ne1618 NXP Semiconductors, ne1618 Datasheet - Page 8

• Manufacturer Part Number: ne1618
• Description: Temperature Monitor For Microprocessor Systems
• Manufacturer: NXP Semiconductors

During the POR state of the device, the on-board A-to-D converter is
Philips Semiconductors
Table 2. Register assignments
Power-on reset (POR)
When the power is applied to the NE1618 while the device STDBY
input pin is at low state, the device will enter into its power–on reset
state and its registers are reset to their default values as shown in
the Table 2 resulting in:
Notice that the content of the register that has indeterminate default
value will be unknown.
disabled and the measurement function of the device is inactive.
However, the SMBus interface is alive to bus communication
meaning that reading and writing the registers can be performed. If
there is no SMBus activity then the device will draw a small power
supply current less than 10 A. Writing temp limits into the limits
registers if needed should usually be performed at this stage.
Starting conversion
Upon POR, if the STDBY input pin is set to HIGH while the
RUN/STOP bit 6 of the configuration register is equal to zero as
default, then the device will enter into its free-running operation
mode in which the device A-to-D converter is enabled and the
2002 Jan 04
REGISTER NAME
RDID
RDRV
RIT
RET
REET
RS
RC
RCR
RIHL
RILL
REHL
RELL
WC
WCR
WIHL
WILL
WEHL
WELL
OSHT
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
Interrupt latch is cleared, the ALERT output driver is off and the
ALERT pin is pulled to HIGH by an external pull-up resister.
The conversion rate is set to the default value of about 0.2 Hz
Temp limits for both channels are +127 C for high limit and
–55 C for low limit.
Register pointer is set to 00 for ready to reading the RIT data.
Temperature monitor for microprocessor systems
COMMAND BYTE
FEH
FFH
00H
01H
10H
02H
03H
04H
05H
06H
07H
08H
09H
0AH
0BH
0Ch
0Dh
0Eh
0Fh
11H
12H
13H
14H
15H
POR STATE
N/A
N/A
0000 0000
0000 0000
0000 0000
N/A
0000 0000
0000 0010
0111 1111
1100 1001
0111 1111
1100 1001
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
8
order to set the flags and interruption accordingly at the end of every
current is reduced to less than 10 a if there is no SMBus activity, all
data in the device registers are retained. However, the SMBus is still
measurement function is activated. In this mode, the device cycles
the measurements of local temp and remote temp automatically and
periodically. The conversion period is defined by the programmable
conversion rate stored in the conversion register. It also performs
comparisons between readings and limits of the temperature in
conversion. Measured values are stored in the temp registers,
results of limit comparisons are reflected by the status of the flag
bits in the status register and interruption is reflected by the logical
level of the ALERT output pin. Temp and status data can be read at
any time. Temp limit values should be written into the limit registers
before starting conversion to avoid false conditions of the status.
Low power standby modes
The device can be put into one of the two standby modes from the
free-running state at any time: hardware standby mode by setting
the STDBY input pin to LOW, or software standby mode by setting
the RUN/STOP bit 6 of the configuration register to 1. In either
standby mode, the free-running operation is stopped, the supply
active and reading or writing registers can still be performed. The
main difference between the two standby modes is related to the
activation of the A-to-D conversion: data conversion can be
activated in the software standby mode but not in the hardware
standby mode. In software standby mode, an one-shot command
will initiate a single conversion which has the same effect in
comparing with any conversion that occurs when the device is in its
FUNCTION
Read device ID
Read device revision
Read internal or local temp
Read external or remote temp
Read extended external temp
Read status
Read configuration
Read conversion rate
Read internal temp HIGH limit
Read internal tem low limit
Read external temp HIGH limit
Read external temp LOW limit
Write configuration
Write conversion rate
Write internal temp HIGH limit
Write internal temp LOW limit
Write external temp HIGH limit
Write external temp LOW limit
One shot command
Reserved
Reserved
Reserved
Reserved
Reserved
NE1618
Product data