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Microchip Technology AT49LH00B4-33JC
- Part No.:
- AT49LH00B4-33JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT49LH00B4-33JC.pdf
- Description:
- IC FLASH 4MBIT PAR 33MHZ 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,190
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Product details
Overview
AT49LH00B4-33JC 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 provides hardware write protection via TBL and WP pins for secure firmware updates.
For engineers reviewing the AT49LH00B4-33JC datasheet, AT49LH00B4-33JC pinout, AT49LH00B4-33JC application, or AT49LH00B4-33JC equivalent, this page delivers verified interface behavior, sector-protection architecture, boot-sector partitioning, 33 MHz PCI clock synchronization, and dual-mode pin functionality - all critical for BIOS firmware integrity, in-system programming, and chipset compatibility validation.
Technical Context
The AT49LH00B4-33JC implements a dual-interface architecture: FWH/LPC mode (enabled by low IC pin) uses 5-signal communication (FWH4/LFRAME + FWH/LAD[3:0]) synchronized to a 33 MHz PCI clock, supporting automatic FWH/LPC cycle detection and full register access; A/A Mux mode (IC high) employs 11-pin multiplexed address (A[10:0]) and 8-pin data (I/O[7:0]) with R/C latching for manufacturing programming.
Its memory array 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 hardware TBL/WP pins enable independent read/write protection - essential for preserving boot code while updating application firmware.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 4 Mbit (512 KB) total capacity, sufficient for modern BIOS firmware images with room for recovery modules. |
| Interface Standard | Intel LPC Interface Spec. Rev. 1.1 compliant - ensures interoperability with Intel 8xx/E7xxx/E8xxx chipsets and non-Intel LPC hosts. |
| Supply Voltage | 3.0 V to 3.6 V single supply - eliminates need for voltage translators in 3.3 V system designs. |
| Boot Architecture | Top-boot with bottom partitioning - isolates critical boot code in protected 64 KB sector at highest address (070000H–07FFFFH). |
| Erase Flexibility | Two erase command sets - enables either optimized mixed-sector layout or uniform 64 KB erasure for simplified firmware update logic. |
| Write Protection | Dual hardware pins: TBL (top boot lock) and WP (all other sectors lock) - provides physical, non-volatile protection independent of register state. |
| Clock Requirement | 33 MHz PCI bus clock - aligns with standard southbridge timing, eliminating need for dedicated oscillator. |
Pinout & Package
AT49LH00B4-33JC is packaged in a 32-lead PLCC (Plastic Leaded Chip Carrier) with industry-standard footprint and lead pitch. Pin functions are dual-mode: FWH/LPC interface active when IC = low; A/A Mux interface active when IC = high.
| 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 (20–100 kΩ), so optional pull-down if only FWH/LPC used. |
| FWH4/LFRAME | LPC Frame / Write Enable (A/A Mux) | Indicates start/abort of FWH/LPC cycles; serves as WE in A/A Mux mode - enables cycle-aware power management and precise timing control. |
| FWH/LAD[3:0] | Address/Data Bus (FWH/LPC) | 4-bit multiplexed bus carrying START, IDSEL, MADDR, MSIZE, SYNC, and data nibbles - reduces pin count vs parallel interfaces while maintaining full command visibility. |
| TBL & WP | Hardware Write Protect Inputs | TBL locks top 64 KB boot sector; WP locks remaining sectors - provides fail-safe, non-software-dependent protection against accidental corruption. |
| ID[3:0] | Device Identification Inputs | Strappable 4-bit ID for multi-device LPC bus - allows up to 16 devices on same bus; boot device must be ID=0000. |
| GPI[4:0] | General-Purpose Inputs | Five configurable inputs readable via GPI register - supports board-level configuration flags, revision coding, or debug status without extra GPIO controllers. |
Key Features
| Feature | Design Value |
|---|---|
| Auto-detect FWH/LPC cycles | Eliminates host-side interface negotiation - device identifies cycle type from START field (1101b/1110b/0000b), enabling seamless integration across Intel and non-Intel platforms. |
| Top-boot + flexible sectoring | Reduces wasted BIOS space by allocating small sectors (8 KB/16 KB) for infrequently updated modules - increases usable firmware density without increasing die size. |
| Dual-interface support | Enables in-system FWH/LPC operation for field updates while reserving A/A Mux for high-speed factory programming - decouples development and production workflows. |
| Fixed program/erase timing | Guarantees consistent latency across lifetime - no system-level calibration required, simplifying BIOS update timing logic and improving reliability over 100k+ cycles. |
| PCI-compliant I/O buffers | Ensures signal integrity and timing compliance on 33 MHz LPC buses - avoids timing closure issues in dense motherboard layouts. |
Applications
| PC BIOS Storage | Notebook Firmware Hub |
|---|---|
Use Scenario: Storing core boot firmware, POST routines, and UEFI drivers in desktop motherboards with Intel 8-series chipsets. IC Role / Device Role / Timing Role: Firmware Hub (FWH) acting as primary boot memory mapped at top of 4 GB address space, accessed via FWH cycles synchronized to 33 MHz PCI clock. Use Value: Hardware TBL pin prevents corruption of boot sector during OS-initiated updates; sector locking registers allow selective reprogramming of non-critical modules. | Use Scenario: Hosting compressed BIOS image and recovery firmware in space-constrained laptop mainboards using non-Intel chipsets. IC Role / Device Role / Timing Role: LPC Flash memory responding to LPC memory read/write cycles initiated by southbridge, with auto-detection of cycle type based on START field. Use Value: Dual-interface capability allows factory programming via A/A Mux (high speed, parallel) and field updates via LPC (low pin count, minimal routing). |
| Industrial Control BIOS | Embedded System Recovery Storage |
Use Scenario: Providing tamper-resistant boot code for ruggedized industrial PCs operating in extended temperature ranges. IC Role / Device Role / Timing Role: Secure firmware storage with hardware write protection (TBL + WP) and fixed-timing erase - ensures deterministic update behavior under thermal stress. Use Value: Top-boot architecture isolates bootloader in smallest possible protected sector (64 KB), minimizing attack surface while preserving full 4 Mbit for application firmware. | Use Scenario: Storing dual-image recovery firmware in network appliances requiring fail-safe rollback after failed updates. IC Role / Device Role / Timing Role: Partitioned memory array with independent sector locking - enables simultaneous storage of active and backup firmware images in separate, individually protected sectors. Use Value: Mixed-sector layout (two 8 KB + one 16 KB + one 32 KB + seven 64 KB) allows granular allocation: small sectors for version metadata, large sectors for binary images. |
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 W29GL032C | 32-Mbit density, supports SPI and Parallel interfaces, lacks native FWH auto-detection and TBL pin; requires software-managed sector protection. | Targeted at newer embedded systems with SPI-based firmware loading; not drop-in compatible due to different interface protocol and pinout. | Select when higher density and SPI flexibility outweigh need for Intel FWH compliance and hardware boot protection. |
| Macronix MX29LV320ET | 32-Mbit, 3.0–3.6 V, supports Common Flash Interface (CFI); offers uniform 64 KB sectors but no top-boot partitioning or TBL/WP pins. | Suitable for legacy BIOS designs requiring CFI-compliant flash; lacks hardware boot-sector lock, requiring firmware-level safeguards. | Choose for cost-sensitive applications where full FWH feature set is unnecessary and CFI toolchain support is preferred. |
Compared with AT49LH00B4-33JC, W29GL032C offers greater density and SPI versatility but sacrifices Intel FWH cycle auto-detection and hardware boot protection; MX29LV320ET provides CFI compatibility and larger capacity but lacks top-boot architecture and dual hardware write protect - making AT49LH00B4-33JC uniquely suited for secure, Intel-platform BIOS implementations requiring guaranteed boot integrity.
Availability
AT49LH00B4-33JC is available at Aetrix Electronics and suitable for PC motherboard design, notebook firmware development, and industrial control BIOS applications requiring stable component supply, long-lifecycle support, and verified LPC interface compliance.
Supply support for AT49LH00B4-33JC 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 full support for legacy Atmel flash memory products including the AT49LH00B4 series.
The AT49LH00B4 product line was specifically engineered for BIOS firmware storage in x86 computing platforms, emphasizing LPC interface fidelity, hardware-based security primitives, and manufacturing-friendly dual-interface programmability.
FAQ
What interface modes does the AT49LH00B4-33JC support, and how are they selected?
The AT49LH00B4-33JC supports two interface modes: FWH/LPC (for in-system operation) and Address/Address Multiplexed (A/A Mux, for manufacturing programming). Mode selection is controlled by the IC pin: low enables FWH/LPC; high enables A/A Mux. The IC pin is internally pulled down, so no external connection is needed if only FWH/LPC operation is required. This dual-mode capability ensures AT49LH00B4-33JC can serve both field-updatable BIOS storage and high-throughput factory programming.
How does the AT49LH00B4-33JC handle boot sector protection?
The AT49LH00B4-33JC provides hardware-level boot sector protection via the TBL (Top Boot Lock) pin: when held low, it permanently disables program and erase operations to the 64 KB top boot sector, regardless of sector locking register state. This physical lock complements software-controlled sector locking registers, creating a defense-in-depth mechanism for critical boot code. The AT49LH00B4-33JC's top-boot architecture places this protected sector at the highest memory address (070000H–07FFFFH), ensuring it loads first during system initialization.
Can the AT49LH00B4-33JC be used with non-Intel chipsets?
Yes, the AT49LH00B4-33JC supports LPC memory read/write cycles and can function as standard LPC Flash with non-Intel chipsets. Its auto-detection circuitry distinguishes between FWH and LPC cycles based on the START field value (0000b for LPC, 1101b/1110b for FWH), allowing transparent interoperability. When used in LPC mode, the device responds to standard LPC memory cycles initiated by the southbridge, making AT49LH00B4-33JC suitable for AMD, VIA, and other non-Intel platform designs requiring BIOS storage.
What are the valid memory sector configurations for the AT49LH00B4-33JC?
The AT49LH00B4-33JC supports two distinct erase configurations selectable via different erase commands: (1) eleven sectors comprising one 64 KB top boot sector, six 64 KB main sectors, one 32 KB sector, one 16 KB sector, and two 8 KB sectors; or (2) eight uniform 64 KB sectors. This flexibility allows system designers to optimize memory layout - using smaller sectors for infrequently updated modules (e.g., version strings) and larger ones for firmware binaries - maximizing usable space within the 4 Mbit AT49LH00B4-33JC array.
Does the AT49LH00B4-33JC require multiple supply voltages for programming?
No, the AT49LH00B4-33JC operates from a single 3.0 V to 3.6 V supply for all functions - read, program, and erase - eliminating the need for charge pumps or auxiliary voltage rails. This simplifies power delivery design and improves reliability in 3.3 V systems. Programming and erase times are fixed and independent of cumulative cycling history, so no voltage calibration or timing adjustment is required across the device's lifetime, ensuring consistent AT49LH00B4-33JC performance in production and field environments.
AT49LH00B4-33JC 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)
AT49LH00B4-33JC FAQ
1.How can I place an order for AT49LH00B4-33JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT49LH00B4-33JC 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 AT49LH00B4-33JC reliable?
The price and inventory of AT49LH00B4-33JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT49LH00B4-33JC is usually 5 days.
3.What payment methods are accepted for AT49LH00B4-33JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT49LH00B4-33JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT49LH00B4-33JC?
AT49LH00B4-33JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT49LH00B4-33JC 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 AT49LH00B4-33JC?
For technical support, including AT49LH00B4-33JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT49LH00B4-33JC requirements.
6.How does Aetrix verify that AT49LH00B4-33JC is sourced from the original manufacturer or authorized distributors?
All AT49LH00B4-33JC 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 AT49LH00B4-33JC meets industry standards.
7.What is the process for return or replacement of AT49LH00B4-33JC?
All AT49LH00B4-33JC units undergo pre-shipment inspection (PSI). If there is an issue with AT49LH00B4-33JC, 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 AT49LH00B4-33JC part is unused and in its original packaging.
Return procedure for AT49LH00B4-33JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT49LH00B4-33JC Tags
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