Electronic Components Datasheet Search |
|
ADT6504 Datasheet(PDF) 8 Page - Analog Devices |
|
ADT6504 Datasheet(HTML) 8 Page - Analog Devices |
8 / 16 page ADT6501/ADT6502/ADT6503/ADT6504 Data Sheet Rev. B | Page 8 of 16 THEORY OF OPERATION CIRCUIT INFORMATION The ADT6501/ADT6502/ADT6503/ADT6504 are 11-bit digital temperature sensors with a 12th bit acting as the sign bit. An on-board temperature sensor generates a voltage precisely proportional to absolute temperature, which is compared to an internal voltage reference and input to a precision digital modulator. The 12-bit output from the modulator is input into a digital comparator where it is compared with a factory-set trip level. The output trip pin is activated if the temperature measured is greater than, in the case of the ADT6501/ADT6502, or less than, in the case of the ADT6503/ADT6504, the factory-set trip level. Overall accuracy for the ADT650x family is ±6°C (maximum) from −45°C to +115°C. The on-board temperature sensor has excellent accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. The ADT6501/ADT6503 have active low, open-drain output structures that can sink current. The ADT6502/ADT6504 have active high, push-pull output structures that can sink and source current. On power- up, the output becomes active when the first conversion is completed, which typically takes 30 ms. The sensor output is digitized by a first-order, ∑-∆ modulator, also known as the charge balance type analog-to-digital converter (ADC). This type of converter utilizes time domain oversampling and a high accuracy comparator to deliver 11 bits of effective accuracy in an extremely compact circuit. CONVERTER DETAILS The Σ-Δ modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1-bit digital-to- analog converter (DAC). Similar to the voltage-to-frequency converter, this architecture creates a negative feedback loop and minimizes the integrator output by changing the duty cycle of the comparator output in response to input voltage changes. The comparator samples the output of the integrator at a much higher rate than the input sampling frequency; this is called oversampling. Oversampling spreads the quantization noise over a much wider band than that of the input signal, improving overall noise performance and increasing accuracy. FACTORY-PROGRAMMED THRESHOLD RANGE The ADT6501/ADT6502/ADT6503/ADT6504 are available with factory-set threshold levels ranging from −45°C to +115°C in 10°C temperature steps. The ADT6501/ADT6503 outputs are intended to interface to reset inputs of microprocessors. The ADT6502/ADT6504 are intended for driving circuits of applications such as fan control circuits. Table 4 lists the available temperature threshold ranges. Table 4. Factory-Set Temperature Threshold Ranges Device Threshold (TTH) Range ADT6501 +35°C < TTH < +115°C ADT6502 +35°C < TTH < +115°C ADT6503 −45°C < TTH < +15°C ADT6504 −45°C < TTH < +15°C HYSTERESIS INPUT The HYST pin is used to select a temperature hysteresis of 2°C or 10°C. The digital comparator ensures excellent accuracy for the hysteresis value. If the HYST pin is connected to VCC, a hysteresis of 10°C is selected. If the HYST pin is connected to GND, a hysteresis of 2°C is selected. The HYST pin should not be left floating. Hysteresis prevents oscillation on the output pin when the temperature is approaching the trip point and after the output pin is activated. For example, if the temperature trip is 45°C and the hysteresis selected is 10°C, the temperature would have to go as low as 35°C before the output deactivates. TEMPERATURE CONVERSION The conversion clock for the part is generated internally. No external clock is required. The internal clock oscillator runs an automatic conversion sequence. During this automatic conversion sequence, a conversion is initiated every 600 ms. At this time, the part powers up its analog circuitry and performs a temperature conversion. This temperature conversion typically takes 30 ms, after which the analog circuitry of the part automatically shuts down. The analog circuitry powers up again 570 ms later, when the 600 ms timer times out and the next conversion begins. The result of the most recent temperature conversion is compared with the factory-set trip point value. If the temperature measured is greater than the trip point value, the output is activated. The output is deactivated once the temperature crosses back over the trip point threshold plus whatever temperature hysteresis is selected. Figure 15 to Figure 18 show the transfer function for the output trip pin of each generic model. |
Similar Part No. - ADT6504 |
|
Similar Description - ADT6504 |
|
|
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 |