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

STMicroelectronics A6985F

Name: A6985F
Brand: STMicroelectronics
SKU: A6985F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A6985F

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: A6985F.pdf

Description:: IC REG BUCK ADJ 500MA 16HTSSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

A6985F from STMicroelectronics is an AEC-Q100 qualified automotive synchronous step-down switching regulator delivering 500 mA DC 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 - designed for cold-crank–tolerant body electronics and low-noise car audio power rails.

For engineers reviewing the A6985F datasheet, A6985F pinout, A6985F application, or A6985F equivalent, key selection criteria include LCM/LNM mode selection via MLF pinstrapping, adjustable soft-start timing, embedded output voltage supervisor with RST open-collector output, and peak-current-mode control architecture with 100% duty cycle capability.

Technical Context

The A6985F implements a peak-current-mode control architecture with pulse-by-pulse high-side/low-side current sensing, enabling precise constant-current protection and foldback under short-circuit. Its internal P-channel high-side switch (R_DS(ON) = 360 mΩ) and N-channel low-side switch (R_DS(ON) = 150 mΩ) support 100% duty cycle operation for cold-crank survival down to 4 V input.

Two configurable operating modes are hardware-selected: Low Noise Mode (LNM) fixes f_SW for EMI-sensitive applications like car audio, while Low Consumption Mode (LCM) enables frequency skipping to achieve 30 µA I_Q at light load. The embedded voltage supervisor provides programmable RST threshold (80–96% of V_OUT) with adjustable delay via external capacitor on DELAY pin.

Key Specifications

Parameter	Value and Actual Design Meaning
Output current	0.5 A DC continuous - supports microcontrollers, sensors, and infotainment subsystems in automotive body domains.
Input voltage range	4 V to 38 V - meets ISO 16750-2 load dump (35 V/100 ms) and cold-crank (4.5 V/15 s) requirements.
Quiescent current (LCM)	30 µA at V_OUT = 3.3 V - enables always-on functionality during vehicle parking without battery drain.
Shutdown current	8 µA typical - ensures ultra-low leakage when inhibited via SS/INH pin.
Switching frequency	250 kHz to 2 MHz - selectable via FSW pinstrapping; enables compact magnetics and EMI optimization.
Output voltage options	Fixed 3.3 V or 5 V, or adjustable from 0.85 V to V_IN - supports diverse logic supply and analog rail needs.
Thermal shutdown	165 °C with 30 °C hysteresis - protects against sustained overload or poor PCB thermal design.

Pinout & Package

HTSSOP16 package with exposed thermal pad (R_thJA = 40 °C/W), requiring solder connection of exposed pad to SGND/PGND for thermal performance and EMI integrity.

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-collector reset output	Asserts low when V_OUT falls below programmable threshold; supports µC/FPGA reset sequencing with adjustable delay.
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	Mode-select / sync input	In LNM: accepts external clock for master/slave synchronization; in LCM: selects skip current level.
5 FSW	Frequency selection	Resistor divider to V_CC/GND sets f_SW from 250 kHz to 2 MHz before soft-start completes.
6 MLF	Mode and RST threshold select	Configures LNM vs. LCM and sets RST trip point (80–96% of V_OUT) via resistor strapping.
7 COMP	Error amplifier output	Connects external compensation network (RC + C) to stabilize loop response across load/line variations.
8 DELAY	RST assertion timing	External capacitor sets delay between V_OUT recovery and RST deassertion; floating = Power Good behavior.
13–14 LX	Power switch node	High-frequency switching node connecting internal HS/LS MOSFETs to external inductor; requires tight layout.
15 VIN	Main power input	Accepts 4–38 V DC; must be decoupled with ≥4.7 µF ceramic capacitor near pin.
16 VBIAS	Internal bias supply	Optional connection to regulated output improves light-load efficiency by reducing I_Q path losses.

Key Features

Feature	Design Value
Peak-current-mode control	Enables fast transient response and inherent cycle-by-cycle overcurrent protection without external sense resistor.
Embedded voltage supervisor	Programmable RST threshold and delay eliminates need for external reset IC in automotive MCU/FPGA power domains.
100% duty cycle capability	Maintains regulation down to 4 V input - critical for engine start/cold-crank scenarios in 12 V automotive systems.
Switchover biasing (VBIAS)	Reduces light-load quiescent current by sourcing internal analog circuitry from V_OUT instead of VIN.
Adjustable soft-start	Prevents inrush current and output overshoot during power-up via external capacitor on SS/INH pin.
Overvoltage protection (OVP)	Actively discharges output capacitor if V_OUT exceeds 1.2× reference - prevents damage to downstream loads.

Applications

Car Body Control Module (LCM)

Car Audio Power Supply (LNM)

Use Scenario: Powering door module ECUs, seat position controllers, and lighting drivers during vehicle parking and ignition cycles.

IC Role / Device Role / Timing Role: Primary 3.3 V/5 V buck converter providing always-on, low-quiescent-power supply with cold-crank resilience.

Use Value: 30 µA I_Q in LCM extends battery life during weeks-long parking; 100% duty cycle sustains operation at 4.5 V during cranking.

Use Scenario: Generating clean 5 V rail for DSPs, ADCs, and amplifiers in head unit and amplifier modules.

IC Role / Device Role / Timing Role: Fixed-frequency PWM buck regulator synchronized to system clock to avoid beat frequencies in audio band.

Use Value: Constant f_SW in LNM minimizes output voltage ripple across full load range, meeting <10 mV_PP noise spec for analog audio stages.

Automotive Infotainment Core Supply

ADAS Camera Power Sequencing

Use Scenario: Delivering stable 1.2 V or 1.8 V core voltage to SoCs and FPGAs in display clusters and telematics units.

IC Role / Device Role / Timing Role: Adjustable-output buck regulator with programmable soft-start and output voltage sequencing via RST pin.

Use Value: RST open-collector output enables power-up sequencing of multiple rails (e.g., core → I/O → memory) using simple pull-up resistors.

Use Scenario: Powering image sensor modules requiring strict voltage ramp timing and fault signaling during boot.

IC Role / Device Role / Timing Role: Supervised buck converter with adjustable RST delay and OVP to ensure safe camera initialization and fault isolation.

Use Value: Programmable RST threshold (80–96% of V_OUT) and DELAY capacitor allow precise alignment with sensor power-good timing requirements.

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 8 A output, 2.7–36 V input, 15 µA I_Q, but no embedded voltage supervisor or RST output.	Lacks integrated reset supervision - requires external supervisor IC for sequenced power-up in SoC designs.	Choose when higher current and lower I_Q outweigh need for integrated RST and sequencing.
TPS62933-Q1	3 A output, 3–36 V input, 12 µA I_Q, fixed 3.3 V/5 V options only, no adjustable V_OUT or LCM/LNM mode selection.	No light-load mode switching - uses DCS-Control for ripple reduction, less effective than A6985F's LCM for ultra-low I_Q.	Prefer for high-current, low-noise applications where adjustable output and dual-mode operation are unnecessary.

Compared with LM61480-Q1 and TPS62933-Q1, the A6985F uniquely integrates voltage supervision, programmable RST, and hardware-selectable LCM/LNM modes - making it optimal for cost-sensitive, space-constrained automotive body and audio systems requiring both ultra-low I_Q and robust fault signaling.

Availability

A6985F is available at Aetrix Electronics and suitable for automotive body control, car audio power supplies, infotainment core rails, and ADAS camera modules requiring stable component supply across extended temperature and qualification lifecycles.

Supply support for A6985F 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 sensors - with broad AEC-Q100 product portfolio and deep automotive system expertise.

The A6985F belongs to ST's automotive DC-DC converter family, engineered specifically for body electronics and infotainment systems demanding cold-crank resilience, ultra-low quiescent current, and integrated supervision functions.

FAQ

What is the purpose of the VBIAS pin on the A6985F?

The VBIAS pin allows the internal LDO to draw bias current from the regulated output voltage instead of VIN, reducing light-load quiescent current by up to 70% when VBIAS is connected to VOUT. This switchover occurs automatically when VBIAS exceeds 2.85 V, improving efficiency in always-on automotive applications without requiring external control logic.

How does the A6985F implement output voltage sequencing?

Sequencing is achieved using the open-collector RST pin: when configured with appropriate resistor strapping on MLF and an external capacitor on DELAY, RST remains low until VOUT reaches its target and stabilizes for a user-defined time. This signal can drive enable pins of downstream regulators or reset lines of digital loads to enforce strict power-up order.

Can the A6985F operate with input voltage below 4 V?

No - the absolute minimum operating input voltage is 4 V per datasheet specifications. Below this, the internal UVLO circuit disables the regulator to prevent unstable operation. However, the device supports 100% duty cycle down to 4 V, enabling continued regulation during automotive cold-crank events where battery voltage dips to ~4.5 V for up to 15 seconds.

What is the maximum allowable junction temperature for continuous operation?

The A6985F guarantees full electrical performance up to 135 °C junction temperature. Thermal shutdown activates at 165 °C (typical) with 30 °C hysteresis, but continuous operation above 135 °C risks parameter drift and reduced reliability. PCB layout must maintain R_thJA ≤ 40 °C/W using the exposed pad tied to SGND/PGND for automotive ambient conditions up to 105 °C.

A6985F 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:: 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

A6985F FAQ

1.How can I place an order for A6985F through Aetrix?

Please submit a Request for Quotation (RFQ) for A6985F 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 A6985F reliable?

The price and inventory of A6985F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6985F is usually 5 days.

3.What payment methods are accepted for A6985F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6985F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A6985F?

A6985F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A6985F 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 A6985F?

For technical support, including A6985F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6985F requirements.

6.How does Aetrix verify that A6985F is sourced from the original manufacturer or authorized distributors?

All A6985F 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 A6985F meets industry standards.

7.What is the process for return or replacement of A6985F?

All A6985F units undergo pre-shipment inspection (PSI). If there is an issue with A6985F, 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 A6985F part is unused and in its original packaging.

Return procedure for A6985F:

1.Submit a request within 90 days.

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

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