|
|
PDF NCT275 Data sheet ( Hoja de datos )
| Número de pieza | NCT275 | |
| Descripción | Industry Standard Digital Temperature Sensor | |
| Fabricantes | ON Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de NCT275 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
|
No Preview Available !
NCT275
Industry Standard Digital
Temperature Sensor in CSP
Package with 2-wire
Interface
The NCT275 is a twoïwire serially programmable temperature
sensor with an overïtemperature/interrupt output pin to signal out of
limit conditions. This is an openïdrain pin and can operate in either
comparator or interrupt mode. Temperature measurements are
converted into digital form using a high resolution (12 bit),
sigmaïdelta, analogïtoïdigital converter (ADC). The device operates
over the –55°C to +125°C temperature range.
Communication with the NCT275 is accomplished via the
SMBus/I2C interface which is compatible with industry standard
protocols. Through this interface the NCT275s internal registers may
be accessed. These registers allow the user to read the current
temperature, change the configuration settings and adjust the
temperature limits.
The NCT275 has a wide supply voltage range of 3.0 V to 5.5 V. The
average supply current is 575 mA at 3.3 V. It also offers a shutdown
mode to conserve power. The typical shutdown current is 3 mA.
The NCT275 is available in a space saving 6 ball CSP package as
NCT275A and NCT275B. NCT275B gives I2C address options of
0x48 and 0x4A while NCT275A gives address options of 0x49 and
0x4B. NCT275 is also fully register compatible with the NCT75,
LM75 and TMP75.
Features
• 12ïbit TemperatureïtoïDigital Converter
• Input Voltage Range from 3.0 V to 5.5 V
• Temperature Range from ï55°C to +125°C
• SMBus/I2C Interface
• Over Temperature Indicator
• Support for SMBus ALERT
• Shutdown Mode for Low Power Consumption
• OneïShot Mode
• Available in 6 Ball CSP Package with Multiple Address Options
• These are PbïFree Devices
Typical Applications
• Computer Thermal Monitoring
• Thermal Protection
• Isolated Sensors
• Battery Management
• Office Electronics
• Electronic Test Equipment
• Thermostat Controls
• System Thermal Management
http://onsemi.com
MARKING
DIAGRAM
WLCSP6
CASE 567JR
XXX
A
Y
W
G
XXX
AYW
G
= 75A (NCT275A)
= 75B (NCT275B)
= Assembly Location
= Year
= Work Week
= PbïFree Package
PIN CONNECTIONS
SDA
A2
A1 VDD
SCL B2
B1 A1
OS/ALERT
C2
C1 GND
(Bottom View)
VDD SDA
A1 NCT275 SCL
GND
OS/ALERT
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information ion page 12 of
this data sheet.
© Semiconductor Components Industries, LLC, 2014
August, 2014 ï Rev. 0
1
Publication Order Number:
NCT275/D
1 page  
NCT275
FUNCTIONAL DESCRIPTION
The NCT275 temperature sensor converts an analog
temperature measurement to a digital representation by
using an onïchip measurement transistor and a 12 bit
DeltaïSigma ADC.
The device includes an open drain ALERT output which
can be used to signal that the programmed temperature limit
has been exceeded.
The two main modes of operation are normal and
shutdown mode. In normal mode the NCT275 performs
a new temperature conversion every 80 ms. This new value
is then updated to the temperature value register (address
0x00) and also compared to the TOS register limit (default
= 80°C). If the temperature value register is read during the
conversion sequence the value returned is the
previously stored value. A bus read does not affect the
conversion that is in progress.
In shutdown mode temperature conversion is disabled and
the temperature value register holds the last valid
temperature reading. The NCT275 can still be
communicated with in this mode as the interface is still
active. The device mode is controlled via bit 0 of the
configuration register. While in shutdown mode a
conversion can be initiated by writing an arbitrary value to
the oneïshot register (0x04).
This has the effect of powering up the NCT275,
performing a conversion, comparing the new temperature
with the programmed limit and then going back into
shutdown mode.
The OS/ALERT pin can be configured in many ways to
allow it to be used in many different system configurations.
The over temperature output can be configured to operate
as a comparator type output (which is self clearing once the
temperature has returned below the hysteresis value) or an
interrupt type output (which requires the master to read an
internal register AND the temperature to return below the
hysteresis value before going into an inactive state). The
ALERT pin can also be configured as an active high or active
low output.
While the ADC of the NCT275 can theoretically measure
temperatures in the range of ï128°C to 127°C, the NCT275
is guaranteed to measure from ï55°C to +125°C. Table 1
shows the relevant temperature bits for a 12 bit temperature
reading. A 2ïbyte read is required to obtain the full 12 bit
temperature reading. If an 8 bit (1°C resolution) reading is
required then a single byte read is sufficient.
Temperature Measurement Results
The results of the on chip temperature measurements are
stored in the temperature value register and compared with
the TOS and THYST limit register.
The temperature value, TOS and THYST registers are
16 bits wide and have a resolution of 0.0625°C. The data is
stored as a 12 bit 2s complement word. The data is left
justified; D15 is the MSB and is the sign bit. The four LSBs
(D3 to D0) are always 0 as they are not part of the result.
Table 1. 12ïBit TEMPERATURE DATA FORMAT
Temperature
Binary Value D15
to D4
Hex Value
ï55 1100 1001 0000
0xC90
ï25 1110 0111 0000
0xE70
ï0.0625
1111 1111 1111
0xFFF
0 0000 0000 0000 0x000
+0.0625
0000 0000 0001
0x001
+25 0001 1001 0000
0x190
+75.25
0100 1011 0100
0x4B4
+100
0110 0100 0000
0x640
+125
0111 1101 0000
0x7D0
12ïBit Temperature Data Format
Positive Temperature = ADC Code (decimal)/16
Example 190h = 400d/16 = +255C
Negative Temperature = (ADC Code(decimal) ï 4096)/16
Example E70h = (3696d – 4096)/16 = ï255C
ONEïSHOT MODE
One of the features of the NCT275 is a OneïShot
Temperature Measurement Mode. This mode is useful if
reduced power consumption is a design requirement.
To enable oneïshot mode bit 5 of the configuration
register need to be set. Once, enabled, the NCT275 goes
immediately into shutdown mode. Here, the current
consumption is reduced to a typical value of 3 mA. Writing
address 0x04 to the address pointer register initiates a
oneïshot temperature measurement. This powers up the
NCT275, carries out a temperature measurement, and then
powers down again. The data written to this register is
irrelevant and is not stored. It is the write operation that
causes the oneïshot conversion.
http://onsemi.com
5
5 Page 
NCT275
READING DATA
Reading data from the NCT275 is done in two different
ways depending on the register being read. The
configuration register is only 8 bits wide so a single byte
read is used for this (shown in Figure 8). This consists of the
device address followed by the data from the register.
Reading the data in the temperature value register requires
a two byte read (shown in Figure 9). This consists of the
device address, followed by two bytes of data from the
temperature register (the first byte is the MSB). In both cases
the address pointer register of the register being read must
be written to prior to performing a read operation.
OS/ALERT OUTPUT OVERTEMPERATURE MODES
The OS/ALERT output pin can operate in two different
modes – overtemperature mode and SMBus
alert mode. The pin defaults to overtemperature mode on
power up. This means that it becomes active when the
measured temperature meets or exceeds the limit stored in
the TOS setpoint register. At this point it can deal with the
event in one of two ways which depends on the mode it is in.
The two overtemperature modes are comparatormode and
interrupt mode. Comparator is the default mode on power
up. More information on comparator and interrupt modes
alsong with the SMBus alert mode are explained below.
Comparator Mode
In Comparator Mode, the OS/ALERT pin becomes active
when the measured temperature equals or exceeds the limit
stored in the TOS setpoint register. The pin returns to its
inactive status when the temperature drops below the THYST
setpoint register value.
NOTE: Shutdown mode does not reset the output state for
comparator mode.
Interrupt Mode
In the interrupt mode, the OS/ALERT pin becomes active
when the temperature equals or exceeds the TOS limit for
a consecutive number of faults. It can be reset by performing
a read operation on any register in the NCT275. The output
can only become active again when the TOS limit has been
equalled or exceeded. Figure 11 shows how both the
interrupt and comparator modes operate in relation to the
output pin (OS/ALERT). It also shows the operation of the
polarity in the configuration register.
http://onsemi.com
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet NCT275.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| NCT275 | Industry Standard Digital Temperature Sensor | ON Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |