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

STMicroelectronics A6985FTR

Name: A6985FTR
Brand: STMicroelectronics
SKU: A6985FTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A6985FTR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: A6985FTR.pdf

Description:: IC REG BUCK ADJ 500MA 16HTSSOP

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Product details

Overview

A6985FTR from STMicroelectronics is an AEC-Q100 qualified automotive synchronous step-down DC-DC regulator delivering 500 mA output current, operating from 4 V to 38 V input, with 30 µA quiescent current in Low Consumption Mode (LCM) at 3.3 V output, and featuring peak current mode control, embedded voltage supervisor (RST), and adjustable soft-start - deployed in car body electronics and parking-mode systems.

For engineers reviewing the A6985FTR datasheet, A6985FTR pinout, A6985FTR application, or A6985FTR equivalent, key selection criteria include LCM/LNM mode selection via MLF pinstrapping, VIN cold-crank/load-dump compliance, RST open-collector sequencing capability, and HTSSOP16 thermal performance (R_thJA = 40 °C/W).

Technical Context

The A6985FTR 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 dual operational modes-Low Noise Mode (LNM) enforces fixed-frequency PWM for low ripple in audio applications, while Low Consumption Mode (LCM) enables burst-mode operation to minimize IQ at light load.

It integrates a transconductance error amplifier, adjustable soft-start (via SS/INH), synchronization capability (SYNCH/ISKP), and switchover functionality between VIN and VBIAS supply paths to reduce light-load losses. The RST output supports voltage sequencing and reset assertion with user-defined delay via external capacitor on DELAY pin.

Key Specifications

Parameter	Value and Actual Design Meaning
Output current	0.5 A DC - sufficient for microcontroller, sensor, or FPGA power rails in automotive ECUs.
Input voltage range	4 V to 38 V - meets ISO 16750-2 cold crank (4.5 V) and load dump (35 V) requirements.
Quiescent current (LCM)	30 µA at VOUT = 3.3 V - enables >1-year battery hold-up in always-on parking-mode modules.
Switching frequency	250 kHz to 2 MHz - selectable via FSW pinstrapping; higher frequencies allow smaller magnetics and compact layout.
R_DS(on) HS / LS	360 mΩ / 150 mΩ - reduces conduction loss and improves efficiency at medium-to-heavy loads.
Output voltage options	Fixed 3.3 V or 5 V, or adjustable from 0.85 V to VIN - supports diverse logic and analog rail requirements.
Thermal resistance	R_thJA = 40 °C/W - validated on ST reference board; enables 0.5 A operation up to +105 °C ambient with proper PCB copper.

Pinout & Package

Package: HTSSOP16 (exposed pad), RoHS-compliant, R_thJA = 40 °C/W, R_thJC = 5 °C/W. Exposed pad must be connected to both SGND and PGND for thermal and electrical integrity.

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-collector reset output	Asserts low when VOUT falls below programmable threshold; supports power-up sequencing and digital load reset.
2 VCC	Analog supply input	Supplies internal reference and bias circuitry; requires ≥470 nF ceramic decoupling to GND.
3 SS/INH	Soft-start / inhibit control	Pull to GND 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 sync; in LCM: sets current threshold for pulse-skipping.
5 FSW	Frequency selection	Resistor divider to VCC/GND sets fSW before soft-start; E24 series only; enables 250 kHz–2 MHz tuning.
6 MLF	Mode and RST threshold select	Configures LNM vs. LCM and selects RST trip point (80–96% of VOUT) via resistor strapping.
7 COMP	Error amplifier output	Connects external compensation network (RC + C) to stabilize loop response and ensure phase margin.
8 DELAY	RST delay timing	External capacitor sets time delay before RST release after VOUT recovers above threshold.
9 VOUT	Feedback sense node	Connects to output rail or resistive divider for adjustable versions; internal 3.3 V/5 V references are factory-trimmed.
10 SGND	Signal ground	Reference for analog blocks (error amp, comparators); must be star-connected to avoid noise coupling.
11–12 PGND	Power ground	High-current return path for LX switches; connects to exposed pad and separate low-impedance plane.
13–14 LX	Switching node	Drives external inductor; requires tight layout with minimal trace length to reduce EMI and ringing.
15 VIN	Main input supply	Accepts 4–38 V; requires bulk and high-frequency input capacitors near VIN–PGND pins.
16 VBIAS	Switchover auxiliary supply	Connect to regulated output to reduce light-load IQ; internal switchover threshold ~3.0 V.

Key Features

Feature	Design Value
Peak current mode control	Enables fast transient response and inherent cycle-by-cycle overcurrent protection without slope compensation.
Embedded output voltage supervisor (RST)	Provides configurable reset signal with adjustable delay and hysteresis for reliable µC/FPGA power-up sequencing.
Low Consumption Mode (LCM)	Reduces IQ to 30 µA at light load while maintaining regulation - critical for battery-powered parking functions.
Low Noise Mode (LNM)	Maintains constant switching frequency and minimizes output ripple across full load range - suitable for car audio rails.
Synchronization capability	Supports master/slave configuration with fan-out to 6 slave devices, enabling multi-rail ECU clock alignment and EMI reduction.
100% duty cycle operation	Allows dropout < 100 mV at light load, supporting cold-crank operation down to 4.5 V input with 3.3 V output.

Applications

Body Control Module (BCM)

Automotive Infotainment Power

Use Scenario: Powering MCU, CAN transceiver, and door/window sensors in vehicle body electronics with extended parking operation.

IC Role / Device Role / Timing Role: Primary 3.3 V/5 V buck regulator with LCM mode for ultra-low standby IQ and RST sequencing for safe MCU boot.

Use Value: Enables >1-year battery life during vehicle off-state while meeting AEC-Q100 Grade 1 (−40 °C to +125 °C) reliability.

Use Scenario: Supplying low-noise 3.3 V rail to DSP, ADC, and audio codecs in head unit or amplifier modules.

IC Role / Device Role / Timing Role: Fixed-frequency LNM-mode regulator synchronized to system clock to suppress switching noise in sensitive analog paths.

Use Value: Achieves < 10 mV_pp output ripple across 0–500 mA, eliminating audible switching artifacts in audio playback.

Engine Control Unit (ECU) Auxiliary Rail

ADAS Camera Module Power

Use Scenario: Generating stable 5 V supply for LIN transceivers and EEPROM in engine bay ECUs subject to load dump transients.

IC Role / Device Role / Timing Role: Input-tolerant buck regulator with 38 V max rating, overvoltage protection, and thermal shutdown for harsh under-hood environments.

Use Value: Survives 35 V/100 ms load dump events without latch-off, and maintains regulation during 4.5 V cold crank.

Use Scenario: Providing compact, efficient 1.2 V or 1.8 V core supply (via adjustable version) to image sensor and ISP in surround-view cameras.

IC Role / Device Role / Timing Role: Adjustable-output buck with soft-start and sequencing support to coordinate power-up with sensor initialization sequence.

Use Value: Delivers precise 0.85–VIN output with ±1% feedback accuracy and < 100 ns soft-start jitter for deterministic camera boot timing.

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
LMQ66430QRNXTQ1	Higher 3 A output, 3.3 V fixed, 2.5 µA IQ, but no RST output or LCM/LNM mode selection.	Lacks integrated voltage supervisor and programmable light-load modes - requires external reset IC and control logic.	Choose when higher current and lower IQ are prioritized over sequencing and dual-mode flexibility.
TPS62933QPWRQ1	3 A output, 15 µA IQ, 2.5–18 V input, but only 18 V max input - insufficient for 38 V automotive load dump.	Not rated for full automotive input range; requires upstream TVS or pre-regulator for 35 V transients.	Choose only for sub-18 V subsystems (e.g., infotainment USB-C PD rails) where size and IQ are critical.

Compared with LM66430QRNXTQ1 and TPS62933QPWRQ1, the A6985FTR uniquely combines AEC-Q100 qualification, 38 V input tolerance, integrated RST sequencing, and dual LCM/LNM operation - making it optimal for cost-sensitive, space-constrained body electronics requiring robust parking-mode operation.

Availability

A6985FTR is available at Aetrix Electronics and suitable for automotive body control modules, infotainment power supplies, and ADAS camera modules requiring stable component supply across extended temperature and lifecycle requirements.

Supply support for A6985FTR 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-grade analog, power, and microcontroller solutions since 1987.

The A6985FTR belongs to ST's automotive power management portfolio, engineered specifically for ASIL-B compatible systems needing high-reliability, low-IQ DC-DC conversion in harsh environments.

FAQ

What is the maximum allowable junction temperature for continuous operation?

The A6985FTR is specified for continuous operation up to +135 °C junction temperature; thermal shutdown activates at +165 °C typical. Designers must calculate power dissipation using R_DS(on), switching losses, and R_thJA = 40 °C/W to ensure TJ remains within limits under worst-case load and ambient conditions.

How is the RST output threshold configured for a 5 V output version?

For the A6985F5V variant, RST threshold is set by MLF pinstrapping: e.g., 8.2 kΩ to GND selects 80% of VOUT (4.0 V min), while 39 kΩ to GND selects 96% (4.704 V min). Thresholds are factory-characterized and listed in Table 8 of the datasheet, with ±2% hysteresis.

Can the A6985FTR operate with 100% duty cycle, and under what conditions?

Yes - the A6985FTR supports 100% duty cycle in LCM mode when VOUT is close to VIN and load is light, enabling dropout < 100 mV. This occurs automatically during cold-crank (e.g., VIN = 4.5 V → VOUT = 3.3 V) and is enabled by its P-channel high-side switch architecture.

Is external compensation required, and what is the recommended network for 500 kHz operation?

Yes - external compensation is mandatory via the COMP pin. For 500 kHz fSW with 3.3 V output and 10 µH inductor, ST recommends a Type II network: 100 kΩ series resistor, 1 nF capacitor to GND, and 220 pF capacitor from COMP to VOUT - values optimized for phase margin >60° per AN5067.

A6985FTR 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:: Adjustable

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 38V

Voltage - Output (Min/Fixed):: 0.85V

Voltage - Output (Max):: 38V

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

A6985FTR FAQ

1.How can I place an order for A6985FTR through Aetrix?

Please submit a Request for Quotation (RFQ) for A6985FTR 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 A6985FTR reliable?

The price and inventory of A6985FTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6985FTR is usually 5 days.

3.What payment methods are accepted for A6985FTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6985FTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A6985FTR?

A6985FTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A6985FTR 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 A6985FTR?

For technical support, including A6985FTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6985FTR requirements.

6.How does Aetrix verify that A6985FTR is sourced from the original manufacturer or authorized distributors?

All A6985FTR 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 A6985FTR meets industry standards.

7.What is the process for return or replacement of A6985FTR?

All A6985FTR units undergo pre-shipment inspection (PSI). If there is an issue with A6985FTR, 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 A6985FTR part is unused and in its original packaging.

Return procedure for A6985FTR:

1.Submit a request within 90 days.

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

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