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Microchip Technology AT49LH00B4-33JX-T
- Part No.:
- AT49LH00B4-33JX-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT49LH00B4-33JX-T.pdf
- Description:
- IC FLASH 4MBIT PAR 33MHZ 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,153
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Product details
Overview
AT49LH00B4-33JX-T 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 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 secure boot code retention.
For engineers reviewing the AT49LH00B4-33JX-T datasheet, AT49LH00B4-33JX-T pinout, AT49LH00B4-33JX-T application, or AT49LH00B4-33JX-T equivalent, this device serves as a legacy-compliant, sector-configurable BIOS flash with automatic FWH/LPC cycle detection, 33 MHz PCI clock synchronization, and flexible in-system or manufacturing programming modes.
Technical Context
The AT49LH00B4-33JX-T implements a dual-mode interface architecture controlled by the IC pin: low enables FWH/LPC mode (5-signal, 33 MHz PCI-synchronized, byte-level read/write), high enables A/A Mux mode (11-pin multiplexed address + 8-bit data). Its Command User Interface (CUI) orchestrates command execution across both interfaces to manage nonvolatile memory operations.
Memory organization supports two erase configurations: eleven sectors (64 KB top boot + six 64 KB + one 32 KB + one 16 KB + two 8 KB) or eight uniform 64 KB sectors. Sector locking registers and dedicated TBL/WP hardware pins enable granular, persistent read/write protection - critical for BIOS integrity in Intel 8xx/E7xxx/E8xxx and non-Intel chipset designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 4 Mbit (512 KB) total capacity, sufficient for full BIOS firmware images in legacy x86 platforms. |
| Interface Standard | Complies with Intel LPC Interface Spec. Rev. 1.1 and supports Firmware Hub (FWH) protocol for Intel chipsets and generic LPC memory cycles for non-Intel systems. |
| Supply Voltage | 3.0 V to 3.6 V single supply - eliminates need for separate VPP programming voltage and simplifies power design in 3V systems. |
| Operating Clock | 33 MHz PCI bus clock - synchronizes FWH/LPC transactions with standard southbridge timing without external clock generation. |
| Sector Architecture | Top-boot configuration with 64 KB boot sector + configurable sub-sectors (32 KB/16 KB/8 KB); enables efficient BIOS module partitioning and minimizes wasted space. |
| Write Protection | Dual hardware protection: TBL pin locks top boot sector independently; WP pin protects all other sectors - provides layered security against accidental overwrite. |
| Package Type | 32-lead PLCC (JX suffix), RoHS-compliant and green (Pb/halide-free) - suitable for through-hole rework and legacy motherboard layouts. |
Pinout & Package
AT49LH00B4-33JX-T is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC) package with gull-wing leads, compatible with standard PLCC sockets and wave-solder processes. Pin functions are dual-role, supporting both FWH/LPC and A/A Mux interfaces depending on IC pin state.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IC | Interface Configuration Control | Input that selects operational mode: low = FWH/LPC interface; high = A/A Mux interface. Internally pulled down; optional connection if only FWH/LPC used. |
| TBL | Top Boot Sector Lock | Hardware write protect for 64 KB top boot sector - prevents program/erase regardless of sector lock register state when held low. |
| WP | Write Protect | Hardware write protect for all sectors except top boot - active low; complements TBL for hierarchical BIOS protection. |
| ID[3:0] | Device Identification Inputs | Strappable 4-bit ID for multi-device LPC/FWH bus - enables up to 16 devices; boot device must be ID=0000. |
| GPI[4:0] | General-Purpose Inputs | Five user-configurable inputs readable via GPI register - provide board-level flexibility for strap options or status sensing during boot. |
| FWH4/LFRAME | LPC Frame / FWH Start Signal | Indicates start/abort of FWH/LPC cycles; sampled low to initiate transaction - essential for cycle synchronization and peripheral power management. |
| FWH/LAD[3:0] | LPC Address/Data Bus | 4-bit multiplexed bus carrying START, IDSEL, MADDR, MSIZE, SYNC, and data - implements full FWH/LPC protocol with nibble-serial transfer. |
| RST / INIT | Reset Inputs | RST resets internal automation and disables writes; INIT mirrors RST behavior and connects to chipset INIT signal - ensures deterministic boot-state recovery. |
Key Features
| Feature | Design Value |
|---|---|
| Auto-detect FWH/LPC cycles | Eliminates system-level interface configuration overhead - device autonomously decodes START field (1101b/1110b/0000b) to route commands correctly. |
| Configurable sector erase layout | Two erase command options yield either 11-sector (optimized for BIOS modularity) or 8-uniform-sector (simplified programming) memory maps - improves firmware update efficiency. |
| Dual-interface support | FWH/LPC for in-system operation + A/A Mux for high-speed manufacturing programming - reduces test time and enables field reprogramming without socket removal. |
| Fixed program/erase timing | Timing independent of cumulative P/E cycles - removes need for system calibration or wear-leveling logic in BIOS update routines. |
| PCI-compliant I/O buffers | Ensures signal integrity and timing compliance on 33 MHz LPC buses - avoids bus contention or setup/hold violations in dense motherboard layouts. |
Applications
| Desktop PC BIOS Storage | Notebook Embedded Controller Interface |
|---|---|
|
Use Scenario: Storing core BIOS firmware, POST routines, and ACPI tables on Intel 8xx-series chipset-based motherboards. IC Role / Device Role / Timing Role: Firmware Hub (FWH) acting as primary boot memory - responds to ICH-initiated FWH memory cycles with deterministic latency under 33 MHz PCI clock. Use Value: Hardware TBL pin ensures immutable boot sector; sector locking registers allow selective update of non-critical modules without risking boot failure. |
Use Scenario: Providing BIOS code and configuration data for embedded controller (EC) firmware in clamshell-form-factor notebooks. IC Role / Device Role / Timing Role: LPC Flash memory accessed via EC's LPC master interface - uses LPC memory cycles for runtime updates and factory calibration data storage. Use Value: Dual-interface capability allows A/A Mux programming during final assembly and FWH/LPC updates in service mode - reducing repair turnaround time. |
| Industrial Control Panel Boot Memory | Legacy Server BMC Firmware Storage |
|
Use Scenario: Hosting BIOS and platform initialization code in fanless industrial PCs using non-Intel chipsets (e.g., VIA CN896). IC Role / Device Role / Timing Role: LPC Flash device responding to southbridge LPC memory reads/writes - leverages auto-detection to operate without chipset-specific firmware patches. Use Value: Uniform 64 KB sector option simplifies field firmware upgrades; GPI[4:0] pins enable hardware revision strapping for variant-specific initialization sequences. |
Use Scenario: Storing Baseboard Management Controller (BMC) firmware and sensor configuration in rack-mount servers with E7505/E8500 chipsets. IC Role / Device Role / Timing Role: FWH device integrated into ICH-based management engine subsystem - supports secure boot verification via locked top-boot sector. Use Value: ID[3:0] strapping enables coexistence with other FWH peripherals (e.g., TPM, Super I/O); RST/INIT dual reset ensures BMC firmware reload after watchdog timeout. |
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 |
|---|---|---|---|
| Winbond W39L040P70Z | 4 Mbit, 3.3 V, PLCC-32, LPC-compliant but lacks FWH mode and auto-detection - requires explicit LPC-only host configuration. | Supports only LPC memory cycles; not usable as FWH with Intel chipsets requiring FWH protocol handshake. | Select when targeting non-Intel platforms where FWH compatibility is unnecessary and cost optimization is prioritized. |
| Spansion S29GL032N90TFI010 | 32 Mbit, 3.0–3.6 V, TSOP-48, supports CFI command set and wider voltage range - no native LPC/FWH interface; requires bridge ASIC or FPGA glue logic. | Requires external interface translation; incompatible with direct LPC bus attachment - suited for custom embedded controllers, not standard PC chipsets. | Choose only for new designs needing higher density and willing to implement interface bridging; not drop-in for AT49LH00B4-33JX-T. |
Compared with Winbond W39L040P70Z and Spansion S29GL032N90TFI010, the AT49LH00B4-33JX-T uniquely delivers native dual-mode (FWH + LPC) operation with automatic cycle detection and hardware boot-sector protection - making it irreplaceable in legacy Intel-platform BIOS designs requiring guaranteed FWH compliance and in-system update safety.
Availability
AT49LH00B4-33JX-T is available at Aetrix Electronics and suitable for desktop motherboard BIOS, notebook EC firmware, industrial control panel boot memory, and legacy server BMC applications requiring stable component supply and long-term lifecycle support.
Supply support for AT49LH00B4-33JX-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
Microchip Technology acquired Atmel in 2016 and maintains legacy Atmel flash product lines including the AT49LH series. The company specializes in microcontrollers, analog, and memory solutions for industrial, automotive, and computing markets.
The AT49LH00B4-33JX-T belongs to Atmel's legacy firmware hub flash family, engineered specifically for BIOS and embedded controller firmware storage in x86 platforms compliant with Intel's LPC and FWH specifications - emphasizing reliability, sector granularity, and dual-interface flexibility.
FAQ
What interface modes does the AT49LH00B4-33JX-T support?
The AT49LH00B4-33JX-T supports two distinct interface modes: FWH/LPC mode (enabled when IC pin is low) for in-system operation with Intel or non-Intel chipsets, and A/A Mux mode (enabled when IC pin is high) for high-speed manufacturing programming. Mode selection is static at power-up and cannot be changed dynamically during operation.
Does the AT49LH00B4-33JX-T require a separate programming voltage?
No, the AT49LH00B4-33JX-T performs all read, program, and erase operations using only its 3.0–3.6 V VCC supply - no external VPP voltage is needed. This simplifies power design and eliminates high-voltage circuitry on the motherboard, reducing bill-of-materials cost and board area.
How does hardware write protection work on the AT49LH00B4-33JX-T?
The AT49LH00B4-33JX-T implements two independent hardware write protect pins: TBL (active low) locks only the 64 KB top boot sector, while WP (active low) protects all remaining sectors. Both override software-based sector locking registers, providing fail-safe protection against accidental firmware corruption during updates.
Can the AT49LH00B4-33JX-T be used with non-Intel chipsets?
Yes, the AT49LH00B4-33JX-T supports LPC memory cycles and can function as standard LPC flash with non-Intel chipsets (e.g., VIA, SiS, NVIDIA nForce). Its auto-detection logic identifies LPC vs. FWH cycles based on the START field, enabling seamless integration without host-side mode switching logic.
What is the significance of the "Not Recommended for New Design" notice on the AT49LH00B4-33JX-T datasheet?
The "Not Recommended for New Design" status indicates Microchip no longer promotes the AT49LH00B4-33JX-T for newly initiated projects due to newer alternatives like the SST39VF series. However, Aetrix Electronics continues full supply chain support for existing designs, including lifecycle management and obsolescence mitigation for deployed AT49LH00B4-33JX-T systems.
AT49LH00B4-33JX-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- 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-T FAQ
1.How can I place an order for AT49LH00B4-33JX-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT49LH00B4-33JX-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 AT49LH00B4-33JX-T reliable?
The price and inventory of AT49LH00B4-33JX-T 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-T is usually 5 days.
3.What payment methods are accepted for AT49LH00B4-33JX-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT49LH00B4-33JX-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT49LH00B4-33JX-T?
AT49LH00B4-33JX-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT49LH00B4-33JX-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 AT49LH00B4-33JX-T?
For technical support, including AT49LH00B4-33JX-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT49LH00B4-33JX-T requirements.
6.How does Aetrix verify that AT49LH00B4-33JX-T is sourced from the original manufacturer or authorized distributors?
All AT49LH00B4-33JX-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 AT49LH00B4-33JX-T meets industry standards.
7.What is the process for return or replacement of AT49LH00B4-33JX-T?
All AT49LH00B4-33JX-T units undergo pre-shipment inspection (PSI). If there is an issue with AT49LH00B4-33JX-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 AT49LH00B4-33JX-T part is unused and in its original packaging.
Return procedure for AT49LH00B4-33JX-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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