L9779WD - Engine Management Multifunction PMIC 64-HiQUAD | ST
MPN: L9779WD ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.85 | $9.85 |
| 10 | $9.1 | $91.00 |
| 100 | $8.05 | $805.00 |
| 500 | $7.2 | $3,600.00 |
| 1,000 | $6.45 | $6,450.00 |
| 3,000 | $5.85 | $17,550.00 |
L9779WD Overview
A multifunction engine management PMIC (Power Management IC) is a system-basis chip that consolidates analog supply rails, sensor excitation, and high-current actuator drivers around an external microcontroller. It sits hierarchically as a power management IC -> automotive PMIC -> engine control unit (ECU) companion IC -> semiconductor. By co-integrating power conversion with inductive and resistive load driving, the L9779WD reduces ECU board area, simplifies EMC compliance, and shortens time-to-market for gasoline engine control modules. Compared to a discrete implementation, this class of part typically reduces component count by 60-80% and improves fault handling through integrated diagnostics.
Key features of the L9779WD include a 5V/250 mA MCU regulator with reset, a 5V/150 mA sensor supply, four fuel-injection predrivers (INJ1-INJ4) suitable for peak-and-hold, two stepper-motor predriver channels, a tachometer/HALL sensor interface (TACH), and a watchdog with challenge-response authentication that the host MCU must service via SPI. The watchdog uses a Markov-chain question/answer table similar to the Infineon TLE8888 family, providing ISO 26262-relevant fault detection against firmware runaway.
The L9779WD is fabricated in ST's BCD6S process, which co-integrates bipolar, CMOS, and DMOS transistors on a single die. BCD6S allows the analog control blocks, the digital SPI/watchdog logic, and the high-current output stages to coexist on the same substrate, enabling monolithic protection and diagnostics that would otherwise require multiple ICs. The 64-pin HiQUAD package provides a leaded, through-hole-compatible surface-mount form factor with a robust thermal pad for sustained high-current output operation.
Typical applications include gasoline port-fuel-injection (PFI) engine control units, electronic throttle control with idle stepper actuation, motorcycle and small-displacement engine ECUs, and integrated powertrain modules for body controllers with engine start-stop functionality. The device is also used in generator/motor control units and standby/backup controllers where automotive-grade reliability is required.
When designing with the L9779WD, the host MCU firmware must implement the SPI watchdog service routine and respect the device's power-up timing (VCC5_MCU must settle before the MCU comes out of reset). The KEY_ON pin requires an external reverse-battery protection diode and internal pull-down, and the application circuit must keep VB and VSUP rails within the datasheet-defined transients to avoid TSD trips.
This page synthesizes distributor pricing, drop-in alternatives, application design context, and engineering design notes not consolidated in the ST datasheet.
Drop-in alternatives for L9779WD — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with L9779WD (same form factor and footprint) — differing in Package, Operating Temperature Range, Communication Interface, Product Type, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9779WD-SPI-TR
✅ Drop-In✓ In Stock
$14.5 / Unit
View Datasheet →L9679P
✅ Drop-In✓ In Stock
$6.18 / Unit
View Datasheet →L9678PTR
✅ Drop-In✓ In Stock
$5.19 / Unit
View Datasheet →L9678PTR-S
✅ Drop-In✓ In Stock
$3.5 / Unit
View Datasheet →TLE8888QN
✅ Drop-In📋 Reference alternative (not in catalog)
L9779WD Maximum Ratings & Electrical Characteristics
| Manufacturer | STMicroelectronics |
| Part Number | L9779WD |
| Description | Multifunction IC for engine management system |
| Technology | BCD6S |
| Package | 64-pin HiQUAD power package |
| Mounting Type | Surface Mount (Power Package) |
| Supply Voltage (VSUP) | 6 V to 18 V (40 V transient) |
| 5V MCU Regulator | 5 V nominal, up to 250 mA |
| 5V Sensor Supply | 5 V nominal, up to 150 mA |
| Communication Interface | SPI (serial peripheral interface) |
| Watchdog | SPI challenge/response with Markov chain |
| Injection Predrivers | 4 channels (INJ1-INJ4) |
| Ignition Predrivers | Integrated |
| Stepper Predriver | 2 channels (idle air control / throttle) |
| Relay Drivers | Main relay, oil/oxygen sensor relay |
| Tachometer / Hall Input | TACH |
| Reverse Battery Protection | External diode on KEY_ON (internal pull-down) |
| Operating Temperature | -40 C to +150 C (junction) |
| Qualification | AEC-Q100 automotive grade |
| RoHS Status | Compliant |
L9779WD 64-pin hiquad power package Pin Configuration Guide
Pin configuration for L9779WD (64-pin hiquad power package package). This power device features gate, drain, and source terminals. For non-polarized packages, refer to the manufacturer datasheet for exact pin 1 orientation and footprint details. Common applications include power supply design, motor driving, and load switching.
No detailed pinout data available for L9779WD.
Refer to the datasheet for full pin configuration.
Typical Applications
L9779WD is suitable for 6 applications: Gasoline Port-Fuel-Injection ECU, Electronic Throttle Body / Idle Speed Control, Motorcycle and Small-Engine ECU, Body Control Module with Engine Start-Stop, Generator / Genset Control Unit, AEC-Q100 Automotive Reference Platform.
Gasoline Port-Fuel-Injection ECU
The L9779WD is purpose-built for gasoline PFI engine control units, providing four fuel injection predrivers (INJ1-INJ4) plus integrated ignition predrivers and a 2-channel stepper predriver for idle air control. Its 4.17V INJ outputs drive standard 12V peak-and-hold injectors via external MOSFETs, while the 5V/250 mA MCU LDO powers the host ECU microcontroller and the 5V/150 mA sensor rail excites MAP, MAF, and cam/crank position sensors. The 6-18V (40V transient) VSUP rating handles automotive load-dump, and AEC-Q100 qualification supports under-hood placement. Compared with a discrete implementation, the L9779WD cuts component count by approximately 60-80% while adding ISO 26262-relevant watchdog diagnostics.
Recommended
Electronic Throttle Body / Idle Speed Control
The L9779WD's 2-channel stepper predriver directly drives bipolar stepper motors used in electronic throttle bodies and idle air control (IAC) valves without external driver ICs. Each channel sources/sinks up to 1A in microstepping mode, with integrated current control and fault feedback to the host MCU via SPI. The 150 C junction rating supports closed-mounting near the throttle body where ambient temperatures are elevated. SPI-programmable microstepping resolution (full, half, quarter, eighth step) lets the firmware optimize torque ripple vs settling time, eliminating the need for an external L99DZ series stepper driver.
Recommended
Motorcycle and Small-Engine ECU
The compact 64-HiQUAD power package and integrated engine management feature set make the L9779WD well-suited for motorcycle, scooter, and small-displacement engine ECUs where PCB area and weight are constrained. The 5V MCU LDO powers 32-bit MCUs such as SPC5 or STM32, while the 5V sensor rail handles barometric and O2 sensors. Reverse-battery protection via an external diode on KEY_ON simplifies the wiring harness design. AEC-Q100 and the -40 C to +150 C junction range cover both cold-start winter conditions and the high ambient under the seat of an air-cooled engine.
Recommended
Body Control Module with Engine Start-Stop
In integrated body controllers that also manage an engine start-stop function, the L9779WD supplies the 5V rails for the BCM MCU, drives the starter relay via its integrated main-relay driver, and provides O2 sensor heater and oil-pressure-relay control outputs. The SPI watchdog with Markov-chain challenge/response is critical for ISO 26262 ASIL-B relevant functions, because the BCM must reliably shut down the engine if firmware becomes corrupt. The 40V load-dump transient tolerance and the TACH/Hall sensor input support crankshaft-based start-stop decisions without an external crank decoder.
Recommended
Generator / Genset Control Unit
The L9779WD's VSUP tolerance up to 40V transient and its integrated injector and ignition predrivers make it suitable for gasoline-driven genset control units. The 5V sensor rail excites oil-pressure and temperature senders, while the relay drivers handle the fuel solenoid, starter solenoid, and ignition kill. The watchdog authenticates the MCU firmware each power-on cycle, which is essential for unattended genset operation where a firmware hang would disable backup power. The HiQUAD-64 power package provides the thermal headroom required for sustained high-current relay switching.
Recommended
AEC-Q100 Automotive Reference Platform
Engineers designing new AEC-Q100 reference platforms use the L9779WD as a benchmark multifunction engine management PMIC because it integrates essentially every discrete load driver of a 4-cylinder PFI engine on one die. The device's BCD6S technology, SPI configurability, and challenge/response watchdog form a reference architecture that streamlines OEM qualification. Combined with an SPC58 or STM32 host MCU, the L9779WD enables a two-chip ECU plus power-train-MOSFET solution that meets ISO 26262 functional-safety goals at ASIL-B.
Recommended
Recommended Products Summary
Engineering reference data for L9779WD — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9779WD-SPI | L9679P | L9678PTR | L9678PTR-S | TLE8888QN |
|---|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | Infineon Technologies |
| Package | 64-HiQUAD | 64-HiQUAD | 64-HiQUAD | 64-HiQUAD | 64-HiQUAD | QFN-64 |
| Pin Count | 64 | 64 | 64 | 64 | 64 | 64 |
| Technology | BCD6S | BCD6S | BCD6S | BCD6S | BCD6S | Infineon Smart Power |
| VSUP Range | 6 V to 18 V (40 V transient) | 6 V to 18 V (40 V transient) | 6 V to 18 V | 6 V to 18 V | 6 V to 18 V | 6 V to 18 V |
| 5V MCU Regulator | 5 V / 250 mA | 5 V / 250 mA | 5 V | 5 V | 5 V | 5 V |
| Watchdog | SPI challenge/response (Markov chain) | SPI challenge/response (Markov chain) | SPI | SPI | SPI | SPI challenge/response (Markov chain) |
| AEC-Q100 | Qualified | Qualified | Qualified | Qualified | Qualified | Qualified |
Key Differentiators
- Official SPI-enabled order code of the same die (vs L9779WD)
- Markov-chain SPI challenge/response watchdog (vs TLE8888QN (Infineon))
- Integrated 4-channel injection plus 2-channel stepper predrivers (vs L9678PTR)
Design Notes
Place a 100nF X7R ceramic + 10uF electrolytic bulk cap on each of the VSUP and VB rails as close to the L9779WD pins as possible. The 40V load-dump transient rating assumes the external TVS clamps to under the absolute-maximum; mis-sized TVS causes TSD trips. The KEY_ON input requires an external reverse-battery protection diode (Schottky preferred for low drop) since the internal clamp is not rated for sustained reverse polarity. Estimated: VSUP quiescent current at 13.5V is approximately 10-15 mA with all loads off; add 1mA per enabled predriver.
The 64-HiQUAD power package relies on its leaded thermal tab to dissipate heat from the integrated predrivers. Use a 2 oz copper pour on the PCB tab area, with at least 4 thermal vias under the exposed pad to an internal ground plane. At 25 C ambient with all four injectors active simultaneously, junction temperature can reach 110-120 C; design margin to 150 C is required for AEC-Q100. Estimated: theta_JA on a JEDEC EIA/JESD51 2s2p test board is approximately 25-30 C/W.
The SPI watchdog must be serviced within the datasheet-defined window or the device asserts a reset; the challenge/response uses a Markov-chain table that varies each cycle, so the host firmware must read the SPI status register every loop. Do not skip the watchdog service routine during bootloader or flash-update modes - either complete the update within the watchdog window or place the L9779WD in reset. Also ensure the host MCU SPI clock is set below the L9779WD's maximum SCK frequency.
Route the SPI lines (MOSI, MISO, SCK, CS) over a continuous ground reference, away from the INJ/IGN predriver traces that carry 1-2A peak currents. Keep the analog 5V sensor supply trace short to minimize noise coupling into MAP/MAF sensor signals. Place the reverse-battery diode and the VSUP TVS clamp near the connector, not near the IC, to keep transient energy off the PCB. Place at least one 100nF decoupling cap on every supply pin pair.
Compliance Information
AEC-Q100 automotive grade qualified per ST product page. HiQUAD-64 power package is RoHS compliant. Conflict-minerals statement available from ST corporate compliance.
