Document Outline
- FEATURES
- APPLICATIONS
- DESCRIPTION
- PIN CONFIGURATION
- PIN DESCRIPTION
- ORDERING INFORMATION
- FUNCTIONAL BLOCK DIAGRAM
- TYPICAL OPERATING CIRCUIT
- ABSOLUTE MAXIMUM RATINGS
- ELECTRICAL CHARACTERISTICS
- SMBus INTERFACE AC SPECIFICATIONS
- FUNCTIONAL DESCRIPTION
- PC BOARD LAYOUT CONSIDERATION
- Data sheet status
- Definitions
- Disclaimers
Philips
Semiconductors
NE1618
Temperature monitor for
microprocessor systems
Product data
Supersedes data of 2001 Oct 03
File under Integrated Circuits, IC11 Handbook
2002 Jan 04
INTEGRATED CIRCUITS
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2
2002 Jan 04
8532299 27510
FEATURES
Monitors local and remote temperature
Accuracy
2
C local (on-chip) sensor
1.5
C remote sensor with 1
C resolution
1.0
C remote sensor with 0.125
C resolution
No calibration required
Programmable over/under temperature alarm
SMBus 2-wire serial interface
3 V to 3.6 V supply range
80
A supply current in operating mode
3
A (typical) supply current in standby mode
Small 16-lead QSOP package
APPLICATIONS
Desktop computers
Notebook computers
Smart battery packs
Industrial controllers
Telecom equipment
DESCRIPTION
The NE1618 is an accurate two-channel temperature monitor. It
measures the temperature of itself and the temperature of a remote
sensor. It can replace the NE1617 for a more precise measurement
to the remote temperature when it operates in extended mode. The
remote sensor is a diode connected transistor being in the form of
either a discrete NPN/PNP, such as the 2N3904/2N3906, or a diode
connected PNP built into another die, such as is done on some
INTEL microprocessors.
The temperature of both the remote and local sensors are stored in
the registers that can be read via a 2-wire SMBus. The data in the
temp reading registers are updated at the end of every data
conversion when the conversion is enable. At all time, data
conversion is initiated automatically in the rate defined by the
programmable data in the conversion rate register. However, a
conversion can be forced to occur immediately by a one-shot
programming.
The local temp is always measured with a resolution of 1.0
C but
the remote temp can be measured in either one of two modes:
extended mode with a resolution of 0.125
C and basic mode with a
resolution of 1.0
C. The mode is set up automatically according to
the programmable data stored in the conversion rate register. (See
Table 6). Extended mode is set when the conversion rate is slow
(rate 0.7 Hz or less) and normal mode is set when the rate is high
(conversion rate of 2, 4, or 8 Hz).
There is also an alarm that senses either an over or under
temperature condition. The trip points for this alarm are also
programmable. The device can have 1 of 9 addresses (determined
by 2 address pins), so there can be up to 9 of the NE1618 on the
SMBus. It can also be put in a standby mode (in order to save
power). This can be done either with software (over the SMBus) or
with hardware (using the STBY pin).
PIN CONFIGURATION
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
TEST1
V
DD
D+
D
TEST5
ADD1
GND
GND
TEST16
STBY
SCLK
TEST13
SDATA
ALERT
ADD0
TEST9
SL01238
NE1618
Figure 1. Pin configuration
PIN DESCRIPTION
PIN #
FUNCTION
DESCRIPTION/COMMENTS
1
TEST1
Factory use only
1
2
V
DD
Positive supply
2
3
D+
Positive side of remote sensor
4
D
Negative side of remote sensor
5
TEST5
Factory use only
1
6
ADD1
Device address pin (3-State)
7
GND
Ground
8
GND
Ground
9
TEST9
Factory use only
1
10
ADD0
Device address pin (3-State)
11
ALERT
Open drain output used as
interrupt or SMBus alert
12
SDATA
SMBus serial data input/output
open drain
13
TEST13
Factory use only
1
14
SCLK
SMBus clock input
15
STBY
Hardware standby input pin
HIGH = normal operating mode
LOW = standby mode
16
TEST16
Factory use only
1
NOTES:
1. These pins should either floating or be tied to ground.
2. V
DD
pin should be decoupled by a 0.1
F capacitor.
ORDERING INFORMATION
PART NUMBER
PACKAGE
DRAWING NUMBER
NE1618DS
16-lead QSOP package
1
SOT5191
NOTE:
1. Also called "SSOP16".
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
3
FUNCTIONAL BLOCK DIAGRAM
COMMAND POINTER
REGISTER
LOCAL TEMP HIGH
LIMIT REGISTER
LOCAL TEMP LOW
LIMIT REGISTER
REMOTE TEMP HIGH
LIMIT REGISTER
REMOTE TEMP LOW
LIMIT REGISTER
CONFIGURATION
REGISTER
LOCAL TEMP HIGH
THRESHOLD
LOCAL LOW TEMP
THRESHOLD
REMOTE HIGH TEMP
THRESHOLD
REMOTE LOW TEMP
THRESHOLD
STATUS REGISTER
SMBUS INTERFACE
ONE-SHOT
REGISTER
CONVERSION RATE
REGISTER
LOCAL TEMP
DATA REGISTER
REMOTE TEMP
DATA REGISTER
ADDRESS
DECODER
INTERRUPT
MASKING
A-TO-D
CONVERTER
CONTROL
LOGIC
LOCAL TEMP
SENSOR
ANALOG
MUX
ALERT
ADD0
ADD1
D
D+
STDBY
SCLK
SDATA
TEST16
TEST13
TEST9
TEST5
TEST1
GND
GND
V
DD
SL01236
DEVICE ID
DEVICE REV
EXTENDED TEMP
REGISTER
Figure 2. Functional block diagram.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
4
TYPICAL OPERATING CIRCUIT
SL01237
2
15
14
12
11
10
6
7
8
SHIELDED
TWISTED PAIR
(NOTE 1)
REMOTE SENSOR
3
4
C
1
(NOTE 2)
0.1
F
V
DD
CLOCK
DATA
MICROCONTROLLER
INTERRUPT
R
10 k
NE1618
R
10 k
R
10 k
NOTES:
1. May be required if remote diode is in a noisy environment and/or several feet from the NE1618.
2. May be required in noisy environment. Up to 2200 pF may be used.
Figure 3. Typical operating circuit.
ABSOLUTE MAXIMUM RATINGS
PARAMETER
MIN.
MAX.
UNIT
V
DD
to GND
0.3
+6
V
D+, ADD0, ADD1
0.3
V
DD
+0.3
V
D to GND
0.3
+0.8
V
SCLK, SDATA, ALERT, STBY
0.3
+6
V
Input current SDATA
1
+50
mA
D current
1
mA
ESD
Human Body Model
2000
V
Machine Model
200
V
Operating temperature range
0
+120
C
Maximum junction temperature
+150
C
Storage temperature range
65
+150
C
NOTE:
1. This is a stress rating only. Functional operation of the device as indicated in the operational section is not applied to this absolute maximum
rating. Stress above those listed in "Absolute maximum ratings" may cause permanent damage to the device, and exposure to any of these
rating conditions for extended periods may affect device reliability.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
5
ELECTRICAL CHARACTERISTICS
V
DD
= 3.3 V; T
amb
= 5
C to +120
C; unless otherwise noted.
PARAMETER
CONDITIONS
LIMITS
UNIT
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Temperature resolution
1
C
Local temperature error
T
amb
= +60
C to +100
C
V
DD
= 3.3 V
0.75
1.5
C
V
DD
= 5.0 V
1
1.25
2.0
C
T
amb
= 0
C to +120
C
V
DD
= 3.3 V
2.0
3.0
C
V
DD
= 5.0 V
1
2.5
3.5
C
Remote temperature error
(1 C
l i
)
T
remote
= +60
C to +100
C
V
DD
= 3.3 V
3.0
C
(1
C resolution)
V
DD
= 5.0 V
1
3.5
C
T
remote
= 0
C to +120
C
V
DD
= 3.3 V
5.0
C
V
DD
= 5.0 V
1
5.5
C
Extended Remote temp error
(0 12
C
l i
)
T
remote
= +70
C to +100
C
V
DD
= 3.3 V
1.0
C
(0.125
C resolution)
V
DD
= 5.0 V
1
1.5
C
T
remote
= 0
C to +120
C
V
DD
= 3.3 V
3.0
C
V
DD
= 5.0 V
1
3.5
C
Extended relative temp error
2
(0 12
C
l i
)
T
remote
= +70
C to +100
C
V
DD
= 3.3 V
0.25
C
(0.125
C resolution)
V
DD
= 5.0 V
1
0.75
C
T
remote
= 0
C to +120
C
V
DD
= 3.3 V
0.50
C
V
DD
= 5.0 V
1
1.0
C
Under voltage lockout
3
V
DD
input disables A/D conversion
4
2.1
2.95
V
Power-on reset threshold
V
DD
input falling edge
5
1.0
2.5
V
Power supply current (average)
Conversion data = 02h
80
160
A
Conversion data = 05h
100
270
A
Power supply current (standby)
SMBus inactive
3
10
A
Conversion time (busy duration)
Basic measurement
150
ms
Extended measurement
750
ms
Conversion rate error
Percentage error in programmed rate > 1 Hz
6
30
+30
%
Remote sensor source current
HIGH level
100
A
LOW level
10
A
Address pin bias current
Momentary as the address is being read
7,8
50
A
NOTES:
1. The NE1618 is optimized for 3.3 V
DD
operation. The listed accuracy limits for 5 V
DD
operation are guaranteed by design and 100% QA
sample tested in production.
2. Guaranteed by design.
3. Definition of Under Voltage Lockout (UVL): The value of V
DD
below which the internal A/D converter is disabled. This is designed to be a
minimum of 200 mV above the power-on reset. During the time that it is disabled, the temperature that is in the "read temperature registers"
will remain at the value that it was before the A/D was disabled. This is done to eliminate the possibility of reading unexpected false
temperatures due to the A/D converter not working correctly due to low voltage. In case of power-up (rising V
DD
), the reading that is stored
in the "read temperature registers" will be the default value of 0
C. V
DD
will rise to the value of UVL, at which point the A/D will function
correctly and normal temperatures will be read.
4. V
DD
(rising edge) voltage below which the ADC is disabled.
5. V
DD
(falling edge) voltage below which the logic is reset.
6. For conversion rate
1 Hz, extended measurement requires about 400 ms more for conversion.
7. Address is read at power-up and at start of conversion for all conversions except the fastest rate.
8. Due to the bias current, any pull-up/down resistors should be
2 k
.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
6
SMBus INTERFACE AC SPECIFICATIONS
V
DD
= 3.0 V to 3.6 V; T
amb
= 0
C to +125
C unless otherwise noted.
These specifications are guaranteed by design and not tested in production.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
V
IH
Logic input high voltage for STBY, SCLK, SDATA
V
DD
= 3 V to 5.5 V
2.2
V
V
IL
Logic input low voltage for STBY, SCLK, SDATA
V
DD
= 3 V to 5.5 V
0.8
V
I
OL
Logic output low sink current for
ALERT
SDATA
V
OL
= 0.4 V
V
OL
= 0.6 V
1.0
6.0
mA
mA
I
IH
& I
IL
Logic input current
V
IN
= V
DD
or GND
1.0
1.0
A
C
IN
SMBus input capacitance for SCLK, SDATA
5
pF
f
SCLK
SCLK operating frequency
See Figure 4
0
100
kHz
t
LOW
SCLK low time
See Figure 4
4.7
5.0
s
t
HIGH
SCLK high time
See Figure 4
4.0
5.0
s
t
BUF
SMBus free time.
Delay from SDA stop to SDA start
See Figure 4
4.7
s
t
HD:STA
Hold time of start condition.
Delay from SDA start to first SCL HL
See Figure 4
4.0
s
t
HD:DAT
Hold time of data.
Delay from SCL HL to SDA edges
See Figure 4
0
ns
t
SU:DAT
set-up time of data.
Delay from SDA edges to SCL LH
See Figure 4
250
ns
t
SU:STA
set-up time of repeat start condition.
Delay from SCL LH to restart SDA
See Figure 4
250
ns
t
SU:STO
set-up time of stop condition.
Delay from SCL LH to SDA stop.
See Figure 4
4.0
s
t
F
Fall time of SCL and SDA
See Figure 4
1.0
s
t
BUF
P
S
SCLK
SDATA
SL01204
t
HD:STA
S
P
t
LOW
t
R
t
F
t
HD:STA
t
HD:DAT
t
HIGH
t
SU:DAT
t
SU:STA
t
SU:STO
Figure 4. Timing measurements.
NOTE:
The NE1618 does not include the SMBus timeout capability (t
LOW:SEXT
and t
LOW:MEXT
).
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
7
FUNCTIONAL DESCRIPTION
Serial bus interface
The NE1618 can be connected to a compatible 2-wire serial
interface System Management Bus (SMBus) as a slave device
under the control of a master device, using two device terminals
SCLK and SDATA. The controller will provide a clock signal to the
device SCLK pin and write/read data to/from the device through the
device SDATA pin. External pull-up resistors, about 10 k
each,
are needed for these two terminals due to the open drain circuitry.
Data of 8-bit digital byte or word are used for communication
between the controller and the device using SMBus protocols which
will be described more in the SMBus interface section. The
operation of the device to the bus is described with details in the
following sections.
Slave address
The 7-bit address data of the NE1618 on the bus is defined by
three-level logical connections applied to the device address pins
ADD0 and ADD1. They are either opened or connected directly to
the GND or V
DD
with the use of a resistor which value should be
equal to or less than 2 k
. The selectable addresses are listed in
Table 1. Any one of those nine combinations can be used for any
device and more than one devices can reside on the same bus
without conflict. Notice that because the state of the device address
pins is sampled and latched not only at the power-up step but also
at starting point of every conversion, the address connections must
be permanently existent.
Table 1. Device slave address
ADD0 pin
ADD1 pin
7-BIT ADDRESS DATA
GND
GND
0011 000
GND
NC
0011 001
GND
V
DD
0011 010
NC
GND
0101 001
NC
NC
0101 010
NC
V
DD
0101 011
V
DD
GND
1001 100
V
DD
NC
1001 101
V
DD
V
DD
1001 110
1. NC = Not Connected.
Registers
The NE1618 contains a number of registers which names,
commands, power-on reset (POR) status and functions are listed in
Table 2. It includes:
Configuration register to provide control and configuration the
NE1618
Status register to provide the flags resulting from temp limit
comparisons
Measuring and limits temp registers
ID and test registers
The registers are used to store either programmable data for setting
device operation or resultant data from device measurement. Data
are stored in registers by 8-bit digital byte, either in 2's complement
format for temperature-related data or in straight format for others.
The register command byte is used to addressing the register in
SMBus communication. Writing and reading registers will be
performed on the SMBus by a controller. The registers are divided
into two groups: only-read registers named with a prefix of R and
only-write registers named with a prefix of W (including the
one-shot register OSHT). You should write programmable data to
the only-write registers and read data from the only-read registers.
Attempting to write to any R register or read from any W register
will produce an invalid result: the writing data would be ignored, the
reading data would be equal to FFh. Some of registers are in pair
representing a same item for different bus operations: read and
write, for example, RC and WC are related to the device
configuration, one for reading and the other for writing.
The reserved registers are used only at the manufacturer for test
purposes.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
8
Table 2. Register assignments
REGISTER NAME
COMMAND BYTE
POR STATE
FUNCTION
RDID
FEH
N/A
Read device ID
RDRV
FFH
N/A
Read device revision
RIT
00H
0000 0000
Read internal or local temp
RET
01H
0000 0000
Read external or remote temp
REET
10H
0000 0000
Read extended external temp
RS
02H
N/A
Read status
RC
03H
0000 0000
Read configuration
RCR
04H
0000 0010
Read conversion rate
RIHL
05H
0111 1111
Read internal temp HIGH limit
RILL
06H
1100 1001
Read internal tem low limit
REHL
07H
0111 1111
Read external temp HIGH limit
RELL
08H
1100 1001
Read external temp LOW limit
WC
09H
N/A
Write configuration
WCR
0AH
N/A
Write conversion rate
WIHL
0BH
N/A
Write internal temp HIGH limit
WILL
0Ch
N/A
Write internal temp LOW limit
WEHL
0Dh
N/A
Write external temp HIGH limit
WELL
0Eh
N/A
Write external temp LOW limit
OSHT
0Fh
N/A
One shot command
RESERVED
11H
N/A
Reserved
RESERVED
12H
N/A
Reserved
RESERVED
13H
N/A
Reserved
RESERVED
14H
N/A
Reserved
RESERVED
15H
N/A
Reserved
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 poweron reset
state and its registers are reset to their default values as shown in
the Table 2 resulting in:
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.
Notice that the content of the register that has indeterminate default
value will be unknown.
During the POR state of the device, the on-board A-to-D converter is
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
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
order to set the flags and interruption accordingly at the end of every
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
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
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
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
9
free-running mode. In hardware standby mode, the A-to-D converter
is disabled and conversion operation is inhibited.
Notice that if a hardware standby command is received when the
device is in free-running mode with a conversion is in progress, the
conversion cycle will stop and the register data will not be updated.
Temperature measurement
The NE1618 contains an on-chip temp sensor for measuring the
local or internal temperature and provides input pins D+ and D for
connecting to a remote temp sensor in order to measure the remote
or external temperature. The remote sensor should be a diode-type
sensor and must be connected to the D+ and D pins properly:
anode to the D+ and cathode to the D.
The method of temp measurement is based on the difference of the
diode VBE at two operating current levels given by:
VBE = (KT/q)*LN(N)
where:
K: Boltzman's constant
T: absolute temperature in
K
q: electron charge
LN: natural logarithm
N: ratio of the two operating currents
Because, in measuring the remote diode VBE, the NE1618 provides
two current sources of about 10
A and 100
A and the sensed
voltage between two pins D+ and D is limited within 0.25 V and
0.95 V, the external diode should be selected to meet these current
and voltage requirements. The diode-connected PNP transistor
provided on the Pentium series microprocessor is typically used, or
the discrete diode-connected low-power transistor 2N3904 is
recommended.
When the temperature is measured, local and remote, the
VBE is
converted into digital data by the on-chip sigma-delta A-to-D
converter. The results are stored in the three temp registers (RIT,
RET and REET) and also compared with the limits stored in the
temp limits registers in order to set accordingly the flag bits in the
status register and to generate interruption if any fault condition
occurs. The content of temp registers are updated upon completion
of every conversion and they can be read at any time.
In the addition of providing the basic measurement with a resolution
of 1
C, the NE1618 includes the extended measurement for the
remote temp with a resolution 0.125
C. The extended measurement
can be used in enhanced application for monitoring precisely the die
temp of integrated circuits. Because the extended measurement is
corporate with an on-board 11-bit A-to-D converter, the resulted data
is an 11-bit digital number which is divided into two groups for
storing into two registers RET and REET. The group of eight MSB
bits of the data is stored in the RET register and the group of three
LSB bits of the data is stored in the REET register in its MSB
positions. Therefore, the data of those two registers must be
correctly combined to get the extended remote temp data.
When the device is in basic measuring mode (by setting the
conversion rate data higher than 04h) the A-to-D converter uses
only 8 bits for the conversion, the REET content is cleared. Only the
8-bit data stored in the RET with resolution of 1
C is significant for
the remote temperature.
Notice that the extended measurement only works if the device is in
its free-running operation mode. It does not work when the device is
in its standby mode and the conversion is activated by a one-shot
command. A one-shot command will produce the same result as of
basic measurement instead of the extended measurement even
though the slow conversion rate has been selected.
Temperature data format
For local temp measurement, because the extended mode has no
effect to the measurement, the resulted temp value can be integer
number which is equivalent to the 2's complement value of the 8-bit
byte data of the RIT register with 1
C resolution as shown in
Table 3.
For remote temp measurement, the resulted temp value can be a
floating number which is made up by two parts: the integer portion is
derived from the RET data using data format as shown in Table 3
and the decimal or extended portion is derived from the REET data
using data format as shown in Table 4. Notice that when the device
is in basic measurement mode (by setting the conversion data more
than 04h) the extended portion is always equal to 0 and the resulted
data is only the one which is derived from RET register with 1
C
resolution.
Table 3. Temperature data format (RIT & RET)
TEMPERATURE (
C)
8-BIT DIGITAL DATA
+127
0 111 1111
+126
0 111 1110
+100
0 110 0100
+50
0 011 0010
+25
0 001 1001
+1
0 000 0001
0
0 000 0000
Table 4. Extended data format (REET)
TEMPERATURE (
C)
8-BIT DIGITAL DATA
0.000
0000 0000
0.125
0010 0000
0.250
0100 0000
0.375
0110 0000
0.500
1000 0000
0.625
1010 0000
0.750
1100 0000
0.875
1110 0000
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
10
Configuration register
The configuration register is used to mask the Alert interrupt and/or
to put the device in software standby mode. Only two bits 6 and 7 of
this register are used as listed in Table 5. Bit 7 is used to mask the
device ALERT output from Alert interruption when this bit is set to 1,
and bit 6 is used to activate the standby software mode when this bit
is set to to 1.
This register can be written or read using the commands of registers
named WC and RC accordingly. Upon power-on reset (POR), both
bits are reset to zero.
Table 5. Configuration register bit assignments
BIT
NAME
POR
STATE
FUNCTION
7 (MSB)
MASK
0
Mask ALERT interrupt:
Interrupt is enabled when
this bit is LOW, and disabled
when this bit is HIGH.
6
RUN/STOP
0
Standby or run mode
control:
When LOW, running mode is
enabled. When HIGH,
standby mode is initiated.
5 to 0
RESERVED
n/a
n/a
Conversion rate register
The conversion rate register is used to store programmable
conversion data, which defines the time interval between
conversions in standard free-running auto-convert mode. Table 6
shows all applicable data and rates for the device. Only three LSB
bits of the register are used and other bits are reserved for future
use. This register can be written to and read back over the SMBus
using commands of the registers named WCR and RCR
respectively. The POR default conversion data is 02h.
Because of the timing asynchronization, when changing the
conversion rate from fast to slow, or vice versa, you may get an
invalid data for the external temp reading, and an Alert interruption
as well. Therefore, caution must be taken when doing a change of
conversion rate. Changing conversion should be done in one of the
following ways:
1. Apply this sequential operation:
a. Put the device into its standby mode (by setting bit6 of the
WC register).
b. Wait at least 750 ms (to ensure the current conversion if
there is one to be completed).
c. Change the conversion rate (by writing the conversion data
into the WCR register).
d. Put the device back into its normal mode (by clearing bit6 of
the WC register).
2. Writing the conversion data to the conversion register WCR
when the busy bit is off. The busy bit can be monitored by
reading the Status Register (SR) bit 7.
We suggest that method "1." is preferred because it will provide the
correct temp data in a defined time. Releasing the device from
shutdown mode by clearing bit6 of the WC register also initiates a
new conversion, and all the register data will be updated at the end
of the conversion in 750 ms (max.) for slow rate, and 170 ms for fast
rate.
The device will be automatically put into the extended measurement
mode when the conversion rate data is less than or equal to 04h.
Otherwise, it will be in basic measurement mode for the remote
temp.
Notice that the average supply current, as well as the device power
consumption, is increased with the conversion rate.
Table 6. Conversion rate control byte
DATA
CONVERSION
RATE (Hz)
AVERAGE
SUPPLY CURRENT
(
A Typ. @ V
DD
= 3.3 V)
00h
0.06
TBD
01h
0.12
TBD
02h
0.22
TBD
03h
0.40
TBD
04h
0.70
TBD
05h
2
TBD
06h
4
TBD
07h
8
TBD
08h to FFh
Reserved
n/a
Temperature limit registers
The device has four registers to be used for storing programmable
temperature limits, including the high limit and the low limit for each
channel of the external and internal diodes. Data of the temperature
register (RIT and RET) for each channel are compared with the
contents of the temperature limit registers of the same channel,
resulting in alarm conditions. If measured temperature either equals
or exceeds the corresponding temperature limits, an Alert interrupt is
asserted and the corresponding flag bit in the status register is set.
The temperature limit registers can be written to and read back
using commands of registers named WIHL, WILL, WEHL, WELL,
RIHL, RILL, REHL, RELL accordingly. The POR default values are
+127
C (0111 1111) for the HIGH limit and 55
C (1100 1001) for
the LOW limit.
Notice that only the RET data is used in limit comparison and REET
data is ignored.
One-shot command
The one shot command is not actually a data register as such and a
write operation to it will initiate an ADC conversion. The send byte
format of the SMBus, as described later, with the use of OSHT
command (0Fh), is used for this writing operation. In normal
free-running-conversion operation mode of the device, a one-shot
command immediately forces a new conversion cycle to begin.
However, if a conversion is in progress when a one-shot command
is received, the command is ignored. In software standby mode, the
one-shot command generates a single conversion and comparison
cycle and then puts the device back in its standby mode after the
conversion. In hardware standby mode, the one shot is inhibited.
Notice that a one-shot command will clear the REET register and
set a basic measurement for that cycle.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
11
Status register
The content of the status register reflects condition status resulting
from all of these activities: comparisons between temperature
measurements and temperature limits, the status of ADC
conversion, and the hardware condition of the connection of external
diode to the device. Bit assignments and bit functions of this register
are listed in Table 7. This register can only be read using the
command of register named RS. Upon POR, the status of all flag
bits are reset to zero. The status byte is cleared by any successful
read of the status register unless the fault condition persists.
Notice that any one of the fault-conditions, except the conversion
busy, also introduces an Alert interrupt to the SMBus that will be
described in the following section. Also, whenever a one-shot
command is executed, the status byte should be read after the
conversion is completed, which is about 170 ms after the one-shot
command is sent.
Table 7. Status register bit assignment
BIT
NAME
POR
STATE
FUNCTION
7 (MSB)
BUSY
n/a
High when the ADC is busy
converting
6
IHLF*
0
High when the internal
temperature high limit has tripped
5
ILLF*
0
High when the internal
temperature low limit has tripped
4
EHLF*
0
High when the external
temperature high limit has tripped
3
ELLF*
0
High when the external
temperature low limit has tripped
2
OPEN*
SHORT
0
High when the external diode is
opened or shorted
1 to 0
n/a
0
Reserved
*
These flags stay high until the status register is read or POR is
activated.
Alert interrupt
The ALERT output is used to signal Alert interruption from the
device to the SMBus and is active low. Because this output is an
open-drain output, a pull-up resistor (10 k
typ.) to V
DD
is required,
and slave devices can share a common interrupt line on the same
SMBus. An Alert interrupt is asserted by the device whenever any
one of the fault conditions, as described in the Status register
section, occurs: measured temperature equals or exceeds
corresponding temp limits, the remote diode is physically
disconnected from the device pins. Alert interrupt signal is latched
and can only be cleared by reading the Alert Response byte from
the Alert Response Address which is a special slave address to the
SMBus. The ALERT output can not be reset by reading the device
status register. The device was designed to accommodate the Alert
interrupt detection capability of the SMBus.
Basically, the SMBus provides Alert response interrupt pointers in
order to identify the slave device which has caused the Alert
interrupt. The 7-bit Alert slave address is 0001 100 and the Alert
response byte reflects the slave address of the device which has
caused Alert interrupt. Bit assignments of the Alert response byte
are listed in Table 8. The ALERT output will be reset to HIGH state
upon reading the Alert response slave address unless the fault
condition persists.
Table 8. Alert response bit assignment
(Alert response address = 0001 100)
ALERT
RESPONSE
BIT
NAME
ADDRESS
BIT
FUNCTION
7 (MSB)
ADD7
Indicate address B6 of alerted device
6
ADD6
Indicate address B5 of alerted device
5
ADD5
Indicate address B4 of alerted device
4
ADD4
Indicate address B3 of alerted device
3
ADD3
Indicate address B2 of alerted device
2
ADD2
Indicate address B1 of alerted device
1
ADD1
Indicate address B0 of alerted device
0 (LSB)
1
Logic 1
Fault detection
The NE1618 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
ALERT
OUTPUT
RET DATA
STORAGE
STATUS SET
FLAG
Opened
Low
128
C
B2 & B3
Shorted
Low
128
C
B2 & B3
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 9 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 (A).
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.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
12
Table 9. SMBus Interface Protocols
SL01239
SMBus INTERFACE PROTOCOLS:
WRITE BYTE FORMAT (To write a data byte to the device register) :
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
(TO NEXT)
SDA
a6
a5
a4
a3
a2
a1
a0
D7
D6
D5
D4
D3
D2
D1
D0
(TO NEXT)
S
w
A
A
1
2
3
4
5
6
7
8
9
SCL
(CONT)
SDA
(CONT)
D7
D6
D5
D4
D3
D2
D1
D0
A
P
READ BYTE FORMAT (To read a data byte from the device register):
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
(TO NEXT)
SDA
a6
a5
a4
a3
a2
a1
a0
D7
D6
D5
D4
D3
D2
D1
D0
(TO NEXT)
S
W
A
A
P
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
(CONT)
SDA
(CONT)
a6
a5
a4
a3
a2
a1
a0
D7
D6
D5
D4
D3
D2
D1
D0
S
R
A
NA
P
RESTART
RECEIVE BYTE FORMAT (To read a data byte from already pointed register):
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
(CONT)
SDA
(CONT)
a6
a5
a4
a3
a2
a1
a0
D7
D6
D5
D4
D3
D2
D1
D0
S
R
A
NA
P
DEVICE ADDRESS
DATA FROM DEVICE REGISTER
DEVICE ADDRESS
DEVICE REGISTER COMMAND
DATA TO BE WRITTEN TO RGTR
DEVICE ADDRESS
DEVICE REGISTER COMMAND
STOP
STOP
DEVICE ADDRESS
DATA FROM DEVICE REGISTER
SEND BYTE FORMAT (To generate a oneshot command) :
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
SDA
a6
a5
a4
a3
a2
a1
a0
D7
D6
D5
D4
D3
D2
D1
D0
S
w
A
A
P
STOP
DEVICE ADDRESS
ONESHOT COMMAND
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
13
PC BOARD LAYOUT CONSIDERATION
Because the NE1618 is used to measure a very small voltage from
the remote sensor, care must be taken to minimize noise induced at
the sensor inputs, especially in the computer motherboard noisy
environment. These precautions should be considered:
Place the NE1618 as close as possible to the remote sensor. It
can be from 4 to 8 inches, as long as the worst noise sources
such as clock generator, data and address buses, CRTs are
avoided.
Route the D+ and D lines in parallel and close together with
ground guards enclosed.
Leakage currents due to PC board contamination must be
considered. Error can be introduced by the leakage current as
shown on the characteristics curve (Temperature Error vs. PC
Board Resistance).
Use wide tracks to reduce inductance and noise pickup that may
be introduced by narrow ones. The width of 10 mil and space of
10 mil are recommended.
GND
D+
D
GND
SL01218
Place a bypass capacitor of 0.1
F close to the V
DD
pin and an
input filter capacitor of 2200 pF close to the D+ and D pins.
A shielded twisted pair is recommended for a long distance
remote sensor. Connect the shield of the cable at the device side
to the NE1618 GND pin and leave the shield at the remote end
unconnected to avoid ground loop. Also notice that the series
resistance of the cable may introduce measurement error;
1
can introduce about 0.5
C.
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
14
SSOP16:
plastic shrink small outline package; 16 leads;
body width 3.9 mm; lead pitch 0.635 mm
SOT519-1
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
15
NOTES
Philips Semiconductors
Product data
NE1618
Temperature monitor for microprocessor systems
2002 Jan 04
16
Definitions
Short-form specification -- The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition -- Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 60134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information -- Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support -- These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes -- Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
Contact information
For additional information please visit
http://www.semiconductors.philips.com.
Fax: +31 40 27 24825
For sales offices addresses send e-mail to:
sales.addresses@www.semiconductors.philips.com.
Koninklijke Philips Electronics N.V. 2002
All rights reserved. Printed in U.S.A.
Date of release: 01-02
Document order number:
9397 750 09274
Philips
Semiconductors
Data sheet status
[1]
Objective data
Preliminary data
Product data
Product
status
[2]
Development
Qualification
Production
Definitions
This data sheet contains data from the objective specification for product development.
Philips Semiconductors reserves the right to change the specification in any manner without notice.
This data sheet contains data from the preliminary specification. Supplementary data will be
published at a later date. Philips Semiconductors reserves the right to change the specification
without notice, in order to improve the design and supply the best possible product.
This data sheet contains data from the product specification. Philips Semiconductors reserves the
right to make changes at any time in order to improve the design, manufacturing and supply.
Changes will be communicated according to the Customer Product/Process Change Notification
(CPCN) procedure SNW-SQ-650A.
Data sheet status
[1] Please consult the most recently issued data sheet before initiating or completing a design.
[2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at URL
http://www.semiconductors.philips.com.
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