Automotive Door Electronics Move to Zone Control

A modern car door is no longer a lock and a window switch. It carries the latch, the window lift, power fold and axis motors for the mirror, the mirror heater, puddle and handle lighting, an electrochromic dimming glass layer and, increasingly, a LIN or CAN node of its own. Every one of those loads needs a driver stage, current monitoring and diagnostics, and the wiring harness that used to carry them back to the body controller is exactly what OEMs are trying to delete.

That shift is why door zone ICs now sit at the centre of body electronics sourcing. Instead of a relay box and a handful of discrete FETs, the door module is built around one device that supplies its own regulated rails, talks on the vehicle bus and drives every actuator behind the trim panel. Two STMicroelectronics parts cover that requirement at different levels of integration, and both are on the shelf now with 22+ to 25+ date codes.

L99DZ70XPTR: Six Bridges and Five High-Side Drivers in PowerSSO-36

The L99DZ70XPTR is the actuator half of the story. It is a microcontroller driven multifunctional door actuator driver that puts six half bridges and five high-side drivers into a single PowerSSO-36 package, enough for up to five DC motors and five grounded resistive loads at the same time. Bridge ratings are graded to real door loads rather than to a single headline number:

• One full bridge for 6 A loads (RDS(on) 150 mOhm) for the window lift or a heavy latch motor
• Two half bridges for 3 A loads (300 mOhm) and two half bridges for 0.75 A loads (1600 mOhm)
• One 6 A high-side driver (90 mOhm), two configurable high-side drivers up to 1.5 A (500 mOhm) or 0.4 A (1800 mOhm), and two 0.5 A high-side drivers (1600 mOhm)
• Current monitor output on every high-side driver, plus separated half bridges for the door lock motor

All operating modes - forward, reverse, brake and high impedance - are selected over SPI, and every diagnostic flag comes back the same way, so the module firmware sees an open load, a short or an over-temperature event without extra sensing hardware. An integrated SPI-driven module also controls electrochromic mirror glass together with one external MOS transistor, which removes a separate dimming circuit from the mirror assembly. The device is specified from -40 C to +150 C.

L99DZ100GTR: A Complete Door Zone System in LQFP-64

The L99DZ100GTR goes one step further and integrates the power supply and the communication physical layers as well. It is a door zone system IC built for electronic control modules that need enhanced power management: two low-drop voltage regulators with several standby modes, an embedded LIN transceiver and an HS-CAN interface with selective wake-up, all in LQFP-64 and all AEC-Q100 qualified.

In practice the choice is straightforward. Where a body controller already provides the 5 V rail and the bus transceiver, the L99DZ70XPTR is the smaller and cheaper way to drive every load in the door. Where the door node is standalone - a zonal architecture with a smart connector behind the trim - the L99DZ100GTR replaces the regulator, the transceiver and the driver stage with one part and keeps quiescent current low through selective wake-up.

Signal Conditioning Behind the Driver Stage

Door and body designs also carry analog signal chains: motor current sensing, position feedback and audio for the hands-free microphone. The MAX274BENG+ from Maxim Integrated fits that role as an eighth-order continuous-time lowpass active filter in a 24-pin DIP. Four cascaded sections with a resistor-programmed 150 kHz corner give a steep roll-off without a clock, so there is no aliasing and no digital noise injected next to sensitive harness signals. It runs from a single 2.37 V to 5.5 V supply and is supplied with 21+20+ date codes.

Stock, Traceability and Samples

All three parts ship from Shenzhen stock in original manufacturer packing - tape and reel for the ST devices, factory tubes for the Maxim filter - with desiccant, humidity indicator and full lot traceability. Orders are quoted against your BOM with quantity breaks, and samples can be released for qualification testing before a production order is placed.

Send part numbers and target quantities to sales@bluetotech.com for pricing, lead time and shipping cost. Minimum order quantity is 10 pieces, delivery is 2-3 working days after confirmation.