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Allegro MicroSystems A8498SLJ-T
- Part No.:
- A8498SLJ-T
- Manufacturer:
- Allegro MicroSystems
- Package:
- 8-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
A8498SLJ-T.pdf
- Description:
- IC REG BUCK ADJ 3A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,256
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Product details
Overview
A8498SLJ-T from Allegro MicroSystems is a wide-input, current-mode buck regulator with integrated 450 mΩ DMOS switch, supporting 8–50 V input and delivering up to 3.0 A at adjustable 0.8–24 V output; features fixed off-time control, thermal shutdown at 165°C, and 0.8 V ±2% feedback reference-used in automotive telematics, industrial 24/36 V bus systems, and lead-acid battery chargers.
For engineers reviewing the A8498SLJ-T datasheet, A8498SLJ-T pinout, A8498SLJ-T application, or A8498SLJ-T equivalent, key selection criteria include VIN undervoltage lockout (6.9 V typ), soft-start time (10 ms nominal), RDS(on) (450 mΩ @ 25°C), TSET-based off-time programming, and SOIC-8 LJ package with exposed thermal pad for thermal management.
Technical Context
The A8498SLJ-T implements fixed off-time, current-mode control with internal blanking (200 ns) to suppress diode reverse-recovery transients. It operates in continuous or discontinuous conduction mode and enters cycle-skipping at light loads to maintain regulation.
Its VBIAS pin accepts VOUT (3.3–5 V recommended) to power internal circuitry, reducing bias current draw from VIN and improving efficiency; ENB enables logic-level on/off control with 1.0 V threshold, while FB regulates output via external resistor divider referenced to 0.8 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8–50 V - supports 12 V automotive, 24/36 V industrial, and 42 V battery-charger inputs without external pre-regulation |
| Output Current | 3.0 A continuous - limited by thermal design and PCB heat sinking; max junction temperature 150°C |
| Feedback Reference | 0.8 V ±2% - enables precise output setting from 0.8 V to 24 V using standard resistor ratios |
| RDS(on) | 450 mΩ @ 25°C - determines conduction loss and impacts thermal rise under full load |
| Thermal Resistance | 35 °C/W (RθJA, 4-layer PCB) - defines required copper area and thermal vias for 3 A operation at 85°C ambient |
| Soft Start Time | 10 ms nominal - controls inrush current into COUT and prevents input supply sag during startup |
| UVLO Threshold | 6.9 V (typ), 0.9 V hysteresis - ensures reliable start-up after brownout and prevents oscillation near dropout |
Pinout & Package
Package: 8-lead SOIC with exposed thermal pad (JEDEC MS-012BA compliant, suffix LJ); thermal pad must be soldered to PCB ground plane with ≥4 thermal vias for rated 3 A performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 – BOOT | Gate drive boost node | Charges high-side gate driver bootstrap capacitor; requires 0.01 µF ceramic capacitor to LX |
| 2 – ENB | Enable/disable logic input | Active-low enable; <1.0 V disables regulator and discharges output; open-circuit = disable |
| 3 – TSET | Fixed off-time programming | Resistor to GND sets tOFF (e.g., 63.4 kΩ → ~7 µs @ VBIAS = 5 V); critical for min-on-time compliance |
| 4 – GND | Power and signal ground | Common return for LX, FB, ENB, TSET; must connect directly to thermal pad and low-impedance ground plane |
| 5 – FB | Output voltage feedback | Compares divided VOUT to 0.8 V reference; high-impedance input (±100 nA bias) demands low-noise layout |
| 6 – VBIAS | Bias supply input | Accepts VOUT (3.3–5 V optimal) to power internal circuitry; improves efficiency vs. VIN-derived bias |
| 7 – LX | Switching node | Connects to inductor and catch diode anode; high dV/dt node requiring short, low-inductance routing |
| 8 – VIN | Main power input | 8–50 V supply input; requires local 0.22 µF + 220 µF input capacitance with low ESR |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 450 mΩ DMOS switch | Eliminates external high-side MOSFET and gate driver; reduces BOM count and layout complexity |
| Adjustable fixed off-time control | Enables stable operation across wide VIN/VOUT ratios without loop compensation components |
| VBIAS-powered bias supply | Improves full-load efficiency by >2% vs. VIN-derived bias when VOUT ≥ 3.3 V |
| Thermal shutdown with 15°C hysteresis | Protects against sustained overload or poor heatsinking; auto-recovery with soft start prevents restart oscillation |
| Cycle-skipping light-load mode | Maintains ±3% output regulation down to ~10 mA without external LDO or PFM controller |
Applications
| Automotive Telematics | Industrial 24 V Bus Power |
|---|---|
|
Use Scenario: Powering GPS modules, cellular modems, and CAN controllers in vehicle infotainment systems with 9–16 V battery input and load dump protection. IC Role / Device Role / Timing Role: Primary 3.3 V/3 A buck regulator; handles cold-crank (6.6 V UVLO) and load dump transients via 50 V absolute max VIN rating. Use Value: Eliminates need for pre-regulator stage; 35 °C/W thermal resistance enables compact placement near RF modules without forced air. |
Use Scenario: Converting 24 V factory automation bus to 3.3 V for PLC I/O modules, sensors, and microcontrollers. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator; fixed off-time architecture maintains stability despite varying line/load conditions in noisy industrial environments. Use Value: 0.8 V feedback reference allows precise 3.3 V output (±3%) across -20°C to 85°C ambient, meeting IEC 61000-4 immunity requirements. |
| Lead-Acid Battery Charger | POS Terminal Power |
|
Use Scenario: Providing regulated 3.3 V supply for charger control MCU and display in 42 V battery charging systems. IC Role / Device Role / Timing Role: Secondary regulator downstream of main charger IC; withstands 42 V input with no derating. Use Value: 50 V absolute max VIN and 6.9 V UVLO ensure robust operation during charge termination and float stages without external clamping. |
Use Scenario: Powering embedded ARM processors and touchscreens in retail point-of-sale terminals powered from 12 V DC adapters. IC Role / Device Role / Timing Role: Compact, thermally efficient 3.3 V source; SOIC-LJ package fits tight board space constraints typical in handheld POS devices. Use Value: Exposed thermal pad and 35 °C/W RθJA allow full 3 A output in 12 mm × 5 mm footprint without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDRCRQ1 | 4.5–65 V input, 0.6 A output, integrated FET, current-mode control; smaller 10-pin WSON package | Lower current rating limits use to sub-1 A loads; higher VIN range suits 48 V telecom but not 3 A industrial loads | Select when input exceeds 50 V or board space is constrained; not suitable for 3 A continuous duty. |
| MP2451DT-LF-Z | 4.5–36 V input, 0.6 A output, 2 MHz fixed frequency, no TSET pin; requires external compensation | Lacks programmable off-time and thermal pad; unsuitable for >1 A or high-ambient industrial use | Prefer for cost-sensitive, low-current consumer apps; lacks A8498SLJ-T's 3 A capability and thermal robustness. |
Compared with LM5164QDRCRQ1 and MP2451DT-LF-Z, the A8498SLJ-T uniquely delivers 3.0 A at 8–50 V with SOIC-LJ thermal packaging and TSET-programmable timing-making it the only option among the three qualified for sustained 3 A operation in automotive and industrial 24/36/42 V systems.
Availability
A8498SLJ-T is available at Aetrix Electronics and suitable for automotive telematics, industrial 24 V bus power, and lead-acid battery charger designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for A8498SLJ-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 Manchester, NH, serving automotive, industrial, and consumer markets since 1989.
The A8498 product line delivers wide-input, high-current buck regulators optimized for rugged applications including automotive battery systems, industrial power supplies, and uninterruptible power sources-emphasizing thermal resilience, input transient tolerance, and minimal external component count.
FAQ
What is the maximum continuous output current of the A8498SLJ-T?
The A8498SLJ-T is rated for 3.0 A continuous output current under proper thermal conditions: 4-layer PCB with exposed thermal pad soldered and ≥4 thermal vias, ambient temperature ≤85°C, and junction temperature held ≤150°C. At 25°C ambient, full 3 A is achievable with minimal copper; derating applies above 60°C ambient per the RθJA = 35 °C/W spec.
How is the switching frequency set on the A8498SLJ-T?
The A8498SLJ-T uses fixed off-time control-not fixed frequency-so fSW varies with input/output voltage and load. Off-time (tOFF) is set by the RTSET resistor on the TSET pin (e.g., 63.4 kΩ yields ~7 µs at VBIAS = 5 V); on-time (tON) is calculated dynamically from volt-second balance. Typical fSW ranges from ~100 kHz to 300 kHz depending on operating point.
Can the A8498SLJ-T operate with VOUT below 3.3 V?
Yes, the A8498SLJ-T supports output voltages from 0.8 V to 24 V via the FB resistor divider. However, VBIAS should not be connected to VOUT if VOUT < 3.3 V, as internal bias circuitry then draws current from VIN instead-reducing efficiency. For 1.8 V or 2.5 V outputs, leave VBIAS unconnected or tie to a separate 3.3–5 V rail.
What is the purpose of the BOOT pin on the A8498SLJ-T?
The BOOT pin on the A8498SLJ-T supplies the gate drive voltage for the internal high-side DMOS switch. It must be connected to a 0.01 µF ceramic capacitor between BOOT and LX to generate the boosted voltage needed to fully enhance the MOSFET. Incorrect BOOT capacitor placement or value causes erratic switching or failure to start.
Does the A8498SLJ-T require external compensation components?
No, the A8498SLJ-T uses current-mode, fixed off-time control architecture that does not require external loop compensation components like Type II or III networks. Stability is inherent across its operating range; only standard input/output capacitors, inductor, catch diode, FB divider, and TSET resistor are needed for full functionality.
A8498SLJ-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):
- 50V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 24V
- Current - Output:
- 3A
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC-EP
A8498SLJ-T FAQ
1.How can I place an order for A8498SLJ-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A8498SLJ-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 A8498SLJ-T reliable?
The price and inventory of A8498SLJ-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A8498SLJ-T is usually 5 days.
3.What payment methods are accepted for A8498SLJ-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A8498SLJ-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A8498SLJ-T?
A8498SLJ-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A8498SLJ-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 A8498SLJ-T?
For technical support, including A8498SLJ-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A8498SLJ-T requirements.
6.How does Aetrix verify that A8498SLJ-T is sourced from the original manufacturer or authorized distributors?
All A8498SLJ-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 A8498SLJ-T meets industry standards.
7.What is the process for return or replacement of A8498SLJ-T?
All A8498SLJ-T units undergo pre-shipment inspection (PSI). If there is an issue with A8498SLJ-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 A8498SLJ-T part is unused and in its original packaging.
Return procedure for A8498SLJ-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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