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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

STMicroelectronics A6985F3V3

Name: A6985F3V3
Brand: STMicroelectronics
SKU: A6985F3V3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A6985F3V3

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 16-PowerTSSOP (0.173", 4.40mm Width)

Datasheet:: A6985F3V3.pdf

Description:: IC REG BUCK 3.3V 500MA 16HTSSOP

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Product details

Overview

A6985F3V3 from STMicroelectronics is an AEC-Q100 qualified automotive synchronous step-down switching regulator delivering 500 mA DC output at fixed 3.3 V, operating from 4 V to 38 V input, featuring 30 µA quiescent current in Low Consumption Mode (LCM), peak current mode control, and integrated output voltage supervisor with open-drain RST for microcontroller reset sequencing in cold-crank automotive body electronics.

For engineers reviewing the A6985F3V3 datasheet, A6985F3V3 pinout, A6985F3V3 application, or A6985F3V3 equivalent, key selection criteria include its 30 µA LCM IQ at 3.3 V output, HTSSOP16 thermal resistance (R_thJA = 40 °C/W), dual-mode operation (LCM/LNM), embedded overvoltage and thermal protection, and pin-strappable soft-start, frequency, and reset threshold.

Technical Context

The A6985F3V3 implements a peak current mode architecture with pulse-by-pulse high-side/low-side current sensing, enabling precise constant-current protection and foldback during short-circuit. Its internal transconductance error amplifier (100 dB gain) and adjustable soft-start (via external capacitor on SS/INH) control inrush current and stabilize loop response.

It supports two distinct operational modes: Low Noise Mode (LNM) enforces constant-frequency PWM with synchronization capability (up to 6 slaves) and minimized output ripple for car audio; Low Consumption Mode (LCM) enables burst-mode operation at light load to achieve 30 µA quiescent current while maintaining regulated 3.3 V output and 93% RST threshold accuracy.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	0.5 A DC maximum - sufficient for powering automotive MCUs, sensors, and infotainment subsystems without external boost stages.
Input Voltage Range	4 V to 38 V - meets ISO 7637-2 load dump (35 V transient) and cold-crank (4.5 V minimum) requirements for 12 V automotive systems.
Quiescent Current (LCM)	30 µA at V_OUT = 3.3 V - enables >1-year battery standby in always-on body control modules during vehicle parking.
Switching Frequency	250 kHz to 2 MHz (pin-strappable) - allows optimization of inductor size vs. EMI; 2 MHz enables <1 mm height solutions.
R_DS(on) HS / LS	360 mΩ / 150 mΩ - reduces conduction loss at medium-to-heavy loads, improving full-load efficiency above 85%.
Reset Threshold Accuracy	±3% (93% of V_OUT) - ensures reliable µC/FPGA power-good assertion with minimal external components.
Thermal Shutdown	165 °C with 30 °C hysteresis - protects silicon during sustained overload or poor PCB heatsinking in enclosed automotive enclosures.

Pinout & Package

HTSSOP16 package (exposed pad, R_thJA = 40 °C/W) with 0.65 mm pitch; requires exposed pad soldered to SGND/PGND for thermal and electrical integrity.

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-drain reset output	Asserts low when V_OUT falls below programmed threshold; delay set by external capacitor on DELAY pin for sequenced power-up.
2 VCC	Analog supply rail	Powers internal reference and error amplifier; requires ≥470 nF ceramic decoupling to suppress noise coupling into feedback path.
3 SS/INH	Soft-start / inhibit input	Pulled low disables regulator; internal 4 µA current source charges external capacitor to control ramp time and limit inrush.
4 SYNCH/ISKP	Sync input / skip level select	In LNM: accepts external clock for master/slave sync; in LCM: selects current threshold for burst-mode entry/exit.
5 FSW	Frequency selection	Resistor divider to VCC/GND sets f_SW from 250 kHz–2 MHz before soft-start; avoids dynamic frequency shifts during startup.
6 MLF	Mode and reset threshold select	Configures LCM/LNM and RST trip point (e.g., 93% or 80% of V_OUT) via resistor strapping prior to SS phase.
7 COMP	Error amplifier output	Connects to RC compensation network; high-impedance node requiring careful layout to avoid instability from parasitic capacitance.
8 DELAY	RST assertion timing	External capacitor sets delay between V_OUT recovery and RST deassertion; floating = immediate RST release (Power-Good behavior).
9 VOUT	Feedback sense input	Monitors regulated output via internal 0.85 V reference and fixed 3.3 V divider; no external resistors required for A6985F3V3.
10 SGND	Signal ground reference	Reference for analog blocks (error amp, references); must be star-connected to PGND at single point to avoid ground bounce.
11–12 PGND	Power ground return	Low-impedance return path for high di/dt switch currents; connects directly to exposed pad and input/output capacitors.
13–14 LX	Switching node	Drives external inductor; high dv/dt node requiring minimized trace area and guard ring to reduce EMI and capacitive coupling.
15 VIN	Main input supply	Accepts 4–38 V; requires local 10 µF ceramic + bulk electrolytic for transient energy storage during load dump events.
16 VBIAS	Efficiency-boost bias supply	Optional connection to regulated output to reduce IQ by ~60% in LCM; improves light-load efficiency without adding external regulators.

Key Features

Feature	Design Value
Automotive qualification	AEC-Q100 Grade 1 (−40 °C to +125 °C ambient) - validated for under-hood and cabin applications with zero early-life failure targets.
Embedded voltage supervisor	Programmable RST threshold with 2% hysteresis and adjustable delay - eliminates need for discrete reset IC in MCU-based modules.
Dual operational modes	Pin-selectable LCM (30 µA IQ) and LNM (constant f_SW, <15 mV_PP ripple) - enables one BOM to serve both battery-sensitive and noise-sensitive subsystems.
Synchronization support	Master/slave sync up to 6 devices in LNM; external clock input accepts 266.5 kHz–2 MHz - simplifies multi-rail ECU power sequencing and EMI reduction.
Overvoltage & thermal protection	Active OVP discharges output capacitor; thermal shutdown at 165 °C with 30 °C hysteresis - prevents damage during fault conditions without external circuitry.
100% duty cycle capability	Enables dropout <100 mV at 500 mA - sustains regulation during cold-crank down to 4.5 V input, critical for engine start reliability.

Applications

Body Control Module (BCM)

Automotive Infotainment Power

Use Scenario: Powering CAN/LIN transceivers, door lock actuators, and interior lighting controllers in parked vehicle state.

IC Role / Device Role / Timing Role: Primary 3.3 V supply with ultra-low quiescent current to minimize battery drain during extended parking.

Use Value: 30 µA LCM IQ extends 12 V lead-acid battery life beyond 12 months without recharge, meeting OEM parasitic draw limits.

Use Scenario: Generating clean 3.3 V rail for DSPs, touch controllers, and display interfaces in head units.

IC Role / Device Role / Timing Role: Low-noise regulated supply operating in LNM with synchronized switching to avoid audible beat frequencies.

Use Value: Constant-frequency 2 MHz operation minimizes output ripple (<15 mV_PP) and eliminates AM-band interference in sensitive audio circuits.

Engine Control Unit (ECU) Sensor Interface

ADAS Camera Power Supply

Use Scenario: Providing stable 3.3 V to pressure, temperature, and knock sensors exposed to under-hood thermal cycling.

IC Role / Device Role / Timing Role: Input-tolerant buck converter with 38 V max rating and thermal shutdown for harsh environment resilience.

Use Value: Withstands 35 V load dump transients and operates continuously from −40 °C to +125 °C ambient, eliminating external TVS/clamping.

Use Scenario: Powering image signal processors and MIPI PHYs in surround-view cameras requiring precise power sequencing.

IC Role / Device Role / Timing Role: Regulator with programmable RST and DELAY for controlled power-up of camera SoCs and ISPs.

Use Value: Adjustable reset delay ensures ISP firmware initializes only after stable 3.3 V is confirmed, preventing boot failures.

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TPS62933RQWR	Lower IQ (15 µA), but 3.0 V min input and no AEC-Q100 qualification; uses DCS-Control topology instead of peak current mode.	Not suitable for cold-crank (4.5 V) or automotive qualification requirements; better for industrial battery-powered systems.	Select only if AEC-Q100 is not required and input never drops below 3.0 V.
MAX20012AATP+	Higher output current (750 mA), 3.5 µA shutdown current, but fixed 2.2 MHz f_SW; lacks RST supervisor and adjustable soft-start.	Targets higher-power ADAS domains; requires external reset IC and compensation tuning for stability across loads.	Choose when >500 mA is needed and system-level reset sequencing is handled externally.

Compared with TPS62933RQWR and MAX20012AATP+, the A6985F3V3 uniquely combines AEC-Q100 qualification, 4 V cold-crank support, integrated RST supervision, and pin-selectable LCM/LNM - making it the only solution that satisfies full automotive body electronics requirements without supplemental components.

Availability

A6985F3V3 is available at Aetrix Electronics and suitable for automotive body control modules, infotainment subsystems, and ADAS camera power supplies requiring stable component supply across long production lifecycles and stringent qualification compliance.

Supply support for A6985F3V3 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

STMicroelectronics is a global semiconductor leader specializing in automotive-grade power management, microcontrollers, and sensing technologies, with manufacturing certified to IATF 16949 and AEC-Q200 component standards.

The A6985F series belongs to ST's automotive DC-DC converter product line, designed specifically for robust, low-IQ power conversion in body electronics, infotainment, and ADAS domains where cold-crank resilience and EMI control are mandatory.

FAQ

What is the recommended input capacitor configuration for A6985F3V3 in automotive applications?

Use a 10 µF X7R ceramic capacitor placed within 3 mm of VIN and PGND pins, plus a 47–100 µF low-ESR tantalum or polymer capacitor for bulk energy storage. This combination handles ISO 7637-2 pulse 5a (load dump) transients and provides low-impedance paths for high-frequency switching noise, ensuring stable operation during cranking and load dump events.

How does the switchover feature on VBIAS improve efficiency?

When VBIAS is connected to the regulated 3.3 V output, the internal LDO switches its bias supply from VIN to VBIAS, reducing total quiescent current from 70 µA to 50 µA in LCM mode. This 30% IQ reduction directly extends battery standby time in always-on modules without requiring additional external regulators or complex power routing.

Can A6985F3V3 be used without the external compensation network on COMP?

No - the COMP pin requires an external RC network (typically 1–10 kΩ resistor + 100–1000 pF capacitor) to stabilize the current-mode control loop. Omitting it causes oscillation or poor transient response. ST provides exact values in Application Note AN5067 based on selected inductor and output capacitor values.

What is the maximum allowable thermal resistance for a custom PCB using A6985F3V3 in HTSSOP16?

To maintain junction temperature ≤135 °C at 500 mA output and 38 V input, the total thermal resistance (R_thJA) must not exceed 40 °C/W - matching ST's demo board spec. Achieving this requires a minimum 200 mm² copper pour connected to the exposed pad with ≥4 thermal vias (0.3 mm diameter) to inner ground planes.

A6985F3V3 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 16-PowerTSSOP (0.173", 4.40mm Width)

Packaging:: Tube

Product Status:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 38V

Voltage - Output (Min/Fixed):: 3.3V

Voltage - Output (Max):: -

Current - Output:: 500mA

Frequency - Switching:: 250kHz ~ 2MHz

Synchronous Rectifier:: Yes

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: 16-HTSSOP

A6985F3V3 FAQ

1.How can I place an order for A6985F3V3 through Aetrix?

Please submit a Request for Quotation (RFQ) for A6985F3V3 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for A6985F3V3 reliable?

The price and inventory of A6985F3V3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6985F3V3 is usually 5 days.

3.What payment methods are accepted for A6985F3V3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6985F3V3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A6985F3V3?

A6985F3V3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A6985F3V3 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for A6985F3V3?

For technical support, including A6985F3V3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6985F3V3 requirements.

6.How does Aetrix verify that A6985F3V3 is sourced from the original manufacturer or authorized distributors?

All A6985F3V3 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A6985F3V3 meets industry standards.

7.What is the process for return or replacement of A6985F3V3?

All A6985F3V3 units undergo pre-shipment inspection (PSI). If there is an issue with A6985F3V3, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The A6985F3V3 part is unused and in its original packaging.

Return procedure for A6985F3V3:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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