Digital temperature sensor signal conversion
Given the oscillator frequency versus temperature transfer function curve. The oscillator frequency output can be voltage controlled.
Find the temperature output mode: (1) with I1 = NI2 into the above formula,
(2) where N: I1 / I2 current ratio,
K: Boltzmann constant,
T: Kelvin absolute temperature.
N, K, and q are known constants,
(ΔVBE) The bias diode of the transistor is configured in Figure 1 to prevent noise from the measurement interference. The maximum ΔVBE from the sensing transistor is tens of millivolts, Therefore, it is necessary to effectively deal with the gain pole pair signal, Achieve ADC requirements. Gain level with switched capacitor circuit and chopper amplifier. The ADC converts the analog signal proportional to the absolute temperature to a digital word (expressed in ° C).
In the description of the above working principle, The digital temperature sensor sense IC contains a sense transistor. This method is commonly referred to as local temperature sensing. Can also be extended to the transistor IC, This configuration is often referred to as remote temperature sensing. When using an external transistor, You must add an extra parameter to Equation 1 and Equation 2. This parameter is the ideal factor of the transistor nf, Nf is a measure of the ideal performance deviation of the transistor.
If the temperature changes, The processor will command the power management system to change the control voltage, Thereby maintaining a stable frequency over the temperature range. emiconductor manufacturers typically include IC processing functions in their temperature sensors. Because the ADC is part of the digital IC, And only a small part of the time used to measure the temperature. Therefore, some IC manufacturers have put the analog input channels into the IC (simply insert a multiplexer before the ADC input). The digital temperature IC's ADC typically has a slow transition time, Therefore, the analog input channel can only measure slow signals.
High-speed signal conversion is not possible.One of the common applications of these analog inputs is system voltage monitoring, Hope FSR accuracy of 1%. The newer devices combine DACs and temperature sensors into a single package. When measuring the temperature of the hot zone, Must be important to judge the temperature, And according to the level of temperature to take appropriate action. Each circuit has an optimum performance temperature, Programmable ADT7316 ADC output. The design of the complete temperature monitoring system, Can monitor or control the speed of many fans and measure the limit supply voltage and multiple thermal areas (Including any connected transistor connected to a high-performance IC diode or discrete transistor) and temperature.