LM75BD [NXP]
Digital temperature sensor and thermal watchdog; 数字温度传感器和热看门狗型号: | LM75BD |
厂家: | NXP |
描述: | Digital temperature sensor and thermal watchdog |
文件: | 总29页 (文件大小:164K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LM75B
Digital temperature sensor and thermal watchdog
Rev. 02 — 9 December 2008
Product data sheet
1. General description
The LM75B is a temperature-to-digital converter using an on-chip band gap temperature
sensor and Sigma-Delta A-to-D conversion technique with an overtemperature detection
output. The LM75B contains a number of data registers: Configuration register (Conf) to
store the device settings such as device operation mode, OS operation mode, OS polarity
and OS fault queue as described in Section 7 “Functional description”; temperature
register (Temp) to store the digital temp reading, and set-point registers (Tos and Thyst) to
store programmable overtemperature shutdown and hysteresis limits, that can be
communicated by a controller via the 2-wire serial I2C-bus interface. The device also
includes an open-drain output (OS) which becomes active when the temperature exceeds
the programmed limits. There are three selectable logic address pins so that eight devices
can be connected on the same bus without address conflict.
The LM75B can be configured for different operation conditions. It can be set in normal
mode to periodically monitor the ambient temperature, or in shutdown mode to minimize
power consumption. The OS output operates in either of two selectable modes:
OS comparator mode or OS interrupt mode. Its active state can be selected as either
HIGH or LOW. The fault queue that defines the number of consecutive faults in order to
activate the OS output is programmable as well as the set-point limits.
The temperature register always stores an 11-bit 2's complement data giving a
temperature resolution of 0.125 °C. This high temperature resolution is particularly useful
in applications of measuring precisely the thermal drift or runaway. When the LM75B is
accessed the conversion in process is not interrupted (i.e., the I2C-bus section is totally
independent of the Sigma-Delta converter section) and accessing the LM75B
continuously without waiting at least one conversion time between communications will
not prevent the device from updating the Temp register with a new conversion result. The
new conversion result will be available immediately after the Temp register is updated.
The LM75B powers up in the normal operation mode with the OS in comparator mode,
temperature threshold of 80 °C and hysteresis of 75 °C, so that it can be used as a
stand-alone thermostat with those pre-defined temperature set points.
2. Features
I Pin-for-pin replacement for industry standard LM75 and LM75A and offers improved
temperature resolution of 0.125 °C and specification of a single part over power supply
range from 2.8 V to 5.5 V
I I2C-bus interface with up to 8 devices on the same bus
I Power supply range from 2.8 V to 5.5 V
I Temperatures range from −55 °C to +125 °C
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
I Frequency range 20 Hz to 400 kHz with bus fault time-out to prevent hanging up the
bus
I 11-bit ADC that offers a temperature resolution of 0.125 °C
I Temperature accuracy of:
N ±2 °C from −25 °C to +100 °C
N ±3 °C from −55 °C to +125 °C
I Programmable temperature threshold and hysteresis set points
I Supply current of 1.0 µA in shutdown mode for power conservation
I Stand-alone operation as thermostat at power-up
I ESD protection exceeds 4500 V HBM per JESD22-A114, 450 V MM per
JESD22-A115 and 2000 V CDM per JESD22-C101
I Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
I Small 8-pin package types: SO8, TSSOP8 and 3 mm × 2 mm XSON8U
3. Applications
I System thermal management
I Personal computers
I Electronics equipment
I Industrial controllers
4. Ordering information
Table 1.
Ordering information
Type
Topside Package
number
mark
Name
Description
Version
LM75BD
LM75BD SO8
plastic small outline package; 8 leads; body width 3.9 mm
SOT96-1
SOT505-1
SOT996-2
LM75BDP
LM75BGD
LM75B
75B
TSSOP8 plastic thin shrink small outline package; 8 leads; body width 3 mm
XSON8U plastic extremely thin small outline package; no leads; 8 terminals;
UTLP based; body 3 × 2 × 0.5 mm
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
2 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
5. Block diagram
V
CC
LM75B
BIAS
REFERENCE
POINTER
REGISTER
CONFIGURATION
REGISTER
TEMPERATURE
REGISTER
COUNTER
TIMER
BAND GAP
TEMP SENSOR
11-BIT
SIGMA-DELTA
A-to-D
TOS
REGISTER
CONVERTER
OSCILLATOR
COMPARATOR/
INTERRUPT
THYST
REGISTER
POWER-ON
RESET
OS
LOGIC CONTROL AND INTERFACE
002aad453
A2 A1 A0
SCL SDA
GND
Fig 1. Block diagram of LM75B
6. Pinning information
6.1 Pinning
1
2
3
4
8
7
6
5
SDA
SCL
OS
V
CC
1
2
3
4
8
7
6
5
SDA
SCL
OS
V
CC
A0
A1
A2
A0
A1
A2
LM75BD
LM75BDP
GND
GND
002aad455
002aad454
Fig 2. Pin configuration for SO8
Fig 3. Pin configuration for TSSOP8
SDA
SCL
OS
1
2
3
4
8
7
6
5
V
CC
A0
A1
A2
LM75BGD
GND
002aae234
Transparent top view
Fig 4. Pin configuration for XSON8U
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
3 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
6.2 Pin description
Table 2.
Symbol
SDA
SCL
OS
Pin description
Pin
1
Description
Digital I/O. I2C-bus serial bidirectional data line; open-drain.
Digital input. I2C-bus serial clock input.
Overtemp Shutdown output; open-drain.
Ground. To be connected to the system ground.
Digital input. User-defined address bit 2.
Digital input. User-defined address bit 1.
Digital input. User-defined address bit 0.
Power supply.
2
3
GND
A2
4
5
A1
6
A0
7
VCC
8
7. Functional description
7.1 General operation
The LM75B uses the on-chip band gap sensor to measure the device temperature with
the resolution of 0.125 °C and stores the 11-bit 2's complement digital data, resulted from
11-bit A-to-D conversion, into the device Temp register. This Temp register can be read at
any time by a controller on the I2C-bus. Reading temperature data does not affect the
conversion in progress during the read operation.
The device can be set to operate in either mode: normal or shutdown. In normal operation
mode, the temp-to-digital conversion is executed every 100 ms and the Temp register is
updated at the end of each conversion. During each ‘conversion period’ (Tconv) of about
100 ms the device takes only about 10 ms, called ‘temperature conversion time’ (tconv(T)),
to complete a temperature-to-data conversion and then becomes idle for the time
remaining in the period. This feature is implemented to significantly reduce the device
power dissipation. In shutdown mode, the device becomes idle, data conversion is
disabled and the Temp register holds the latest result; however, the device I2C-bus
interface is still active and register write/read operation can be performed. The device
operation mode is controllable by programming bit B0 of the configuration register. The
temperature conversion is initiated when the device is powered-up or put back into normal
mode from shutdown.
In addition, at the end of each conversion in normal mode, the temperature data (or Temp)
in the Temp register is automatically compared with the overtemperature shutdown
threshold data (or Tth(ots)) stored in the Tos register, and the hysteresis data (or Thys
)
stored in the Thyst register, in order to set the state of the device OS output accordingly.
The device Tos and Thyst registers are write/read capable, and both operate with 9-bit
2's complement digital data. To match with this 9-bit operation, the Temp register uses
only the 9 MSB bits of its 11-bit data for the comparison.
The way that the OS output responds to the comparison operation depends upon the OS
operation mode selected by configuration bit B1, and the user-defined fault queue defined
by configuration bits B3 and B4.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
4 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
In OS comparator mode, the OS output behaves like a thermostat. It becomes active
when the Temp exceeds the Tth(ots), and is reset when the Temp drops below the Thys
.
Reading the device registers or putting the device into shutdown does not change the
state of the OS output. The OS output in this case can be used to control cooling fans or
thermal switches.
In OS interrupt mode, the OS output is used for thermal interruption. When the device is
powered-up, the OS output is first activated only when the Temp exceeds the Tth(ots); then
it remains active indefinitely until being reset by a read of any register. Once the OS output
has been activated by crossing Tth(ots) and then reset, it can be activated again only when
the Temp drops below the Thys; then again, it remains active indefinitely until being reset
by a read of any register. The OS interrupt operation would be continued in this sequence:
Tth(ots) trip, Reset, Thys trip, Reset, Tth(ots) trip, Reset, Thys trip, Reset, etc. Putting the
device into the shutdown mode by setting the bit 0 of the configuration register also resets
the OS output.
In both cases, comparator mode and interrupt mode, the OS output is activated only if a
number of consecutive faults, defined by the device fault queue, has been met. The fault
queue is programmable and stored in the two bits, B3 and B4, of the Configuration
register. Also, the OS output active state is selectable as HIGH or LOW by setting
accordingly the configuration register bit B2.
At power-up, the device is put into normal operation mode, the Tth(ots) is set to 80 °C, the
Thys is set to 75 °C, the OS active state is selected LOW and the fault queue is equal to 1.
The temp reading data is not available until the first conversion is completed in about
100 ms.
The OS response to the temperature is illustrated in Figure 5.
T
th(ots)
T
hys
reading temperature limits
OS reset
OS active
OS output in comparator mode
OS reset
OS active
(1)
(1)
(1)
OS output in interrupt mode
002aae334
(1) OS is reset by either reading register or putting the device in shutdown mode. It is assumed that
the fault queue is met at each Tth(ots) and Thys crossing point.
Fig 5. OS response to temperature
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
5 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
7.2 I2C-bus serial interface
The LM75B can be connected to a compatible 2-wire serial interface I2C-bus as a slave
device under the control of a controller or master device, using two device terminals, SCL
and SDA. The controller must provide the SCL clock signal and write/read data to/from the
device through the SDA terminal. Notice that if the I2C-bus common pull-up resistors have
not been installed as required for I2C-bus, then an external pull-up resistor, about 10 kΩ,
is needed for each of these two terminals. The bus communication protocols are
described in Section 7.10.
7.2.1 Bus fault time-out
If the SDA line is held LOW for longer than tto (75 ms minimum / 13.3 Hz; guaranteed at
50 ms minimum / 20 Hz), the LM75B will reset to the idle state (SDA released) and wait
for a new START condition. This ensures that the LM75B will never hang up the bus
should there be conflict in the transmission sequence.
7.3 Slave address
The LM75B slave address on the I2C-bus is partially defined by the logic applied to the
device address pins A2, A1 and A0. Each of them is typically connected either to GND for
logic 0, or to VCC for logic 1. These pins represent the three LSB bits of the device 7-bit
address. The other four MSB bits of the address data are preset to ‘1001’ by hard wiring
inside the LM75B. Table 3 shows the device’s complete address and indicates that up to
8 devices can be connected to the same bus without address conflict. Because the input
pins, SCL, SDA and A2 to A0, are not internally biased, it is important that they should not
be left floating in any application.
Table 3.
Address table
1 = HIGH; 0 = LOW.
MSB
LSB
1
0
0
1
A2
A1
A0
7.4 Register list
The LM75B contains four data registers beside the pointer register as listed in Table 4.
The pointer value, read/write capability and default content at power-up of the registers
are also shown in Table 4.
Table 4.
Register table
Register Pointer R/W
POR
state
Description
name
value
Conf
01h
R/W
00h
Configuration register: contains a single 8-bit data
byte; to set the device operating condition; default = 0.
Temp
Tos
00h
03h
read only n/a
Temperature register: contains two 8-bit data bytes;
to store the measured Temp data.
R/W
5000h
Overtemperature shutdown threshold register:
contains two 8-bit data bytes; to store the
overtemperature shutdown Tth(ots) limit;
default = 80 °C.
Thyst
02h
R/W
4B00h
Hysteresis register: contains two 8-bit data bytes;
to store the hysteresis Thys limit; default = 75 °C.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
6 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
7.4.1 Pointer register
The Pointer register contains an 8-bit data byte, of which the two LSB bits represent the
pointer value of the other four registers, and the other 6 MSB bits are equal to 0, as shown
in Table 5 and Table 6. The Pointer register is not accessible to the user, but is used to
select the data register for write/read operation by including the pointer data byte in the
bus command.
Table 5.
Pointer register
B7
B6
B5
B4
B3
B2
B[1:0]
0
0
0
0
0
0
pointer value
Table 6.
Pointer value
B1
0
B0
0
Selected register
Temperature register (Temp)
Configuration register (Conf)
Hysteresis register (Thyst)
0
1
1
0
1
1
Overtemperature shutdown register (Tos)
Because the Pointer value is latched into the Pointer register when the bus command
(which includes the pointer byte) is executed, a read from the LM75B may or may not
include the pointer byte in the statement. To read again a register that has been recently
read and the pointer has been preset, the pointer byte does not have to be included. To
read a register that is different from the one that has been recently read, the pointer byte
must be included. However, a write to the LM75B must always include the pointer byte in
the statement. The bus communication protocols are described in Section 7.10.
At power-up, the Pointer value is equal to 00 and the Temp register is selected; users can
then read the Temp data without specifying the pointer byte.
7.4.2 Configuration register
The Configuration register (Conf) is a write/read register and contains an 8-bit
non-complement data byte that is used to configure the device for different operation
conditions. Table 7 shows the bit assignments of this register.
Table 7.
Conf register
Legend: * = default value.
Bit Symbol
B[7:5] reserved
Access Value Description
R/W 000* reserved for manufacturer’s use; should be kept as
zeroes for normal operation
OS fault queue programming
queue value = 1
B[4:3] OS_F_QUE[1:0] R/W
00*
01
10
11
queue value = 2
queue value = 4
queue value = 6
B2
OS_POL
R/W
OS polarity selection
OS active LOW
0*
1
OS active HIGH
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
7 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
Table 7.
Conf register …continued
Legend: * = default value.
Bit
Symbol
Access Value Description
B1
OS_COMP_INT R/W
OS operation mode selection
OS comparator
0*
1
OS interrupt
B0
SHUTDOWN
R/W
device operation mode selection
normal
0*
1
shutdown
7.4.3 Temperature register
The Temperature register (Temp) holds the digital result of temperature measurement or
monitor at the end of each analog-to-digital conversion. This register is read-only and
contains two 8-bit data bytes consisting of one Most Significant Byte (MSByte) and one
Least Significant Byte (LSByte). However, only 11 bits of those two bytes are used to store
the Temp data in 2’s complement format with the resolution of 0.125 °C. Table 8 shows the
bit arrangement of the Temp data in the data bytes.
Table 8.
MSByte
Temp register
LSByte
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
When reading register Temp, all 16 bits of the two data bytes (MSByte and LSByte) are
provided to the bus and must be all collected by the controller to complete the bus
operation. However, only the 11 most significant bits should be used, and the 5 least
significant bits of the LSByte are zero and should be ignored. One of the ways to calculate
the Temp value in °C from the 11-bit Temp data is:
1. If the Temp data MSByte bit D10 = 0, then the temperature is positive and Temp value
(°C) = +(Temp data) × 0.125 °C.
2. If the Temp data MSByte bit D10 = 1, then the temperature is negative and
Temp value (°C) = −(2’s complement of Temp data) × 0.125 °C.
Examples of the Temp data and value are shown in Table 9.
Table 9.
Temp register value
11-bit binary
Hexadecimal value
Decimal value
Value
(2’s complement)
011 1111 1000
011 1111 0111
011 1111 0001
011 1110 1000
000 1100 1000
000 0000 0001
000 0000 0000
111 1111 1111
3F8
3F7
3F1
3E8
0C8
001
000
7FF
1016
1015
1009
1000
200
1
+127.000 °C
+126.875 °C
+126.125 °C
+125.000 °C
+25.000 °C
+0.125 °C
0
0.000 °C
−1
−0.125 °C
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
8 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
Table 9.
Temp register value …continued
11-bit binary
Hexadecimal value
Decimal value
Value
(2’s complement)
111 0011 1000
110 0100 1001
110 0100 1000
738
649
648
−200
−439
−440
−25.000 °C
−54.875 °C
−55.000 °C
For 9-bit Temp data application in replacing the industry standard LM75, just use only
9 MSB bits of the two bytes and disregard 7 LSB of the LSByte. The 9-bit Temp data with
0.5 °C resolution of the LM75B is defined exactly in the same way as for the standard
LM75 and it is here similar to the Tos and Thyst registers.
The only MSByte of the temperature can also be read with the use of a one-byte reading
command. Then the temperature resolution will be 1.00 °C instead.
7.4.4 Overtemperature shutdown threshold (Tos) and hysteresis (Thyst) registers
These two registers, are write/read registers, and also called set-point registers. They are
used to store the user-defined temperature limits, called overtemperature shutdown
threshold (Tth(ots)) and hysteresis temperature (Thys), for the device watchdog operation.
At the end of each conversion the Temp data will be compared with the data stored in
these two registers in order to set the state of the device OS output; see Section 7.1.
Each of the set-point registers contains two 8-bit data bytes consisting of one MSByte and
one LSByte the same as register Temp. However, only 9 bits of the two bytes are used to
store the set-point data in 2’s complement format with the resolution of 0.5 °C. Table 10
and Table 11 show the bit arrangement of the Tos data and Thyst data in the data bytes.
Notice that because only 9-bit data are used in the set-point registers, the device uses
only the 9 MSB of the Temp data for data comparison.
Table 10. Tos register
MSByte
LSByte
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
Table 11. Thyst register
MSByte
LSByte
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
When a set-point register is read, all 16 bits are provided to the bus and must be collected
by the controller to complete the bus operation. However, only the 9 most significant bits
should be used and the 7 LSB of the LSByte are equal to zero and should be ignored.
Table 12 shows examples of the limit data and value.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
9 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
Table 12. Tos and Thyst limit data and value
11-bit binary
Hexadecimal value
Decimal value
Value
(2’s complement)
0 1111 1010
0 0011 0010
0 0000 0001
0 0000 0000
1 1111 1111
1 1100 1110
1 1001 0010
0FA
032
001
000
1FF
1CE
192
250
50
+125.0 °C
+25.0 °C
+0.5 °C
0.0 °C
1
0
−1
−0.5 °C
−50
−110
−25.0 °C
−55.0 °C
7.5 OS output and polarity
The OS output is an open-drain output and its state represents results of the device
watchdog operation as described in Section 7.1. In order to observe this output state, an
external pull-up resistor is needed. The resistor should be as large as possible, up to
200 kΩ, to minimize the Temp reading error due to internal heating by the high OS sinking
current.
The OS output active state can be selected as HIGH or LOW by programming bit B2
(OS_POL) of register Conf: setting bit OS_POL to logic 1 selects OS active HIGH and
setting bit B2 to logic 0 sets OS active LOW. At power-up, bit OS_POL is equal to logic 0
and the OS active state is LOW.
7.6 OS comparator and interrupt modes
As described in Section 7.1, the device OS output responds to the result of the
comparison between register Temp data and the programmed limits, in registers Tos and
Thyst, in different ways depending on the selected OS mode: OS comparator or
OS interrupt. The OS mode is selected by programming bit B1 (OS_COMP_INT) of
register Conf: setting bit OS_COMP_INT to logic 1 selects the OS interrupt mode, and
setting to logic 0 selects the OS comparator mode. At power-up, bit OS_COMP_INT is
equal to logic 0 and the OS comparator is selected.
The main difference between the two modes is that in OS comparator mode, the OS
output becomes active when Temp has exceeded Tth(ots) and reset when Temp has
dropped below Thys, reading a register or putting the device into shutdown mode does not
change the state of the OS output; while in OS interrupt mode, once it has been activated
either by exceeding Tth(ots) or dropping below Thys, the OS output will remain active
indefinitely until reading a register, then the OS output is reset.
Temperature limits Tth(ots) and Thys must be selected so that Tth(ots) > Thys. Otherwise, the
OS output state will be undefined.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
10 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
7.7 OS fault queue
Fault queue is defined as the number of faults that must occur consecutively to activate
the OS output. It is provided to avoid false tripping due to noise. Because faults are
determined at the end of data conversions, fault queue is also defined as the number of
consecutive conversions returning a temperature trip. The value of fault queue is
selectable by programming the two bits B4 and B3 (OS_F_QUE[1:0]) in register Conf.
Notice that the programmed data and the fault queue value are not the same. Table 13
shows the one-to-one relationship between them. At power-up, fault queue data = 0 and
fault queue value = 1.
Table 13. Fault queue table
Fault queue data
Fault queue value
OS_F_QUE[1]
OS_F_QUE[0]
Decimal
0
0
1
1
0
1
0
1
1
2
4
6
7.8 Shutdown mode
The device operation mode is selected by programming bit B0 (SHUTDOWN) of register
Conf. Setting bit SHUTDOWN to logic 1 will put the device into shutdown mode. Resetting
bit SHUTDOWN to logic 0 will return the device to normal mode.
In shutdown mode, the device draws a small current of approximately 1.0 µA and the
power dissipation is minimized; the temperature conversion stops, but the I2C-bus
interface remains active and register write/read operation can be performed. When the
shutdown is set, the OS output will be unchanged in comparator mode and reset in
interrupt mode.
7.9 Power-up default and power-on reset
The LM75B always powers-up in its default state with:
• Normal operation mode
• OS comparator mode
• Tth(ots) = 80 °C
• Thys = 75 °C
• OS output active state is LOW
• Pointer value is logic 00 (Temp)
When the power supply voltage is dropped below the device power-on reset level of
approximately 1.0 V (POR) for over 2 µs and then rises up again, the device will be reset
to its default condition as listed above.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
11 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
7.10 Protocols for writing and reading the registers
The communication between the host and the LM75B must strictly follow the rules as
defined by the I2C-bus management. The protocols for LM75B register read/write
operations are illustrated in Figure 6 to Figure 11 together with the following definitions:
1. Before a communication, the I2C-bus must be free or not busy. It means that the SCL
and SDA lines must both be released by all devices on the bus, and they become
HIGH by the bus pull-up resistors.
2. The host must provide SCL clock pulses necessary for the communication. Data is
transferred in a sequence of 9 SCL clock pulses for every 8-bit data byte followed by
1-bit status of the acknowledgement.
3. During data transfer, except the START and STOP signals, the SDA signal must be
stable while the SCL signal is HIGH. It means that the SDA signal can be changed
only during the LOW duration of the SCL line.
4. S: START signal, initiated by the host to start a communication, the SDA goes from
HIGH to LOW while the SCL is HIGH.
5. RS: RE-START signal, same as the START signal, to start a read command that
follows a write command.
6. P: STOP signal, generated by the host to stop a communication, the SDA goes from
LOW to HIGH while the SCL is HIGH. The bus becomes free thereafter.
7. W: write bit, when the write/read bit = LOW in a write command.
8. R: read bit, when the write/read bit = HIGH in a read command.
9. A: device acknowledge bit, returned by the LM75B. It is LOW if the device works
properly and HIGH if not. The host must release the SDA line during this period in
order to give the device the control on the SDA line.
10. A’: master acknowledge bit, not returned by the device, but set by the master or host
in reading 2-byte data. During this clock period, the host must set the SDA line to
LOW in order to notify the device that the first byte has been read for the device to
provide the second byte onto the bus.
11. NA: Not Acknowledge bit. During this clock period, both the device and host release
the SDA line at the end of a data transfer, the host is then enabled to generate the
STOP signal.
12. In a write protocol, data is sent from the host to the device and the host controls the
SDA line, except during the clock period when the device sends the device
acknowledgement signal to the bus.
13. In a read protocol, data is sent to the bus by the device and the host must release the
SDA line during the time that the device is providing data onto the bus and controlling
the SDA line, except during the clock period when the master sends the master
acknowledgement signal to the bus.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
12 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
1
1
2
0
3
0
4
1
5
6
7
8
9
1
0
2
0
3
0
4
0
5
0
6
0
7
0
8
1
9
1
0
2
0
3
0
4
5
6
7
8
9
SCL
SDA
S
A2 A1 A0 W
A
A
D4 D3 D2 D1 D0
A
P
device address
START
pointer byte
configuration data byte
device
write
device
acknowledge
device
acknowledge
STOP
acknowledge
001aad624
Fig 6. Write configuration register (1-byte data)
1
1
2
0
3
0
4
1
5
6
7
8
9
1
0
2
0
3
0
4
0
5
6
0
7
0
8
1
9
(next)
SCL
SDA
0
A
RS (next)
S
A2 A1 A0
W
A
device address
pointer byte
START
device
acknowledge
RE-START
write
device
acknowledge
1
1
2
3
0
4
1
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL (cont.)
SDA (cont.)
0
A2 A1 A0
R
A
D7 D6 D5 D4 D3 D2 D1 D0 NA
data byte from device
P
device address
master not
STOP
read
acknowledged
device
acknowledge
001aad625
Fig 7. Read configuration register including pointer byte (1-byte data)
1
1
2
0
3
0
4
1
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
SDA
A2 A1 A0
R
A
D7 D6 D5 D4 D3 D2 D1 D0 NA
data byte from device
P
S
device address
START
master not
STOP
read
acknowledged
device
acknowledge
001aad626
Fig 8. Read configuration or temp register with preset pointer (1-byte data)
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
13 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
1
1
2
0
3
0
4
1
5
6
7
8
9
1
0
2
0
3
0
4
0
5
0
6
0
7
8
9
SCL
(next)
(next)
SDA
S
A2 A1 A0
W
A
P1 P0
A
device address
pointer byte
START
device
acknowledge
write
device
acknowledge
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL (cont.)
SDA (cont.)
D7 D6 D5 D4 D3 D2 D1 D0
MSByte data
A
D7 D6 D5 D4 D3 D2 D1 D0
LSByte data
A
P
device
STOP
acknowledge
device
acknowledge
002aad036
Fig 9. Write Tos or Thyst register (2-byte data)
1
1
2
0
3
0
4
1
5
6
7
8
9
1
0
2
0
3
0
4
0
5
0
6
0
7
8
9
0
SCL
SDA
(next)
S
A2 A1 A0 W
A
P1 P0
device
A
RS (next)
device address
START
pointer byte
RE-START
write
device
acknowledge
acknowledge
1
1
2
0
3
0
4
1
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL (cont)
SDA (cont)
A2 A1 A0
R
A
D7 D6 D5 D4 D3 D2 D1 D0 A' D7 D6 D5 D4 D3 D2 D1 D0 NA
P
device address
MSByte from device
master
LSByte from device
master not
read
device
acknowledge
STOP
acknowledge
acknowledged
002aad037
Fig 10. Read Temp, Tos or Thyst register including pointer byte (2-byte data)
1
1
2
0
3
0
4
1
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
SDA
S
A2 A1 A0
R
A
D7 D6 D5 D4 D3 D2 D1 D0 A' D7 D6 D5 D4 D3 D2 D1 D0 NA
P
device address
START
MSByte from device
master
LSByte from device
master not
read
device
acknowledge
STOP
acknowledge
acknowledged
002aad038
Fig 11. Read Temp, Tos or Thyst register with preset pointer (2-byte data)
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
14 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
8. Application design-in information
8.1 Typical application
power supply
0.1 µF
BUS
PULL-UP
RESISTORS
10 kΩ
10 kΩ
10 kΩ
V
CC
8
SCL
SDA
2
1
2
I C-BUS
OS
DETECTOR OR
INTERRUPT LINE
3
LM75B
A2
A1
A0
5
6
7
DIGITAL LOGIC
4
GND
002aad457
Fig 12. Typical application
8.2 LM75A and LM75B comparison
Table 14. LM75A and LM75B comparison
Description
LM75A
no
LM75B
yes
availability of the XSON8U (3 mm × 2 mm) package type
OS output auto-reset when SHUTDOWN bit is set in interrupt mode[1]
support single-byte reading of the Temp registers without bus lockup[2]
no
yes
no
yes
bus fault time-out (75 ms, 200 ms)[3]
no
yes
[4]
minimum data hold time (tHD;DAT
)
10 ns
0 ns
ratio of conversion time / conversion period (typical)[5]
supply current in shutdown mode (typical value)
HBM ESD protection level (minimum)
100 ms / 100 ms
3.5 µA
>2000 V
>200 V
>1000 V
10 ms / 100 ms
0.2 µA
>4500 V
>450 V
>2000 V
MM ESD protection level (minimum)
CDM ESD protection level (minimum)
[1] This option is updated to be compatible with the competitive parts. When the OS output has been activated in the interrupt mode due to
a temp limit violation, if the Configuration Shutdown bit B0 is set (to the LM75A), then the OS output activated status remains
unchanged, while (to the LM75B) the OS will be reset. The latter is compatible with the operation condition of the competitive parts.
[2] The LM75 series is intentionally designed to provide two successive temperature data bytes (MSByte and LSByte) for the 11-bit data
resolution and both bytes should be read in a typical application. In some specific applications, when only the MSByte is read using a
single-byte read command, it often happens that if bit D7 of the LSByte is zero, then the device will hold the SDA bus in a LOW state
forever, resulting in a bus hang-up problem, and the bus cannot be released until the device power is reset. This condition exists for the
LM75A but not for the LM75B. For the LM75B the temperature can be read either one byte or two bytes without a hang-up problem.
[3] The bus time-out is included for releasing the LM75B device operation whenever the SDA input is kept at a LOW state for too long
(longer than the LM75B time-out duration) due to a fault from the host. The trade-off for this option is the limitation of the I2C-bus low
frequency operation to be limited to 20 Hz. This option is compatible with some of the latest versions of the competitive parts.
[4] The data hold time is improved to increase the timing margin in I2C-bus operation.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
15 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
[5] The LM75B performs the temperature-to-data conversions with a much higher speed than the LM75A. While the LM75A takes almost
the whole of conversion period (Tconv) time of about 100 ms to complete a conversion, the LM75B takes only about 1⁄10 of the period, or
about 10 ms. Therefore, the conversion period (Tconv) is the same, but the temperature conversion time (tconv(T)) is different between the
two parts. A shorter conversion time is applied to significantly reduce the device’s average power dissipation. During each conversion
period, when the conversion is completed, the LM75B becomes idled and the power is reduced, resulting in a lesser average power
consumption.
8.3 Temperature accuracy
Because the local channel of the temperature sensor measures its own die temperature
that is transferred from its body, the temperature of the device body must be stabilized and
saturated for it to provide the stable readings. Because the LM75B operates a a low power
level, the thermal gradient of the device package has a minor effect on the measurement.
The accuracy of the measurement is more dependent upon the definition of the
environment temperature, which is affected by different factors: the printed-circuit board
on which the device is mounted; the air flow contacting the device body (if the ambient air
temperature and the printed-circuit board temperature are much different, then the
measurement may not be stable because of the different thermal paths between the die
and the environment). The stabilized temperature liquid of a thermal bath will provide the
best temperature environment when the device is completely dipped into it. A thermal
probe with the device mounted inside a sealed-end metal tube located in consistent
temperature air also provides a good method of temperature measurement.
8.4 Noise effect
The LM75B device design includes the implementation of basic features for a good noise
immunity:
• The low-pass filter on both the bus pins SCL and SDA;
• The hysteresis of the threshold voltages to the bus input signals SCL and SDA, about
500 mV minimum;
• All pins have ESD protection circuitry to prevent damage during electrical surges. The
ESD protection on the address, OS, SCL and SDA pins it to ground. The latch-back
based device breakdown voltage of address/OS is typically 11 V and SCL/SDA is
typically 9.5 V at any supply voltage but will vary over process and temperature. Since
there are no protection diodes from SCL or SDA to VCC, the LM75B will not hold the
I2C lines LOW when VCC is not supplied and therefore allow continued I2C-bus
operation if the LM75B is de-powered.
However, good layout practices and extra noise filters are recommended when the device
is used in a very noisy environment:
• Use decoupling capacitors at VCC pin.
• Keep the digital traces away from switching power supplies.
• Apply proper terminations for the long board traces.
• Add capacitors to the SCL and SDA lines to increase the low-pass filter
characteristics.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
16 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
9. Limiting values
Table 15. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter
Conditions
Min
−0.3
−0.3
−5.0
-
Max
+6.0
+6.0
+5.0
10.0
+6.0
+150
150
Unit
V
VCC
VI
supply voltage
input voltage
at input pins
at input pins
on pin OS
V
II
input current
mA
mA
V
IO(sink)
VO
Tstg
Tj
output sink current
output voltage
on pin OS
−0.3
−65
-
storage temperature
junction temperature
°C
°C
10. Recommended operating conditions
Table 16. Recommended operating characteristics
Symbol Parameter Conditions
Min
2.8
Typ
Max
Unit
V
VCC
supply voltage
-
-
5.5
Tamb
ambient temperature
−55
+125
°C
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
17 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
11. Static characteristics
Table 17. Static characteristics
VCC = 2.8 V to 5.5 V; Tamb = −55 °C to +125 °C; unless otherwise specified.
Symbol
Parameter
Conditions
Min
−2
−3
-
Typ[1]
Max
+2
+3
-
Unit
°C
Tacc
temperature accuracy
Tamb = −25 °C to +100 °C
Tamb = −55 °C to +125 °C
11-bit digital temp data
normal mode
-
-
°C
Tres
temperature resolution
0.125
10
°C
tconv(T)
temperature conversion
time
-
-
ms
Tconv
conversion period
normal mode
-
-
-
100
100
-
-
ms
µA
µA
IDD(AV)
average supply current
normal mode: I2C-bus inactive
normal mode: I2C-bus active;
200
300
f
SCL = 400 kHz
shutdown mode
HIGH-level input voltage digital pins (SCL, SDA, A2 to A0)
LOW-level input voltage digital pins
-
0.2
1.0
µA
V
VIH
0.7 × VCC
-
VCC + 0.3
VIL
−0.3
-
0.3 × VCC
V
VI(hys)
hysteresis of input voltage SCL and SDA pins
A2, A1, A0 pins
-
300
-
mV
mv
µA
µA
V
-
150
-
IIH
HIGH-level input current
LOW-level input current
digital pins; VI = VCC
digital pins; VI = 0 V
−1.0
-
-
-
-
-
-
+1.0
+1.0
0.4
0.8
10
6
IIL
−1.0
VOL
LOW-level output voltage SDA and OS pins; IOL = 3 mA
IOL = 4 mA
-
-
V
ILO
output leakage current
number of faults
SDA and OS pins; VOH = VCC
-
µA
Nfault
programmable; conversions in
overtemperature-shutdown fault
queue
1
Tth(ots)
overtemperature
shutdown threshold
temperature
default value
-
80
-
°C
Thys
Ci
hysteresis temperature
input capacitance
default value
digital pins
-
-
75
20
-
-
°C
pF
[1] Typical values are at VCC = 3.3 V and Tamb = 25 °C.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
18 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
002aae198
002aae199
300
300
V
= 5.5 V
4.5 V
3.3 V
2.8 V
CC
I
I
DD(AV)
(µA)
DD(AV)
(µA)
V
= 5.5 V
4.5 V
3.3 V
2.8 V
CC
200
100
0
200
100
0
−75
−25
25
75
125
(°C)
−75
−25
25
75
125
(°C)
T
T
amb
amb
Fig 13. Average supply current versus temperature;
I2C-bus inactive
Fig 14. Average supply current versus temperature;
I2C-bus active
002aae200
002aae201
0.5
0.5
I
V
DD(sd)
(µA)
OL(OS)
(V)
0.4
0.4
V
= 5.5 V
4.5 V
3.3 V
2.8 V
CC
V
= 5.5 V
4.5 V
3.3 V
2.8 V
CC
0.3
0.2
0.1
0
0.3
0.2
0.1
0
−75
−25
25
75
125
(°C)
−75
−25
25
75
125
(°C)
T
T
amb
amb
Fig 15. Shutdown mode supply current
versus temperature
Fig 16. LOW-level output voltage on pin OS
versus temperature; IOL = 4 mA
002aae202
002aae203
0.5
2.0
V
OL(SDA)
T
(°C)
acc
(V)
0.4
0.3
0.2
0.1
0
V
= 5.5 V
4.5 V
3.3 V
2.8 V
CC
1.0
0
−1.0
−2.0
−75
−25
25
75
125
(°C)
−75
−25
25
75
125
(°C)
T
T
amb
amb
Fig 17. LOW-level output voltage on pin SDA
versus temperature; IOL = 4 mA
Fig 18. Typical temperature accuracy versus
temperature; VCC = 3.3 V
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
19 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
12. Dynamic characteristics
Table 18. I2C-bus interface dynamic characteristics[1]
VCC = 2.8 V to 5.5 V; Tamb = −55 °C to +125 °C; unless otherwise specified.
Symbol
fSCL
Parameter
Conditions
Min
0.02
0.6
1.3
100
100
0
Typ
Max
Unit
kHz
µs
SCL clock frequency
HIGH period of the SCL clock
LOW period of the SCL clock
hold time (repeated) START condition
data set-up time
see Figure 19
-
400
tHIGH
-
-
-
-
-
-
-
-
tLOW
-
µs
tHD;STA
tSU;DAT
tHD;DAT
tSU;STO
tf
-
ns
-
ns
data hold time
-
ns
set-up time for STOP condition
fall time
100
-
-
ns
SDA and OS outputs;
250
ns
CL = 400 pF; IOL = 3 mA
[2][3]
tto
time-out time
75
-
200
ms
[1] These specifications are guaranteed by design and not tested in production.
[2] This is the SDA time LOW for reset of serial interface.
[3] Holding the SDA line LOW for a time grater than tto will cause the LM75B to reset SDA to the idle state of the serial bus communication
(SDA set HIGH).
SDA
t
BUF
t
t
LOW
t
t
SP
SU;DAT
HD;STA
t
f
t
r
t
r
t
f
SCL
t
t
t
SU;STO
HD;STA
SU;STA
t
HIGH
S
Sr
P
S
t
HD;DAT
002aab271
Fig 19. Timing diagram
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
20 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
13. Package outline
SO8: plastic small outline package; 8 leads; body width 3.9 mm
SOT96-1
D
E
A
X
v
c
y
H
M
A
E
Z
5
8
Q
A
2
A
(A )
3
A
1
pin 1 index
θ
L
p
L
1
4
e
w
M
detail X
b
p
0
2.5
5 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
A
(1)
(1)
(2)
UNIT
A
A
A
b
c
D
E
e
H
L
L
p
Q
v
w
y
Z
θ
1
2
3
p
E
max.
0.25
0.10
1.45
1.25
0.49
0.36
0.25
0.19
5.0
4.8
4.0
3.8
6.2
5.8
1.0
0.4
0.7
0.6
0.7
0.3
mm
1.27
0.05
1.05
0.041
1.75
0.25
0.01
0.25
0.01
0.25
0.1
8o
0o
0.010 0.057
0.004 0.049
0.019 0.0100 0.20
0.014 0.0075 0.19
0.16
0.15
0.244
0.228
0.039 0.028
0.016 0.024
0.028
0.012
inches 0.069
0.01 0.004
Notes
1. Plastic or metal protrusions of 0.15 mm (0.006 inch) maximum per side are not included.
2. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
PROJECTION
ISSUE DATE
VERSION
IEC
JEDEC
JEITA
99-12-27
03-02-18
SOT96-1
076E03
MS-012
Fig 20. Package outline SOT96-1 (SO8)
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
21 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
TSSOP8: plastic thin shrink small outline package; 8 leads; body width 3 mm
SOT505-1
D
E
A
X
c
y
H
v
M
A
E
Z
5
8
A
(A )
2
A
3
A
1
pin 1 index
θ
L
p
L
1
4
detail X
e
w M
b
p
0
2.5
5 mm
scale
DIMENSIONS (mm are the original dimensions)
A
(1)
(2)
(1)
A
A
A
b
c
D
E
e
H
E
L
L
p
UNIT
v
w
y
Z
θ
1
2
3
p
max.
0.15
0.05
0.95
0.80
0.45
0.25
0.28
0.15
3.1
2.9
3.1
2.9
5.1
4.7
0.7
0.4
0.70
0.35
6°
0°
mm
1.1
0.65
0.25
0.94
0.1
0.1
0.1
Notes
1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.
2. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
PROJECTION
ISSUE DATE
VERSION
IEC
JEDEC
JEITA
99-04-09
03-02-18
SOT505-1
Fig 21. Package outline SOT505-1 (TSSOP8)
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
22 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
XSON8U: plastic extremely thin small outline package; no leads;
8 terminals; UTLP based; body 3 x 2 x 0.5 mm
SOT996-2
D
B
A
E
A
A
1
detail X
terminal 1
index area
e
1
C
M
M
v
C
C
A
B
b
e
L
1
y
y
w
C
1
1
4
L
2
L
8
5
X
0
1
2 mm
scale
DIMENSIONS (mm are the original dimensions)
A
UNIT
A
1
b
D
E
e
e
1
L
L
L
v
w
y
y
1
1
2
max
0.05 0.35
0.00 0.15
2.1
1.9
3.1
2.9
0.5
0.3
0.15
0.05
0.6
0.4
mm
0.5
0.5
1.5
0.1
0.05 0.05
0.1
REFERENCES
OUTLINE
VERSION
EUROPEAN
PROJECTION
ISSUE DATE
IEC
- - -
JEDEC
JEITA
07-12-18
07-12-21
SOT996-2
- - -
Fig 22. Package outline SOT996-2 (XSON8U)
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
14. Soldering of SMD packages
This text provides a very brief insight into a complex technology. A more in-depth account
of soldering ICs can be found in Application Note AN10365 “Surface mount reflow
soldering description”.
14.1 Introduction to soldering
Soldering is one of the most common methods through which packages are attached to
Printed Circuit Boards (PCBs), to form electrical circuits. The soldered joint provides both
the mechanical and the electrical connection. There is no single soldering method that is
ideal for all IC packages. Wave soldering is often preferred when through-hole and
Surface Mount Devices (SMDs) are mixed on one printed wiring board; however, it is not
suitable for fine pitch SMDs. Reflow soldering is ideal for the small pitches and high
densities that come with increased miniaturization.
14.2 Wave and reflow soldering
Wave soldering is a joining technology in which the joints are made by solder coming from
a standing wave of liquid solder. The wave soldering process is suitable for the following:
• Through-hole components
• Leaded or leadless SMDs, which are glued to the surface of the printed circuit board
Not all SMDs can be wave soldered. Packages with solder balls, and some leadless
packages which have solder lands underneath the body, cannot be wave soldered. Also,
leaded SMDs with leads having a pitch smaller than ~0.6 mm cannot be wave soldered,
due to an increased probability of bridging.
The reflow soldering process involves applying solder paste to a board, followed by
component placement and exposure to a temperature profile. Leaded packages,
packages with solder balls, and leadless packages are all reflow solderable.
Key characteristics in both wave and reflow soldering are:
• Board specifications, including the board finish, solder masks and vias
• Package footprints, including solder thieves and orientation
• The moisture sensitivity level of the packages
• Package placement
• Inspection and repair
• Lead-free soldering versus SnPb soldering
14.3 Wave soldering
Key characteristics in wave soldering are:
• Process issues, such as application of adhesive and flux, clinching of leads, board
transport, the solder wave parameters, and the time during which components are
exposed to the wave
• Solder bath specifications, including temperature and impurities
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
24 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
14.4 Reflow soldering
Key characteristics in reflow soldering are:
• Lead-free versus SnPb soldering; note that a lead-free reflow process usually leads to
higher minimum peak temperatures (see Figure 23) than a SnPb process, thus
reducing the process window
• Solder paste printing issues including smearing, release, and adjusting the process
window for a mix of large and small components on one board
• Reflow temperature profile; this profile includes preheat, reflow (in which the board is
heated to the peak temperature) and cooling down. It is imperative that the peak
temperature is high enough for the solder to make reliable solder joints (a solder paste
characteristic). In addition, the peak temperature must be low enough that the
packages and/or boards are not damaged. The peak temperature of the package
depends on package thickness and volume and is classified in accordance with
Table 19 and 20
Table 19. SnPb eutectic process (from J-STD-020C)
Package thickness (mm) Package reflow temperature (°C)
Volume (mm3)
< 350
235
≥ 350
220
< 2.5
≥ 2.5
220
220
Table 20. Lead-free process (from J-STD-020C)
Package thickness (mm) Package reflow temperature (°C)
Volume (mm3)
< 350
260
350 to 2000
> 2000
260
< 1.6
260
250
245
1.6 to 2.5
> 2.5
260
245
250
245
Moisture sensitivity precautions, as indicated on the packing, must be respected at all
times.
Studies have shown that small packages reach higher temperatures during reflow
soldering, see Figure 23.
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
25 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
maximum peak temperature
= MSL limit, damage level
temperature
minimum peak temperature
= minimum soldering temperature
peak
temperature
time
001aac844
MSL: Moisture Sensitivity Level
Fig 23. Temperature profiles for large and small components
For further information on temperature profiles, refer to Application Note AN10365
“Surface mount reflow soldering description”.
15. Abbreviations
Table 21. Abbreviations
Acronym
A-to-D
CDM
Description
Analog-to-Digital
Charged Device Model
ElectroStatic Discharge
Human Body Model
Inter-Integrated Circuit bus
Input/Output
ESD
HBM
I2C-bus
I/O
LSB
Lease Significant Bit
Least Significant Byte
Machine Model
LSByte
MM
MSB
Most Significant Bit
Most Significant Byte
Power-On Reset
MSByte
POR
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
16. Revision history
Table 22. Revision history
Document ID
LM75B_2
Release date
Data sheet status
Change notice
Supersedes
20081209
Product data sheet
-
LM75B_1
Modifications:
• added XSON8U package option (affects Section 2 “Features”, Table 1 “Ordering information”,
Section 6.1 “Pinning”, Table 14 “LM75A and LM75B comparison”, Section 13 “Package outline”)
LM75B_1
20081204
Product data sheet
-
-
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
27 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
17. Legal information
17.1 Data sheet status
Document status[1][2]
Product status[3]
Development
Definition
Objective [short] data sheet
This document contains data from the objective specification for product development.
This document contains data from the preliminary specification.
This document contains the product specification.
Preliminary [short] data sheet Qualification
Product [short] data sheet Production
[1]
[2]
[3]
Please consult the most recently issued document before initiating or completing a design.
The term ‘short data sheet’ is explained in section “Definitions”.
The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status
information is available on the Internet at URL http://www.nxp.com.
to result in personal injury, death or severe property or environmental
17.2 Definitions
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences of
use of such information.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Limiting values — Stress above one or more limiting values (as defined in
the Absolute Maximum Ratings System of IEC 60134) may cause permanent
damage to the device. Limiting values are stress ratings only and operation of
the device at these or any other conditions above those given in the
Characteristics sections of this document is not implied. Exposure to limiting
values for extended periods may affect device reliability.
Short data sheet — A short data sheet is an extract from a full data sheet
with the same product type number(s) and title. A short data sheet is intended
for quick reference only and should not be relied upon to contain detailed and
full information. For detailed and full information see the relevant full data
sheet, which is available on request via the local NXP Semiconductors sales
office. In case of any inconsistency or conflict with the short data sheet, the
full data sheet shall prevail.
Terms and conditions of sale — NXP Semiconductors products are sold
subject to the general terms and conditions of commercial sale, as published
at http://www.nxp.com/profile/terms, including those pertaining to warranty,
intellectual property rights infringement and limitation of liability, unless
explicitly otherwise agreed to in writing by NXP Semiconductors. In case of
any inconsistency or conflict between information in this document and such
terms and conditions, the latter will prevail.
17.3 Disclaimers
General — Information in this document is believed to be accurate and
reliable. However, NXP Semiconductors does not give any representations or
warranties, expressed or implied, as to the accuracy or completeness of such
information and shall have no liability for the consequences of use of such
information.
No offer to sell or license — Nothing in this document may be interpreted
or construed as an offer to sell products that is open for acceptance or the
grant, conveyance or implication of any license under any copyrights, patents
or other industrial or intellectual property rights.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
17.4 Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in medical, military, aircraft,
space or life support equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
I2C-bus — logo is a trademark of NXP B.V.
18. Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
LM75B_2
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 02 — 9 December 2008
28 of 29
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
19. Contents
1
2
3
4
5
General description . . . . . . . . . . . . . . . . . . . . . . 1
17.3
17.4
Disclaimers. . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Ordering information. . . . . . . . . . . . . . . . . . . . . 2
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 3
18
19
Contact information . . . . . . . . . . . . . . . . . . . . 28
Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6
6.1
6.2
Pinning information. . . . . . . . . . . . . . . . . . . . . . 3
Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 4
7
7.1
7.2
7.2.1
7.3
Functional description . . . . . . . . . . . . . . . . . . . 4
General operation. . . . . . . . . . . . . . . . . . . . . . . 4
I2C-bus serial interface . . . . . . . . . . . . . . . . . . . 6
Bus fault time-out . . . . . . . . . . . . . . . . . . . . . . . 6
Slave address . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Register list. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pointer register . . . . . . . . . . . . . . . . . . . . . . . . . 7
Configuration register . . . . . . . . . . . . . . . . . . . . 7
Temperature register. . . . . . . . . . . . . . . . . . . . . 8
Overtemperature shutdown threshold (Tos)
7.4
7.4.1
7.4.2
7.4.3
7.4.4
and hysteresis (Thyst) registers . . . . . . . . . . . . 9
OS output and polarity . . . . . . . . . . . . . . . . . . 10
OS comparator and interrupt modes . . . . . . . 10
OS fault queue . . . . . . . . . . . . . . . . . . . . . . . . 11
Shutdown mode . . . . . . . . . . . . . . . . . . . . . . . 11
Power-up default and power-on reset. . . . . . . 11
Protocols for writing and reading the registers 12
7.5
7.6
7.7
7.8
7.9
7.10
8
Application design-in information . . . . . . . . . 15
Typical application. . . . . . . . . . . . . . . . . . . . . . 15
LM75A and LM75B comparison . . . . . . . . . . . 15
Temperature accuracy . . . . . . . . . . . . . . . . . . 16
Noise effect. . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1
8.2
8.3
8.4
9
Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . 17
Recommended operating conditions. . . . . . . 17
Static characteristics. . . . . . . . . . . . . . . . . . . . 18
Dynamic characteristics . . . . . . . . . . . . . . . . . 20
Package outline . . . . . . . . . . . . . . . . . . . . . . . . 21
10
11
12
13
14
Soldering of SMD packages . . . . . . . . . . . . . . 24
Introduction to soldering . . . . . . . . . . . . . . . . . 24
Wave and reflow soldering . . . . . . . . . . . . . . . 24
Wave soldering . . . . . . . . . . . . . . . . . . . . . . . . 24
Reflow soldering . . . . . . . . . . . . . . . . . . . . . . . 25
14.1
14.2
14.3
14.4
15
16
Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . 26
Revision history. . . . . . . . . . . . . . . . . . . . . . . . 27
17
17.1
17.2
Legal information. . . . . . . . . . . . . . . . . . . . . . . 28
Data sheet status . . . . . . . . . . . . . . . . . . . . . . 28
Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.
© NXP B.V. 2008.
All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
Date of release: 9 December 2008
Document identifier: LM75B_2
相关型号:
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