Electronic Components Datasheet Search |
|
MAX6647MUA Datasheet(PDF) 6 Page - Maxim Integrated Products |
|
MAX6647MUA Datasheet(HTML) 6 Page - Maxim Integrated Products |
6 / 16 page The DXP-DXN differential input voltage range is 0.25V to 0.95V. Excess resistance in series with the remote diode causes +0.5°C (typ) error per ohm. Remote Temperature Measurement Range The MAX6646/MAX6647/MAX6649 measure remote temperatures significantly above the +120°C limit of many temperature sensors. External diode-connected transistors work well as temperature sensors up to approximately +145°C, where accuracy begins to degrade. Thermal diodes on some CPUs have charac- teristics that produce “apparent temperatures” far above actual operating temperatures. The MAX6646/ MAX6647/MAX6649 measure apparent temperatures as high as +170°C, as long as the actual temperature is less than +145°C. A/D Conversion Sequence A conversion sequence consists of a local temperature measurement and a remote temperature measurement. Each time a conversion begins, whether initiated auto- matically in the free-running autonomous mode (RUN = 0) or by writing a one-shot command, both channels are converted, and the results of both measurements are available after the end of a conversion. A BUSY status bit in the status byte indicates that the device is performing a new conversion. The results of the previous conversion are always available, even if the ADC is busy. Low-Power Standby Mode Standby mode reduces the supply current to less than 12µA by disabling the ADC and timing circuitry. Enter standby mode by setting the RUN bit to 1 in the configu- ration byte register (Table 6). All data is retained in mem- ory, and the SMBus interface is active and listening for SMBus commands. Standby mode is not a shutdown mode. With activity on the SMBus, the device draws more supply current (see Typical Operating Characteristics). In standby mode, the MAX6646/MAX6647/MAX6649 can be forced to perform A/D conversions through the one-shot command, regardless of the RUN bit status. If a standby command is received while a conversion is in progress, the conversion cycle is truncated, and the data from that conversion is not latched into a tempera- ture register. The previous data is not changed and remains available. Supply-current drain during the 125ms conversion period is 250µA (typ). Slowing down the conversion rate reduces the average supply current (see Typical Operating Characteristics). Between conversions, the conversion rate timer consumes 25µA (typ) of supply current. In standby mode, supply current drops to 3µA (typ). SMBus Digital Interface From a software perspective, the MAX6646/MAX6647/ MAX6649 appear as a set of byte-wide registers that contain temperature data, alarm threshold values, and control bits. A standard SMBus-compatible 2-wire serial interface is used to read temperature data and write control bits and alarm threshold data. The MAX6646/MAX6647/MAX6649 employ four standard SMBus protocols: write byte, read byte, send byte, and receive byte (Figures 1, 2, and 3). The shorter receive byte protocol allows quicker transfers, provided that the correct data register was previously selected by a read byte instruction. Use caution when using the shorter pro- tocols in multimaster systems, as a second master could overwrite the command byte without informing the first master. Temperature data can be read from the read internal temperature (00h) and read external temperature (01h) registers. The temperature data format for these regis- ters is 8 bits for each channel, with the LSB representing 1°C (Table 1). The MSB is transmitted first. An additional 3 bits can be read from the read external extended temperature register (10h), which extends the data to 11 bits and the resolution to 0.125°C per LSB. An additional 3 bits can be read from the read internal extended temperature register (11h), which extends the data to 11 bits and the resolution to 0.125°C per LSB (Table 2). When a conversion is complete, the main temperature register and the extended temperature register are updated simultaneously. Ensure that no conversions are completed between reading the main register and the extended register, so that both registers contain the result of the same conversion. +145°C Precision SMBus-Compatible Remote/ Local Sensors with Overtemperature Alarms 6 _______________________________________________________________________________________ FRACTIONAL TEMP (°C) DIGITAL OUTPUT 0.000 000X XXXX 0.125 001X XXXX 0.250 010X XXXX 0.375 011X XXXX 0.500 100X XXXX 0.625 101X XXXX 0.750 110X XXXX 0.875 111X XXXX Table 2. Extended Resolution Temperature Register Data Format (10h, 11h) |
Similar Part No. - MAX6647MUA |
|
Similar Description - MAX6647MUA |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |