onsemi NCV8508D2T50R4

Overview

NCV8508D2T50R4 from onsemi is a 5.0 V, 250 mA automotive-grade LDO voltage regulator with integrated watchdog, wakeup, and RESET functions. It features ±3.0% output accuracy, 450 mV typical dropout at 150 mA, 100 µA typical quiescent current, and operates across -40°C to +150°C junction temperature. It powers microprocessors in severe automotive environments and battery-operated systems requiring ultra-low standby power.

For engineers reviewing the NCV8508D2T50R4 datasheet, pinout, applications, or equivalent options, key selection criteria include its 45 V input tolerance, internal fuse leads in D2PAK-7 package, AEC-Q100 qualification, and resistor-programmable timing for RESET delay, wakeup period, and wakeup-to-RESET delay.

Technical Context

The NCV8508D2T50R4 integrates a precision bandgap reference, thermal shutdown, short-circuit protection, and a buffered 1.25 V Delay pin that sets all timing parameters via external R_DELAY. Its watchdog circuit monitors falling edges on WDI, triggering RESET if no edge occurs within one wakeup cycle.

RESET asserts low when V_OUT drops >7.0% below nominal (i.e., <4.65 V), during power-up, or upon watchdog timeout. The wakeup output delivers a 50% duty-cycle square wave whose period is programmable from 18 ms to 50 ms using R_DELAY = 60 kΩ or 120 kΩ, respectively.

Key Specifications

Pinout & Package

D2PAK-7 (TO-263-7) package with exposed tab electrically connected to GND; optimized for high-current, high-thermal-stress automotive use. Thermal resistance R_JA = 44°C/W on 1"-pad board enables 1.5 W continuous dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO-with-watchdog applications.

Compared with TLV70750PDRVR and MAX16150ATP+T, the NCV8508D2T50R4 uniquely combines AEC-Q100 Grade 0 qualification, 45 V input tolerance, and full micropower supervision (watchdog, wakeup, RESET) in a thermally robust D2PAK-7 package-making it the only drop-in solution for safety-critical automotive power domains requiring both reliability and functional safety awareness.

Availability

NCV8508D2T50R4 is available at Aetrix Electronics and suitable for automotive engine control, body electronics, ADAS camera ECUs, and transmission control units requiring stable component supply across extended temperature and high-reliability lifecycle demands.

Supply support for NCV8508D2T50R4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, with leadership in automotive, industrial, cloud, and IoT markets.

The NCV8508 series belongs to onsemi's Automotive Power Management portfolio, designed specifically for ASIL-ready power subsystems in engine, chassis, and body electronics where AEC-Q100 compliance, transient robustness, and functional supervision are mandatory.

FAQ

What is the maximum input voltage the NCV8508D2T50R4 can withstand during automotive load dump events?

The NCV8508D2T50R4 is rated for 45 V DC continuous input and can survive 60 V peak transients per ISO 7637-2 Pulse 5a (load dump) without external protection. This capability is enabled by internal overvoltage clamping and fused leads, making it suitable for direct battery connection in engine bay applications. The device remains functional after such events, preserving system uptime and eliminating need for discrete TVS diodes in many designs.

How does the NCV8508D2T50R4 generate its wakeup signal, and what determines its frequency?

The NCV8508D2T50R4 generates a 50% duty-cycle square-wave wakeup signal using an internal timing circuit referenced to the 1.25 V Delay pin. The wakeup period is set by an external resistor R_DELAY connected between Delay and GND: T_WAKEUP = (4.17 × 10⁻⁷) × R_DELAY. With R_DELAY = 60 kΩ, period is 25 ms; with 120 kΩ, it is 50 ms. This programmability allows designers to optimize between power savings and wake responsiveness without changing the NCV8508D2T50R4 itself.

Is the NCV8508D2T50R4 pin-compatible with other packages in the NCV8508 family, such as SO-16L or SO-8 EP?

No, the NCV8508D2T50R4 uses the D2PAK-7 (TO-263-7) package with 7 leads and an exposed GND tab, while the SO-16L and SO-8 EP variants have different pin counts, pinouts, and thermal characteristics. The D2PAK-7 has dedicated GND pins (pins 4–7) and a Kelvin Sense pin (pin 3), whereas SO-16L uses multiple NC pins and shares GND across four pins in different locations. PCB layout and thermal pad design must be specific to the D2PAK-7 footprint for the NCV8508D2T50R4.

What is the purpose of the Sense pin on the NCV8508D2T50R4, and how should it be connected?

The Sense pin (pin 3) on the NCV8508D2T50R4 provides Kelvin feedback for remote output voltage sensing. When connected directly to the load-side of the output trace (e.g., at the MCU VDD pin), it compensates for IR drop across PCB traces, improving load regulation to ±1.5%. If remote sensing is unnecessary, Sense must be tied directly to VOUT (pin 1) at the regulator output pad. Leaving Sense floating will cause regulation instability and is strictly prohibited per the datasheet.

Does the NCV8508D2T50R4 require an external capacitor on the Delay pin, and what happens if R_DELAY is omitted?

No external capacitor is required on the Delay pin of the NCV8508D2T50R4; only a precision resistor (R_DELAY) between Delay and GND sets timing. If R_DELAY is omitted or open-circuit, the Delay pin floats, causing unpredictable wakeup period, RESET delay, and watchdog timeout behavior - potentially leading to system lockup or uncontrolled resets. The datasheet specifies R_DELAY tolerance ≤1% and tempco ≤100 ppm/°C to maintain timing accuracy across temperature.