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STMicroelectronics A6984TR
- Part No.:
- A6984TR
- Manufacturer:
- STMicroelectronics
- Package:
- 10-VFDFN Exposed Pad
- Datasheet:
-
A6984TR.pdf
- Description:
- IC REG BUCK 3.3V 400MA 10VFDFPN
- Quantity:
- Payment:
- Shipping:
Inventory:3,986
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Product details
Overview
A6984TR from STMicroelectronics is an AEC-Q100 qualified automotive synchronous step-down switching regulator delivering 400 mA DC output current across 4.5 V to 36 V input range, featuring adjustable switching frequency (250–600 kHz), 0.9 V to 3.3 V adjustable/fixed output, and dual low-noise (LNM) or low-consumption (LCM) operating modes - deployed in car body control modules and ADAS power rails.
For engineers reviewing the A6984TR datasheet, A6984TR pinout, A6984TR application, or A6984TR equivalent, this device supports critical automotive power sequencing via PGOOD open-collector output, enables compact layout with VFDFPN10 4×4 mm package, and offers verified light-load efficiency optimization through VBIAS-assisted biasing and constant-on-time control architecture.
Technical Context
The A6984TR implements a constant-on-time (COT) control scheme with frequency feed-forward correction, ensuring fast load transient response and near-constant switching frequency over input voltage variation. Its on-time generator uses an external resistor (TON pin) and internal capacitance to set nominal fSW, while PWM comparator modulates off-time to compensate for conduction losses.
Two configurable operating modes are implemented via LNM pin strapping: Low Noise Mode (LNM) enforces nearly constant-frequency PWM for minimal output ripple in car audio/sensor rails; Low Consumption Mode (LCM) employs pulse-skipping to achieve 75 µA quiescent current at light load with controlled ripple - both modes leverage VBIAS to source bias current from regulated output, improving light-load efficiency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 36 V - supports full automotive battery range including cold-crank (4.5 V) and load-dump (36 V) transients. |
| Output Current | 400 mA DC - sufficient for powering microcontrollers, sensors, and CAN transceivers in body electronics. |
| Quiescent Current (LCM) | 75 µA at light load (VOUT = 3.3 V) - enables always-on functionality during vehicle parking without excessive battery drain. |
| Switching Frequency | 250 kHz to 600 kHz (adjustable via TON resistor) - allows EMI tuning and inductor size optimization for space-constrained modules. |
| Output Voltage Options | Fixed 3.3 V (no external divider) or adjustable down to 0.9 V - simplifies BOM for standard logic rails and supports custom core voltages. |
| Valley Current Limit | 350 mA - provides robust short-circuit protection while maintaining stable regulation under partial overload. |
| PGOOD Output | Open-collector, rail-to-rail compatible - enables precise power-rail sequencing and system-level fault reporting in multi-rail ECUs. |
Pinout & Package
Package: VFDFPN10, 4 mm × 4 mm × 1.0 mm, exposed thermal pad, side-wettable flanks for automated optical inspection.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - PGOOD | Power Good status indicator | Open-collector output pulled low when FB voltage drops below 84% of target - used for sequencing and fault signaling. |
| 2 - FB | Error amplifier inverting input | Connects to voltage divider (or VCC for fixed 3.3 V); sets output voltage with 0.9 V reference threshold. |
| 3 - TON | Frequency setting node | External resistor to VIN sets switching frequency; parasitic capacitance requires board-specific calibration for precise fSW. |
| 4 - EN | Enable control input | Active-high logic; internal hysteresis (650 mV) prevents chatter during slow-rising enable signals. |
| 5 - GND | Power ground reference | Common return for LX, VCC, and analog circuitry; must be low-inductance connection to thermal pad. |
| 6 - LX | Switching node | Drives external inductor; high dv/dt node requiring tight layout and minimized trace length to reduce EMI. |
| 7 - VIN | Main input supply | Accepts 4.5–36 V; includes UVLO (3.1–4.5 V rising edge) and integrated input slew-rate limiting. |
| 8 - VCC | Internal LDO output | 3.3 V regulated supply for controller; requires 1 µF ceramic capacitor; disabled when VBIAS > 3.2 V to improve efficiency. |
| 9 - VBIAS | Bias voltage input | Connected to regulated output to source quiescent current - reduces IQ to 75 µA in LCM mode and enables VCC bypass. |
| 10 - LNM | Mode selection strap | Connect to VCC for Low Noise Mode (constant fSW); connect to GND for Low Consumption Mode (pulse skipping). |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated high-side (0.6 Ω typ) and low-side (0.4 Ω typ) MOSFETs eliminate external diode - improves efficiency by ≥15% at medium/heavy loads vs. asynchronous designs. |
| VBIAS-assisted biasing | Allows quiescent current sourcing from regulated output instead of VIN - cuts light-load IQ from 200 µA to 75 µA in LCM mode, extending battery life in parked-state applications. |
| Constant-on-time (COT) control | Delivers <10 µs load transient response and inherent stability with ceramic output capacitors - eliminates need for external compensation network. |
| Dual operational modes | LNM ensures <±10 mV output ripple across 0–400 mA load; LCM maintains >85% efficiency at 1 mA load - selectable via single pin strap. |
| PGOOD open-collector output | Supports direct interfacing with MCU reset inputs or FPGA power-good latches - enables reliable multi-rail startup coordination without external pull-ups. |
Applications
| Body Control Module (BCM) | ADAS Camera Power Supply |
|---|---|
|
Use Scenario: Powering microcontroller, LIN transceiver, and door-lock actuators in vehicle body domain controller. IC Role / Device Role / Timing Role: Primary 3.3 V buck regulator with sequenced startup and parking-mode LCM operation. Use Value: 75 µA IQ in LCM extends battery standby time beyond 30 days; PGOOD enables safe MCU boot after stable 3.3 V rail establishment. |
Use Scenario: Supplying image sensor and ISP in forward-facing ADAS camera module. IC Role / Device Role / Timing Role: Low-noise 3.3 V rail generator with ripple-controlled LNM mode and thermal shutdown. Use Value: LNM mode limits output ripple to <10 mV p-p across full load range - prevents image noise and sensor ADC errors. |
| Automotive Infotainment Audio Rail | Telematics Control Unit (TCU) |
|
Use Scenario: Providing clean 3.3 V supply to audio codec and DSP in head-unit systems. IC Role / Device Role / Timing Role: Dedicated low-noise buck converter with fixed 3.3 V output and EMI-optimized fSW. Use Value: Near-constant switching frequency in LNM avoids heterodyning with audio band; VFDFPN10 package minimizes PCB area. |
Use Scenario: Powering cellular modem, GNSS receiver, and secure MCU in connected vehicle telematics unit. IC Role / Device Role / Timing Role: High-reliability 3.3 V regulator with AEC-Q100 qualification and thermal shutdown. Use Value: 150 °C thermal shutdown and -40 °C to 125 °C guaranteed operation ensure robustness in under-hood mounting locations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar automotive synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62130ARGTR | Non-AEC-Q100; 3–17 V input; 3.0 V fixed output only; no LNM/LCM mode selection. | Lacks automotive qualification and dual-mode operation - unsuitable for safety-critical or parked-mode applications. | Select only for non-automotive industrial use where qualification and ultra-low IQ are not required. |
| MAX20004AATP/V+T | AEC-Q100 Grade 1; 3.5–36 V input; 400 mA; 70 µA IQ in skip mode; no VBIAS pin or LNM option. | Matches LCM-like efficiency but lacks low-noise mode and VBIAS flexibility - limited for audio/sensor rails. | Prefer when strict thermal performance (−40°C to +150°C TJ) is prioritized over ripple-sensitive applications. |
Compared with TPS62130ARGTR and MAX20004AATP/V+T, the A6984TR uniquely combines AEC-Q100 qualification, dual LNM/LCM modes, VBIAS-enabled IQ optimization, and PGOOD sequencing - making it the only choice for automotive systems requiring both parked-mode efficiency and real-time low-noise operation.
Availability
A6984TR is available at Aetrix Electronics and suitable for automotive body electronics, ADAS camera modules, and infotainment audio subsystems requiring stable component supply across extended temperature and lifecycle demands.
Supply support for A6984TR 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 silicon solutions for automotive, industrial, and consumer markets with emphasis on reliability and functional safety.
The A6984TR belongs to ST's automotive-grade power management portfolio, engineered specifically for ASIL-B compatible systems requiring high efficiency, low noise, and robust operation across harsh automotive environments.
FAQ
What is the minimum off-time specification for the A6984TR, and why does it matter?
The A6984TR has a typical minimum off-time of 300 ns (max 400 ns), which directly constrains maximum achievable duty cycle and thus upper limit of output voltage at high input voltages and heavy loads. This parameter ensures reliable feedback sampling and prevents control loop instability during high-VIN, high-duty-cycle operation - critical for maintaining regulation in 24 V commercial vehicle applications.
How does VBIAS improve light-load efficiency, and what voltage range is supported?
VBIAS allows the A6984TR to draw bias current from the regulated output instead of VIN when VBIAS > 3.2 V, disabling the internal VCC LDO and reducing total IQ from ~200 µA to 75 µA in LCM mode. VBIAS operates from GND to VIN, with falling/rising thresholds at 2.4–2.6 V and 2.6–3.2 V respectively - enabling seamless integration with existing 3.3 V rails.
Can the A6984TR be used without an external resistor divider for 3.3 V output?
Yes - the A6984TR supports fixed 3.3 V output by connecting FB directly to VCC and tying VBIAS to the output. This configuration leverages an internal 0.9 V reference and precision resistor network, eliminating external resistors and associated tolerance/temperature drift errors - validated across −40°C to +125°C junction temperature.
What is the role of the TON pin, and how is switching frequency calibrated?
The TON pin accepts an external resistor to VIN to set nominal switching frequency between 250 kHz and 600 kHz. Due to board parasitic capacitance (~7.5 pF typical), actual fSW requires oscilloscope measurement and RTON fine-tuning per layout - Equation TON ≈ 0.9 × RTON × 7.5 pF / VIN ensures accurate design targeting before prototyping.
A6984TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 10-VFDFN Exposed Pad
- 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):
- 4.5V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 400mA
- Frequency - Switching:
- 250kHz ~ 600kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-VFDFPN (4x4)
A6984TR FAQ
1.How can I place an order for A6984TR through Aetrix?
Please submit a Request for Quotation (RFQ) for A6984TR 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 A6984TR reliable?
The price and inventory of A6984TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6984TR is usually 5 days.
3.What payment methods are accepted for A6984TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6984TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6984TR?
A6984TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6984TR 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 A6984TR?
For technical support, including A6984TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6984TR requirements.
6.How does Aetrix verify that A6984TR is sourced from the original manufacturer or authorized distributors?
All A6984TR 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 A6984TR meets industry standards.
7.What is the process for return or replacement of A6984TR?
All A6984TR units undergo pre-shipment inspection (PSI). If there is an issue with A6984TR, 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 A6984TR part is unused and in its original packaging.
Return procedure for A6984TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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