Disclaimer: Automotive repairs should be performed by qualified professionals. Always consult the specific ECU manufacturer's documentation before attempting repairs.
Viewed from the flat face with leads downward:
Engine bay electronics are prone to severe electrical anomalies. According to the component parameters indexed on UTSOURCE , the architectural layout embeds: to stop thermal runaway. Short-Circuit Protection to safeguard internal logic cells.
The NEC B58944 is engineered to survive the harsh electrical and thermal environments found under the hood of passenger and industrial vehicles. The device combines power switching capabilities with onboard fault management. Specification Detail NEC Corporation (Legacy) / Renesas Package Type SOP-28 (Small Outline Package, 28-Pins) Primary Function Automotive Power Switch / Intelligent ECU Peripheral Driver Common ECU Pairings Bosch ME7.4.4, ME7.5, ME7.9.6, EDC16, EDC7 Integration Features
, typically found in Bosch systems such as the EDC16 diesel engine computer. In some technical documentation and inventory listings, it is cross-referenced or identified as the D43256BGU-70Y , which is a 256K-bit CMOS Static RAM. Key Technical Specifications Manufacturer Package Type SOP-28 (Small Outline Package, 28-pin) Primary Function ECU Driver / Solid State High-Side Relay Memory Specs 32K words x 8 bits (if identified as D43256BGU) Access Time Voltage Supply 4.5V to 5.5V (Standard CMOS) Operating Temp 0°C to 70°C (Standard) Applications and Features Engine Control:
Given its widespread use in Bosch ECUs, which manage critical engine functions, the prevailing wisdom is that the B58944 is first and foremost a .
Officially, none exists. Renesas support (as of 2021) recommends using a cross-reference or a generic TO-220 NPN datasheet.
The most consistent information points to as the original and primary manufacturer.
The NEC B58944 datasheet 2021 provides detailed information on the component's technical specifications, features, and applications. The datasheet includes:
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This discrepancy is likely explained by how these components are labeled and sold. The part number is often found in association with the NEC B58944, and this is indeed a 32K x 8-bit CMOS Static RAM manufactured by NEC (later Renesas). An SRAM chip is a volatile memory component that temporarily holds data the ECU needs for rapid calculations.
The NEC B58944 is widely used in various applications across industries, including:
ME7.4.4, ME7.5, ME7.5.10, ME7.9.6, ME7.9.20.
The component acts as an auxiliary operational memory buffer.
When the chip fails, specialized shops rely on components sourced from providers like Jotrin Electronics or UTSource to perform board-level replacements. Replacement requires a hot-air rework station to desolder the 28-pin configuration safely without tearing the underlying copper circuit pads.
: Marked as "Tape & Reel" and "Lead-free/RoHS Compliant," showing that even decades-old designs had been updated to meet modern environmental standards. The Component’s Secret