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

STMicroelectronics A6985F3V3TR

Name: A6985F3V3TR
Brand: STMicroelectronics
SKU: A6985F3V3TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A6985F3V3TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: A6985F3V3TR.pdf

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

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Product details

Overview

A6985F3V3TR 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 embedded output voltage supervisor for microcontroller reset sequencing.

For engineers reviewing the A6985F3V3TR datasheet, A6985F3V3TR pinout, A6985F3V3TR application, or A6985F3V3TR equivalent, key selection criteria include cold-crank robustness (100% duty cycle), dual LCM/LNM operational modes, adjustable soft-start, synchronization capability, and HTSSOP16 thermal performance (R_thJA = 40 °C/W).

Technical Context

The A6985F3V3TR implements peak current mode architecture with pulse-by-pulse high-side/low-side current sensing for constant-current protection and foldback under short-circuit. Its integrated P-channel high-side switch enables 100% duty cycle operation, satisfying automotive cold-crank requirements down to 4 V input.

Two configurable operating modes are supported: Low Noise Mode (LNM) enforces constant-frequency PWM with minimized output ripple for car audio; Low Consumption Mode (LCM) enables discontinuous conduction for ultra-low 30 µA I_Q at light load while maintaining regulated output. The RST open-collector output provides programmable reset timing via external capacitor on DELAY pin.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	0.5 A DC maximum - supports medium-power automotive ECUs and body control modules without external boost stages.
Input Voltage Range	4 V to 38 V - meets ISO 7637-2 load dump and cold-crank specifications for 12 V automotive systems.
Quiescent Current (LCM)	30 µA at 3.3 V out - enables always-on functionality during vehicle parking with minimal battery drain.
Switching Frequency	250 kHz to 2 MHz - adjustable via FSW pinstrapping; higher frequencies reduce external inductor/capacitor size.
R_DS(on) HS / LS	360 mΩ / 150 mΩ - low conduction losses improve efficiency across 0.1–0.5 A load range.
Thermal Shutdown	165 °C with 30 °C hysteresis - protects silicon during sustained overload or poor PCB heatsinking.
Reset Threshold Accuracy	±3% over temperature - ensures reliable microcontroller reset assertion during power-up and brownout.

Pinout & Package

Package: HTSSOP16 (exposed pad), R_thJA = 40 °C/W, RoHS-compliant, automotive-grade moisture sensitivity level MSL3.

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-collector reset output	Asserts low when VOUT falls below programmed threshold; DELAY pin sets release delay for power-good sequencing.
2 VCC	Analog supply rail	Powers internal reference and error amplifier; requires ≥470 nF ceramic decoupling for stability.
3 SS/INH	Soft-start / inhibit control	Pulled low disables regulator; internal 4 µA current source charges external capacitor for controlled ramp-up.
4 SYNCH/ISKP	Sync input / skip level select	In LNM: accepts external clock for master/slave synchronization; in LCM: selects current threshold for pulse-skipping.
5 FSW	Frequency selection	Resistor divider to VCC/GND sets fSW before soft-start; E24 series values support 250 kHz–2 MHz range.
6 MLF	Mode and reset threshold select	Configures LNM vs. LCM and sets RST trip point (e.g., 93% or 80% of VOUT) via resistor strapping.
7 COMP	Error amplifier output	Connects to compensation network (RC + C) to stabilize loop response across line/load transients.
8 DELAY	Reset delay timing	External capacitor sets RST assertion delay after VOUT exceeds threshold; floating = immediate Power Good.
9 VOUT	Feedback sense node	Monitors regulated output; internal 3.3 V reference used for A6985F3V3TR; no external divider required.
10 SGND	Signal ground	Reference for analog circuitry; must be separated from PGND and connected to exposed pad.
11–12 PGND	Power ground	High-current return path for LX switches; tied to SGND only at single-point star connection.
13–14 LX	Switching node	Connects to external inductor; high di/dt node requiring tight layout and Kelvin routing to minimize ringing.
15 VIN	Main input supply	Accepts 4–38 V; requires bulk capacitance near pin to suppress load-dump transients.
16 VBIAS	Efficiency-boost bias supply	Optional connection to regulated output reduces I_Q further; switchover threshold at 2.85–3.2 V.

Key Features

Feature	Design Value
Automotive qualification	AEC-Q100 Grade 1 (−40 °C to +125 °C ambient), qualified for safety-critical body electronics.
Low-noise constant-frequency mode	LNM fixes fSW and minimizes output ripple across full load range - suitable for sensitive car audio supplies.
Ultra-low-light-load efficiency	30 µA I_Q in LCM extends battery life in always-on modules like door controllers and sensors.
Programmable reset sequencing	RST output with adjustable DELAY timing enables controlled power-up of multi-rail digital loads (MCU/FPGA).
Robust fault protection	Integrated OVP, thermal shutdown, and pulse-by-pulse current limiting prevent damage during fault conditions.

Applications

Body Control Module (BCM)

Infotainment Power Supply

Use Scenario: Centralized power management for door locks, lighting, and window controls in modern vehicles.

IC Role / Device Role / Timing Role: Primary 3.3 V buck regulator supplying MCU, CAN transceivers, and sensor interfaces.

Use Value: 100% duty cycle operation maintains regulation during cold-crank (down to 4 V), ensuring uninterrupted BCM function.

Use Scenario: Clean, low-noise 3.3 V rail for DSPs, audio codecs, and display controllers in head units.

IC Role / Device Role / Timing Role: Secondary regulated supply operating in Low Noise Mode (LNM) to suppress switching artifacts.

Use Value: Constant-frequency LNM operation reduces conducted EMI and output ripple to <15 mV_pp, meeting CISPR 25 Class 5 limits.

Telematics Control Unit (TCU)

ADAS Camera Power

Use Scenario: Always-on connectivity module requiring low standby current and fast wake-up from sleep.

IC Role / Device Role / Timing Role: Main system regulator in Low Consumption Mode (LCM), with RST coordinating MCU reset timing.

Use Value: 30 µA quiescent current enables >1-year battery hold-up in disconnected state without parasitic drain.

Use Scenario: Compact power solution for front/rear camera modules mounted in constrained spaces.

IC Role / Device Role / Timing Role: Single-chip 3.3 V supply with integrated sequencing to meet image sensor startup timing requirements.

Use Value: Adjustable soft-start and RST delay ensure synchronized power-up of sensor, ISP, and interface logic.

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
LM61480-Q1	Higher 3.5 A output, 2.7–36 V input, 15 µA I_Q; uses current-mode control but lacks embedded RST supervisor.	Better suited for high-current ADAS domain controllers; requires external reset IC for sequencing.	Select when >0.5 A output or lower I_Q is critical, and RST functionality can be added externally.
TPS62933-Q1	3 A output, 3–36 V input, 12 µA I_Q; supports FPWM/PSM modes but no pin-strappable LNM/LCM or DELAY-based RST timing.	Ideal for infotainment SoCs needing higher current; reset must be implemented via GPIO or dedicated supervisor.	Choose for scalable power delivery where integrated sequencing is not required and board space allows larger inductors.

Compared with LM61480-Q1 and TPS62933-Q1, the A6985F3V3TR offers unique integration of automotive-grade reset supervision with programmable delay, dual LCM/LNM optimization, and HTSSOP16 thermal performance - making it optimal for compact, cost-sensitive 0.5 A automotive subsystems requiring guaranteed sequencing and ultra-low standby power.

Availability

A6985F3V3TR is available at Aetrix Electronics and suitable for automotive body electronics, telematics control units, and infotainment subsystems requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.

Supply support for A6985F3V3TR 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 headquartered in Geneva, Switzerland, designing and manufacturing automotive, industrial, and power management ICs with vertical fabrication capabilities.

The A6985F belongs to ST's automotive-grade power management portfolio, engineered specifically for robust, low-I_Q DC-DC conversion in harsh vehicle environments - emphasizing cold-crank resilience, EMI control, and functional safety readiness.

FAQ

What is the purpose of the VBIAS pin on the A6985F3V3TR?

The VBIAS pin allows connection to the regulated output voltage to reduce quiescent current consumption. When VBIAS is supplied at 3.3 V, the internal regulator switches biasing from VIN to VBIAS, lowering I_Q by up to 75% in LCM mode. It features a switchover threshold of 2.85–3.2 V and must be left unconnected or tied to GND if unused.

How does the RST output behave during power-up and fault conditions?

The RST pin is an open-collector output that goes low when VOUT drops below the threshold set by MLF strapping (e.g., 93% of 3.3 V = ~3.07 V). During power-up, RST remains low until VOUT exceeds the threshold and the DELAY capacitor charges to 1.234 V, after which RST releases. Under overvoltage or thermal shutdown, RST asserts low immediately.

Can the A6985F3V3TR operate with input voltages below 4 V?

No - the absolute minimum operating input voltage is 4 V per datasheet specification. Below this, the internal UVLO circuit disables the regulator to prevent unstable operation. The device supports 100% duty cycle down to 4 V, enabling regulation during cold-crank events, but will not start or sustain regulation at 3.9 V or lower.

What layout recommendations are critical for stable operation?

Place the input capacitor ≤5 mm from VIN and PGND pins; use separate SGND and PGND planes joined only at the exposed pad; route LX with minimum loop area and avoid vias; place feedback resistors close to VOUT/SGND; and connect the exposed thermal pad to both SGND and PGND using ≥6 thermal vias (0.3 mm diameter) for optimal R_thJA.

A6985F3V3TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

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

A6985F3V3TR FAQ

1.How can I place an order for A6985F3V3TR through Aetrix?

Please submit a Request for Quotation (RFQ) for A6985F3V3TR 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 A6985F3V3TR reliable?

The price and inventory of A6985F3V3TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6985F3V3TR is usually 5 days.

3.What payment methods are accepted for A6985F3V3TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6985F3V3TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A6985F3V3TR?

A6985F3V3TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A6985F3V3TR 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 A6985F3V3TR?

For technical support, including A6985F3V3TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6985F3V3TR requirements.

6.How does Aetrix verify that A6985F3V3TR is sourced from the original manufacturer or authorized distributors?

All A6985F3V3TR 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 A6985F3V3TR meets industry standards.

7.What is the process for return or replacement of A6985F3V3TR?

All A6985F3V3TR units undergo pre-shipment inspection (PSI). If there is an issue with A6985F3V3TR, 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 A6985F3V3TR part is unused and in its original packaging.

Return procedure for A6985F3V3TR:

1.Submit a request within 90 days.

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

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