Electronic Components Datasheet Search |
|
FM75 Datasheet(PDF) 5 Page - Fairchild Semiconductor |
|
FM75 Datasheet(HTML) 5 Page - Fairchild Semiconductor |
5 / 15 page PRODUCT SPECIFICATION FM75 REV. 1.0.5 10/2/03 5 Basic Operation The FM75 temperature sensing circuitry continuously produces an analog voltage that is proportional to the device temperature. At regular intervals the FM75 converts the analog voltage to a two’s complement digital value, which is placed into the temperature register. The FM75 has an SMBus compatible digital serial interface which allows the user to access the data in the temperature register at any time. In addition, the serial interface gives the user easy access to all other FM75 registers to customize operation of the device. The FM75 temperature-to-digital conversion can have 9, 10, 11, or 12-bit resolution as selected by the user, providing 0.5°C, 0.25°C, 0.125°C, and 0.0625°C temperature resolution, respectively. At power-up the default conversion resolution is 9-bits. The conversion resolution is controlled by the R0 and R1 bits in the Configuration Register. Table 1 gives examples of the relationship between the output digital data and the external temperature. The 9-bit, 10-bit, 11-bit and 12-bit columns in Table 1 indicate the right-most bit in the output data stream that can contain temperature information for each conversion accuracy. Since the output digital data is in two’s-complement format, the most significant bit of the temperature is the “sign” bit. If the sign bit is a zero, the temperature is positive and if the sign bit is a one, the temperature is negative. The FM75 has a Shutdown Mode that reduces the operating current of the FM75 to 150nA. This mode is controlled by the SD bit in the configuration register. Power Up Default Conditions The FM75 always powers up in the following default state: • Thermostat mode: Comparator Mode • O.S. polarity: active low •Fault tolerance: 1 fault (i.e., F0 = 0 and F1 = 0 in the Configuration Register) •TOS = 80°C •THYST = 75°C •Register pointer: 00 (Temperature Register) • Conversion resolution: 9 bits (i.e., R0 = 0 and R1 = 0 in the Configuration Register) After power up these conditions can be reprogrammed via the serial interface. Refer to the Serial Data Bus Operation section for FM75 programming instructions. Thermal Alarm Function The FM75 thermal alarm function provides user program- mable thermostat capability and allows the FM75 to function as a stand alone thermostat without using the serial interface. The Over-Limit Signal (O.S.) output is the alarm output. This signal is an open drain output, and at power-up this pin is configured with active-low polarity. Table 1. Relationship Between Temperature and Digital Output The O.S. polarity is controlled by the POL bit in the Configuration Register. The user-programmable upper trip-point temperature for the thermal alarm is stored in the TOS Register, and the user-programmable hysteresis tem- perature (i.e., the lower trip point) is stored in the THYST Register. The thermal alarm has two modes of operation: Comparator Mode and Interrupt Mode. At power-up the default is Comparator Mode. The alarm mode is controlled by the CMP/INTR bit in the Configuration Register. Fault Tolerance For both Comparator and Interrupt modes, the alarm “fault tolerance” setting plays a role in determining when the O.S. 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 bits F0 and F1 in the Configuration Register. These bits can be used to set the fault tolerance to 1, 2, 4 or 6 as shown in Table 4. At power-up, these bits both default to 0 (fault tolerance = 1). Temperature Digital Output g i S f o r e b m u N d e s u s t i b y b n o i s r e v n o c n o i t u l o s e r t i b 9 t i b 0 1 t i b 1 1 t i b 2 1 s y a w l A o r e z ll A s e r u t a r e p m e T n o i t u l o s e R t i B - 2 1 0 0 0 0 n o i t u l o s e R t i B - 11 0 0 0 0 0 n o i t u l o s e R t i B - 10 0 0 0 0 0 0 n o i t u l o s e R t i B - 90 0 0 0 0 0 0 C ° 5 2 1 + 01 1 11 0 1 10 0 0 0 0 0 0 0 C ° 5 2 6 0 . 0 0 1 + 00 1 10 0 1 00 0 0 1 0 0 0 0 C ° 5 2 1 . 0 5 + 01 1 00 1 0 00 0 1 0 0 0 0 0 C ° 5 2 . 2 1 + 00 0 00 0 1 10 1 0 0 0 0 0 0 C ° 0 00 0 00 0 0 00 0 0 0 0 0 0 0 C ° 5 . 0 2 - 10 1 11 1 0 11 0 0 0 0 0 0 0 C ° 5 2 . 3 3 - 11 0 10 1 1 11 1 0 0 0 0 0 0 C ° 5 2 6 0 . 5 4 - 11 0 10 1 0 01 1 1 1 0 0 0 0 C ° 5 5 - 10 0 11 0 0 10 0 0 0 0 0 0 0 |
Similar Part No. - FM75 |
|
Similar Description - FM75 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |