STTS751 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.
Contents STTS751 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3 SMBus interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4 5 2/36 3.1 SMBus protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2 WRITE byte . . . . . .
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 . . . . . . . . . . . . . . . . . . . . . . . . . .
List of tables STTS751 List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Table 17. Table 18. Table 19. Table 20. Table 21. Table 22. Table 23. Table 24. Table 25. Table 26. Table 27. Table 28. Table 29. Table 30. Table 31. Table 32. Table 33. Table 34. Table 35. 4/36 Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STTS751 List of figures List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pinout - SOT23-6L and UDFN-6L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . .
Description 1 STTS751 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.
STTS751 Description Figure 2. Pinout - SOT23-6L and UDFN-6L SOT23-6L UDFN-6L Addr/Therm 1 6 SDA GND 2 5 EVENT VDD 3 4 SCL SCL 1 6 SDA EVENT 2 5 GND VDD 3 4 Addr/Therm AM03029v1 Table 3. Pin descriptions Pin Name Description SOT23-6L UDFN-6L 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.
Description Figure 3. STTS751 Block diagram V DD REGISTERS Address Pointers Temperature Registers Status SMBus Interface SDA Configuration Conversion Rate SCL High Limit Registers Interrupt Enabling EVENT Low Limit Registers VDD One-Shot Therm LIMIT Addr/Therm Therm HYSTERESIS Sensor Control Logic SMBus Timeout Product ID Manufacturer ID Revision ID A to D Converter Digital Comparator Alert Response GND Figure 4.
STTS751 2 Functional description 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).
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.
STTS751 3.2 SMBus interface WRITE byte The WRITE byte protocol is used to write one byte of data to the registers as shown in Table 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 Register address ACK Data ACK Stop 1 bit 7 bits 1 bit 1 bit 8 bits 1 bit 8 bits 1 bit 1 bit 3.3 READ byte The READ byte protocol is used to read one byte of data from the registers as shown in Table 5. Table 5.
SMBus interface 3.6 STTS751 SMBus addresses The STTS751 is available in two versions. Each version has 4 slave addresses determined by the pull-up resistor value connected to the Addr/Therm pin. Refer to Table 1 for valid address and recommended resistor values. The device will not respond to an invalid slave address. 3.7 SMBus timeout The STTS751 supports SMBus timeout which is enabled by default at power-up. This can be disabled via bit 7 in the timeout register, refer to Section 4.
STTS751 4 STTS751 register summary STTS751 register summary The STTS751 uses 8-bit registers. Variables longer than 8 bits are managed in byte pairs. For example, when reading a 10-bit temperature value (10 bits is the default resolution.) the application must read two registers and then concatenate the upper byte with the 2 most significant bits of the lower byte. Table 9 below summarizes the register map for the device. Accessing any invalid address results in indeterminate data. Table 9.
STTS751 register summary 4.1 STTS751 STTS751 register formats and details The STTS751 register set is comprised of the 16 addresses shown in Table 9. The individual registers are accessed by transferring their addresses via the SMBus interface as shown in Section 3.2, 3.3, and 3.4. In the case of the RECEIVE byte sequence (Section 3.5) the address used is the address sent in the previous WRITE, READ or SEND byte sequence.
STTS751 4.3 STTS751 register summary Temperature limit register format The high and low limit registers have the same format as the temperature register with the integer portion of the two's complement value stored in the high byte and the fractional portion in the low byte. These registers are read-write. Note that the high limit defaults to 85 °C. Table 12.
STTS751 register summary 4.5 Status register Table 14. Status register STTS751 ADDR (hex) R/W Register b7 b6 b5 b4 b3 b2 01 R Status Busy THIGH TLOW RFU RFU RFU b1 b0 RFU THRM Power-up default (hex) undefined The STTS751 status register is read-only and located at address 01h. The various status bits function as described below. Busy: [7] Bit =1 when a temperature conversion is in progress. THIGH: [6] Bit = 1 indicates temperature high limit has been exceeded (TA > high limit).
STTS751 4.6 STTS751 register summary Configuration register The STTS751 configuration register is read/write and controls the functionality of temperature measurements. It is located at address 03h. The configuration register bits function as described below. Table 15. Configuration register ADDR (hex) R/W Register 03 R/W Configuration b7 b6 MASK1 RUN/STOP b5 b4 b3 b2 b1 b0 Power-up default (hex) 0 RFU Tres1 Tres0 RFU RFU 00 Description MASK1: [bit 7] 0: EVENT is enabled.
STTS751 register summary STTS751 Tres1:Tres0 [bits 3 and 2] These bits select one of the four programmable resolutions for temperature data on the STTS751 providing resolutions down to 0.0625 °C/LSB. The default resolution is 10 bits, 0.25 °C/LSB. Table 16. Conversion resolution Tres1:Tres0 Temperature resolution LSB step size (°C) 00 10 bits (default) 0.25 01 11 bits 0.125 11 12 bits 0.0625 10 9 bits 0.5 RFU [bits 1 and 0] Not used - reserved. 4.
STTS751 STTS751 register summary Table 18. Conversion rates CONV[3:0] (hex) Conversions per second Typical current (µA) 0 0.0625 15 1 0.125 2 0.25 3 0.5 4 1 5 2 6 4 7 8 8 16 9 32 A-F reserved Comment 20 50 9, 10, or 11-bit resolutions only 125 9 or 10-bit resolutions only Note: The user must program the conversion rate and resolution bits (Tres1:Tres0 in the configuration register, address 03h) to be consistent with this table.
STTS751 register summary 4.9 STTS751 Therm limit The Therm limit is a read/write register located at address 20h. The power-on default value is 85 °C (55h). The format is 8-bit, two's complement integer. This is the same format as the upper byte of the temperature register (Section 4.2: Temperature register format). Whenever the temperature exceeds the value of the therm limit, the Addr/Therm output will be asserted (low). See Section 6 for more information. Table 20.
STTS751 STTS751 register summary 4.12 STTS751 product ID The two versions of the STTS751 as shown in Table 1 can be identified via the read-only Product ID register at address FDh. The STTS751-0 has a Product ID of 00h. The STTS751-1 has a Product ID of 01h. Table 23. Product ID register ADDR (hex) R/W Register FD R Product ID 4.
EVENT output 5 STTS751 EVENT output The STTS751 EVENT output is open drain and requires a pull-up resistor. The EVENT pin is asserted (low) whenever the temperature exceeds the high limit or is equal to or below the low limit. Once asserted, the output will remain asserted until the STTS751 receives an SMBus Alert Response Address (ARA) from the host and acknowledges with its slave address. The output will be deasserted when the ARA is acknowledged.
STTS751 6 Addr/Therm output Addr/Therm output The Addr/Therm pin functions normally as an output to alert the system of an over temperature condition. It is open drain and requires a pull-up resistor. During power-up, the pull-up value is sensed by the STTS751 to determine what its slave address will be as depicted in Table 1. The Therm output is asserted low whenever the temperature exceeds the Therm limit (address 20h).
Maximum ratings 7 STTS751 Maximum ratings Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 26.
STTS751 8 DC and AC parameters DC and AC parameters This section summarizes the operating measurement conditions, and the DC and AC characteristics of the device. The parameters in the DC and AC characteristics tables that follow, are derived from tests performed under the measurement conditions summarized in Table 27: Operating and AC measurement conditions. Designers should check that the operating conditions in their circuit match the operating conditions when relying on the quoted parameters.
DC and AC parameters Table 28. STTS751 DC and AC characteristics Symbol Description VDD Supply voltage IDD ISB Test condition(1) Min Typ(2) 2.25 Operating current dependent upon conversion rate Max Unit 3.6 V 0.0625 conversions/second(3) 15 35 µA 1 conversion/second(3) 20 40 µA 8 conversions/second 50 85 µA 32 conversions/second 125 250 µA 3 8 µA 0 °C to 85 °C ±1.0 ±1.5 °C –40 °C to +125 °C ±2.0 ±2.5 °C 9-bit temperature data 0.
STTS751 Table 28. DC and AC parameters DC and AC characteristics (continued) Symbol Description Test condition(1) Min Pull-up supply voltage (open drain) (Addr/Therm) VPV EVENT, SDA, SCL VPOR Power On Reset threshold (POR) - TS VDD falling edge tTIMEOUT SMBus timeout(5) tSP Spike suppression Pulse width of spikes that must be suppressed by the input filter Typ(2) Max Unit –0.3 3.6 V –0.3 5.5 V 1.75 V 25 Input filter on SCL and SDA 35 ms 50 ns 1.
Package mechanical data 9 STTS751 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark.
STTS751 Package mechanical data Figure 9. UDFN-6L (2 mm x 2 mm x 0.5 mm) package mechanical drawing 8187820_A Table 30. UDFN-6L (2 mm x 2 mm x 0.5 mm) package mechanical data mm inches Sym Min Typ Max Min Typ Max A 0.45 0.50 0.55 0.018 0.020 0.022 A1 0.00 0.05 0.000 A3 0.065 0.002 0.003 b 0.20 0.25 0.30 0.008 0.010 0.012 D 1.95 2.00 2.05 0.077 0.079 0.081 E 1.95 2.00 2.05 0.077 0.079 0.081 e L 0.65 0.50 0.60 0.026 0.70 Doc ID 16483 Rev 5 0.020 0.024 0.
Package mechanical data STTS751 Figure 10. SOT23-6L (2.90 mm x 2.80 mm) package mechanical drawing 7049717_G Table 31. SOT23-6L (2.90 mm x 2.80 mm) package mechanical data mm inches Sym Min Typ A Min Typ 1.45 A1 0.00 A2 0.90 b c Max 0.057 0.15 0.000 1.30 0.035 0.30 0.50 0.012 0.020 0.08 0.22 0.003 0.009 1.15 0.006 0.045 D 2.90 0.114 E 2.80 0.110 E1 1.60 0.063 e 0.95 0.037 e1 1.90 0.075 0.051 L 0.30 0.45 0.60 0.012 0.018 0.
STTS751 Package mechanical data Figure 11. UDFN-6L package footprint 8187820_A(LP) Figure 12.
Package mechanical data STTS751 Figure 13. Carrier tape for UDFN-6L and SOT23-6L packages P0 E P2 D T A0 F TOP COVER TAPE W B0 P1 CENTER LINES OF CAVITY K0 USER DIRECTION OF FEED AM03073v1 Table 32. Carrier tape dimensions for UDFN-6L and SOT23-6L packages Package W D E P0 P2 F A0 B0 K0 P1 T Unit UDFN-6L 8.00 ±0.30 1.50 +0.10/ –0.00 1.75 ±0.10 4.00 ±0.10 2.00 ±0.05 3.50 ±0.05 2.20 ±0.10 2.20 ±0.10 0.75 ±0.10 4.00 ±0.10 0.25 ±0.05 mm SOT23-6L 8.00 +0.30/ –0.10 1.
STTS751 Package mechanical data Figure 14. Reel schematic T 40mm min. Access hole At slot location B D C N A G measured Tape slot In core for Full radius Tape start 2.5mm min.width At hub AM04928v1 Table 33. Reel dimensions for 8 mm carrier tape - UDFN-6L and SOT23-6L packages A B (max) (min) 180 mm (7 inch) 1.5 mm Note: C 13 mm ± 0.2 mm D N (min) (min) 20.2 mm 60 mm G 8.4 mm + 2/–0 mm T (max) 14.
Part numbering 10 STTS751 Part numbering Table 34. Ordering information scheme Example: STTS751-0 DP 3 F Device type STTS751-0 STTS751-1 Package DP = UDFN-6L WB = SOT23-6L Temperature range 3 = –40 °C to 125 °C Shipping method F = ECOPACK® package, tape & reel E = ECOPACK® package, tubes For other options, or for more information on any aspect of this device, please contact the ST sales office nearest you.
STTS751 11 Revision history Revision history Table 35. Document revision history Date Revision 06-Nov-2009 1 Initial release. 2 Updated Features; removed Therm2 throughout document (from Section 1, 2, 3.8, 4.6, 4.10, 5, Figure 1, 2, 3, 4, 6, Table 2, 3, 15, 28); updated Figure 3, Section 3.4, Section 4.6, Section 4.8, Section 4.10, Table 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25; added package footprints (Figure 11 and 12); minor textual changes.
STTS751 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.
