1.2 Space Efficiency of Multilayer Wiring
Thick-film technology supports multilayer wiring, allowing multiple circuit layers to be stacked vertically, significantly increasing circuit density. For DC-DC power modules, this means integrating all components—transformers, filter inductors, control chips, power switches—within a limited space. The LHP10 series module measures only 39.2mm × 23mm × 8.01mm, yet delivers 10W of output power and provides up to three independent voltage outputs, exemplifying the spatial advantages of thick-film technology.
Key Advantages of Thick-Film Hybrid Integrated Circuits:
- Operating temperature range from -55°C to +210°C (storage temperature)
- Ceramic substrate provides excellent heat dissipation path with low thermal resistance
- Multilayer wiring enables high-density integration and small module footprint
- Noble metal pastes ensure long-term reliability with no risk of electromigration
- Suitable for batch production with good consistency
2. High-Frequency Conversion Technology: The Path to Efficient Conversion
The LHP10 series high-temperature DC-DC modules employ a high-frequency conversion operating mode, which is the key technological approach for achieving high efficiency and small size. Its working principle can be summarized in three core steps: "inversion – isolation – rectification."
2.1 High-Frequency Inversion: DC to AC Conversion
The module first converts the 24V–72V DC input voltage into a high-frequency AC signal via power switching transistors. The switching frequency typically ranges from 100kHz to 500kHz, much higher than conventional line frequency (50/60Hz). High-frequency operation offers two significant advantages: First, the size of transformers and filter inductors is inversely proportional to switching frequency, enabling substantial miniaturization of magnetic components. Second, although switching losses increase, losses in magnetic components decrease, potentially improving overall efficiency. The LHP10 series achieves a typical conversion efficiency of 75%, leading among similar high-temperature power products.
2.2 Isolation Transformer: Electrical Isolation and Voltage Conversion
The high-frequency AC signal passes through an isolation transformer for voltage conversion and electrical isolation. Isolation is an important safety requirement in LWD systems—if a failure occurs in the downstream circuitry, the high-voltage input does not directly conduct to the measurement path, protecting personnel safety and equipment integrity. The LHP10 series provides 1000V isolation voltage (500V for some specifications) between input and output, fully meeting industrial safety standards. The transformer uses high-frequency magnetic core materials (such as ferrite or amorphous alloy) that maintain stable magnetic performance at 200°C.
2.3 Synchronous Rectification: AC to DC Final Conversion
The transformer's secondary output is rectified and filtered to produce a smooth DC voltage. Modern DC-DC modules often employ synchronous rectification, replacing conventional diodes with power MOSFETs to further reduce conduction losses. Output filtering uses low-ESR capacitors and multi-stage LC filter networks to keep ripple ≤1% of Vout, ensuring a "clean" power supply for precision measurement circuits.
3. Wide-Input Voltage and Multiple-Output Design
The downhole supply voltage in LWD systems is often non-constant—cable voltage drop varies with depth, with long cables having resistances of tens of ohms, causing the input voltage to fluctuate over a wide range. The LHP10 series modules support a wide input voltage range of 24V–72V, accommodating these complex operating conditions.
Input/Output Characteristics:
- Input voltage range: 24V–72V DC
- Supports single, dual, or triple outputs
- Output voltage options: 3.3V, 5V, 9V, 12V, 15V, 18V, 24V
- Maximum output power per module: 10W
- Output power derating to 40% (4W) at 200°C case temperature
The multiple-output design is another highlight of the LHP10 series. Downhole systems typically require power for different loads such as sensors, preamplifier circuits, and digital processing units, each with different voltage requirements. The LHP10 series provides up to three independent outputs, with common-ground or isolated configurations available between outputs, flexibly adapting to various system architectures.
4. Protection Features and Reliability Design
While high-frequency conversion technology offers excellent performance, it also introduces some reliability challenges. The LHP10 series ensures long-term stable operation in harsh environments through multiple protection mechanisms.
4.1 Overcurrent and Short-Circuit Protection
When the output current exceeds the rated value or a short circuit occurs, the module enters "hiccup" mode—automatically reducing output power and maintaining a low-power state. Once the short circuit is removed, the module automatically resumes normal output. This design avoids overheating damage from sustained high currents while enabling automatic recovery without manual intervention.
4.2 Temperature Protection and Derating Design
The LHP10 series incorporates built-in temperature protection. When the case temperature reaches 200°C, the module continues to operate but automatically derates output power to 40% of the rated value (4W). This design allows the system to operate in a degraded mode under extreme conditions, buying time for safe equipment retrieval.
4.3 Transient Response Optimization
During load steps or input voltage steps, DC-DC module outputs exhibit overshoot and recovery periods. The LHP10 series features a transient recovery time of up to 20ms with overshoot of approximately 10%, balancing response speed while avoiding excessive voltage fluctuations.
5. Typical Application Scenarios
Based on thick-film hybrid integrated circuit and high-temperature conversion technologies, the LHP10 series 200°C ultra-high-temperature DC-DC power modules provide unique value in the following scenarios:
Core Application Areas:
- Logging While Drilling (LWD): Provides stable power conversion for downhole MWD/LWD instruments
- Wireline logging: Surface and downhole power supply for high-temperature well sections (≥175°C)
- Deep earth exploration: Power supply systems for instrumentation in 10,000-meter deep wells
- Oil well logging: Power for high-temperature high-pressure (HTHP) well logging equipment
- Geothermal energy development: Power support for downhole geothermal well instruments
- Aerospace: Power supply for high-temperature electronic equipment near engine compartments
6. Technical Selection Recommendations
When selecting high-temperature DC-DC power supplies for LWD systems, the following points are recommended:
1. Determine the maximum case temperature: Estimate the actual module case temperature based on well depth and geothermal gradient, selecting a product with adequate margin above the operating temperature limit. It is recommended that case temperature not exceed 80% of the rated temperature.
2. Calculate total power consumption: Sum the total current requirements of downstream circuits and select a module with at least 30% output power margin. For the LHP10 series, operation in the 30%–70% rated power range provides the most stable performance.
3. Determine voltage configuration: Select appropriate output voltages and number of channels based on load types. For multiple outputs, note whether common-ground or isolated configuration is required.
4. Consider mounting method: The module uses a pin-type package (nickel-plated copper pins) and supports PCB soldering installation. Ensure soldering temperature does not exceed 300°C and soldering time does not exceed 10 seconds.
