STCN75DS2F ,Digital temperature sensor and thermal watchdogFunctional description . . . . . . 153.1 Registers and register set formats . . . . . . 153 ..
STCS05ADR ,0.5 A max constant current LED driverElectrical characteristics . . . . . 65 Timing . . . . . 76 Typical performance characte ..
STCS05DR ,0.5A MAX CONSTANT CURRENT LED DRIVERElectrical characteristics . . . . . 65 Timing . . . . . 76 Typical performance characte ..
STCS2 ,2A MAX CONSTANT CURRENT LED DRIVERElectrical characteristics . . . . . 65 Timing . . . . . 76 Typical performance characte ..
STCS2ASPR ,2A MAX CONSTANT CURRENT LED DRIVERElectrical characteristics . . . . . 65 Timing . . . . . 76 Typical performance characte ..
STD100N03LT4 , N-CHANNEL 30V - 0.0045Ω - 80A - DPAK - IPAK Planar STripFET™ MOSFET
STV9302 ,VERTICAL DEFLECTION PROCESSOR FOR MONITOR/TV. 2 APP/60V WITH FLYBACK GENERATORABSOLUTE MAXIMUM RATINGSSymbol Parameter Value UnitVOLTAGEV Supply Voltage (pin 2) - Note 1 and Not ..
STV9302A ,VERTICAL DEFLECTION BOOSTER FOR 2 APP MONITOR/TV APPLICATIONS WITH 70 V FLYBACK GENERATORElectrical Characteristics(V = 32 V, T = 25°C, unless otherwise specified)S AMB Symbol Parameter Te ..
STV9306 ,BUS CONTROLLED VERTICAL DEFLECTION SYSTEM WITH EAST/WEST CORRECTION OUTPUT CIRCUITapplications. It integrates both the verticaldeflection and E/W correction circuitries neces-sary i ..
STV9306B ,BUS-CONTROLLED VERTICAL DEFLECTION SYSTEM WITH EAST/WEST CORRECTION OUTPUT CIRCUITElectrical CharacteristicsoV = 24 V, R = 0.5 Ω, Normal mode, T = 25 C, unless otherwise specified.S ..
STV9325 ,40V; vertical deflection booster for 2.5-app TV/monitor applications with 70-V flyback generatorElectrical Characteristics(V = 34 V, T = 25°C, unless otherwise specified)S AMB Symbol Parameter Te ..
STV9326 ,Vertical Deflection Booster for 3-App TV/Monitor Applications with 60-V Flyback GeneratorAbsolute Maximum Ratings Symbol Parameter Value UnitVoltageV Supply Voltage (pin 2) - Note 1 and No ..
STCN75DS2F
Digital temperature sensor and thermal watchdog
March 2012 Doc ID 13307 Rev 9 1/36
STCN75Digital temperature sensor and thermal watchdog
Datasheet − production data
Features Measures temperatures from –55 °C to
+125 °C (–67 °F to +257 °F) ±0.5 °C (typ) accuracy ±2 °C (max) accuracy from –25 °C to
+100 °C Low operating current:125 µA (typ) No external components required 2-wire I2 C/SMBus-compatible serial interface Selectable bus address allows connection
of up to eight devices on the bus Wide power supply range - operating voltage
range: 2.7 V to 5.5 V Conversion time is 45 ms (typ) Programmable temperature threshold and
hysteresis set points Pin- and software-compatible with TCN75
(drop-in replacement) Power-up defaults permit standalone operation
as a thermostat Shutdown mode to minimize power
consumption Output pin (open drain) can be configured for
interrupt or comparator/thermostat mode (dual
purpose event pin) MSOP8 (TSSOP8) package
Contents STCN752/36 Doc ID 13307 Rev 9
Contents Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.1 Serial communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 T emperature sensor output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.1 SDA (open drain) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.2 SCL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.3 OS/INT (open drain) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.4 GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3.5 A2, A1, A0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3.6 VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1 Applications information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Thermal alarm function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Comparator mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.4 Interrupt mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.5 Fault tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6 Shutdown mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.7 T emperature data format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.1 Registers and register set formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.1 Command/pointer register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.2 Configuration register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.3 Temperature register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1.4 Overlimit temperature register (TOS) . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1.5 Hysteresis temperature register (THYS) . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Power-up default conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.3 Serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 2-wire bus characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.1 Bus not busy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.2 Start data transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.3 Stop data transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
STCN75 ContentsDoc ID 13307 Rev 9 3/36
3.4.4 Data valid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.5 Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.5 READ mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.6 WRITE mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Typical operating characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
List of tables STCN75
4/36 Doc ID 13307 Rev 9
List of tables
Table 1. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 2. Fault tolerance setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 3. Relationship between temperature and digital output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 4. Command/pointer register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 5. Register pointers selection summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 6. Configuration register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 7. Temperature register format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 8. TOS and THYS register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 9. STCN75 serial bus slave addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 10. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 11. Operating and AC measurement conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 12. DC and AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 13. AC characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 14. MSOP8 (TSSOP8) – 8-lead, thin shrink small outline (3 mm x 3 mm) package
mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 15. Carrier tape dimensions for MSOP8 (TSSOP8) package. . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 16. Reel dimensions for 12 mm carrier tape - MSOP8 (TSSOP8) package. . . . . . . . . . . . . . . 33
Table 17. Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 18. Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
STCN75 List of figures
Doc ID 13307 Rev 9 5/36
List of figures
Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 2. Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3. Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. Typical 2-wire interface connections diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 5. Serial bus data transfer sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 6. Acknowledgement sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 7. Slave address location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 8. Typical 2-byte READ from preset pointer location (e.g. temp - TOS, THYS) . . . . . . . . . . . . 22
Figure 9. Typical pointer set followed by an immediate READ for 2-byte register (e.g. temp). . . . . . 22
Figure 10. Typical 1-byte READ from the cofiguration register with preset pointer . . . . . . . . . . . . . . . 22
Figure 11. Typical pointer set followed by an immediate READ from the configuration register . . . . . 23
Figure 12. Configuration register WRITE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 13. TOS and THYS WRITE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 14. Temperature variation vs. voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 15. Bus timing requirements sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 16. MSOP8 (TSSOP8) – 8-lead, thin shrink small outline (3 mm x 3 mm) package
mechanical drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 17. Carrier tape for MSOP8 (TSSOP8) package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 18. Reel schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Description STCN75
6/36 Doc ID 13307 Rev 9
1 Description
The STCN75 is a high-precision digital CMOS temperature sensor IC with a sigma-delta
temperature-to-digital converter and an I2 C-compatible serial digital interface. It is targeted
for general applications such as personal computers, system thermal management,
electronics equipment, and industrial controllers, and is packaged in the industry-standard
8-lead TSSOP package.
The device contains a bandgap temperature sensor and 9-bit ADC which monitor and
digitize the temperature to a resolution up to 0.5 °C. The STCN75 is typically accurate to
(±3 °C - max) over the full temperature measurement range of –55 °C to 125 °C with ±2 °C
accuracy in the –25 °C to +100 °C range. The STCN75 is pin-for-pin and software
compatible with the TCN75.
The STCN75 is specified for operating at supply voltages from 2.7 V to 5.5 V. Operating at
3.3 V, the supply current is typically (125 µA).
The onboard sigma-delta analog-to-digital converter (ADC) converts the measured
temperature to a digital value that is calibrated in degrees centigrade; for Fahrenheit
applications a lookup table or conversion routine is required.
The STCN75 is factory-calibrated and requires no external components to measure
temperature.
1.1 Serial communications
The STCN75 has a simple 2-wire I2 C-compatible digital serial interface which allows the
user to access the data in the temperature register at any time. It communicates via the
serial interface with a master controller which operates at speeds up to 400 kHz. Three pins
(A0, A1, and A2) are available for address selection, and enable the user to connect up to 8
devices on the same bus without address conflict.
In addition, the serial interface gives the user easy access to all STCN75 registers to
customize operation of the device.
STCN75 Description
Doc ID 13307 Rev 9 7/36
1.2 Temperature sensor output
The STCN75 T emperature Sensor has a dedicated open drain overlimit signal/interrupt
(OS/INT) output which features a thermal alarm function. This function provides a user-
programmable trip and turn-off temperature. It can operate in either of two selectable
modes: Section 2.3: Comparator mode Section 2.4: Interrupt mode.
At power-up the STCN75 immediately begins measuring the temperature and converting
the temperature to a digital value.
The measured temperature value is compared with a temperature limit (which is stored in
the 16-bit (TOS) READ/WRITE register), and the hysteresis temperature (which is stored in
the 16-bit (THYS) READ/WRITE register). If the measured value exceeds these limits, the
OS/INT pin is activated (see Figure 3 on page8).
Note: See Pin descriptions on page 8 for details.
Figure 1. Logic diagram SDA and OS/INT are open drain.
Table 1. Signal names SDA and OS/INT are open drain.
Description STCN75
8/36 Doc ID 13307 Rev 9
Figure 2. Connections SDA and OS/INT are open drain.
Figure 3. Functional block diagram
1.3 Pin descriptions
See Figure 1 on page 7 and Table 1 on page7 for a brief overview of the signals
connected to this device.
1.3.1 SDA (open drain)
This is the serial data input/output pin for the 2-wire serial communication port.
1.3.2 SCL
This is the serial clock input pin for the 2-wire serial communication port.
1.3.3 OS/INT (open drain)
This is the overlimit signal/interrupt alert output pin. It is open drain, so it needs a pull-up
resistor. In Interrupt mode, it outputs a pulse whenever the measured temperature exceeds
the programmed threshold (TOS). It behaves as a thermostat, toggling to indicate whether
the measured temperature is above or below the threshold and hysteresis (THYS).
STCN75 Description
Doc ID 13307 Rev 9 9/36
1.3.4 GND
Ground; it is the reference for the power supply. It must be connected to system ground.
1.3.5 A2, A1, A0
A2, A1, and A0 are selectable address pins for the 3 LSBs of the I2 C interface address.
They can be set to VDD or GND to provide 8 unique address selections.
1.3.6 VDD
This is the supply voltage pin, and ranges from +2.7 V to +5.5 V.
Operation STCN75
10/36 Doc ID 13307 Rev 9
2 Operation
After each temperature measurement and analog-to-digital conversion, the STCN75 stores
the temperature as a 16-bit two’s complement number (see Table 5: Register pointers
selection summary on page 16) in the 2-byte temperature register (see Table 7 on page 17).
The most significant bit (S) indicates if the temperature is positive or negative: for positive numbers S = 0, and for negative numbers S = 1.
The most recently converted digital measurement can be read from the temperature register
at any time. Since temperature conversions are performed in the background, reading the
temperature register does not affect the operation in progress.
The temperature data is provided by the 9 MSBs (bits 15 through 7). Bits 6 through 0 are
unused. Table 3 on page 14 gives examples of the digital output data and corresponding
temperatures. The data is compared to the values in the TOS and THYS registers, and then
the OS/INT is updated based on the result of the comparison and the operating mode.
The alarm fault tolerance is controlled by the FT1 and FT0 bits in the configuration register.
They are used to set up a fault queue. This prevents false tripping of the OS/INT pin when
the STCN75 is used in a noisy environment (see T able 2 on page 13).
The active state of the OS/INT output can be changed via the polarity bit (POL) in the
configuration register. The power-up default is active-low.
If the user does not wish to use the thermostat capabilities of the STCN75, the
OS/INToutput should be left floating.
Note: If the thermostat is not used, the TOS and THYS registers can be used for general storage of
system data.
STCN75 Operation
Doc ID 13307 Rev 9 11/36
2.1 Applications information
STCN75 digital temperature sensors are optimal for thermal management and thermal
protection applications. They require no external components for operations except for pull-
up resistors on SCL, SDA, and OS/INT outputs. A 0.1 µF bypass capacitor on VDD is
recommended. The sensing device of STCN75 is the chip itself. The typical interface
connection for this type of digital sensor is shown in Figure 4 on page 11.
Intended applications include: System thermal management Computers/disk drivers Electronics/test equipment Power supply modules Consumer products Battery management Fax/printers management Automotive
Figure 4. Typical 2-wire interface connections diagram SDA and OS/INT are open drain.
2.2 Thermal alarm function
The STCN75 thermal alarm function provides user-programmable thermostat capability and
allows the STCN75 to function as a standalone thermostat without using the serial interface.
The OS/INT output is the alarm output. This signal is an open drain output, and at power-up,
this pin is configured with active-low polarity by default.
Operation STCN75
12/36 Doc ID 13307 Rev 9
2.3 Comparator mode
In comparator mode, each time a temperature-to-digital (T-to-D) conversion occurs, the new
digital temperature is compared to the value stored in the TOS and THYS registers. If a fault
tolerance number of consecutive temperature measurements are greater than the value
stored in the TOS register, the OS/INT output will be asserted.
For example, if the FT1 and FT0 bits are equal to “10” (fault tolerance = 4), four consecutive
temperature measurements must exceed TOS to activate the OS/INT output. Once the
OS/INT output is active, it will remain active until the first time the measured temperature
drops below the temperature stored in the THYS register, whereupon it will reset to its
inactive state.
Putting the device into shutdown mode does not clear OS/INT in comparator mode.
2.4 Interrupt mode
In interrupt mode, the OS/INT output becomes active when the measured temperature
exceeds the TOS value a consecutive number of times as determined by the fault tolerance
bits (FT1, FT0) value in the configuration register. Once activated, the OS/INT can only be
cleared by reading from any register (temperature, configuration, TOS, or THYS) on the
device. Once the OS/INT has been deactivated, it will only be reactivated when the
measured temperature falls below the THYS value a consecutive number of times equal to
the FT value. This mode is better suited for interrupt driven microprocessor based systems.
STCN75 Operation
Doc ID 13307 Rev 9 13/36
2.5 Fault tolerance
For both comparator and interrupt modes, the alarm “fault tolerance” setting plays a role in
determining when the OS/INT output will be activated. Fault tolerance refers to the number
of consecutive times an error condition must be detected before the user is notified. Higher
fault tolerance settings can help eliminate false alarms caused by noise in the system. The
alarm fault tolerance is controlled by the bits (4 and 3) in the configuration register. These
bits can be used to set the fault tolerance to 1, 2, 4, or 6 as shown in Table 2. At power-up,
these bits both default to logic '0'.
Note: OS output will be asserted one tCONV after fault tolerance is met, provided that the error
condition remains.
2.6 Shutdown mode
For power-sensitive applications, the STCN75 offers a low-power shutdown mode. The SD
bit in the configuration register controls shutdown mode. When SD is changed to logic '1,'
the conversion in progress will be completed and the result stored in the temperature
register, after which the STCN75 will go into a low-power standby state. The OS/INT output
will be cleared if the thermostat is operating in Interrupt mode and the OS/INT will remain
unchanged in comparator mode. The 2-wire interface remains operational in shutdown
mode, and writing a '0' to the SD bit returns the STCN75 to normal operation.
Table 2. Fault tolerance setting
Operation STCN75
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2.7 Temperature data format
Table 3 shows the relationship between the output digital data and the external temperature. emperature data for the temperature, TOS, and THYS registers is represented as a 9-bit,
two’s complement word.
The left-most bit in the output data stream contains temperature polarity information for
each conversion. If the sign bit is '0', the temperature is positive and if the sign bit is '1,' the
temperature is negative.
Table 3. Relationship between temperature and digital output
STCN75 Functional description
Doc ID 13307 Rev 9 15/36
3 Functional description
The STCN75 registers have unique pointer designations which are defined in Table 5 on
page 16. Whenever any READ/WRITE operation to the STCN75 register is desired, the
user must “point” to the device register to be accessed.
All of these user-accessible registers can be accessed via the digital serial interface at
anytime (see Section 3.3: Serial interface on page 19), and they include: Command register/address pointer register Configuration register Temperature register Overlimit signal temperature register (TOS) Hysteresis temperature register (THYS)
3.1 Registers and register set formats
3.1.1 Command/pointer register
The most significant bits (MSBs) of the command register must always be zero. Writing a '1'
into any of these bits will cause the current operation to be terminated (bit 2 through bit 7
must be kept '0', see Table4).
The command register retains pointer information between operations (see Table 5).
Therefore, this register only needs to be updated once for consecutive READ operations
from the same register. All bits in the command register default to '0' at power-up.
Table 4. Command/pointer register format
Functional description STCN75
16/36 Doc ID 13307 Rev 9
3.1.2 Configuration register
The configuration register is used to store the device settings such as device operation
mode, OS/INT operation mode, OS/INT polarity, and OS/INT fault queue.
The configuration register allows the user to program various options such as thermostat
fault tolerance, thermostat polarity, thermostat operating mode, and shutdown mode. The
user has READ/WRITE access to all of the bits in the configuration register except the MSB
(Bit7), which is reserved as a “Read only” bit (see Table 6). The entire register is volatile and
thus powers-up in its default state only.
Table 5. Register pointers selection summary
Table 6. Configuration register format Indicates operation mode; 0 = comparator mode, and 1 = interrupt mode (see Section 2.3: Comparator mode and
Section 2.4: Interrupt mode). The OS is active-low ('0').
STCN75 Functional description
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3.1.3 Temperature register
The temperature register is a two-byte (16-bit) “Read only” register (see Table 7). Digital
temperatures from the T-to-D converter are stored in the temperature register in two’s
complement format, and the contents of this register are updated each time the T -to-D
conversion is finished.
The user can read data from the temperature register at any time. When a T-to-D
conversion is completed, the new data is loaded into a comparator buffer to evaluate fault
conditions and will update the temperature register if a read cycle is not ongoing. If a READ
is ongoing, the previous temperature will be read. Accessing the STCN75 continuously
without waiting at least one conversion time between communications will prevent the
device from updating the temperature register with a new temperature conversion result.
Consequently, the STCN75 should not be accessed continuously with a wait time of less
than tCONV (max).
All unused bits following the digital temperature will be zero. The MSB position of the
temperature register always contains the sign bit for the digital temperature, and bit 14
contains the temperature MSB. All bits in the temperature register default to zero at power-
up.
3.1.4 Overlimit temperature register (TOS)
TOS register is a two-byte (16-bit) READ/WRITE register that stores the user-programmable
upper trip-point temperature for the thermal alarm in two’s complement format (see Table8
on page 18). This register defaults to 80 °C at power-up (i.e., 0101 0000 0000 0000).
The format of the TOS register is identical to that of the temperature register. The MSB
position contains the sign bit for the digital temperature and Bit14 contains the temperature
MSB.
For 9-bit conversions, the trip-point temperature is defined by the 9 MSBs of the TOS
register, and all remaining bits are “Don’t cares” (x).
Table 7. Temperature register format(1) These are comparable formats to the LM75.
Functional description STCN75
18/36 Doc ID 13307 Rev 9
3.1.5 Hysteresis temperature register (T HYS)
THYS register is a two-byte (16-bit) READ/WRITE register that stores the user-
programmable lower trip-point temperature for the thermal alarm in two’s complement
format (see Table 8). This register defaults to 75 °C at power-up
(i.e., 0100 1011 0000 0000).
The format of this register is the same as that of the temperature register. The MSB position
contains the sign bit for the digital temperature and bit 14 contains the temperature MSB.
3.2 Power-up default conditions
The STCN75 always powers up in the following default states: Thermostat mode = comparator mode Polarity = active-low Fault tolerance = 1 fault (i.e., relevant bits set to '0' in the configuration register) TOS = 80 °C T HYS = 75 °C Register pointer = 00 (temperature register)
Note: After power-up these conditions can be reprogrammed via the serial interface.
Table 8. TOS and THYS register format(1) These are comparable formats to the DS75 and LM75.
