT output
The ALERT output is used to signal Alert interruptions from the
device to the SMBus or other system interrupt handler and it is
active LOW. Because this is an open drain output, a pull-up resistor
(typically 10 kΩ) to V_DD is required. Several slave devices can share
a common interrupt line on the same SMBus.
The ALERT function is very versatile and accommodates three
separate operating modes: 1) a temperature comparator, 2) a
system interrupt based on temperature, and 3) an SMBus Alert
Response Address (ARA) response. The ARA and interrupt modes
are different only in how the user interacts with the SA56004X.
At the end of every temperature reading, digital comparators
determine if the readings are above the HIGH or T_CRIT setpoint or
below the LOW setpoint register values. If so, the corresponding bit
in the Status register is set. If the ALERT mask bit 7 of the
Configuration register is not HIGH, then, any bit set in the Status
register, other than the BUSY (D7) and OPEN (D2), will cause the
ALERT output pin to be active-LOW. An alert will be triggered after
any conversion cycle that finds the temperature is out of the limits
defined by the setpoint registers. In order to trigger an ALERT in all
alert modes, the ALERT mask bit 7 of the Configuration register
must be cleared (not HIGH).
ALERT output in Comparator Mode
When operating the SA56004X in a system that utilizes a SMBus
controller not having an interrupt, the ALERT output may be
operated as a temperature comparator. In this mode, when the
condition that triggered the ALERT to be asserted is no longer
present, the ALERT output is released as it goes HIGH. In order to
use the ALERT output as a temperature comparator, bit D0, the
ALERT configure bit, in the ALERT Mode (AM) register must be set
HIGH. This is not the POR default.
ALERT output in Interrupt Mode
In the interrupt mode, the ALERT output is used to provide an
interrupt signal that remains asserted until the interrupt service
routine has elapsed. In the interrupt operating mode, a read of the
Status register will set the ALERT mask bit 7 of the Configuration
register if any of the temperature alarm bits of the status register is
set with exception of BUSY (D7) and OPEN (D2). This protocol
prevents further ALERT output triggering until the master device has
reset the ALERT mask bit at the end of the interrupt service routine.
The Status register bits are cleared only upon a read of the status
register by the serial bus master (See Figure 13). In order for the
ALERT output to be used as an interrupt, the ALERT Configure bit
D0 of the ALERT Mode (AM) register must be set LOW. Note, this is
the POR default.
Remote Temp
High Limit
Remote
Diode Temp
SA56004–X
ALERT pin
Status Register
Bit 4(RHIGH)
A
B,C
D
E, F
SR02502
Figure 13. ALERT output in Interrupt Mode
The following events summarizes the ALERT output interrupt mode
of operation:
Event A: Master senses ALERT output being active-LOW.
Event B: Master reads the SA56004X Status register to determine
what cause the ALERT interrupt.
Event C: SA56004X clears the Status register, resets the ALERT
output HIGH, and sets the ALERT mask bit 7 in the Configuration
register.
Event D: A new conversion result indicates the temperature is still
above the high limit, however the ALERT pin is not activated due to
the ALERT mask.
2004 Oct 06
14