NXP’s automatic transmission block diagram

Description

Low fuel consumption, reduced CO2 emissions, further electrification of the drivetrain and increased comfort will result in high growth of automatic transmission solutions. Different clutch concepts – wet or dry double-clutch – which manage start/stop functions and automatic transmission will increase the complexity of the system and require more sensors, and more drivers for the actuators.

NXPs technology and product advancements are driving up overall drivetrain efficiency and helping to reduce fuel consumption, CO2 emissions and costs.

Driving diverse loads
The required load currents in a transmission control system goes from several mA for driving LEDs that display the status of the instrument cluster, up to more than 20 A for driving brushless motors for double-clutch systems. NXP offers discrete solutions such as small-signal MOSFETs or low VCEsat (BISS) transistors, constant current sources (PSSI), high-side loadswitches (PBLS family) and logic devices for small or medium loads, such as indicator lamps or relays to control the power supply of the solenoids.

To drive the numerous solenoid based shift elements and pressure regulating solenoids, NXPs automotive Power MOSFET devices in advanced TrenchMOS technology are the perfect choice for precise control. To transfer the power from the engine to the wheels immediately after the restart of a start/stop system, you require brushless DC motor support to power the hydraulic system. A perfect choice is the highly innovative LFPAK devices with a footprint 46% smaller than that of DPAK with similar thermal performance, ideal for modern transmission systems with small form factor. TrenchPLUS is a range of standard MOSFETs with added protection features, including current and temperature sensing components, overvoltage clamps and gate protection (ESD) diodes.

All of these products have some characteristics in common, with low conduction losses and innovative packages to save board space and provide cost-effective solutions.

In-vehicle communication
Besides offering standalone transceivers for all networking protocols for transmission control systems, such as LIN, CAN and FlexRay, NXP offer advanced functionality such as failure management and power saving, with highly integrated in-vehicle-networking products such as system basis chip (SBC) families. The SBCs combine one or several bus transceivers, voltage regulators, I/O pins and the option of a watchdog in a single IC. The combination of these integrated functions offers advanced low-power mode control and smart fail-safe behavior. Pin compatible family devices with different transceiver options support scalable platforms by simply changing the population of the printed circuit board.

Magnetoresistive and Temperature Sensors
NXP’s magnetoresistive (MR) angular sensor systems of the KMA family are ideal for a variety of transmission control functions to measure the position of the clutch or gear selector lever to calculate the correct position. Also the MR based rotational speed sensors are widely used to measure the wheel speed and NXP provides customized solutions. The same sensor family measures input shaft and output shaft speed to determine gear range and control clutch slip. These MR devices provide an output signal virtually independent of magnet tolerances, magnet temperature coefficients, magnet-sensor distance and positioning tolerances, guaranteeing reliability and simplifying your manufacturing process.

Our silicon-based temperature sensors, which offer a virtually linear characteristic over their entire operating range, ensure highly accurate measurement with a long operating life. The KTY series can be used in systems for overheating protection, and heating control. Used throughout the car, they contribute considerably to a more efficient, safe, and more comfortable ride.

I/O protection
NXP offers a series of ESD protection devices out of the PESD family, specifically designed to protect automotive networks. The MMBZ series offers single line bidirectional or dual-line unidirectional transient overvoltage protection in a small SOT23 package. Surge protection up to 600W is assured by the Transient Voltage Suppressor (TVS) product family.

Low Ohmic Power MOSFET devices in advanced TrenchMOS technology allow robust reverse polarity protection solutions.

Glue logic
Beside a complete portfolio of standard logic products with different supply voltage range and speed in innovative packages, NXP offers dedicated devices as low Ohmic analog switches, analog and digital multiplexers and I/O expansion devices to strive for cost optimized engine control solutions.

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