Liquid Flow Sensor LD20
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LD20-2600B Liquid Flow Sensor Single-Use Liquid Flow Sensor for Biomedical Applications ▪ ▪ ▪ ▪ ▪ Compact, cost-effective, high performance Fast and reliable detection of failure modes Calibrated and temperature compensated Low flow sensing up to 1000 ml/h Millisecond-fast response time Product Summary The LD20 sensor family is Sensirion’s series of digital single-use liquid flow sensors designed for high-volume applications. It enables precise and reliable measurements of dynamic liquid flow rates from a few hundred µl/h up to 1000 ml/h bi-directionally. The LD20 sensors feature a digital interface (I2C) via metal contact pads. The LD20 series builds on the latest generation CMOSens® sensor chip that is at the heart of Sensirion’s flow sensing platform and allows to achieve an outstanding performance. The patented CMOSens® technology combines the sensor element, signal processing and digital calibration on a small CMOS chip. The wellproven CMOS technology is perfectly suited for high-quality mass production and is the ideal choice for demanding and cost-sensitive OEM applications. Benefits of Sensirion’s CMOSens® Technology ▪ High reliability ▪ Best signal to noise ratio ▪ Industry-proven technology with a track record of more than 15 years ▪ Designed for mass production and high process capability ▪ Optimized for low cost

Contents 1 Sensor Performance 3 3 Sensor Output Signal Description 6 www.sensirion.com Version 1 - D1 - February 2018 2/18

1 Sensor PerformanceThe following Table 1 lists the specifications of the single-use liquid flow sensor LD20-2600B. Parameter Table 1: Specifications for single-use liquid flow sensor LD20-2600B (all data for medium H2O, at 23°C) www.sensirion.com Version 1 - D1 - February 2018 3/18 Flow rate at which the sensor output saturates. See section 1.1 for performance between full scale and saturation point. Additional accuracy error in case liquid and ambient temperatures are similar but both deviating from 23 °C. Maximum additional offset when flow channel is vertical.

1.1 Specification Charts The LD20 flow sensors show bi-directional, linear transfer characteristics. The product comes fully calibrated for water. Rel. accuracy (±% of measured value) LD20-2600B Relative Accuracy with H2 O Figure 1: Liquid flow sensor accuracy and repeatability across the flow range of the LD20-2600B. Relative error in ±% of measured value for H2O. LD20-2600B Absolute Accuracy with H2 O Flow rate (ml/h H2O, for positive flow direction) Figure 2: Liquid flow sensor accuracy and repeatability across the positive flow range of the LD20-2600B. Absolute error in ml/h for H2O.

5 Flow path empty. Short term storage refers to temporary conditions during e.g. transport. 6 ESD level of sensor chip. ESD level of entire system or device to be determined by customer. www.sensirion.com Version 1 - D1 - February 2018 5/18

3 Sensor Output Signal Description 3.1 Flow Rate Measurement After the sensor receives the “start continuous measurement” command it enters the continuous measurement mode and continuously performs measurements of ~0.5 ms length. Therefore, the flow rate value is updated every 0.5 ms (see Table 3). The output flow rate value corresponds to the average ݑ of all individual 0.5 ms measurements Űݑ Űݑ since the last read out. This has the benefit that the user can read out the sensor at his own desired speed, without losing information and thus prevents aliasing. During the first 100 ms of...

3.3.1 Detection of Air-in-Line Owing to the thermal measurement principle of Sensirion’s liquid flow sensors, the sensors can differentiate between air or liquid media filling the flow channel. When air is passing through the sensor, bit 0 of the signaling flags is set to high (= 1). The flag returns to 0 (= low) as soon as the air has passed the point of measurement. Note that the corresponding bit 0 in the signaling flag output stays high until it is read out. See below. Since the air column has an impact on the fluidic profile inside the sensor’s flow channel, the High Flow flag (see...

as soon as the flow rate falls below the output limit. Note that the corresponding bit 0 in the signaling flag output stays high until it is read out. 3.4 Sensor Start-Up and Warm-Up Behavior The maximum time for system power-up is 25 ms until the sensor responds to communication requests. After reset or start-up of the sensor, the sensor's internal heater is turned off and must be started by performing a Start Continuous Measurement command (see section 4.3.1). The very first measurement is delayed by approximately 12 ms for all LD20 liquid flow sensors. Due to the thermal measurement...

4 Digital Interface Description The sensor’s digital interface is compatible with the I2C protocol. This chapter describes the available command set. For detailed information about the I2C protocol, please consult the document "NXP I2C-bus specification and user manual" (http://www.nxp.com/documents/user_manual/UM10204.pdf). The physical interface consists of two bus lines, a data line (SDA) and a clock line (SCL) which need to be connected via pull-up resistors to the bus voltage of the system. 4.1 I2C Address The sensor’s I2C address is 8. The I2C header is formed by the I2C address...

The sensor measures both the flow rate and the temperature. Both measurement results can be read out through one single I2C read header when the continuous measurement is running. Table 9: PC command to stop continuous measurement When the sensor is in continuous measurement mode, the sensor must be stopped before it can accept another command. The only exception is the soft reset command. In idle mode the sensor will consume less power, but consider the sleep mode for most effective energy saving. www.sensirion.com Version 1 - D1 - February 2018 10/18

Table 11: Sleep mode commands www.sensirion.com Version 1 - D1 - February 2018 11/18