LM75B
Digital temperature sensor and thermal watchdog
Rev. 6.1 — 6 February 2015
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 two’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 (that is, 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 and benefits
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
I2C-bus interface with up to 8 devices on the same bus
Power supply range from 2.8 V to 5.5 V
Temperatures range from 55 C to +125 C
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
Frequency range 20 Hz to 400 kHz with bus fault time-out to prevent hanging up the
bus
11-bit ADC that offers a temperature resolution of 0.125 C
Temperature accuracy of:
2 C from 25 C to +100 C
3 C from 55 C to +125 C
Programmable temperature threshold and hysteresis set points
Supply current of 1.0 A in shutdown mode for power conservation
Stand-alone operation as thermostat at power-up
ESD protection exceeds 4500 V HBM per JESD22-A114 and 1000 V CDM per
JESD22-C101
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
Small 8-pin package types: SO8, TSSOP8, 3 mm 2 mm XSON8U, and
2 mm 3 mm HWSON8
3. Applications
LM75B
Product data sheet
System thermal management
Personal computers
Electronics equipment
Industrial controllers
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
4. Ordering information
Table 1.
Ordering information
Type
number
Topside
mark
Package
Name
Description
Version
LM75BD
LM75BD
SO8
plastic small outline package; 8 leads; body width 3.9 mm
SOT96-1
LM75BDP
LM75B
TSSOP8
plastic thin shrink small outline package; 8 leads; body width 3 mm
SOT505-1
LM75BGD[1]
75B
XSON8U
plastic extremely thin small outline package; no leads; 8 terminals;
UTLP based; body 3 2 0.5 mm
SOT996-2
LM75BTP
M75
HWSON8 plastic thermal enhanced very very thin small outline package;
no leads; 8 terminals, 2 3 0.8 mm
[1]
SOT1069-2
LM75BGD cannot be production cold temperature tested because of manufacturing process constraints. Although no LM75BGD
complaints have been noted, NXP recommends consideration/use of the LM75BTP instead of the LM75BGD in operating environments
of less than 0 C.
4.1 Ordering options
Table 2.
Ordering options
Type number
Orderable
part number
Package
Packing method
Minimum
order
quantity
Temperature
LM75BD
LM75BD,112
SO8
Standard marking * IC’s tube DSC bulk pack
2000
Tamb = 55 C to +125 C
LM75BD,118
SO8
Reel 13” Q1/T1
*Standard mark SMD
2500
Tamb = 55 C to +125 C
LM75BDP
LM75BDP,118
TSSOP8
Reel 13” Q1/T1
*Standard mark SMD
2500
Tamb = 55 C to +125 C
LM75BGD
LM75BGD,125
XSON8U
Reel 7” Q3/T4 *Standard mark
3000
Tamb = 55 C to +125 C
LM75BTP
LM75BTP,147
HWSON8
Reel 7” Q2/T3 *Standard mark
4000
Tamb = 55 C to +125 C
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
5. Block diagram
VCC
LM75B
BIAS
REFERENCE
BAND GAP
TEMP SENSOR
POINTER
REGISTER
CONFIGURATION
REGISTER
COUNTER
TEMPERATURE
REGISTER
TIMER
TOS
REGISTER
COMPARATOR/
INTERRUPT
THYST
REGISTER
11-BIT
SIGMA-DELTA
A-to-D
CONVERTER
OSCILLATOR
POWER-ON
RESET
OS
LOGIC CONTROL AND INTERFACE
002aad453
A2
Fig 1.
A1
A0
SCL SDA
GND
Block diagram of LM75B
6. Pinning information
6.1 Pinning
SDA
1
8
VCC
SCL
2
7
A0
OS
3
6
SDA
1
8
VCC
SCL
2
7
A0
A1
OS
3
6
A1
A2
GND
4
5
A2
LM75BD
GND
5
4
002aad455
002aad454
Fig 2.
LM75BDP
Pin configuration for SO8
Fig 3.
SDA
1
8
VCC
SCL
2
7
A0
OS
3
6
A1
GND
4
5
A2
Pin configuration for TSSOP8
terminal 1
index area
LM75BGD
SDA
1
SCL
2
LM75B
Product data sheet
A0
OS
3
6
A1
GND
4
5
A2
002aag155
Fig 5.
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Rev. 6.1 — 6 February 2015
7
Transparent top view
Transparent top view
Pin configuration for XSON8U
VCC
LM75BTP
002aae234
Fig 4.
8
Pin configuration for HWSON8
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
6.2 Pin description
Table 3.
Pin description
Symbol
Pin
Description
SDA
1
Digital I/O. I2C-bus serial bidirectional data line; open-drain.
SCL
2
Digital input. I2C-bus serial clock input.
OS
3
Overtemperature Shutdown output; open-drain.
GND
4
Ground. To be connected to the system ground.
A2
5
Digital input. User-defined address bit 2.
A1
6
Digital input. User-defined address bit 1.
A0
7
Digital input. User-defined address bit 0.
VCC
8
Power supply.
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 two’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
two’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
Product data sheet
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LM75B
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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 6.
Tth(ots)
Thys
reading temperature limits
OS reset
OS active
OS output in comparator mode
OS reset
(1)
(1)
(1)
OS active
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 6.
LM75B
Product data sheet
OS response to temperature
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LM75B
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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 k,
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 4 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 4.
Address table
1 = HIGH; 0 = LOW.
MSB
1
LSB
0
0
1
A2
A1
A0
7.4 Register list
The LM75B contains four data registers beside the pointer register as listed in Table 5.
The pointer value, read/write capability and default content at power-up of the registers
are also shown in Table 5.
LM75B
Product data sheet
Table 5.
Register table
Register
name
Pointer
value
R/W
POR
state
Description
Conf
01h
R/W
00h
Configuration register: contains a single 8-bit data
byte; to set the device operating condition; default = 0.
Temp
00h
read only
n/a
Temperature register: contains two 8-bit data bytes;
to store the measured Temp data.
Tos
03h
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.
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LM75B
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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 6 and Table 7. 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 6.
Pointer register
B7
B6
B5
B4
B3
B2
B[1:0]
0
0
0
0
0
0
pointer value
Table 7.
Pointer value
B1
B0
Selected register
0
0
Temperature register (Temp)
0
1
Configuration register (Conf)
1
0
Hysteresis register (Thyst)
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. However, the first
temperature reading will be incorrect and must be ignored. Subsequent reads of the
temperature register will be correct.
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 8 shows the bit assignments of this register.
Table 8.
Conf register
Legend: * = default value.
LM75B
Product data sheet
Bit
Symbol
Access Value Description
B[7:5]
reserved
R/W
B[4:3]
OS_F_QUE[1:0] R/W
000*
reserved for manufacturer’s use; should be kept as
zeroes for normal operation
OS fault queue programming
00*
queue value = 1
01
queue value = 2
10
queue value = 4
11
queue value = 6
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LM75B
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Digital temperature sensor and thermal watchdog
Table 8.
Conf register …continued
Legend: * = default value.
Bit
Symbol
Access Value Description
B2
OS_POL
R/W
OS polarity selection
0*
OS active LOW
1
B1
OS active HIGH
OS_COMP_INT R/W
B0
SHUTDOWN
OS operation mode selection
0*
OS comparator
1
OS interrupt
R/W
device operation mode selection
0*
normal
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 two’s complement format with the resolution of 0.125 C. Table 9 shows
the bit arrangement of the Temp data in the data bytes.
Table 9.
Temp register
MSByte
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) = (two’s complement of Temp data) 0.125 C.
Examples of the Temp data and value are shown in Table 10.
Table 10.
LM75B
Product data sheet
Temp register value
11-bit binary
(two’s complement)
Hexadecimal value
Decimal value
Value
011 1111 1000
3F8
1016
+127.000 C
011 1111 0111
3F7
1015
+126.875 C
011 1111 0001
3F1
1009
+126.125 C
011 1110 1000
3E8
1000
+125.000 C
000 1100 1000
0C8
200
+25.000 C
000 0000 0001
001
1
+0.125 C
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Digital temperature sensor and thermal watchdog
Table 10.
Temp register value …continued
11-bit binary
(two’s complement)
Hexadecimal value
Decimal value
Value
000 0000 0000
000
0
0.000 C
111 1111 1111
7FF
1
0.125 C
111 0011 1000
738
200
25.000 C
110 0100 1001
649
439
54.875 C
110 0100 1000
648
440
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 two’s complement format with the resolution of 0.5 C. Table 11
and Table 12 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 11.
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 12.
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 13 shows examples of the limit data and value.
LM75B
Product data sheet
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Digital temperature sensor and thermal watchdog
Table 13.
Tos and Thyst limit data and value
11-bit binary
(two’s complement)
Hexadecimal value
Decimal value
Value
0 1111 1010
0FA
250
+125.0 C
0 0011 0010
032
50
+25.0 C
0 0000 0001
001
1
+0.5 C
0 0000 0000
000
0
0.0 C
1 1111 1111
1FF
1
0.5 C
1 1100 1110
1CE
50
25.0 C
1 1001 0010
192
110
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 k, 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
Product data sheet
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LM75B
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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 14
shows the one-to-one relationship between them. At power-up, fault queue data = 0 and
fault queue value = 1.
Table 14.
Fault queue table
Fault queue data
Fault queue value
OS_F_QUE[1]
OS_F_QUE[0]
Decimal
0
0
1
0
1
2
1
0
4
1
1
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 A 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 s and then rises up again, the device will be reset
to its default condition as listed above.
LM75B
Product data sheet
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12 of 37
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 7 to Figure 12 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
Product data sheet
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13 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
1
2
3
4
1
0
0
1
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
0
0
0
0
0
0
0
1
A
0
0
0
4
5
6
7
8
9
SCL
SDA
S
A2 A1 A0 W
A
device address
START
pointer byte
write
P
configuration data byte
device
acknowledge
device
acknowledge
Fig 7.
D4 D3 D2 D1 D0 A
device
acknowledge
STOP
001aad624
Write configuration register (1-byte data)
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
(next)
SCL
SDA
S
1
0
0
1
A2
A1
A0 W
0
A
0
0
device address
0
0
0
0
1
A
RS (next)
pointer byte
START
device
acknowledge
1
2
3
4
5
6
7
1
0
0
1
A2
A1
RE-START
device
acknowledge
write
8
9
A0 R
A
1
2
3
4
5
6
7
8
9
SCL (cont.)
SDA (cont.)
D7 D6 D5 D4 D3 D2 D1 D0 NA
device address
data byte from device
STOP
master not
acknowledged
read
device
acknowledge
Fig 8.
P
001aad625
Read configuration register including pointer byte (1-byte data)
1
2
3
4
5
6
7
1
0
0
1
A2
A1
8
9
A0 R
A
1
2
3
4
5
6
7
8
9
SCL
SDA
S
device address
START
D7 D6 D5 D4 D3 D2 D1 D0 NA
data byte from device
read
device
acknowledge
Fig 9.
P
master not
acknowledged
STOP
001aad626
Read configuration or temp register with preset pointer (1-byte data)
LM75B
Product data sheet
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© NXP B.V. 2015. All rights reserved.
14 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
(next)
SDA
S
1
0
0
1
A2
A1
A0
W
A
0
0
0
device address
0
0
device
acknowledge
3
4
P0
(next)
A
device
acknowledge
write
2
P1
pointer byte
START
1
0
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 A
D7 D6 D5 D4 D3 D2 D1 D0
MSByte data
A
P
LSByte data
STOP
device
acknowledge
device
acknowledge
002aad036
Fig 10. Write Tos or Thyst register (2-byte data)
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
0
SCL
SDA
(next)
S
1
0
0
1
A2 A1 A0 W A
0
0
device address
START
0
0
0
0
P1 P0 A RS (next)
pointer byte
1
2
3
4
device
acknowledge
5 6 7 8
1
0
0
1
A2 A1 A0 R
RE-START
device
acknowledge
write
9
A
1
2
3
4
5
6
7
8
1
9
2
3
4
5
6
7
8
9
SCL (cont)
SDA (cont)
D7 D6 D5 D4 D3 D2 D1 D0 A'
device address
D7 D6 D5 D4 D3 D2 D1 D0 NA
MSByte from device
LSByte from device
master
acknowledge
read
device
acknowledge
P
STOP
master not
acknowledged
002aad037
Fig 11. Read Temp, Tos or Thyst register including pointer byte (2-byte data)
1
2
3
4
1
0
0
1
5
6
7
8
9
A2 A1 A0 R
A
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
SCL
SDA
S
device address
START
D7 D6 D5 D4 D3 D2 D1 D0 A' D7 D6 D5 D4 D3 D2 D1 D0 NA
MSByte from device
read
device
acknowledge
master
acknowledge
P
LSByte from device
master not
acknowledged
STOP
002aad038
Fig 12. Read Temp, Tos or Thyst register with preset pointer (2-byte data)
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
8. Application design-in information
8.1 Typical application
power supply
0.1 μF
BUS
10 kΩ
PULL-UP
RESISTORS
10 kΩ
SCL
I2C-BUS
SDA
A2
DIGITAL LOGIC
10 kΩ
VCC
A1
A0
8
2
1
LM75B
3
OS
DETECTOR OR
INTERRUPT LINE
5
6
7
4
GND
002aad457
Fig 13. Typical application
8.2 LM75A and LM75B comparison
Table 15.
LM75A and LM75B comparison
Description
LM75A
availability of the XSON8U (3 mm 2 mm) package type
no
yes
OS output auto-reset when SHUTDOWN bit is set in interrupt mode[1]
no
yes
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]
(tHD;DAT)[4]
LM75B
10 ns
0 ns
ratio of conversion time / conversion period (typical)[5]
100 ms / 100 ms
10 ms / 100 ms
supply current in shutdown mode (typical value)
3.5 A
0.2 A
HBM ESD protection level (minimum)
>2000 V
>4500 V
minimum data hold time
MM ESD protection level (minimum)
>200 V
>450 V
CDM ESD protection level (minimum)
>1000 V
>2000 V
[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
Product data sheet
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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 at 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.
If you would like to calculate the effect of self-heating, use Equation 1 below:
Equation 1 is the formula to calculate the effect of self-heating:
T = R th j-a
V DD I DD AV + V OL SDA I OL sin k SDA + V OL EVENT I OL sin k EVENT
(1)
where:
T = Tj Tamb
Tj = junction temperature
Tamb = ambient temperature
Rth(j-a) = package thermal resistance
VDD = supply voltage
IDD(AV) = average supply current
VOL(SDA) = LOW-level output voltage on pin SDA
VOL(EVENT) = LOW-level output voltage on pin EVENT
IOL(sink)(SDA) = SDA output current LOW
IOL(sink)EVENT = EVENT output current LOW
Calculation example:
Tamb (typical temperature inside the notebook) = 50 C
IDD(AV) = 400 A
VDD = 3.6 V
Maximum VOL(SDA) = 0.4 V
IOL(sink)(SDA) = 1 mA
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
VOL(EVENT) = 0.4 V
IOL(sink)EVENT = 3 mA
Rth(j-a) = 56 C/W
Self heating due to power dissipation is:
T = 56 3.6 0.4 + 0.4 3 + 0.4 1 = 56 C W 3.04 mW = 0.17 C
(2)
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:
•
•
•
•
LM75B
Product data sheet
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.
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
9. Limiting values
Table 16. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
Conditions
Min
Max
Unit
VCC
supply voltage
0.3
+6.0
V
VI
input voltage
at input pins
0.3
+6.0
V
II
input current
at input pins
5.0
+5.0
mA
IO(sink)
output sink current
on pin OS
-
10.0
mA
VO
output voltage
on pin OS
0.3
+6.0
V
Tstg
storage temperature
65
+150
C
Tj
junction temperature
-
150
C
10. Recommended operating conditions
LM75B
Product data sheet
Table 17.
Recommended operating characteristics
Symbol
Parameter
VCC
Tamb
Conditions
Min
Typ
Max
Unit
supply voltage
2.8
-
5.5
V
ambient temperature
55
-
+125
C
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
11. Static characteristics
Table 18. Static characteristics
VCC = 2.8 V to 5.5 V; Tamb = 55 C to +125 C; unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ[1]
Max
Unit
Tacc
temperature accuracy
Tamb = 25 C to +100 C
2
-
+2
C
Tamb = 55 C to +125 C
3
-
+3
C
Tres
temperature resolution
11-bit digital temp data
-
0.125
-
C
tconv(T)
temperature conversion
time
normal mode
-
10
-
ms
Tconv
conversion period
normal mode
-
100
-
ms
IDD(AV)
average supply current
normal mode: I2C-bus inactive
-
100
200
A
-
-
300
A
I2C-bus
normal mode:
fSCL = 400 kHz
active;
shutdown mode
-
0.2
1.0
A
VIH
HIGH-level input voltage
digital pins (SCL, SDA, A2 to A0)
0.7 VCC
-
VCC + 0.3
V
VIL
LOW-level input voltage
digital pins
0.3
-
0.3 VCC
V
VI(hys)
hysteresis of input voltage SCL and SDA pins
-
300
-
mV
A2, A1, A0 pins
-
150
-
mV
IIH
HIGH-level input current
digital pins; VI = VCC
1.0
-
+1.0
A
IIL
LOW-level input current
digital pins; VI = 0 V
1.0
-
+1.0
A
VOL
LOW-level output voltage
SDA and OS pins; IOL = 3 mA
-
-
0.4
V
IOL = 4 mA
-
-
0.8
V
ILO
output leakage current
SDA and OS pins; VOH = VCC
-
-
10
A
Nfault
number of faults
programmable; conversions in
overtemperature-shutdown fault
queue
1
-
6
Tth(ots)
overtemperature
shutdown threshold
temperature
default value
-
80
-
C
Thys
hysteresis temperature
default value
-
75
-
C
Ci
input capacitance
digital pins
-
20
-
pF
[1]
Typical values are at VCC = 3.3 V and Tamb = 25 C.
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
002aae198
300
IDD(AV)
(μA)
200
IDD(AV)
(μA)
VCC = 5.5 V
4.5 V
3.3 V
2.8 V
100
0
−75
−25
25
75
002aae200
0.5
IDD(sd)
(μA)
0.4
VCC = 5.5 V
4.5 V
3.3 V
2.8 V
0.3
0
−75
125
Tamb (°C)
Fig 14. Average supply current versus temperature;
I2C-bus inactive
0.3
0.1
0.1
−25
25
75
0
−75
125
Tamb (°C)
Fig 16. Shutdown mode supply current
versus temperature
25
75
125
Tamb (°C)
002aae201
0.5
VOL(OS)
(V)
0.4
0.2
0
−75
−25
Fig 15. Average supply current versus temperature;
I2C-bus active
0.2
0.3
VCC = 5.5 V
4.5 V
3.3 V
2.8 V
200
100
0.5
VOL(SDA)
(V)
0.4
002aae199
300
VCC = 5.5 V
4.5 V
3.3 V
2.8 V
−25
25
75
125
Tamb (°C)
Fig 17. LOW-level output voltage on pin OS
versus temperature; IOL = 4 mA
002aae202
002aae203
2.0
Tacc
(°C)
VCC = 5.5 V
4.5 V
3.3 V
2.8 V
1.0
0
0.2
−1.0
0.1
0
−75
−25
25
75
125
Tamb (°C)
Fig 18. LOW-level output voltage on pin SDA
versus temperature; IOL = 4 mA
LM75B
Product data sheet
−2.0
−75
−25
25
75
125
Tamb (°C)
Fig 19. Typical temperature accuracy versus
temperature; VCC = 3.3 V
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
12. Dynamic characteristics
Table 19. I2C-bus interface dynamic characteristics[1]
VCC = 2.8 V to 5.5 V; Tamb = 55 C to +125 C; unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
fSCL
SCL clock frequency
see Figure 20
0.02
-
400
kHz
tHIGH
HIGH period of the SCL clock
0.6
-
-
s
tLOW
LOW period of the SCL clock
1.3
-
-
s
tHD;STA
hold time (repeated) START condition
100
-
-
ns
tSU;DAT
data set-up time
100
-
-
ns
tHD;DAT
data hold time
0
-
-
ns
tSU;STO
set-up time for STOP condition
100
-
-
ns
tf
fall time
-
250
-
ns
tto
time-out time
75
-
200
ms
SDA and OS outputs;
CL = 400 pF; IOL = 3 mA
[2][3]
[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 greater than tto will cause the LM75B to reset SDA to the idle state of the serial bus communication
(SDA set HIGH).
0.7 × VDD
0.3 × VDD
SDA
tLOW
tf
tSU;DAT
tr
tHD;STA
tSP
tf
tBUF
tr
0.7 × VDD
0.3 × VDD
SCL
tHD;STA
S
tHIGH
tHD;DAT
tSU;STA
tSU;STO
Sr
P
S
002aab271
Fig 20. Timing diagram
LM75B
Product data sheet
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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
c
y
HE
v M A
Z
5
8
Q
A2
A
(A 3)
A1
pin 1 index
θ
Lp
1
L
4
e
detail X
w M
bp
0
2.5
5 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
UNIT
A
max.
A1
A2
A3
bp
c
D (1)
E (2)
e
HE
L
Lp
Q
v
w
y
Z (1)
mm
1.75
0.25
0.10
1.45
1.25
0.25
0.49
0.36
0.25
0.19
5.0
4.8
4.0
3.8
1.27
6.2
5.8
1.05
1.0
0.4
0.7
0.6
0.25
0.25
0.1
0.7
0.3
0.01
0.019 0.0100
0.014 0.0075
0.20
0.19
0.16
0.15
inches
0.010 0.057
0.069
0.004 0.049
0.05
0.244
0.039 0.028
0.041
0.228
0.016 0.024
0.01
0.01
0.028
0.004
0.012
θ
8o
o
0
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
VERSION
IEC
JEDEC
SOT96-1
076E03
MS-012
JEITA
EUROPEAN
PROJECTION
ISSUE DATE
99-12-27
03-02-18
Fig 21. Package outline SOT96-1 (SO8)
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Digital temperature sensor and thermal watchdog
TSSOP8: plastic thin shrink small outline package; 8 leads; body width 3 mm
D
E
SOT505-1
A
X
c
y
HE
v M A
Z
5
8
A2
pin 1 index
(A3)
A1
A
θ
Lp
L
1
4
detail X
e
w M
bp
0
2.5
5 mm
scale
DIMENSIONS (mm are the original dimensions)
UNIT
A
max.
A1
A2
A3
bp
c
D(1)
E(2)
e
HE
L
Lp
v
w
y
Z(1)
θ
mm
1.1
0.15
0.05
0.95
0.80
0.25
0.45
0.25
0.28
0.15
3.1
2.9
3.1
2.9
0.65
5.1
4.7
0.94
0.7
0.4
0.1
0.1
0.1
0.70
0.35
6°
0°
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.
OUTLINE
VERSION
REFERENCES
IEC
JEDEC
JEITA
EUROPEAN
PROJECTION
ISSUE DATE
99-04-09
03-02-18
SOT505-1
Fig 22. Package outline SOT505-1 (TSSOP8)
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Digital temperature sensor and thermal watchdog
XSON8: plastic extremely thin small outline package; no leads;
8 terminals; body 3 x 2 x 0.5 mm
B
D
SOT996-2
A
E
A
A1
detail X
terminal 1
index area
e1
1
4
8
5
C
C A B
C
v
w
b
e
L1
y
y1 C
L2
L
X
0
1
2 mm
scale
Dimensions (mm are the original dimensions)
Unit(1)
mm
max
nom
min
A
A1
b
0.05 0.35
D
E
2.1
3.1
0.5
0.00 0.15
1.9
e
e1
0.5
1.5
2.9
L
L1
L2
0.5
0.15
0.6
0.3
0.05
0.4
v
0.1
w
y
0.05 0.05
y1
0.1
sot996-2_po
Outline
version
References
IEC
JEDEC
JEITA
European
projection
Issue date
07-12-21
12-11-20
SOT996-2
Fig 23. Package outline SOT996-2 (XSON8U)
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
HWSON8: plastic thermal enhanced very very thin small outline package; no leads;
8 terminals; body 2 x 3 x 0.75 mm
SOT1069-2
X
B
D
A
A2
A
E
A1
A3
terminal 1
index area
detail X
e1
terminal 1
index area
e
1
4
C
C A B
C
v
w
b
y
y1 C
L
K
E2
8
5
D2
0
1
scale
Dimensions
Unit
mm
2 mm
A(1)
A1
A2
max 0.80 0.05 0.65
nom 0.75 0.02 0.55
min 0.70 0.00 0.45
A3
b
D(1)
D2
E(1)
E2
0.2
0.30
0.25
0.18
2.1
2.0
1.9
1.6
1.5
1.4
3.1
3.0
2.9
1.6
1.5
1.4
e
0.5
e1
1.5
K
L
0.40 0.45
0.35 0.40
0.30 0.35
v
0.1
w
y
y1
0.05 0.05 0.05
Note
1. Plastic or metal protrusions of 0.075 mm maximum per side are not included.
References
Outline
version
IEC
JEDEC
JEITA
SOT1069-2
---
MO-229
---
sot1069-2_po
European
projection
Issue date
09-11-18
12-04-18
Fig 24. Package outline SOT1069-2 (HWSON8)
LM75B
Product data sheet
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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
Product data sheet
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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 25) 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 20 and 21
Table 20.
SnPb eutectic process (from J-STD-020D)
Package thickness (mm)
Package reflow temperature (C)
Volume (mm3)
< 350
350
< 2.5
235
220
2.5
220
220
Table 21.
Lead-free process (from J-STD-020D)
Package thickness (mm)
Package reflow temperature (C)
Volume (mm3)
< 350
350 to 2000
> 2000
< 1.6
260
260
260
1.6 to 2.5
260
250
245
> 2.5
250
245
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 25.
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
temperature
maximum peak temperature
= MSL limit, damage level
minimum peak temperature
= minimum soldering temperature
peak
temperature
time
001aac844
MSL: Moisture Sensitivity Level
Fig 25. Temperature profiles for large and small components
For further information on temperature profiles, refer to Application Note AN10365
“Surface mount reflow soldering description”.
LM75B
Product data sheet
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NXP Semiconductors
Digital temperature sensor and thermal watchdog
15. Soldering: PCB footprints
5.50
0.60 (8×)
1.30
4.00
6.60
7.00
1.27 (6×)
solder lands
occupied area
placement accuracy ± 0.25
Dimensions in mm
sot096-1_fr
Fig 26. PCB footprint for SOT96-1 (SO8); reflow soldering
1.20 (2×)
0.60 (6×)
enlarged solder land
0.3 (2×)
1.30
4.00
6.60
7.00
1.27 (6×)
5.50
board direction
solder lands
occupied area
solder resist
placement accurracy ± 0.25
Dimensions in mm
sot096-1_fw
Fig 27. PCB footprint for SOT96-1 (SO8); wave soldering
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
3.600
2.950
0.125
0.725
0.125
5.750
3.200
3.600
5.500
1.150
0.600
0.450
0.650
solder lands
occupied area
Dimensions in mm
sot505-1_fr
Fig 28. PCB footprint for SOT505-1 (TSSOP8); reflow soldering
LM75B
Product data sheet
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LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
2.400 pa + oa
2.000
0.500
0.500
0.250
0.025
0.025
4.250
3.400
pa + oa
2.000
4.000
0.900
solder lands
placement area
solder paste
occupied area
Dimensions in mm
sot996-2_fr
Fig 29. PCB footprint for SOT996-2 (XSON8U); reflow soldering
LM75B
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 6 February 2015
© NXP B.V. 2015. All rights reserved.
32 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
)RRWSULQWLQIRUPDWLRQIRUUHIORZVROGHULQJRI+:621SDFNDJH
627
*[
'
3
&
Q63[
+\
63\
*\
6/\
%\
$\
Q63\
63[
6/[
VROGHUODQG
VROGHUSDVWHGHSRVLW
VROGHUODQGSOXVVROGHUSDVWH
RFFXSLHGDUHD
',0(16,216LQPP
3
$\
%\
&
'
6/[
6/\
63[
63\
*[
*\
+\
Q63[
Q63\
,VVXHGDWH
VRW BIU
Fig 30. PCB footprint for SOT1069-2 (HWSON8); reflow soldering
LM75B
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 6 February 2015
© NXP B.V. 2015. All rights reserved.
33 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
16. Abbreviations
Table 22.
Abbreviations
Acronym
Description
A-to-D
Analog-to-Digital
CDM
Charged-Device Model
ESD
ElectroStatic Discharge
HBM
Human Body Model
I2C-bus
Inter-Integrated Circuit bus
I/O
Input/Output
LSB
Lease Significant Bit
LSByte
Least Significant Byte
MSB
Most Significant Bit
MSByte
Most Significant Byte
POR
Power-On Reset
17. Revision history
Table 23.
Revision history
Document ID
Release date
Data sheet status
Change notice
Supersedes
LM75B v.6.1
20150206
Product data sheet
-
LM75B v.6
Modifications:
•
Section 7.4.1 “Pointer register”: Added text “However, the first temperature reading...” to end of
section. Further explanation of actual operation; no change to device.
LM75B v.6
20140811
Product data sheet
-
LM75B v.5
LM75B v.5
20140122
Product data sheet
-
LM75B v.4
LM75B v.4
20130207
Product data sheet
-
LM75B v.3
LM75B v.3
20111227
Product data sheet
-
LM75B v.2
LM75B v.2
20081209
Product data sheet
-
LM75B v.1
LM75B v.1
20081204
Product data sheet
-
-
LM75B
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 6 February 2015
© NXP B.V. 2015. All rights reserved.
34 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
18. Legal information
18.1 Data sheet status
Document status[1][2]
Product status[3]
Definition
Objective [short] data sheet
Development
This document contains data from the objective specification for product development.
Preliminary [short] data sheet
Qualification
This document contains data from the preliminary specification.
Product [short] data sheet
Production
This document contains the product specification.
[1]
Please consult the most recently issued document before initiating or completing a design.
[2]
The term ‘short data sheet’ is explained in section “Definitions”.
[3]
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.
18.2 Definitions
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.
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.
Product specification — The information and data provided in a Product
data sheet shall define the specification of the product as agreed between
NXP Semiconductors and its customer, unless NXP Semiconductors and
customer have explicitly agreed otherwise in writing. In no event however,
shall an agreement be valid in which the NXP Semiconductors product is
deemed to offer functions and qualities beyond those described in the
Product data sheet.
18.3 Disclaimers
Limited warranty and liability — 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. NXP Semiconductors takes no
responsibility for the content in this document if provided by an information
source outside of NXP Semiconductors.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation - lost
profits, lost savings, business interruption, costs related to the removal or
replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability towards
customer for the products described herein shall be limited in accordance
with the Terms and conditions of commercial sale of NXP Semiconductors.
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.
LM75B
Product data sheet
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors and its suppliers accept 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.
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.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP Semiconductors
accepts no liability for any assistance with applications or customer product
design. It is customer’s sole responsibility to determine whether the NXP
Semiconductors product is suitable and fit for the customer’s applications and
products planned, as well as for the planned application and use of
customer’s third party customer(s). Customers should provide appropriate
design and operating safeguards to minimize the risks associated with their
applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Limiting values — Stress above one or more limiting values (as defined in
the Absolute Maximum Ratings System of IEC 60134) will cause permanent
damage to the device. Limiting values are stress ratings only and (proper)
operation of the device at these or any other conditions above those given in
the Recommended operating conditions section (if present) or the
Characteristics sections of this document is not warranted. Constant or
repeated exposure to limiting values will permanently and irreversibly affect
the quality and reliability of the device.
Terms and conditions of commercial 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, unless otherwise
agreed in a valid written individual agreement. In case an individual
agreement is concluded only the terms and conditions of the respective
agreement shall apply. NXP Semiconductors hereby expressly objects to
applying the customer’s general terms and conditions with regard to the
purchase of NXP Semiconductors products by customer.
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.
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 6 February 2015
© NXP B.V. 2015. All rights reserved.
35 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from competent authorities.
Non-automotive qualified products — Unless this data sheet expressly
states that this specific NXP Semiconductors product is automotive qualified,
the product is not suitable for automotive use. It is neither qualified nor tested
in accordance with automotive testing or application requirements. NXP
Semiconductors accepts no liability for inclusion and/or use of
non-automotive qualified products in automotive equipment or applications.
In the event that customer uses the product for design-in and use in
automotive applications to automotive specifications and standards, customer
(a) shall use the product without NXP Semiconductors’ warranty of the
product for such automotive applications, use and specifications, and (b)
whenever customer uses the product for automotive applications beyond
NXP Semiconductors’ specifications such use shall be solely at customer’s
own risk, and (c) customer fully indemnifies NXP Semiconductors for any
liability, damages or failed product claims resulting from customer design and
use of the product for automotive applications beyond NXP Semiconductors’
standard warranty and NXP Semiconductors’ product specifications.
Translations — A non-English (translated) version of a document is for
reference only. The English version shall prevail in case of any discrepancy
between the translated and English versions.
18.4 Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
I2C-bus — logo is a trademark of NXP Semiconductors N.V.
19. Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
LM75B
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36 of 37
LM75B
NXP Semiconductors
Digital temperature sensor and thermal watchdog
20. Contents
1
2
3
4
4.1
5
6
6.1
6.2
7
7.1
7.2
7.2.1
7.3
7.4
7.4.1
7.4.2
7.4.3
7.4.4
7.5
7.6
7.7
7.8
7.9
7.10
8
8.1
8.2
8.3
8.4
9
10
11
12
13
14
14.1
14.2
14.3
14.4
15
16
17
General description . . . . . . . . . . . . . . . . . . . . . . 1
Features and benefits . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Ordering information . . . . . . . . . . . . . . . . . . . . . 3
Ordering options . . . . . . . . . . . . . . . . . . . . . . . . 3
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pinning information . . . . . . . . . . . . . . . . . . . . . . 4
Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 5
Functional description . . . . . . . . . . . . . . . . . . . 5
General operation . . . . . . . . . . . . . . . . . . . . . . . 5
I2C-bus serial interface . . . . . . . . . . . . . . . . . . . 7
Bus fault time-out . . . . . . . . . . . . . . . . . . . . . . . 7
Slave address . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Register list . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Pointer register . . . . . . . . . . . . . . . . . . . . . . . . . 8
Configuration register . . . . . . . . . . . . . . . . . . . . 8
Temperature register . . . . . . . . . . . . . . . . . . . . 9
Overtemperature shutdown threshold
(Tos) and hysteresis (Thyst) registers. . . . . . . 10
OS output and polarity . . . . . . . . . . . . . . . . . . 11
OS comparator and interrupt modes . . . . . . . 11
OS fault queue . . . . . . . . . . . . . . . . . . . . . . . . 12
Shutdown mode . . . . . . . . . . . . . . . . . . . . . . . 12
Power-up default and power-on reset . . . . . . 12
Protocols for writing and reading the registers 13
Application design-in information . . . . . . . . . 16
Typical application . . . . . . . . . . . . . . . . . . . . . 16
LM75A and LM75B comparison . . . . . . . . . . . 16
Temperature accuracy . . . . . . . . . . . . . . . . . . 17
Noise effect. . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . 19
Recommended operating conditions. . . . . . . 19
Static characteristics. . . . . . . . . . . . . . . . . . . . 20
Dynamic characteristics . . . . . . . . . . . . . . . . . 22
Package outline . . . . . . . . . . . . . . . . . . . . . . . . 23
Soldering of SMD packages . . . . . . . . . . . . . . 27
Introduction to soldering . . . . . . . . . . . . . . . . . 27
Wave and reflow soldering . . . . . . . . . . . . . . . 27
Wave soldering . . . . . . . . . . . . . . . . . . . . . . . . 27
Reflow soldering . . . . . . . . . . . . . . . . . . . . . . . 28
Soldering: PCB footprints. . . . . . . . . . . . . . . . 30
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Revision history . . . . . . . . . . . . . . . . . . . . . . . . 34
18
18.1
18.2
18.3
18.4
19
20
Legal information . . . . . . . . . . . . . . . . . . . . . .
Data sheet status . . . . . . . . . . . . . . . . . . . . . .
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . .
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . .
Contact information . . . . . . . . . . . . . . . . . . . .
Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
35
35
35
36
36
37
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. 2015.
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: 6 February 2015
Document identifier: LM75B
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