NE1617A データシートの表示（PDF） - Philips Electronics
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NE1617A Datasheet PDF : 17 Pages
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Philips Semiconductors
Temperature monitor for microprocessor systems
Product data sheet
NE1617A
Power-up default condition
Upon power-up reset (power is switched off-on), the NE1617A goes
into this default condition:
– Interrupt latch is cleared, the ALERT output is pulled HIGH by the
external pull-up resistor.
– The auto-conversion rate is at 0.25 Hz; conversion rate data is
02H.
– Temperature limits for both channels are +127 °C for high limit,
and –55 °C for low limit.
– Command pointer register is set to 00 for quickly reading the RIT.
Fault detection
The NE1617A has a fault detector to the diode connection. The
connection is checked when a conversion is initiated and the proper
flags are set if the fault condition has occurred.
D+ & D–
Opened
Shorted
ALERT
OUTPUT
Low
Low
RET DATA
STORAGE
127 °C
127 °C
STATUS SET
FLAG
B2 and B4
B4
SMBus interface
The device can communicate over a standard 2-wire serial interface
System Management Bus (SMBus) using the device pins SCLK and
SDATA. The device employs four standard SMBus protocols:
Write Byte, Read Byte, Send Byte and Receive Byte. Data formats
of those protocols are shown in Table 8 with following notifications:
– The SMBus master initiates data transfer by establishing a start
condition (S) and terminates data transfer by generating a stop
condition (P).
– Data is sent over the serial bus in sequence of 9 clock pulses
according to each 8-bit data byte followed by 1-bit status of the
device acknowledgement.
– The 7-bit slave address is equivalent to the selected address of
the device.
– The command byte is equivalent to the selected command of the
device register
– The send byte format is often used for the one-shot conversion
command.
– The receive byte format is used for quicker transfer data from a
device reading register which was previously selected by a read
byte format.
Table 8. SMBus programming format
Write byte format (for writing data byte to the device register):
S ADDRESS
WR
ACK COMMAND ACK
DATA
ACK P
7 bits
1 bit = 0 by
8 bits
by
8 bits
by
device address
device device register device to register device
Read byte format (for reading data byte from the device register):
S ADDRESS
WR
ACK COMMAND ACK
7 bits
1 bit = 0 by
8 bits
by
device address
device device register device
S ADDRESS
RD
ACK
7 bits
1 bit = 1 by
device address
device
DATA
8 bits
from
register
Send byte format (for sending command without data, such as one-shot command):
S ADDRESS
WR
ACK COMMAND ACK P
7 bits
1 bit = 0 by
8 bits
by
device address
device device register device
Receive byte format (for continuously reading from device register):
S ADDRESS
RD
ACK
DATA
NACK P
7 bits
1 bit = 1 by
8 bits
by
device address
device from register controller
NOTES:
S = Start condition
P = Stop condition
ACK = Acknowledged
NACK = Not acknowledged
NACK P
by
controller
2004 Oct 05
13
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