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Allegro MicroSystems A8670EESTR-T
- Part No.:
- A8670EESTR-T
- Manufacturer:
- Allegro MicroSystems
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
A8670EESTR-T.pdf
- Description:
- IC REG BUCK ADJ 2A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,345
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Product details
Overview
A8670EESTR-T from Allegro MicroSystems is a discontinued 2 A synchronous buck regulator with valley current mode control, 7–16 V input range, adjustable 0.6 V output, and integrated fault reporting (FAULT/POK). It delivers high efficiency via 180 mΩ high-side and 40 mΩ low-side MOSFETs and supports >1 MHz operation for low-VOUT/high-VIN conversion in point-of-load server supplies.
For engineers reviewing the A8670EESTR-T datasheet, A8670EESTR-T pinout, A8670EESTR-T application, or A8670EESTR-T equivalent, key selection considerations include its fixed-frequency valley current mode architecture, programmable soft-start and on-time, thermal warning at 140°C, POK delay of 90 μs, and QFN-20 ES package with exposed thermal pad.
Technical Context
The A8670EESTR-T implements valley current mode control with voltage feedforward, enabling stable regulation across wide input/output ratios and fast transient response. Its on-time is set externally via RTON, defining switching frequency between 200 kHz and 1 MHz while maintaining minimum on-time of 50 ns and minimum off-time of 350 ns.
It integrates dual MOSFETs (180 mΩ HS / 40 mΩ LS), a precision 0.6 V ±1% reference, and comprehensive protection: UVLO (6.4 V), thermal warning (140°C), TSD (160°C), LX–GND short detection, timing resistor open-circuit sensing, and pulse-by-pulse current limiting (2.7 A typical, adjustable to 1.3 A).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 2 A continuous; supports peak valley current limit up to 3.3 A (ILIM open) for overload handling. |
| Input Voltage Range | 7–16 V; includes UVLO turn-on at 6.4 V (±0.4 V hysteresis) for reliable startup under brownout. |
| Output Voltage | Adjustable down to 0.6 V ±1% over temperature; set via external FB resistor divider. |
| Switching Frequency | 200–1000 kHz; selected by external RTON; enables optimization of size vs. efficiency in POL designs. |
| Min On-Time / Off-Time | 50 ns / 350 ns; allows 12 V → 0.6 V conversion at >1 MHz without pulse-skipping instability. |
| Fault Reporting | Dedicated open-drain FAULT (thermal warning, TSD, LX–GND short) and POK (90 μs delay, ±5% window) pins for host system monitoring. |
| Thermal Resistance | RθJA = 37 °C/W (4-layer JEDEC PCB); RθJP = 2 °C/W - requires exposed pad soldering for safe 2 A operation. |
Pinout & Package
Package: 20-contact, 4 mm × 4 mm, 0.75 mm nominal height QFN with exposed thermal pad (ES suffix); Pb-free, 100% matte tin plating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1,2,20 | PGND | Power ground return for high-current paths; must connect directly to PCB ground plane with multiple vias. |
| 3 | VIN | Main power input (7–16 V) for control logic and high-side MOSFET drain; requires local 10 μF ceramic bypass. |
| 4 | BIAS | Bias supply decoupling node; connects to 10 μF capacitor for internal LDO stability. |
| 5 | TON | On-time programming input; resistor to VIN sets switching frequency (200–1000 kHz). |
| 6,19 | AGND | Analog ground reference for FB divider; separate from PGND to minimize noise coupling into feedback path. |
| 7 | COMP | Error amplifier output and loop compensation node; connects external R-C network for stability tuning. |
| 8 | FB | Feedback input referenced to 0.6 V ±1% internal reference; sets output voltage via resistor divider. |
| 9 | SS | Soft-start ramp capacitor node; controls output voltage rise time and inrush current (e.g., 10 nF → 600 μs). |
| 10 | POK | Open-drain Power OK output; asserts high after output reaches 90% target + 90 μs delay; pulls low on fault. |
| 11 | FAULT | Open-drain fault indicator; pulls low on thermal warning (140°C), TSD (160°C), or LX–GND short. |
| 12 | BOOT | High-side gate driver bootstrap supply; connects 10 nF ceramic capacitor to LX for floating drive. |
| 13–16 | LX | Switch node connecting internal high-side source and low-side drain; ties to inductor and BOOT capacitor. |
| 17 | EN | Enable input with 1.8 V threshold and 250 mV hysteresis; draws only 1 μA in shutdown. |
| 18 | ILIM | Current limit select: open = 2.7 A typical, GND = 1.3 A typical; enables inductor derating for fault robustness. |
| PAD | Exposed Thermal Pad | Electrically connected to PGND; mandatory soldering to PCB ground plane with ≥4 thermal vias for thermal integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Valley current mode control | Enables stable operation at ultra-low duty cycles (e.g., 0.6 V from 12 V) without subharmonic oscillation. |
| Integrated high-/low-side FETs | 180 mΩ HS / 40 mΩ LS MOSFETs reduce conduction loss and eliminate external switch selection effort. |
| Programmable soft-start | External SS capacitor sets ramp time (e.g., 10 nF → 600 μs), preventing inrush current and output overshoot. |
| Comprehensive fault reporting | Separate FAULT (thermal, short-circuit) and POK (regulation status) outputs enable deterministic system-level response. |
| Pre-bias start-up capability | Allows safe startup into pre-charged output rails without reverse current or latch-up risk. |
| Adjustable pulse-by-pulse current limit | ILIM pin selects full (2.7 A) or half (1.3 A) current limit, simplifying inductor sizing for different fault margins. |
Applications
| Server Point-of-Load Regulation | Network Equipment DC-DC Conversion |
|---|---|
|
Use Scenario: Regulating 1.2 V or 0.8 V core voltage for Xeon or AMD EPYC processors in 1U rack servers. IC Role / Device Role / Timing Role: Primary synchronous buck controller delivering up to 2 A with tight regulation and fast load transient response. Use Value: Valley current mode and 50 ns min on-time support stable 12 V → 0.6 V conversion at 700 kHz, minimizing output filter size. |
Use Scenario: Generating 3.3 V or 5 V intermediate rails for FPGA I/O banks and SerDes in telecom line cards. IC Role / Device Role / Timing Role: Fixed-frequency buck regulator with POK/FAULT signaling for system health monitoring and graceful shutdown. Use Value: 90 μs POK delay and ±5% window ensure accurate power-good assertion before downstream logic initialization. |
| Enterprise Storage Power Management | Industrial Embedded Computing |
|
Use Scenario: Supplying 1.8 V or 2.5 V to NVMe SSD controllers and DRAM buffers in storage arrays. IC Role / Device Role / Timing Role: High-efficiency POL regulator with thermal warning (140°C) and hiccup-mode overload protection. Use Value: Programmable ILIM and hiccup duration (50 μs overload / 300 μs shutdown) prevent sustained overtemperature in confined enclosures. |
Use Scenario: Providing 1.0 V or 1.2 V to ARM-based SoCs in ruggedized edge gateways operating at –40°C to +85°C. IC Role / Device Role / Timing Role: Robust buck converter with ±1% reference accuracy over full temperature range and UVLO hysteresis. Use Value: 0.6 V reference tolerance and 400 mV UVLO hysteresis ensure reliable startup and hold-up during industrial power sags. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | 2 A, 4.5–26 V input, 500 kHz fixed frequency, no FAULT/POK pins, smaller 8-pin SOIC package. | Lacks dedicated fault reporting; suitable for cost-sensitive, non-safety-critical POL where host monitoring is not required. | Choose MP2315DJ-LF-Z when board space is constrained and diagnostic signaling is unnecessary. |
| TPS54202DDCR | 2 A, 4.5–17 V input, adaptive on-time D-CAP2 control, integrated POK, no FAULT pin, 6-pin SOT-23 package. | Uses D-CAP2 for faster transient response but lacks thermal warning flag and LX short-circuit detection. | Choose TPS54202DDCR when fastest load step response is prioritized over comprehensive fault coverage. |
Compared with A8670EESTR-T, MP2315DJ-LF-Z offers lower BOM count but omits critical diagnostics, while TPS54202DDCR improves transient performance yet sacrifices thermal warning and short-circuit detection - making A8670EESTR-T uniquely suited for systems requiring deterministic fault isolation in high-reliability infrastructure.
Availability
A8670EESTR-T is available at Aetrix Electronics and suitable for server point-of-load, network equipment DC-DC, and enterprise storage power management requiring stable component supply despite end-of-life status.
Supply support for A8670EESTR-T 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
Allegro MicroSystems is a U.S.-based semiconductor company specializing in high-performance power ICs and magnetic sensors for automotive and industrial applications.
The A8670 product line was designed as a rugged, feature-rich synchronous buck regulator for infrastructure-grade point-of-load conversion, emphasizing fault resilience, thermal intelligence, and design flexibility in datacenter and telecom systems.
FAQ
Is A8670EESTR-T still in production?
No, A8670EESTR-T is a discontinued product. Allegro MicroSystems ceased production as of December 3, 2013. It is not recommended for new designs, and samples are no longer available. Aetrix Electronics maintains limited legacy stock for existing production continuity, subject to availability verification prior to order placement.
What is the function of the ILIM pin on A8670EESTR-T?
The ILIM pin on A8670EESTR-T selects pulse-by-pulse current limit level: left open for 2.7 A typical valley current limit, or tied to GND for 1.3 A typical. This allows designers to match inductor saturation rating and fault energy handling without changing layout - a key flexibility feature of the A8670EESTR-T architecture.
Can A8670EESTR-T operate with a pre-biased output?
Yes, A8670EESTR-T supports pre-bias start-up. Its valley current mode control and internal circuitry prevent reverse current flow into a pre-charged output rail, enabling safe integration into power sequencing architectures where downstream rails may be powered before the A8670EESTR-T enables.
What thermal design requirements apply to A8670EESTR-T?
A8670EESTR-T requires soldering of its exposed thermal pad to a PCB ground plane using ≥4 thermal vias. With RθJA = 37 °C/W on a 4-layer JEDEC board, continuous 2 A operation demands careful thermal layout - especially given its 150°C max junction temperature and thermal warning activation at 140°C.
How does the FAULT pin differ from the POK pin on A8670EESTR-T?
The FAULT pin on A8670EESTR-T asserts low for critical conditions including thermal warning (140°C), thermal shutdown (160°C), and LX–GND short-circuit detection. The POK pin asserts high only after output reaches 90% of target + 90 μs delay, and pulls low on FB undervoltage/overvoltage - providing distinct, non-overlapping fault classification for system-level diagnostics.
A8670EESTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 7V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 16V
- Current - Output:
- 2A
- Frequency - Switching:
- 200kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-QFN (4x4)
A8670EESTR-T FAQ
1.How can I place an order for A8670EESTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A8670EESTR-T 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 A8670EESTR-T reliable?
The price and inventory of A8670EESTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A8670EESTR-T is usually 5 days.
3.What payment methods are accepted for A8670EESTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A8670EESTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A8670EESTR-T?
A8670EESTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A8670EESTR-T 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 A8670EESTR-T?
For technical support, including A8670EESTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A8670EESTR-T requirements.
6.How does Aetrix verify that A8670EESTR-T is sourced from the original manufacturer or authorized distributors?
All A8670EESTR-T 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 A8670EESTR-T meets industry standards.
7.What is the process for return or replacement of A8670EESTR-T?
All A8670EESTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A8670EESTR-T, 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 A8670EESTR-T part is unused and in its original packaging.
Return procedure for A8670EESTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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