As a core device for clinical POCT (point-of-care testing), the portable coagulation analyzer is widely used in emergency rooms, hospital wards, primary healthcare facilities, and home self-testing scenarios. It rapidly completes the detection of coagulation parameters such as PT, APTT, and INR, providing critical evidence for the diagnosis of thrombotic and bleeding disorders. As a Class II medical device, it operates in complex and variable environments, facing long-term EMC risks such as human body static electricity, power surges, and interface plug/unplug interference. These can easily lead to failures such as system crashes, data anomalies, measurement accuracy drift, and hardware damage, directly threatening diagnostic reliability and patient safety.

Shanghai Leiditech has been deeply engaged in the EMC protection field for over 16 years and is a leading domestic supplier of EMC protection solutions and components. Based on the hardware architecture of portable coagulation analyzers, Leiditech's EMC support team provides an in-depth analysis of ESD and surge protection principles and design solutions, offering a one-stop protection selection guide that is both practical and certification-ready, helping equipment meet mandatory medical standards such as IEC 61000 and YY 0505.

Portable Coagulation Analyzer: Functions and Hardware Architecture

Portable coagulation analyzers use electrochemical or optical detection principles, support micro-volume whole blood testing, and integrate functions such as precise 37°C temperature control, data storage, Bluetooth/USB communication, and lithium battery power supply. They feature small size, low power consumption, fast testing speed, and ease of operation, making them standard equipment in mobile healthcare scenarios.

1. Sample testing and temperature control unit: The core actuation unit responsible for coagulation reaction and signal acquisition, extremely sensitive to electromagnetic interference;

2. Main MCU unit: The device's brain, responsible for computation, storage, and logic control. Electrostatic interference can easily cause program runaway;

3. Communication interface unit: USB (charging + data) and Bluetooth antenna, which are the main channels for external interference intrusion;

4. Power management unit: Lithium battery power supply, DC/DC regulation, charging management. Surge/overvoltage can easily damage power supply chips;

5. Human-machine interface unit: LCD screen and physical buttons. Direct human contact can introduce electrostatic discharge interference.

All external interfaces, power ports, and human-machine interface ports of this device are key design areas for EMC protection.

EMC protection standards and equipment standards for portable coagulation analyzers

As a medical electronic device, the portable coagulation analyzer must comply with mandatory national standards, which also serve as the design benchmark for Leiditech's protection solution:

IEC 61000-4-2: Electrostatic discharge (ESD) immunity test — contact discharge ±8kV, air discharge ±15kV;

 IEC 61000-4-5: Surge (shock) immunity test — power port ±2kV, signal port ±1kV;

 YY 0505-2012: Electromagnetic compatibility requirements for medical electrical equipment (domestic mandatory certification standard);

 IEC 60601: General safety requirements for medical electrical equipment.

ISO 15189:2022 — Medical laboratories — Requirements for quality and competence

CLSI H59-A — Quantitative D-dimer assay for the exclusion of venous thromboembolism

 CLSI H57 — Performance verification of coagulation analyzers

 ISO 22870:2016 — Point-of-care testing (POCT) — Requirements for quality management

 YY/T 0659-2017 — Safety requirements for coagulation analyzers: Compliant with GB 4793.1 (electrical safety) and GB/T 18268.26 (electromagnetic compatibility)

Leiditech's full range of protection components perfectly meet the safety and EMC test requirements for medical equipment.

Leiditech's Targeted ESD and Surge EMC Protection Solution

Based on the hardware architecture of the portable coagulation analyzer, Leiditech's EMC support team provides professional protection design for four vulnerable points: the power port, charging interface, communication interface, and human-machine interface. All solutions take into account miniaturization, low power consumption, and high reliability, making them suitable for PCB layout of portable medical equipment.

Protection for Lithium Battery Charging Port (Type-C)

Port characteristics: External charging + data transmission, in direct contact with an external adapter, making it a primary entry path for surges, ESD, and overvoltage.
Protection requirements: IEC 61000-4-2 ±8kV, IEC 61000-4-5 ±2kV;

Protection principle: Use an ESD array to discharge ESD and surge pulses, clamping the voltage to protect the downstream charging IC;

Leiditech provides surge protection for 3.7V lithium battery power interfaces. Depending on the power supply environment, selectable ESD/TVS devices with appropriate protection currents meet IEC 61000-4-2 Level 4 requirements (30kV contact discharge, 30kV air discharge). For compliance with high-level IEC 61000-4-5 surge testing, high-power devices can be selected to improve overall surge immunity.

DC power interface: Used to connect an external 5V DC input power adapter

Port characteristics: Supplies power to the entire device; surges can directly damage the voltage regulator IC.
Protection requirements: Surge ±2kV, ESD ±8kV contact;

Protection principle: TVS diode protection, fast response, absorbs pulse interference on the power line;

Protection for USB Data Interface / Bluetooth Communication Port

Port characteristics: Data transmission interface and antenna interface; ESD interference can cause communication interruption and data packet loss.
Protection requirements: IEC 61000-4-2 ±15kV, low capacitance, no interference with wireless signals;

Protection principle: Ultra-low capacitance ESD protection devices, unidirectional/bidirectional ESD discharge, no signal attenuation;

Leiditech recommendation: USB 2.0 provides a transmission speed of 500Mbps. This solution uses a single device for protection, saving space, ensuring signal integrity, and filtering out common-mode interference. The SR05 meets IEC 61000-4-2 Level 4 (20kV contact discharge, 20kV air discharge). The SR05W meets IEC 61000-4-2 Level 4 (30kV contact discharge, 30kV air discharge), offering 7 times better performance to withstand various electrical disturbances in industrial applications. If overcurrent protection on Vbus is required, a PTC should be added.

SPI interface: High-speed serial communication interface used to connect memory chips, displays, etc.

Protection for Human-Machine Interface Unit (LCD Screen / Physical Buttons)

Port characteristics: Direct human contact, very high probability of ESD events, which can easily cause screen flickering, button failure, and MCU crashes.
Protection requirement: Contact discharge ±8kV;
Protection principle: ESD diode, quickly discharges human body static electricity and protects the IO port;

• Button

Leiditech recommends using standard low-capacitance discrete devices for ESD protection, meeting IEC 61000-4-2 Level 4 (8kV contact discharge, 15kV air discharge).

LCD screen MIPI interface:

MIPI provides transmission speeds for medium-to-low-speed interfaces (10M-1Gbps). Leiditech recommends using the integrated device ULC3304P10 for protection.  With a parasitic capacitance of <1pF, it ensures signal integrity and complies with IEC 61000-4-2 Level 4 (8kV contact discharge, 15kV air discharge).

Protection for Sample Testing / Temperature Control Drive Unit

Port characteristics: Analog signal acquisition port; interference can directly cause measurement data distortion.
Protection requirements: Low clamping voltage, high-precision protection;

• Analog signal port:

Leiditech recommendation: UART provides a transmission speed of 115200 bps. This solution uses discrete devices for protection, which are convenient to place in the design and ensure signal integrity. The ESDA33CP30, SMDA05CCN, and ULC0542C meet IEC 61000-4-2 Level 4 requirements.

As a high-reliability medical electronic device, ESD and surge EMC protection for the portable coagulation analyzer is a core requirement for product certification and ensuring clinical safety. Shanghai Leiditech has been focused on the R&D and supply of EMC protection components for 16 years. The Leiditech EMC support team can provide one-on-one solution design, testing and rectification, and selection support. The full range of products meets mandatory medical standards such as IEC 61000 and YY 0505.

Choose Leiditech's EMC protection solution to solve ESD, surge, overcurrent, and overvoltage interference issues for portable coagulation analyzers in one stop, helping products quickly pass medical device certification and improving device stability and market competitiveness.