ST STTS751 User Manual
2.25 V low-voltage local digital temperature sensor
Features
■ Operating voltage 2.25 V to 3.6 V
■ Operating temperature –40 °C to +125 °C
■ Programmable
– 10 different conversion rates
0.0625 to 32 conversions/sec.
1 conversion/sec. - default
– 4 different resolutions
9-bit (0.5 °C/LSB) to12-bit (0.0625 °C/LSB)
10-bit (0.25 °C/LSB) - default
■ Low supply current
– 50 µA (typ) for 8 conversions/sec.
– 20 µA (typ) for 1 conversion/sec.
– 3 µA (typ) standby
■ Accuracy
– ±1.0 °C (typ) 0 °C to +85 °C
– ±2.0 °C (typ) –40 °C to +125 °C
■ One-shot mode for power saving
■ Fast conversion time 21 ms (typ) 10-bit
■ Pull-up resistor value allows single pin to select
one of four slave addresses
■ Supports 400 kHz serial clock
Table 1. Device summary
STTS751
UDFN-6L
SOT23-6L
■ SMBus 2.0 compatible
– SMBus ALERT (ARA) support
– SMBus timeout
■ RoHS/green
Applications
■ Solid state drives
■ Portable electronics
■ Notebook computers
■ Smart batteries
■ Servers
■ Telecom
Order code Pull-up resistor value SMBus address Comments
7.5 K ±5% 1001 000 b
STTS751-0DP3F
STTS751-0WB3F
STTS751-1DP3F
STTS751-1WB3F
July 2010 Doc ID 16483 Rev 5 1/36
12 K ±5% 1001 001 b
20 K ±5% 0111 000 b
33 K ±5% 0111 001 b
7.5 K ±5% 1001 010 b
12 K ±5% 1001 011 b
20 K ±5% 0111 010 b
33 K ±5% 0111 011 b
Address selection via resistor pull-up
on Addr/Therm
Address selection via resistor pull-up
on Addr/Therm
pin
pin
www.st.com
1
Contents STTS751
Contents
1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 SMBus interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 SMBus protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 WRITE byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 READ byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4 SEND byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.5 RECEIVE byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6 SMBus addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.7 SMBus timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.8 Alert response address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 STTS751 register summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 STTS751 register formats and details . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 Temperature register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3 Temperature limit register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.4 Temperature examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.5 Status register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6 Configuration register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.7 Conversion rate register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.8 One-shot register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.9 Therm limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.10 Therm hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.11 SMBus timeout register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.12 STTS751 product ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.13 STTS751 manufacturer’s ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.14 STTS751 revision ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5 EVENT output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2/36 Doc ID 16483 Rev 5
STTS751 Contents
6 Addr/Therm output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
10 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Doc ID 16483 Rev 5 3/36
List of tables STTS751
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 3. Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 4. SMBus WRITE byte protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 5. SMBus READ byte protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 6. SMBus SEND byte protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 7. SMBus RECEIVE byte protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 8. SMBus protocol response to ARA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 9. Registers/pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 10. Pointer register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 11. Temperature register (two’s complement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 12. Temperature limit register (two’s complement format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 13. Temperature examples (two’s complement format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 14. Status register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 15. Configuration register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 16. Conversion resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 17. Conversion rate register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 18. Conversion rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 19. One-shot register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 20. Therm limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 21. Therm hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 22. SMBus timeout register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 23. Product ID register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 24. Manufacturer’s ID register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 25. Revision ID register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 26. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 27. Operating and AC measurement conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 28. DC and AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 29. AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 30. UDFN-6L (2 mm x 2 mm x 0.5 mm) package mechanical data . . . . . . . . . . . . . . . . . . . . . 29
Table 31. SOT23-6L (2.90 mm x 2.80 mm) package mechanical data . . . . . . . . . . . . . . . . . . . . . . . 30
Table 32. Carrier tape dimensions for UDFN-6L and SOT23-6L packages . . . . . . . . . . . . . . . . . . . . 32
Table 33. Reel dimensions for 8 mm carrier tape - UDFN-6L and SOT23-6L packages . . . . . . . . . . 33
Table 34. Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 35. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4/36 Doc ID 16483 Rev 5
STTS751 List of figures
List of figures
Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 2. Pinout - SOT23-6L and UDFN-6L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. Application hardware hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5. SMBus timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 6. EVENT
Figure 7. Therm
Figure 8. AC measurement I/O waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 9. UDFN-6L (2 mm x 2 mm x 0.5 mm) package mechanical drawing . . . . . . . . . . . . . . . . . . 29
Figure 10. SOT23-6L (2.90 mm x 2.80 mm) package mechanical drawing . . . . . . . . . . . . . . . . . . . . . 30
Figure 11. UDFN-6L package footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 12. SOT23-6L package footprint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 13. Carrier tape for UDFN-6L and SOT23-6L packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 14. Reel schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Doc ID 16483 Rev 5 5/36
Description STTS751
1 Description
The STTS751 is a digital temperature sensor which communicates over a 2-wire SMBus 2.0
compatible bus. The temperature is measured with a user-configurable resolution between
9 and 12 bits. At 9 bits, the smallest step size is 0.5 °C, and at 12 bits, it is 0.0625 °C. At the
default resolution (10 bits, 0.25 °C/LSB), the conversion time is nominally 21 milliseconds.
The open-drain EVENT
output is used to indicate an alarm condition in which the measured
temperature has exceeded the user-programmed high limit or fallen below the low limit.
When the EVENT
pin is asserted, the host can respond using the SMBus Alert Response
Address (ARA) protocol to which the STTS751 will respond by sending its slave address.
The STTS751 is a 6-pin device that supports user-configurable slave addresses. Via the
pull-up resistor on the Addr/Therm
pin, one of four different slave addresses can be
specified. Two order numbers (STTS751-0 and STTS751-1) provide two different sets of
slave addresses bringing the total available to eight. Thus, up to eight devices can share the
same 2-wire SMBus without ambiguity, thereby allowing monitoring of multiple temperature
zones in an application.
The two-wire interface can support transfer rates up to 400 kHz. Two small footprint
packages are available: a UDFN-6L and a standard SOT23-6L package.
Figure 1. Logic diagram
V
DD
(1)
SDA
EVENT
STTS751-0
STTS751-1
SCL
Addr/Therm
GND
1. This pin may not float.
Table 2. Signal names
Symbol Type Description
Addr/Therm
EVENT
SDA I/O SMBus interface data I/O
SCL Input SMBus interface clock input
V
DD
GND Ground Device ground
6/36 Doc ID 16483 Rev 5
Output Address selection pin / thermal status pin
Output Event (alert) output
Power Device power supply
AM03028v1
STTS751 Description
Figure 2. Pinout - SOT23-6L and UDFN-6L
SOT23-6L
Addr/Therm
GND
V
DD
1
2
3
Table 3. Pin descriptions
Pin
Name Description
SOT23-6L UDFN-6L
14
Addr/Therm
UDFN-6L
SDA
6
5
EVENT
4
SCL
SCL
EVENT
V
DD
1
2
3
6
5
4
SDA
GND
Addr/Therm
Open-drain output that can be used to turn on/off a fan or throttle a CPU
clock in the event of an overtemperature condition.
The pin at power-up determines the SMBus slave address according to the
pull-up resistor value as shown in Ta bl e 1 .
This pin must have a pull-up resistor connected to the same voltage as V
or tied to GND (pin cannot float).
Total capacitance on this pin must be <100 pF.
Note: By tying Addr/Therm
to ground, the device functions as one address
device only. The Therm functionality is then not available. The address for
device STTS751-0 is 72h and the address for device STTS751-1 is 76h.
AM03029v1
DD
25GNDGND
33VDDPower supply V
DD
4 1 SCL SMBus clock
5 2 EVENT
Open-drain interrupt output. Output supports the SMBus Alert (ARA).
Note: This pin may not float.
6 6 SDA SMBus data input/output
Doc ID 16483 Rev 5 7/36
Description STTS751
Figure 3. Block diagram
V
DD
REGISTERS
Address Pointers
Temperature Registers
Status
SDA
SCL
SMBus
Interface
V
DD
Sensor
Control Logic
A to D
Converter
Configuration
Conversion Rate
High Limit Registers
Low Limit Registers
One-Shot
Therm LIMIT
Therm HYSTERESIS
SMBus Timeout
Product ID
Manufacturer ID
Revision ID
Interrupt Enabling
EVENT
Addr/Therm
Figure 4. Application hardware hookup
V
DD
SCL
SDA
STTS751-0
R
STTS751-1
GND
EVENT
Addr/Therm
GND
Digital Comparator
Alert Response
Host
Controller
AM03030v1
Fan
Driver
AM03031v1
8/36 Doc ID 16483 Rev 5
STTS751 Functional description
2 Functional description
The STTS751 digital temperature sensor acquires the temperature and stores it in the
temperature register. The resolution is programmable which allows the host controller to
select the optimal configuration between sensitivity and conversion times. The STTS751
can be placed in standby mode to minimize power consumption.
The user can control the update rate of the temperature measurements via the configuration
register (Table 15 on page 17). Sample rates can be adjusted from once every 16 seconds
up to 32 samples per second, in powers-of-2 steps.
These devices also offer a one-shot feature. When the device is in the standby mode, writing
to the one-shot register initiates a single temperature conversion. The result is compared
with the limit registers, and the outputs updated accordingly. Then the device returns to the
standby mode. Operating the device in this mode allows for very low average power
consumption, thereby making this device ideal for low power applications.
The device supports the SMBus Alert Response address (ARA) protocol. The ARA is polled
by the controller (host) device that supports this protocol whenever it detects that the
EVENT
Section 3.8 on page 12).
The STTS751 contains 16 registers. The register summary is shown in Table 9 on page 13.
Using register addresses not specified in the table may result in an incorrect response.
These registers and their functions are described in more detail in the following sections.
pin has been asserted. The STTS751 will respond with its device address (refer to
Doc ID 16483 Rev 5 9/36
SMBus interface STTS751
3 SMBus interface
3.1 SMBus protocol
The STTS751 communicates over a 2-wire serial interface compatible with the SMBus
standard. Temperature data, alarm limits and configuration information are communicated
over the bus. A detailed timing diagram is shown below in Figure 5.
Figure 5. SMBus timing diagram
SMCLK
SMDATA
T
PS
T
BUF
R
T
HD; STA
T
LOW
T
HD:DAT
T
SU:DAT
T
HIGH
T
F
S - start condition
P - stop condition
S
T
SU:STA
T
HD; STA
The STTS751 supports standard SMBus protocols (see Ta bl e 4 , 5, 6, and 7).
● WRITE byte
● READ byte
● SEND byte
● RECEIVE byte
● Alert response address
T
SU:STO
P
AM03067v1
10/36 Doc ID 16483 Rev 5
STTS751 SMBus interface
3.2 WRITE byte
The WRITE byte protocol is used to write one byte of data to the registers as shown in
Ta bl e 4 . The gray data is sent by the STTS751 while the white data is sent by the host.
Table 4. SMBus WRITE byte protocol
Start Slave address WR ACK
1 bit 7 bits 1 bit 1 bit 8 bits 1 bit 8 bits 1 bit 1 bit
Register
address
ACK Data ACK Stop
3.3 READ byte
The READ byte protocol is used to read one byte of data from the registers as shown in
Ta bl e 5 .
Table 5. SMBus READ byte protocol
Start Slave address WR ACK
1 bit 7 bits 1 bit 1 bit 8 bits 1 bit 1 bit 7 bits 1 bit 1 bit 8 bits 1 bit 1 bit
Register
address
ACK Start Slave address RD ACK Data NACK Stop
3.4 SEND byte
The SEND byte protocol is used to set the internal address register to the correct address. It
sends a register address with no data (see Tab l e 6 ). The SEND byte can be followed by the
RECEIVE byte protocol described below in order to read data from the register.
Table 6. SMBus SEND byte protocol
Start Slave address WR ACK Register address ACK Stop
1 bit 7 bits 1 bit
1 bit 8 bits 1 bit 1 bit
3.5 RECEIVE byte
The RECEIVE byte protocol is used to read data from the register when the internal register
address pointer is known (see Ta b le 7 ). This can be used for consecutive reads of the same
register.
Table 7. SMBus RECEIVE byte protocol
Start Slave address RD ACK Data NACK Stop
1 bit 7 bits 1 bit
1 bit 8 bits 1 bit 1 bit
Doc ID 16483 Rev 5 11/36
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