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Microchip Technology AT49LH00B4-33JX
- Part No.:
- AT49LH00B4-33JX
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT49LH00B4-33JX.pdf
- Description:
- IC FLASH 4MBIT PAR 33MHZ 32PLCC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
AT49LH00B4-33JX from Microchip Technology (formerly Atmel) is a 4-Mbit top-boot, bottom-partitioned firmware hub and LPC flash memory IC designed for BIOS storage in PC and notebook platforms. It supports Intel® Low-Pin Count (LPC) Interface Specification Rev. 1.1, operates at 3.0–3.6 V, features dual-interface operation (FWH/LPC and A/A Mux), and includes hardware write protection via TBL and WP pins for sector-level security.
For engineers reviewing the AT49LH00B4-33JX datasheet, AT49LH00B4-33JX pinout, AT49LH00B4-33JX application, or AT49LH00B4-33JX equivalent, this device is selected for BIOS firmware storage where LPC/FWH compatibility, in-system programmability, top-boot sector protection, and 33 MHz PCI clock synchronization are required - especially in legacy Intel 8xx/E7xxx/E8xxx chipset designs and non-Intel LPC-based systems.
Technical Context
The AT49LH00B4-33JX implements a dual-mode interface architecture: FWH/LPC mode (enabled by low IC pin) uses a 5-signal, 4-bit multiplexed bus (FWH/LAD[3:0] + FWH4/LFRAME) synchronized to a 33 MHz PCI clock, while A/A Mux mode (IC high) employs an 11-pin multiplexed address bus (A[10:0]) and 8-bit data I/O[7:0]. Its Command User Interface (CUI) interprets command sequences to manage internal flash automation independent of program/erase cycle count.
Memory organization supports two configurable sector layouts: eleven sectors (64 KB boot + six 64 KB + one 32 KB + one 16 KB + two 8 KB) or eight uniform 64 KB sectors - selectable via distinct erase commands. Sector locking registers and hardware TBL/WP pins provide hierarchical read/write protection, with TBL exclusively guarding the top 64 KB boot sector and WP protecting all other sectors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 4 Mbit (512 Kbytes) total capacity, sufficient for full BIOS code and configuration data in legacy x86 platforms. |
| Interface Standard | Complies with Intel LPC Interface Spec. Rev. 1.1 and supports both Firmware Hub (FWH) and LPC memory cycles - enabling use with Intel chipsets (8xx/E7xxx/E8xxx) and non-Intel LPC controllers. |
| Supply Voltage | 3.0 V to 3.6 V single supply - eliminates need for separate VPP programming voltage and ensures compatibility with 3.3 V system rails. |
| Boot Sector Configuration | Top-boot architecture with dedicated 64 KB boot sector; hardware write-protected by TBL pin - prevents accidental overwrite of critical startup code. |
| Write Protection | Dual hardware protection: TBL pin locks top boot sector; WP pin locks all remaining sectors - complements register-based sector locking for robust BIOS integrity. |
| Timing Architecture | Fixed program/erase times independent of cumulative cycle count - removes system calibration requirements and guarantees predictable timing across lifetime. |
| Package Type | 32-lead PLCC (JX suffix) - surface-mount, leaded package with through-hole compatibility for rework and legacy manufacturing. |
Pinout & Package
AT49LH00B4-33JX is packaged in a 32-lead Plastic Leaded Chip Carrier (PLCC), pin-compatible with industry-standard socketed BIOS flash footprints. Pin functions are dual-role: FWH/LPC interface dominates in-system operation; A/A Mux interface enables high-speed programming during manufacturing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IC | Interface Configuration Select | Low = FWH/LPC mode (default, internal pull-down); high = A/A Mux mode - determines active interface at power-up/reset. |
| TBL | Top Boot Sector Lock | Hardware write-protection enable for 64 KB top boot sector - overrides software locking when asserted low. |
| WP | Write Protect | Hardware lock for all non-boot sectors - prevents program/erase regardless of sector locking register state. |
| ID[3:0] | Device Identification Inputs | Strappable 4-bit ID for multi-device LPC bus addressing - boot device must be ID=0000; supports up to 16 devices. |
| GPI[4:0] | General-Purpose Inputs | Five user-configurable inputs readable via GPI register - provides board-level flexibility for strap options or status sensing. |
| FWH/LAD[3:0] | LPC Address/Data Multiplex | 4-bit bidirectional bus carrying START, IDSEL, MADDR, MSIZE, SYNC, and data nibbles - requires precise 33 MHz PCI timing alignment. |
| FWH4/LFRAME | LPC Frame Control | Initiates/terminates FWH/LPC cycles; sampled low to detect START field - also serves as WE in A/A Mux mode. |
| RST / INIT | Reset Inputs | RST resets internal logic and disables writes; INIT mirrors RST behavior and connects to chipset INIT signal - both place FWH/LAD[3:0] in high-Z. |
Key Features
| Feature | Design Value |
|---|---|
| Auto-detect FWH vs. LPC cycles | Eliminates external mode-select logic - device decodes START field (1101b/1110b = FWH; 0000b = LPC) to route commands without host intervention. |
| Configurable sector layout | Two erase-command options: eleven mixed-size sectors (optimized for BIOS module isolation) or eight uniform 64 KB sectors (simplifies large-block updates). |
| Dual-interface support | FWH/LPC for in-system operation + A/A Mux for fast factory programming - reduces test time and enables post-silicon firmware updates. |
| Hardware + register sector protection | TBL/WP pins enforce physical write locks; sector locking registers allow dynamic per-sector read/write control - layered security for BIOS integrity. |
| PCI-compliant timing | 33 MHz clock interface with defined TAR/SYNC handshake - ensures interoperability with Intel ICH and standard LPC south bridges without custom timing logic. |
Applications
| Desktop PC BIOS Storage | Notebook BIOS Firmware |
|---|---|
Use Scenario: Storing core boot firmware, POST routines, and hardware initialization code on motherboards using Intel 8xx/E7xxx chipsets. IC Role / Device Role / Timing Role: Firmware Hub (FWH) acting as primary boot memory, responding to ICH-initiated FWH memory cycles with 33 MHz PCI timing compliance. Use Value: Top-boot sector hardware protection (TBL) prevents corruption of critical reset vector and boot loader - ensuring reliable cold boot even after failed firmware updates. |
Use Scenario: Hosting UEFI/legacy BIOS image and configuration variables in space-constrained laptop mainboards with non-Intel LPC controllers. IC Role / Device Role / Timing Role: LPC Flash memory mapped into system memory space, accessed via LPC memory read/write cycles initiated by the EC or south bridge. Use Value: Dual-interface capability allows factory programming via A/A Mux (high-speed parallel) and field updates via LPC - reducing production cost and enabling secure remote BIOS patches. |
| Industrial Control System BIOS | Embedded x86 Platform Firmware |
Use Scenario: Providing fail-safe boot code for ruggedized industrial PCs operating in extended temperature ranges with long product lifecycles. IC Role / Device Role / Timing Role: Nonvolatile firmware storage with hardware write protection (TBL+WP) and fixed-timing erase - immune to voltage brownouts and thermal cycling effects. Use Value: Eleven-sector partitioning isolates watchdog handler, hardware abstraction layer, and update staging area - minimizing risk of partial erase failures during field upgrades. |
Use Scenario: Serving as boot flash in embedded systems based on VIA, AMD Geode, or other x86-compatible chipsets requiring LPC-compatible firmware storage. IC Role / Device Role / Timing Role: LPC Flash device supporting memory-mapped access and sector locking - compatible with open-source coreboot payloads and proprietary BIOS implementations. Use Value: GPI[4:0] inputs enable board-specific strapping (e.g., debug mode, dual-BIOS selection) without additional logic - simplifying BOM and routing in compact designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar firmware hub and LPC flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SST39VF400A-70-4C-NHE | 4 Mbit, 3.3 V, parallel interface only (no LPC/FWH support); 70 ns access time; no TBL/WP pins or sector locking registers. | Requires external CPLD or GPIO-controlled write protection; incompatible with Intel FWH boot protocols and LPC bus enumeration. | Select only for simple parallel-flash systems lacking LPC infrastructure - not suitable as drop-in replacement for AT49LH00B4-33JX in BIOS designs. |
| Winbond W39V040FAZ | 4 Mbit, 3.3 V, supports LPC interface but lacks FWH mode; no TBL pin; uses software-controlled block protection only. | Supports basic LPC memory cycles but cannot emulate Intel Firmware Hub behavior (e.g., IDSEL decoding, START field parsing) required by 8xx-series chipsets. | Acceptable for non-Intel LPC platforms where FWH compatibility is unnecessary - verify chipset LPC controller supports Winbond's command set. |
Compared with SST39VF400A-70-4C-NHE and Winbond W39V040FAZ, the AT49LH00B4-33JX uniquely delivers dual FWH/LPC protocol support, hardware top-boot protection, and configurable sector architecture - making it irreplaceable in Intel-platform BIOS designs requiring certified boot integrity and in-system update capability.
Availability
AT49LH00B4-33JX is available at Aetrix Electronics and suitable for desktop PC motherboard design, notebook BIOS firmware integration, and industrial control system boot storage requiring stable component supply and long-term lifecycle support.
Supply support for AT49LH00B4-33JX 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
Microchip Technology acquired Atmel in 2016 and maintains its legacy flash memory portfolio, emphasizing reliability, longevity, and industrial-grade qualification for embedded firmware applications.
The AT49LH00B4-33JX belongs to Atmel's Firmware Hub and LPC Flash family, engineered specifically for BIOS/UEFI firmware storage in x86 platforms - balancing protocol compliance, hardware security, and manufacturing flexibility.
FAQ
What interface modes does the AT49LH00B4-33JX support, and how are they selected?
The AT49LH00B4-33JX supports two interface modes: FWH/LPC for in-system operation and A/A Mux for manufacturing programming. Mode selection is controlled by the IC pin - held low (default, internal pull-down) for FWH/LPC mode, or driven high for A/A Mux mode. The IC pin state must be set at power-up or before exiting reset and cannot be changed dynamically during operation. This dual-interface design enables both field updates and high-speed factory programming without redesigning the PCB layout.
Does the AT49LH00B4-33JX require a separate programming voltage (VPP)?
No, the AT49LH00B4-33JX does not require a separate VPP programming voltage. It performs all read, program, and erase operations using a single 3.0 V to 3.6 V supply on the VCC pin. This simplifies power delivery design and eliminates the need for charge-pump circuitry or external high-voltage generators - a key advantage over older flash technologies and critical for space-constrained BIOS applications.
How does hardware write protection work on the AT49LH00B4-33JX?
The AT49LH00B4-33JX implements two independent hardware write protection mechanisms: the TBL pin locks only the 64 KB top boot sector when driven low, and the WP pin locks all other sectors when driven low. Both override software-based sector locking registers. This layered protection ensures that critical boot code remains immutable even if firmware-level protections are compromised - a fundamental requirement for BIOS integrity in certified platforms.
Can the AT49LH00B4-33JX be used with non-Intel chipsets?
Yes, the AT49LH00B4-33JX can be used with non-Intel chipsets as an LPC Flash device. When configured for LPC mode (START field = 0000b), it responds to standard LPC memory read/write cycles. Its auto-detection capability identifies LPC cycles independently of FWH cycles, allowing seamless integration into systems using VIA, AMD, or custom south bridges - provided the host controller adheres to the LPC Interface Specification Rev. 1.1 timing and protocol requirements.
What is the significance of the "JX" suffix in AT49LH00B4-33JX?
The "JX" suffix in AT49LH00B4-33JX denotes the 32-lead Plastic Leaded Chip Carrier (PLCC) package with lead-free (RoHS-compliant) finish. This package type is mechanically and electrically compatible with legacy BIOS socket footprints, supports rework via hot-air station, and meets industrial temperature grading requirements. The "33" indicates 33 MHz PCI clock compatibility, confirming timing alignment with standard LPC bus operation.
AT49LH00B4-33JX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- FLASH
- Technology:
- FLASH
- Memory Size:
- 4Mbit
- Memory Organization:
- 512K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- 33 MHz
- Write Cycle Time - Word, Page:
- 50µs
- Access Time:
- -
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT49LH00B4-33JX FAQ
1.How can I place an order for AT49LH00B4-33JX through Aetrix?
Please submit a Request for Quotation (RFQ) for AT49LH00B4-33JX 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 AT49LH00B4-33JX reliable?
The price and inventory of AT49LH00B4-33JX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT49LH00B4-33JX is usually 5 days.
3.What payment methods are accepted for AT49LH00B4-33JX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT49LH00B4-33JX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT49LH00B4-33JX?
AT49LH00B4-33JX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT49LH00B4-33JX 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 AT49LH00B4-33JX?
For technical support, including AT49LH00B4-33JX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT49LH00B4-33JX requirements.
6.How does Aetrix verify that AT49LH00B4-33JX is sourced from the original manufacturer or authorized distributors?
All AT49LH00B4-33JX 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 AT49LH00B4-33JX meets industry standards.
7.What is the process for return or replacement of AT49LH00B4-33JX?
All AT49LH00B4-33JX units undergo pre-shipment inspection (PSI). If there is an issue with AT49LH00B4-33JX, 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 AT49LH00B4-33JX part is unused and in its original packaging.
Return procedure for AT49LH00B4-33JX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT49LH00B4-33JX Tags
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