JH-Micro Technology

China-developed Solutions for Automotive AC Compressors

Modern vehicles increasingly rely on electric AC systems for better efficiency and comfort. Electrically driven compressors outperform mechanical ones with faster response and lower energy consumption.

For optimal control, we recommend AutoChips AC7840x or Flagship FC4150x as the main controller - a market-proven solution. This article examines compressor controller design and China-developed motor control chip options to advance AC technology.
Reference details are as follows:

Block Diagram of AC Compressor System Based on AC7840x/FC4150x

The automotive electric AC compressor motor controller is a critical component of vehicle AC systems, managing compressor start/stop, speed regulation, and motor protection. Key components include:
MCU (Main Controller): Processes signals, executes control algorithms, and adjusts compressor operation.
IPM (Intelligent Power Module): Integrates power semiconductors for precise motor control via PWM, enabling optimal efficiency.
LDO/Voltage Regulator: Maintains stable voltage output despite automotive power fluctuations.
Op-Amp/Comparator: Enhances signal processing, feedback control, and fault diagnosis.
Digital Isolation: Provides noise suppression and fault protection between MCU and CAN.
Isolated Amplifier: Enables accurate current monitoring with electrical isolation.
CAN Bus: Facilitates real-time communication with other vehicle systems.
EEPROM: Stores fault codes and critical data for diagnostics and security.

AutoChips AC7840x Series (Main Controller) Introduction

Company Profile
AutoChips, a wholly-owned subsidiary of NavInfo, specializes in automotive semiconductor design since 2013. With R&D centers in Hefei, Shenzhen, Shanghai, and Wuhan, its product includes MCUs, SoCs, TPMS chips, and audio amplifiers. Its automotive-grade SoC/MCU solutions lead the market, serving 95%+ Chinese OEMs with 70M+ MCUs shipped globally.

Key Highlights
Core: 120MHz ARM Cortex-M4F (AEC-Q100 compliant)
Memory: 1MB CFlash (dual-bank) + 128KB DFlash (ECC) + 128KB SRAM
Interfaces: CAN-FD, SPI, I2C, UART/LIN, ADC, CMP
Security: ISO 26262 ASIL-B, AES-128, TRNG, 17-key management
Low Power: RTC wake-up with 32KB SRAM retention

Advantages
Balancing performance (functional safety), security, and cost-effectiveness, the AC7840x series is ideal for automotive AC compressor control with proven mass-production reliability.

AC7840x System Block Diagram

Flagchip FC4150 Series (Main Controller) Introduction

Company Profile
Founded in October 2020, Suzhou Flagchip develops high-performance automotive SoCs based on ARM Cortex-M4/M7 architectures. With self-developed IP and multi-core lockstep technology, its ISO 26262 ASIL-B to ASIL-D compliant products meet AEC-Q100 standards for body, chassis, powertrain and battery management applications.
Key Highlights
Core: 150MHz Cortex-M4F with FPU and DSP instructions
Memory: 2MB Flash + 256KB D-Flash + 256KB ECC SRAM
Safety: ASIL-B certified with HSM encryption engine
Interfaces: 10/100Mbps Ethernet (IEEE1588/AVB), 6x FlexCAN (CAN-FD/PNET)
Certification: AEC-Q100 Grade 1
Advantages
The FC4150 series delivers high computing power, rich memory resources and robust security, making it an ideal choice for automotive AC compressor control with strong local support.

FC4150Fx System Block Diagram

LN20x42Q1 (LDO) Introduction

Company Profile
LEN technology (Wuxi), founded in 2017, specializes in automotive power management ICs including DC-DC converters, LDOs, multi-channel power supplies, LED drivers and high-side switches. With over 200 million chips shipped to 40+ global automakers and 200+ suppliers, the company holds 57 patents (including 14 international patents) and maintains strict automotive-grade quality standards throughout product lifecycle.
Key Highlights
LN20542Q1:
Input: 2.75V-42V
Fixed 5V output (200mA max)
Ultra-low Iq: <5.5μA (active), <1μA (shutdown)
High-voltage EN pin compatible with VIN/logic signals
Protections: OCP, OTP with auto-recovery
Packages: MSOP8-EP/DFN8 with thermal pad
LN20042Q1:
Adjustable output (200mA max)
<7.5μA Iq (active), <1μA (shutdown)
Programmable PG signal delay for MCU reset
Same protections and packages as LN20542Q1
Advantages
LEN’s LDOs deliver superior performance, reliability and ultra-low power consumption, making them ideal for automotive MCU power applications.

瓴芯LN20x42Q典型应用图

RHC RH1042Q (CAN Transceiver) Introduction

Company Profile
RHC (Hangzhou) is a fabless semiconductor company founded by ex-Maxim engineers. Specializing in high-reliability automotive and industrial analog chips, product roadmap includes CAN/LIN/RS-485 transceivers (short-term), automotive SBCs (mid-term), and NEV-focused solutions (long-term).

Key Highlights
Compliant with ISO11898-2:2016 & SAEJ2284-1/5 standards
Dual modes: Normal (8Mbps+) and Standby (ultra-low power)
Wide common-mode range: ±40V
ntegrated level shifter (2.8V-5.5V logic compatibility)
Robust protections:
±70V bus fault protection
±25kV HBM/±15kV IEC ESD protection
Thermal shutdown & current limiting

Advantages
The RH1042Q delivers industry-leading reliability with comprehensive fault protection, making it ideal for harsh automotive CAN communication environments.

RH1042Q Parameter Table

KKchips HER431 Shunt Regulator

Profile
KKchips founded in 2021, develops automotive-grade ICs for powertrain/chassis applications.
Key Features
2.5V-36V adjustable output (±0.4%)
20ppm/°C, 4.5mV temp drift
1mA-100mA sink current, SOT23 package
AEC-Q100 qualified (-40°C to +125°C)
Advantage
High-precision voltage reference for automotive power systems.

2PAI Pai12xx/Pai8300E (Digital Isolator/Isolation Amplifier)

Profile
2PAI Semiconductor founded in 2017 specializes in analog ICs including digital isolators, drivers, and interface chips for EV/industrial applications. Its patented iDivider™ technology achieves superior isolation performance.
Key Features
Pai12xx Isolators:
1.5-5kVrms isolation
600Mbps speed, 2.5-5.5V operation
Default output fail-safe
Pai8300E Amplifier:
5kVRMS UL1577-certified isolation
Integrated overvoltage/power-loss detection
Compressor current monitoring
Advantage
Industry-leading isolation chips for EV motor control and safety-critical systems.

Pai12xx Application Schematic Diagram

Pai8300E Application Schematic Diagram

Runic Op-Amps/Comparators

Runic Technology specializes in high-performance analog/mixed-signal ICs, offering signal chain (op-amps, comparators, switches) and power management solutions for automotive/industrial applications.
Key Features
Motor Control Applications:
Signal amplification (sensor signals)
Filtering/waveform shaping
Voltage level comparison
Closed-loop feedback control
Advantage
High-reliability op-amps/comparators with excellent electrical characteristics for automotive compressor controllers.

Conclusion

This motor control solution for automotive AC compressors showcases efficient, precise domestic alternatives that enhance energy efficiency, stability, and responsiveness. Together, let's drive greener, smarter automotive innovation.
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