My Inquiry
My Account
Allegro MicroSystems A8697ELJ-T
- Part No.:
- A8697ELJ-T
- Manufacturer:
- Allegro MicroSystems
- Package:
- 8-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
A8697ELJ-T.pdf
- Description:
- IC REG BUCK ADJ 4A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,564
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
A8697ELJ-T from Allegro MicroSystems is a wide-input, constant off-time current-mode buck regulator with integrated 180 mΩ DMOS switch, supporting 8–25 V input and delivering up to 4.0 A at adjustable output voltages down to 0.8 V; used in 12 V automotive accessory power supplies and point-of-sale systems requiring compact, thermally robust DC/DC conversion.
For engineers reviewing the A8697ELJ-T datasheet, A8697ELJ-T pinout, A8697ELJ-T application, or A8697ELJ-T equivalent, this page delivers verified electrical parameters, thermal package data, functional block context, real-world load transient behavior, and validated alternative options for legacy design continuity.
Technical Context
The A8697ELJ-T implements fixed off-time current-mode control with internal ramp generation and cycle-skipping light-load regulation. It uses an external TSET resistor to set off-time (5–200 μs range) and requires an external Schottky diode, inductor, and feedback divider for operation.
Its architecture integrates boot charge circuitry for high-side gate drive, internal bias supply switching between VIN and VBIAS, and thermal shutdown at 165°C with 15°C hysteresis. Protection includes undervoltage lockout (6.9 V ±0.3 V), short-circuit current limiting (2.7–7.2 A), and soft-start (10 ms nominal).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8–25 V - supports unregulated 12 V automotive and industrial bus rails without pre-regulation |
| Max Output Current | 4.0 A continuous - limited by thermal performance on 4-layer PCB with exposed pad |
| Feedback Reference | 0.8 V ±2% - enables precise output setting from 0.8 V to 20 V using external resistor divider |
| Switch RDS(on) | 180 mΩ typical at 25°C - reduces conduction loss and thermal stress in high-current step-down |
| Quiescent Current | 100 μA max when enabled - minimizes standby power in always-on applications |
| Thermal Shutdown | 165°C with 15°C hysteresis - prevents permanent damage during overload or poor heatsinking |
| Soft Start Time | 10 ms nominal - controls inrush current into output capacitor during power-up |
Pinout & Package
Package: 8-lead SOIC with exposed thermal pad (JEDEC MS-012AA, suffix LJ); 6.0 × 4.9 mm body, 1.75 mm height, 1.27 mm lead pitch; thermal pad improves θJA to 35°C/W on 4-layer PCB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - BOOT | Gate drive bootstrap node | Charges high-side driver capacitor; requires 0.01 μF ceramic capacitor to LX |
| 2 - ENB | Enable logic input | Active-high; <1.0 V disables regulator and forces low-IQ state |
| 3 - TSET | Off-time configuration | Resistor-to-ground sets fixed off-time (5–200 μs); determines switching frequency and inductor sizing |
| 4 - GND | Power and signal ground | Common return for all internal circuits; must be connected to exposed thermal pad |
| 5 - FB | Output voltage feedback | Compares divided output to 0.8 V reference; 100 nA bias current enables high-resistor dividers |
| 6 - VBIAS | Bias supply input | Accepts VOUT (3.3–5 V) to improve efficiency; otherwise draws from VIN |
| 7 - LX | Switching node | Connects to inductor and external Schottky diode cathode; high dv/dt node requiring tight layout |
| 8 - VIN | Main power input | 8–25 V supply; requires local 47 μF/25 V electrolytic + 0.1 μF ceramic decoupling |
| Pad - Exposed Thermal Pad | Thermal and electrical ground | Mandatory connection to PCB ground plane via thermal vias; primary heat path for 4 A operation |
Key Features
| Feature | Design Value |
|---|---|
| Integrated DMOS power switch | Eliminates external MOSFET and reduces BOM count and board area in 4 A buck designs |
| Adjustable fixed off-time control | Enables stable operation across wide VIN/VOUT ratios without loop compensation redesign |
| Internal soft-start with 10 ms ramp | Prevents input supply sag and output overshoot during startup under full load |
| Logic-level enable with low-IQ | Reduces system standby power to <100 μA while maintaining fast wake-up capability |
| VBIAS supply selection | Improves full-load efficiency by >2% when VOUT ≥3.3 V, versus drawing bias from VIN |
Applications
| Automotive Accessories | Point-of-Sale Terminals |
|---|---|
|
Use Scenario: Powering USB charging ports and display modules from 12 V vehicle battery with transient tolerance. IC Role / Device Role / Timing Role: Primary 1.06 V/4 A step-down regulator supplying SoC core voltage in portable DVD players and dashcams. Use Value: Wide 8–25 V input handles cold-crank (6.6 V UVLO) and load-dump events; exposed pad sustains 4 A at 85°C ambient. |
Use Scenario: Generating 3.3 V rail for ARM-based payment terminals powered from 12 V wall adapters. IC Role / Device Role / Timing Role: Adjustable buck converter delivering regulated 3.3 V at up to 4 A for processor, memory, and interface ICs. Use Value: Cycle-skipping light-load mode maintains regulation at <10 mA; FB accuracy (±2%) ensures stable I/O voltage across temperature. |
| Networking Equipment | Industrial Control Panels |
|
Use Scenario: Converting 24 V PoE midspan output to 1.8 V for FPGA I/O banks in edge routers. IC Role / Device Role / Timing Role: High-efficiency intermediate regulator in multi-rail power tree, operating at ~173 kHz with 3.8 μH inductor. Use Value: Fixed off-time architecture avoids instability with ceramic output caps; TSET resistor allows frequency tuning for EMI compliance. |
Use Scenario: Providing 5.0 V/3 A for PLC I/O modules in factory automation cabinets with ambient up to 85°C. IC Role / Device Role / Timing Role: Main DC/DC stage converting 24 V industrial bus to isolated 5 V logic supply, with thermal shutdown protection. Use Value: 165°C junction shutdown and 35°C/W thermal resistance prevent field failures under sustained 4 A load in enclosed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A8698ELJ-T | Same pinout, identical architecture, but rated for 5 A max output and higher thermal performance (RθJA = 30°C/W) | Supports higher current loads without derating; requires same PCB layout but improved heatsinking | Preferred for new designs needing >4 A or extended thermal margin; not drop-in due to different current limit and thermal specs |
| MP2451DT-LF-Z | 36 V input, 0.6 A max, no integrated high-side switch - requires external MOSFET and compensation network | Suitable only for sub-1 A applications; lacks thermal pad and integrated switch of A8697ELJ-T | Only viable for low-power replacements where footprint and current capability allow significant redesign |
Compared with A8697ELJ-T, A8698ELJ-T offers higher current headroom and better thermal resistance but shares identical pinout and control scheme, whereas MP2451DT-LF-Z demands full schematic and layout revision due to external switch topology and lower current rating.
Availability
A8697ELJ-T is available at Aetrix Electronics and suitable for automotive accessory power supplies, point-of-sale terminals, and industrial control panels requiring stable component supply despite end-of-life status.
Supply support for A8697ELJ-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 designer of high-performance power ICs and magnetic sensors, headquartered in Worcester, Massachusetts, serving automotive, industrial, and consumer markets since 1989.
The A8697 belongs to Allegro's wide-input buck regulator product line, engineered for rugged 12 V/24 V system integration where space, thermal performance, and input transient resilience are critical.
FAQ
What is the maximum continuous output current supported by the A8697ELJ-T?
The A8697ELJ-T delivers up to 4.0 A continuously under typical conditions: 12 V input, 1.06 V output, 85°C ambient, and proper PCB thermal design with the exposed pad connected to a 4-layer ground plane. Derating applies above 85°C ambient or with reduced copper area; the device enters thermal shutdown at 165°C junction temperature. The A8697ELJ-T datasheet specifies 4.0 A as the validated maximum load current in production test conditions.
Does the A8697ELJ-T require an external Schottky diode, and why?
Yes, the A8697ELJ-T requires an external Schottky diode (e.g., SL42-9C) connected from LX to VOUT. Because it integrates only a high-side DMOS switch-not a synchronous rectifier-the diode provides the return current path during the switch off-time. This asynchronous architecture simplifies design but limits peak efficiency to ~90% at 4 A; the diode must handle ≥4.8 A peak current and withstand the full input voltage.
Can the A8697ELJ-T operate with an output voltage below 0.8 V?
No, the A8697ELJ-T cannot regulate below 0.8 V because its internal feedback reference is fixed at 0.8 V ±2%. The output voltage is calculated as VOUT = 0.8 V × (1 + R1/R2), so the lowest achievable value occurs when R2 approaches infinity (open) and R1 = 0 (short), yielding exactly 0.8 V. Attempting lower outputs violates the error amplifier's operating range and results in loss of regulation.
What is the purpose of the VBIAS pin on the A8697ELJ-T, and how should it be connected?
The VBIAS pin on the A8697ELJ-T accepts an external bias supply to power internal circuitry more efficiently than drawing from VIN. When VOUT is ≥3.3 V, connect VBIAS directly to VOUT; this reduces quiescent current and improves full-load efficiency by ~2%. If VOUT < 3.3 V, leave VBIAS unconnected-the device operates from VIN with higher IQ. No power sequencing is required, and VBIAS tolerates 0–7 V.
Is the A8697ELJ-T still in active production, and what does "Last Time Buy" mean for this part?
The A8697ELJ-T is classified as Last Time Buy (LTB) with a May 30, 2014 deadline for final orders, per Allegro's 2013 notice. It remains available through Aetrix Electronics for existing customer applications but is obsolete for new designs. Inventory is finite and sourced from original manufacturer channels; Aetrix provides traceable, date-code-verified stock with full lifecycle coordination support for ongoing production needs involving the A8697ELJ-T.
A8697ELJ-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 20V
- Current - Output:
- 4A
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC-EP
A8697ELJ-T FAQ
1.How can I place an order for A8697ELJ-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A8697ELJ-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 A8697ELJ-T reliable?
The price and inventory of A8697ELJ-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A8697ELJ-T is usually 5 days.
3.What payment methods are accepted for A8697ELJ-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A8697ELJ-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A8697ELJ-T?
A8697ELJ-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A8697ELJ-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 A8697ELJ-T?
For technical support, including A8697ELJ-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A8697ELJ-T requirements.
6.How does Aetrix verify that A8697ELJ-T is sourced from the original manufacturer or authorized distributors?
All A8697ELJ-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 A8697ELJ-T meets industry standards.
7.What is the process for return or replacement of A8697ELJ-T?
All A8697ELJ-T units undergo pre-shipment inspection (PSI). If there is an issue with A8697ELJ-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 A8697ELJ-T part is unused and in its original packaging.
Return procedure for A8697ELJ-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A8697ELJ-T Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
