Datasheet MAX6576, MAX6577 (Maxim) - 5

MAX6576/MAX6577 SOT Temperature Sensors with Period/Frequency Output MAX6576 MAX6577 CLOCK WAVEFORM OUTPUT CLOCK WAVEFORM OUTPUT tOUT tOUT fOUT = 1 / tOUT fOUT (°K) Figure 1. MAX6576 Timing Diagram Figure 2. MAX6577 Timing Diagram
Applications Information
VDD to select a scalar multiplier of 1Hz/°K. The MAX6577
Quick-Look Circuits
converts the ambient temperature into a square wave with a frequency that is equal to the absolute temperature of Figure 3 shows a quick-look application circuit for the the device in Hertz. The 8051 μC reads the frequency of MAX6576 using a universal counter measuring period. the square-wave output of the MAX6577 into Timer 0 and TS1 and TS0 are both tied to ground to select a scalar displays the temperature as degrees Celsius in binary on multiplier of 10μs/°K. The MAX6576 converts the ambi- Port 1. Listing 1 provides the code for this application. The ent temperature into a square wave with a period that is interface is similar for the MAX6576, except the μC will 10 times the absolute temperature of the device in μs. perform a period measurement. At room temperature, the universal counter will display approximately 2980μs.
Noise Considerations
Figure 4 shows a quick-look application circuit for the The accuracy of the MAX6576/MAX6577 is susceptible to MAX6577 using a universal counter measuring frequency. noise generated both internally and externally. The effects TS1 is tied to ground and TS0 is tied to V of external noise can be minimized by placing a 0.1μF DD to select a scalar multiplier of 1Hz/°K. The MAX6577 converts the ceramic bypass capacitor close to the supply pin of the ambient temperature into a square wave with a frequency devices. Internal noise is inherent in the operation of the that is equal to the absolute temperature of the device devices and is detailed in Table 3. Internal averaging mini- in Hertz. At room temperature, the universal counter will mizes the effect of this noise when using longer scalar display approximately 298Hz. timeout multipliers. The effects of this noise are included in the overall accuracy of the devices as specified in the
Interfacing with a Microcontroller
Electrical Characteristics. Figure 5 shows the MAX6577 interfaced with an 8051 μC. In this example, TS1 is tied to ground and TS0 is tied to www.maximintegrated.com Maxim Integrated │ 5