Overview of In-Vehicle 48V Systems and ADI SOCKETS Introduction | NEXTY Electronics, an Electronic Components and Semiconductor Trading Company

Background to the shift to 48V

With the recent trend toward vehicle electrification, an increasing number of applications are utilizing 48V POWER SUPPLIES instead of conventional 12V POWER SUPPLIES. Typical examples include starter generators, electric turbochargers, electric power steering, electric active suspension, electric brakes, and electric compressors. These require high output and high efficiency, making 48V a suitable option. Demand for 48V ECUs is expected to expand further in the future, as 48V ECUs are superior to high voltages of several hundred volts in terms of fuel economy regulations, comfort, cost, and safety. Meanwhile, existing 12V POWER SUPPLIES will continue to be used for lighting and relatively small applications, and the combined use of 12V and 48V systems is expected to become commonplace when considering overall vehicle optimization.

Benefits of 48V systems

・Improved power supply capacity

Compared to the conventional 12V, it can supply approximately four times the power at the same current, which makes it suitable for applications requiring relatively large amounts of power, such as electric pumps and electric steering.

・Lighter wiring due to reduced current

Higher voltage reduces the required current, allowing for thinner wiring and reduced weight, leading to improved fuel efficiency and vehicle performance.

・Improved fuel efficiency and reduced CO2 emissions

48V mild hybrids enable regenerative braking and engine assist using SECONDARY BATTERIES, which is expected to improve fuel efficiency and reduce exhaust gas emissions.

-Balance between safety and cost

Although the fuel efficiency improvement effect is less than that of vehicles that use high voltages of several hundred volts, such as EVs and HEVs, the 48V system is highly safe and has cost advantages as it does not require expensive insulation measures.

・Flexible system design

By using POWER SUPPLIES IC, 48V⇔12V conversion is possible, allowing coexistence with 12V systems and gradual introduction into existing vehicle designs.

Key points to consider when designing 48V applications

- Review the rated voltage of parts

Higher voltage resistance is required for control ICs, MOS FETS, CAPACITORS, CONNECTORS, etc. If 12V components are used at 48V as is, there is a risk of damage due to excessive voltage resistance or malfunction due to deviation from the operating voltage range, so it is necessary to replace them with 48V compatible parts, such as those with 80V or 100V voltage resistance.

・Improved power loss and thermal design

While 48V reduces current, it is possible that SWITCHES loss and EMI may increase. Thermal design and noise countermeasures must be reviewed.

- Strengthened safety standards and protection circuits

Because 48V poses a greater risk to the human body, safety designs such as overvoltage protection, overcurrent protection, and reverse polarity protection are important.
Compliance with functional safety standards such as ISO26262 may also be required.

ADI SOCKETS Introduction

We will introduce Analog Devices (ADI) products that are ideal for 48V applications. ADI has released a variety of 48V compatible products, mainly analog products, but this article will mainly introduce automotive POWER SUPPLIES supply related products.

LTC7822-1 2-Phase Hybrid Synchronous Buck Controller with Load Current Monitor

The LTC7822-1 is an automotive hybrid step-down synchronous rectifier controller that achieves high efficiency step-down from 48V to 12V. It employs ADI's proprietary hybrid architecture, which uses a soft SWITCHES charge pump to step down 48V to 24V, then converts the 24V to 12V using a two-phase interleaved synchronous buck converter. It supports a wide input voltage range (19V to 90V), achieving up to 98.4% efficiency while maintaining low EMI performance, and maintaining a high efficiency of 97.7% even at 1kW output. It also supports current monitoring, frequency synchronization, and parallel operation, making it ideal for high-power, high-density designs. It contributes to reduced power loss and compact size in data centers and automotive applications.
The EVAL-LTC7822-1-AZ evaluation board featuring the LTC7822-1 has an input voltage range of 36V to 60V, an output of 12V, and achieves approximately 1kW of power. Ideal for converting 48V to 12V, it is ready to use immediately after POWER SUPPLIES on. It also contributes to reducing the time required for initial implementation considerations and performance verification during the design stage.
*An NDA (non-disclosure agreement) is required to obtain a detailed data sheet.

MAX20059 72V/1A Automotive Synchronous Step-Down DC-DC CONVERTERS

The MAX20059 is an automotive synchronous step-down DC-DC CONVERTERS that supports a wide input voltage range from 4.5V to 72V. It features integrated MOS FETS and can deliver up to 1A of output current. The output voltage can be flexibly set from 0.8V to 90% of VIN using an external feedback resistor, and supports PWM or PFM control. The frequency can be set from 200kHz to 2200kHz, and external synchronization is also possible. It is AEC-Q100 qualified and has an operating temperature range of -40 to 125°C, making it ideal for automotive applications such as 48V systems and mild hybrid vehicles. Internal compensation simplifies design, and the device also offers comprehensive protection functions such as soft start, current limit, UVLO, and thermal shutdown.
*Figure 5 is a reference circuit for 16V output.

LTC7001 High Speed 150V High Side NMOS Static SWITCHES Driver

The LTC7001 is a high-speed, high-side N-channel MOS FETS GATE DRIVER that supports input voltages up to 135V (150V absolute maximum). Its integrated charge pump ensures the external MOS FETS remains fully on, enabling 100% duty cycle operation for POWER SUPPLIES line MOS FETS. A typical input-to-output propagation delay of 35ns (CL = 1nF) ensures fast response, and the integrated driver's 1Ω pull-down and 2.2Ω pull-up make it suitable for driving large gate capacitance. Separate pull-up and pull-down pins allow external resistors to adjust the rise and fall slew rates. The LTC7001 features overvoltage and undervoltage lockout, is AEC-Q100 qualified for automotive applications, and is ideal for SWITCHES and high-frequency SWITCHES applications.

AD8410A Current Sense Amplifier with -2V to 70V Input Voltage Range, 2.2MHz Bandwidth, and PWM Rejection

The AD8410A is an automotive-grade, high-precision current sense amplifier with an input common-mode voltage range of -2V to 70V (withstand voltage of -20 to 85V), a gain of 20V/V, and a bandwidth of 2.2MHz. DigiTrim™ technology achieves extremely low offset drift of ±0.21µV/°C and gain error of ±0.13%, while providing high precision with a CMRR of 142dB (typical). Supporting 48V systems and high-side current detection, the device enables bidirectional current measurement even in high-voltage environments such as motor control and DC-DC CONVERTERS, and maintains accuracy even in PWM SWITCHES environments.
DigiTrim™ technology is a patented digital trimming technique developed by ADI that precisely corrects the offset voltage of CMOS amplifiers. Unlike conventional laser trim or ELECTRICALLY ERASABLE PROMS methods, it uses existing analog pins to input adjustment values using special digital keywords, optimizing performance with digitally controlled current sources. After adjustment, the SILICONE FUSES is physically blown and fixed to prevent re-trimming. No additional pads or special equipment are required, and trimming can be performed after packaging, eliminating assembly errors. No process changes are required, and the trim circuit shrinks as the circuit shrinks, achieving high precision while keeping costs down. This innovative technology delivers high precision to low-cost CMOS amplifiers for mass production, reducing costs by up to 30% compared to competitors.

LTC7871 6-Phase Synchronous Bidirectional Buck-Boost Controller

The LTC7871 is a high-performance bidirectional synchronous buck/boost controller designed for automotive 48V/12V dual-battery systems. It can be expanded to a maximum of 24 phases in a 6-phase configuration, and supports input voltages up to 100V and output voltages up to 60V using external MOS FETS and GATE DRIVER. Its unique constant-frequency current-mode control achieves ±1% voltage accuracy and excellent noise immunity. It also features an SPI-compatible serial interface for accessing operating status and fault information, as well as programmable input/output voltage margining.
For automotive 48V applications, the LTC7871 can switch between stepping down from 48V to 12V or stepping up from 12V to 48V in response to a control signal, achieving bidirectional power supply. This enables stable power supply to high-load devices such as engine starters and electric ACTUATORS, and provides flexible support for 48V POWER SUPPLIES designs.
The LTC7871's advantages include high-efficiency (up to 98%) synchronous rectification, accurate INDUCTORS current monitoring, overcurrent protection, and OV/UV monitoring, ensuring both reliability and safety. It also meets the quality requirements of automotive applications, enabling efficient and safe power conversion in electric, hybrid, and industrial POWER SUPPLIES systems.

LTC7060 6-Phase Synchronous Bidirectional Buck/Boost Controller

The LTC7060 is a high-performance half-bridge GATE DRIVER that supports POWER SUPPLIES voltages up to 100 V and is ideal for automotive and industrial POWER SUPPLIES systems. The IC uses a symmetrical floating GATE DRIVER structure to drive two N-channel MOS FETS, allowing both the high-side and low-side drivers to drive MOS FETS using separate ground references, providing excellent noise immunity and transient immunity.
The LTC7060 provides strong gate drive with 0.8 Ω pull-down and 1.5 Ω pull-up to accommodate high-voltage MOS FETS with large gate capacitance. Additionally, the LTC7060 offers numerous features for enhanced safety and control, including adaptive shoot-through protection, programmable dead time, three-state PWM input, VCC UVLO/OVLO, and floating POWER SUPPLIES UVLO.
For automotive 48V POWER SUPPLIES supplies, the evaluation board (DC2886A) combining the LTC7060 and LTC7871 can control bidirectional step-down from 48V to 14V or step-up from 14V to 48V. In step-down mode, it supports output of up to 2.5kW, making it suitable for high-power applications in EVs and hybrid vehicles.
The LTC7060's benefits, including AEC-Q100 qualified automotive reliability, high-efficiency power conversion, and design flexibility, make it an ideal solution for designing 48V POWER SUPPLIES networks that combine safety, efficiency, and scalability.