DYP-L02 Ultrasonic Liquid Level Sensor – Technical Guide

The DYP-L02 Ultrasonic Liquid Level Sensor is designed for non-contact liquid level measurement and upper/lower level detection in sealed containers.

Unlike conventional wetted liquid sensors, the L02 can operate from outside the container without drilling holes or placing a sensing element directly into the liquid.

When mounted underneath a container, it can measure liquid level height. When mounted on the outside wall of a container, it can detect whether liquid is present at a specific monitoring point.

This makes the sensor suitable for applications where direct contact with the liquid is undesirable or where the container needs to remain sealed.

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Key Features #

The DYP-L02 provides:

• Non-contact liquid level measurement
• 2.8–5 V operating voltage
• 20–2000 mm liquid level measurement range
• 1 mm resolution
• Real-time tracking across the measurement range
• Multiple output configurations
• Adaptive blind-zone detection
• Operating temperature from -15°C to +60°C
• Storage temperature from -25°C to +80°C
• ESD protection compliant with IEC 61000-4-2
• Compact sensor design
• Automatic and triggered operating modes

The sensor uses an intelligent algorithm to identify container characteristics and automatically adapt its blind zone.

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Typical Applications #

The L02 can be used for liquid detection through containers made from dense materials including:

• Steel
• Iron
• Glass
• Ceramic
• Non-foamed plastics

It is intended for clean, single-component liquids or miscible liquid mixtures without substantial sediment.

Typical applications include:

• Smart drinking cups
• Smart beer kegs
• Smart liquefied-gas systems
• Intelligent liquid-control equipment
• Sealed-container liquid monitoring

For reliable measurement, the container should have a reasonably regular shape and a relatively flat mounting surface.

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Technical Specifications #

Parameter	L023MUW	L023MTW	L023MGDW	L023MPNW
Operating Voltage	2.8–5 V	2.8–5 V	2.8–5 V	2.8–5 V
Standby Current	1 µA	1 µA	1 µA	1–8000 µA
Average Current	2.5–5 mA	2.5–5 mA	2.5–5 mA	2.5–15 mA
Blind Zone	Adaptive	Adaptive	Adaptive	Adaptive
Liquid Level Range	20–2000 mm	20–2000 mm	20–2000 mm	20–2000 mm
Operating Cycle	1 s	Triggered	1 s	1 s
Output	Automatic UART	Triggered UART	TTL Switching	PNP/NPN Switching
Resolution	1 mm	1 mm	1 mm	1 mm
Response Time	1 s	1 s	1 s	1 s
Repeatability Error	±1 mm	±1 mm	—	—
Measurement Angle	3–12°	3–12°	3–12°	3–12°

For the UART models, room-temperature accuracy is specified as:

±(5 + S × 0.5%) mm

where S represents the current liquid level height.

Actual blind zone and measurement performance depend on the container material and wall thickness.

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Mechanical Dimensions #

According to the mechanical drawing in the specification:

• Sensor diameter: 27.7 ± 0.5 mm
• Sensor height: 17 ± 1 mm
• Cable length: 300 ± 10 mm

The sensor’s compact form factor allows it to be mounted externally on suitable containers.

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Pin / Lead Definitions #

The L02 uses four electrical connections:

Pin	Lead	Description
1	VCC	2.8–5 V power input
2	GND	Power ground
3	TX/H	UART output / active-high TTL output / PNP output
4	RX/L	UART input / active-low TTL output / NPN output

The function of TX/H and RX/L depends on the selected sensor model and output configuration.

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Environmental Conditions #

Parameter	Minimum	Typical	Maximum
Storage Temperature	-25°C	25°C	80°C
Storage Humidity	—	65% RH	90% RH
Operating Temperature	-15°C	25°C	60°C
Operating Humidity	—	65% RH	80% RH

Humidity specifications are non-condensing and vary according to ambient temperature.

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Electrical Conditions #

Parameter	Minimum	Typical	Maximum
Input Voltage	2.8 V	5 V	5.25 V
Peak Current	—	—	130 mA
Input Ripple	—	—	50 mV p-p
Input Noise	—	—	100 mV p-p
ESD	—	—	±4 kV / ±8 kV

The probe housing and output leads comply with IEC 61000-4-2 for the stated ESD specification.

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UART Output #

The L02 supports two UART operating modes depending on the selected model.

Automatic UART #

The sensor performs one measurement every second. The TX line automatically outputs the current measured liquid level.

Triggered UART #

A high-level pulse applied to RX initiates measurement on its falling edge. The sensor then outputs one liquid-level reading through TX.

The interval between triggers must be greater than 1 second.

UART Communication Settings #

Setting	Value
Signal Level	TTL
Data Bits	8
Stop Bits	1
Parity	None
Baud Rate	9600 bps

UART Data Format #

Each reading consists of four bytes:

Field	Description	Length
Header	Fixed value 0xFF	1 byte
Data_H	Upper 8 bits of distance data	1 byte
Data_L	Lower 8 bits of distance data	1 byte
SUM	Checksum	1 byte

The checksum is calculated as:

SUM = (Header + Data_H + Data_L) & 0x00FF

Example:

Header = 0xFF
Data_H = 0x07
Data_L = 0xA1
SUM    = 0xA7

Liquid level:

Liquid Level = Data_H × 256 + Data_L
             = 0x07A1
             = 1953 mm

Therefore, this example represents a measured liquid level of 1953 mm.

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TTL Switching Output #

Active-High Output #

When liquid is detected:

• LED flashes once per second.
• TX output is at VCC.

When no liquid is detected:

• LED remains continuously on.
• TX output is 0 V.

The TTL output provides a logic-level signal only and cannot directly drive a load.

Active-Low Output #

When liquid is detected:

• LED flashes once per second.
• RX output is 0 V.

When no liquid is detected:

• LED remains continuously on.
• RX output is at VCC.

This output is also intended only as a high/low logic signal and cannot directly drive a load.

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PNP / NPN Switching Output #

PNP Output #

When liquid is detected, the internal transistor switches on and output H rises to VCC.

When no liquid is detected, the transistor switches off and output H is 0 V.

Use a resistive load drawing less than 100 mA.

NPN Output #

When liquid is detected, the internal transistor switches on and output L connects directly to GND.

When no liquid is detected, the transistor switches off and output L becomes an open circuit.

The resistive load must draw less than 100 mA.

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LED Status Indicators #

The sensor’s LED provides a quick indication of its operating state:

LED Status	Meaning
Continuously On	Sensor powered; no liquid detected
Slow Flashing	Liquid detected; flashes once per second
Triggered UART	Flashes once for every triggered measurement

In triggered UART mode, the LED remains off when no measurement is being triggered.

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Choosing the Correct DYP-L02 Model #

There are four L02 variants. The output configuration is determined at the factory; one sensor does not simultaneously support multiple output configurations.

Model	Output / Function
DYP-L023MUW-V1.0	Automatic UART output
DYP-L023MTW-V1.0	Triggered UART output; 1 µA standby current
DYP-L023MGDW-V1.0	TTL high/low logic output; cannot drive a load
DYP-L023MPNW-V1.0	PNP/NPN output; load capability up to 100 mA

Which model should I use #

For applications requiring continuous numerical liquid-level data, choose the automatic UART model.

For low-power systems where measurements are initiated only when required, use the triggered UART model.

For simple liquid-present/liquid-absent detection connected to a microcontroller, the TTL version provides a logic-level output.

For applications requiring a switching output capable of driving a resistive load up to 100 mA, use the PNP/NPN version.

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Reliability Testing #

The L02 specification includes environmental, vibration and drop testing, including:

• 60°C / 85% RH powered operation for 72 hours
• -15°C powered operation for 72 hours
• 80°C / 80% RH storage for 72 hours
• -25°C storage for 72 hours
• 10–200 Hz vibration testing
• 1.2 m free-fall testing

After testing, the sensor must remain functional with performance degradation of no more than 10%.

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Important Installation and Usage Notes #

Sensor performance depends on the actual container and installation conditions.

Keep the following points in mind:

1. Blind zone and maximum detectable liquid level vary with container material.
2. Container wall thickness also affects the blind zone and maximum detectable level.
3. Measurements can become unstable when the liquid level is outside the effective measurement range.
4. Significant movement or tilting of the liquid surface can affect readings.
5. Electromagnetic compatibility should be considered during system design.
6. Applications operating close to the sensor’s limiting parameters should be evaluated carefully before final system integration.

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Packaging #

Standard packaging is supplied by default.

Packaging materials may also be customized according to incoming quality control (IQC) requirements.