Datasheet MLX90821 (Melexis) - 8

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MLX90821
Relative Pressure Sensor IC Parameter Symbol Remarks Min Typ(1) Max Units Analog saturation output Vsat high Pull-up ≥ 4.7kΩ 97 100 %Vdd level Pull-down ≥ 4.7kΩ 96 100 Pull-down ≥ 10kΩ 97 100 Vsat low Pull-up ≥ 4.7kΩ 0 3 %Vdd Pull-down ≥ 4.7kΩ 0 3 Power up time analog Time from reaching minimum allowed 1.3 ms supply voltage of 4.5V till having the output within specification Power up time SENT Time from reaching minimum allowed 1.1 ms supply voltage of 4.5V till the first falling edge of the first SENT frame Pressure response time Time needed for the output to change 1 ms analog from an input pressure step to 90% of its final value. Capacitive load 100nF. Using default filter settings PFLT=0 and SSF=1. For response times using different filter settings see Table 10. Pressure response time Default filter setting PFLT = 0 and SSF = 1. 3 SENT SENT(4) Tick time = 3us and Pause Pulse enabled. frames For other configurations refer to Table 10 in chapter 12.1. InP InN digital diagnostic Diagnostic thresholds of 25% of VDDA -16384 16384 lsb levels (low) and 75% of VDDA (high) Pressure output noise BW limited to 50kHz. 2 mVrms analog Input voltage range on 0 3.5 V NTC pin Table 4: Electrical specifications
Detailed General Description
The MLX90821 contains a pressure sensing element which consists of a square diaphragm realized in the silicon chip by backside etching. The diaphragm reacts to a pressure difference between the top and bottom side of the diaphragm. The internal strain increases, in particular at the border of the diaphragm. Here, the piezoresistive elements have been implanted into the silicon diaphragm, which act as a transducer. The sensor interface containing the readout circuit is integrated in the same package as the sensing element. The electronics front end amplifies the signal from the bridge, performs a coarse offset compensation and an ADC conversion. The DSP performs the compensations over temperature. Furthermore, the digital circuit provides some filtering, the possibility to linearize the pressure signal and also implements the clamping function. The analog back end consists of a 12 bit DAC and an output driver. This chip delivers an analog output proportional to the pressure or a SENT output compliant with the rev 4 from April 2016 of the SAE J2716 specification. An accurate factory calibrated external NTC temperature is also available on the SENT output. 4 Number of SENT frames between pressure step and settled output (last frame containing stable pressure data) REV 002 – 17 OCT 2019 Page 8 of 39 3901090821