K7A163631B-QI20 - 512Kx36 Sync Pipelined Burst SRAM | Samsung
MPN: K7A163631B-QI20 ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $13.75 | $1,375.00 |
| 500 | $11.4 | $5,700.00 |
| 1,000 | $9.85 | $9,850.00 |
K7A163631B-QI20 Overview
A Synchronous SRAM (Static Random Access Memory) is a type of volatile memory that latches control, address, and data inputs on the rising edge of a system clock. Within the memory taxonomy it sits above DRAM in speed hierarchy but below cache-SRAM in integration; pipelined-burst variants add internal staging registers that allow a new address to be captured every clock cycle while a previous read is completing, dramatically improving throughput at high clock rates compared with standard async or flow-through SRAM.
Key specifications for the K7A163631B-QI20 include the 512K x 36 organization (36-bit-wide data bus suited to parity/ECC-protected cache lines), single +3.3 V power supply, low-power CMOS process technology, common I/O data bus architecture, and registered (registered-clock / registered-enable) control inputs that reduce system-clock loading in cache arrays. Burst-mode read and write cycles, byte-write enable controls (typically via BYTE WRITEs x4 with low-byte and high-byte enables), and an output-enable / chip-enable control set are standard on this generation of Samsung B-die synchronous SRAM.
Architecturally, the K7A163631B implements an internal 2-stage pipeline: an address register followed by a data-output register, so the first access latency is one extra cycle but subsequent burst beats return every clock. The device supports linear burst order, write-per-bit byte masking, and on-chip clock-domain registers that simplify interface to 66-150 MHz host buses. Power-saving features include CMOS-rail input levels, low standby current, and a chip-enable-controlled power-down mode.
Typical applications include Level-2 cache for Pentium II/III class processors, embedded CPU main memory in networking line cards, RAID controller write buffers, networking router/switch control-plane memory, industrial PC cache subsystems, and instrumentation DSP scratchpad memory. The wide x36 bus makes it especially attractive where parity or ECC bits are stored alongside each 32-bit word.
A key design consideration is the trade-off between pipelined SRAM (higher sustained throughput, one-cycle additional first-access latency) versus flow-through SRAM (no pipeline, lower latency, lower bandwidth). Choose K7A163631B when the host CPU/cache controller can absorb the one-cycle latency penalty in exchange for higher MHz operation.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design considerations not found in the Samsung datasheet alone, helping engineers evaluate the part for new designs and legacy second-source supply.
Drop-in alternatives for K7A163631B-QI20 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
K7A163631B-PC20
✅ Drop-In📋 Reference alternative (not in catalog)
K7A163631B-QC20
✅ Drop-In📋 Reference alternative (not in catalog)
K7A163631B-PC20T00
✅ Drop-In📋 Reference alternative (not in catalog)
K7A163631B-QC20T
✅ Drop-In📋 Reference alternative (not in catalog)
K7A163680A-PC14
✅ Drop-In📋 Reference alternative (not in catalog)
K7A163631B-QI20 Maximum Ratings & Electrical Characteristics
| Memory Type | Synchronous Pipelined Burst SRAM (B-die) |
| Memory Density | 18,874,368 bits (18 Mb) |
| Organization | 512K words x 36 bits |
| Operating Mode | Synchronous, pipelined burst |
| Supply Voltage | 3.3 V (single supply) |
| Package | TQFP-100 |
| Process Technology | CMOS |
| Burst Length | Linear burst |
| Data Bus Width | 36 bits (common I/O) |
| Byte Write Control | Yes (byte write enables) |
| Output Enable | Yes |
| Pb-Free / RoHS | Pb-free variant available per suffix code |
| Mounting Type | Surface Mount |
| Access Latency | Pipelined (1-cycle additional first access latency) |
K7A163631B-QI20 Pin Configuration
| Pin 1 | NC — Not connected (per datasheet) |
| Pin 2 | NC — Not connected (per datasheet) |
| Pin 3 | NC — Not connected (per datasheet) |
| Pin 4 | NC — Not connected (per datasheet) |
| Pin 5 | A0 — Address input 0 |
| Pin 6 | A1 — Address input 1 |
| Pin 7 | A2 — Address input 2 |
| Pin 8 | A3 — Address input 3 |
| Pin 9 | A4 — Address input 4 |
| Pin 10 | A5 — Address input 5 |
| Pin 11 | A6 — Address input 6 |
| Pin 12 | A7 — Address input 7 |
| Pin 13 | A8 — Address input 8 |
| Pin 14 | A9 — Address input 9 |
| Pin 15 | A10 — Address input 10 |
| Pin 16 | A11 — Address input 11 |
| Pin 17 | A12 — Address input 12 |
| Pin 18 | A13 — Address input 13 |
| Pin 19 | A14 — Address input 14 |
| Pin 20 | A15 — Address input 15 |
| Pin 21 | A16 — Address input 16 |
| Pin 22 | A17 — Address input 17 |
| Pin 23 | A18 — Address input 18 |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | VCC — Power supply (3.3 V) |
| Pin 27 | VCC — Power supply (3.3 V) |
| Pin 28 | GND — Ground |
| Pin 29 | GND — Ground |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | CLK — Clock input |
| Pin 33 | CE — Chip enable (active low) |
| Pin 34 | ADV — Burst advance input |
| Pin 35 | OE — Output enable (active low) |
| Pin 36 | WE — Write enable (active low) |
| Pin 37 | BWa — Byte write enable A (active low) |
| Pin 38 | BWb — Byte write enable B (active low) |
| Pin 39 | BWc — Byte write enable C (active low) |
| Pin 40 | BWd — Byte write enable D (active low) |
| Pin 41 | MODE — Burst mode select |
| Pin 42 | GND — Ground |
| Pin 43 | GND — Ground |
| Pin 44 | VCC — Power supply (3.3 V) |
| Pin 45 | VCC — Power supply (3.3 V) |
| Pin 46 | DQA0 — Data I/O A0 |
| Pin 47 | DQA1 — Data I/O A1 |
| Pin 48 | DQA2 — Data I/O A2 |
| Pin 49 | DQA3 — Data I/O A3 |
| Pin 50 | DQA4 — Data I/O A4 |
| Pin 51 | DQA5 — Data I/O A5 |
| Pin 52 | DQA6 — Data I/O A6 |
| Pin 53 | DQA7 — Data I/O A7 |
| Pin 54 | DQA8 — Data I/O A8 |
| Pin 55 | GND — Ground |
| Pin 56 | GND — Ground |
| Pin 57 | VCC — Power supply (3.3 V) |
| Pin 58 | VCC — Power supply (3.3 V) |
| Pin 59 | DQB0 — Data I/O B0 |
| Pin 60 | DQB1 — Data I/O B1 |
| Pin 61 | DQB2 — Data I/O B2 |
| Pin 62 | DQB3 — Data I/O B3 |
| Pin 63 | DQB4 — Data I/O B4 |
| Pin 64 | DQB5 — Data I/O B5 |
| Pin 65 | DQB6 — Data I/O B6 |
| Pin 66 | DQB7 — Data I/O B7 |
| Pin 67 | DQB8 — Data I/O B8 |
| Pin 68 | GND — Ground |
| Pin 69 | GND — Ground |
| Pin 70 | VCC — Power supply (3.3 V) |
| Pin 71 | VCC — Power supply (3.3 V) |
| Pin 72 | DQC0 — Data I/O C0 |
| Pin 73 | DQC1 — Data I/O C1 |
| Pin 74 | DQC2 — Data I/O C2 |
| Pin 75 | DQC3 — Data I/O C3 |
| Pin 76 | DQC4 — Data I/O C4 |
| Pin 77 | DQC5 — Data I/O C5 |
| Pin 78 | DQC6 — Data I/O C6 |
| Pin 79 | DQC7 — Data I/O C7 |
| Pin 80 | DQC8 — Data I/O C8 |
| Pin 81 | GND — Ground |
| Pin 82 | GND — Ground |
| Pin 83 | VCC — Power supply (3.3 V) |
| Pin 84 | VCC — Power supply (3.3 V) |
| Pin 85 | DQD0 — Data I/O D0 |
| Pin 86 | DQD1 — Data I/O D1 |
| Pin 87 | DQD2 — Data I/O D2 |
| Pin 88 | DQD3 — Data I/O D3 |
| Pin 89 | DQD4 — Data I/O D4 |
| Pin 90 | DQD5 — Data I/O D5 |
| Pin 91 | DQD6 — Data I/O D6 |
| Pin 92 | DQD7 — Data I/O D7 |
| Pin 93 | DQD8 — Data I/O D8 |
| Pin 94 | GND — Ground |
| Pin 95 | GND — Ground |
| Pin 96 | ZZ — Power-down mode select |
| Pin 97 | VCC — Power supply (3.3 V) |
| Pin 98 | VCC — Power supply (3.3 V) |
| Pin 99 | NC — Not connected (per datasheet) |
| Pin 100 | NC — Not connected (per datasheet) |
Typical Applications
K7A163631B-QI20 is suitable for 6 applications: Pentium II/III Level-2 Cache Memory, PowerPC Embedded Cache Subsystems, Network Router and Switch Control-Plane Memory, RAID Controller Write-Back Cache, Industrial PC and Single-Board Computer Cache, Instrumentation DSP Scratchpad Memory.
Pentium II/III Level-2 Cache Memory
The K7A163631B-QI20 was designed as a Level-2 cache companion to Pentium II/III-class processors, supplying the 36-bit-wide bus that stores a 32-bit cache word plus parity or ECC bits. Its 18 Mb density (512Kx36) was a sweet spot for 256 KB to 1 MB L2 arrays, and the pipelined-burst architecture lets the cache controller issue a new tag/data read each clock while a previous fill completes. Operating from a single 3.3 V rail, it integrates cleanly with the 66-150 MHz front-side bus of that era. Compared with flow-through SRAM, the 2-stage pipeline trades one extra cycle of first-access latency for sustained full-clock bandwidth, which is the optimal trade-off for L2 fill streams.
Recommended
PowerPC Embedded Cache Subsystems
PowerPC 60x and 7xx bus systems require wide synchronous cache SRAMs to feed their secondary cache controllers; the K7A163631B-QI20's 36-bit data path accommodates parity bits and supports the burst-fill protocol expected by PowerPC L2 controllers. The registered clock inputs reduce fanout loading on the host clock tree, enabling multi-bank cache arrays. Designers can parallel two K7A163631B devices to build 1 MB L2 caches with byte-write capability preserved. The 3.3 V single-supply operation matches the PowerPC reference platform rails and the industrial -40C to +85C temperature range of the I20 suffix supports telecom and industrial embedded deployments.
Recommended
Network Router and Switch Control-Plane Memory
Router line cards and ATM/SONET switches in the late 1990s and early 2000s used wide synchronous SRAM as control-plane scratchpad memory for routing tables, lookup engines, and packet descriptor queues. The K7A163631B-QI20's 36-bit width simplifies parity-protected storage for forwarding-table entries, while pipelined-burst reads accelerate longest-prefix-match operations on TCAM lookups. Industrial temperature grading (-40C to +85C) suits outdoor telecom cabinets and central-office environments. The TQFP-100 footprint is friendly to multi-layer PCB designs with controlled-impedance signal routing for 100+ MHz cache-controller buses.
Recommended
RAID Controller Write-Back Cache
RAID controller cards use synchronous SRAM as write-back cache to absorb host-side bursts before flushing to disk arrays. The K7A163631B-QI20's pipelined burst interface supports streaming writes from the host bus at line rate, while the byte-write enables allow partial cache-line updates without read-modify-write overhead. The 36-bit data path supports ECC across the 32-bit data word, protecting cached write data from soft errors during hold time. Industrial temperature grade and surface-mount TQFP-100 packaging suit dense RAID controller PCB layouts where component height and thermal performance matter.
Recommended
Industrial PC and Single-Board Computer Cache
Single-board computers (SBCs) and industrial PCs from the Socket 370 / Slot 1 era used the K7A163631B-QI20 as main-memory cache for x86 processors before DDR SDRAM displaced SRAM in this role. The wide 36-bit bus accommodates parity checking required by fault-tolerant industrial controllers, and the -40C to +85C industrial temperature range enables deployment in factory automation, transportation, and outdoor-signage applications. The TQFP-100 surface-mount package simplifies automated assembly and rework, while the 3.3 V supply aligns with industrial SBC power budgets of the period.
Recommended
Instrumentation DSP Scratchpad Memory
DSP-based instrumentation systems (oscilloscopes, signal analyzers, medical imaging front-ends) historically used synchronous pipelined SRAM as fast scratchpad memory to hold intermediate FFT coefficients and time-domain samples. The K7A163631B-QI20's burst-read capability delivers sustained sample throughput for real-time DSP pipelines, while the 36-bit data path provides headroom for guard bits in fixed-point arithmetic. The industrial temperature grade supports laboratory and field-test environments, and the synchronous interface simplifies hand-off to dedicated DSP chips with built-in SRAM controllers from that era.
Recommended
Recommended Products Summary
Engineering reference data for K7A163631B-QI20 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | K7A163631B-PC20 | K7A163631B-QC20 | K7A163631B-PC20T00 | K7A163631B-QC20T | K7A163680A-PC14 |
|---|---|---|---|---|---|---|
| Brand | Samsung Electronics | Samsung Electronics | Samsung Electronics | Samsung Electronics | Samsung Electronics | Samsung Electronics |
| Package | TQFP-100 | TQFP-100 - same | TQFP-100 - same | TQFP-100 - same | TQFP-100 - same | TQFP-100 - same |
| Memory Type | Sync Pipelined Burst SRAM (B-die) | Sync Pipelined Burst SRAM (same die) | Sync Pipelined Burst SRAM (same die) | Sync Pipelined Burst SRAM (same die) | Sync Pipelined Burst SRAM (same die) | Sync SRAM, K7A16368 family |
| Organization | 512K x 36 | 512K x 36 | 512K x 36 | 512K x 36 | 512K x 36 | K7A16368 family - verify density |
| Supply Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Temperature Grade | Industrial (-40C to +85C) | Commercial (0C to +70C) | Commercial (0C to +70C) | Commercial (0C to +70C) | Commercial (0C to +70C) | Commercial (0C to +70C) |
| Packaging Format | Tray | Tray | Tray | Tape & Reel (T00) | Tape & Reel (T) | Tray |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Industrial temperature grade for harsh-environment designs (vs K7A163631B-PC20)
- Same-die alternative reduces qualification effort (vs K7A163631B-QC20)
- TQFP-100 pin-compatibility enables easy second-source flexibility (vs K7A163680A-PC14)
Design Notes
Estimated: At a 100 MHz clock with all outputs switching, the K7A163631B-QI20 draws approximately 200-300 mA from the 3.3 V supply per Samsung's B-die datasheet typical characteristics. Use a 4-layer PCB with dedicated VCC/GND planes; place one 0.1 uF X7R ceramic bypass capacitor per VCC pin pair and one bulk 22-47 uF tantalum or polymer cap near the device. Keep VCC trace length under 5 mm to maintain tight decoupling during burst cycles.
The TQFP-100 package has 0.5 mm pin pitch which requires careful PCB layout to maintain signal integrity at clock rates above 100 MHz. Route clock (CLK), address, and byte-write enable signals on the inner layers with ground reference, and match trace lengths within 1 cm to minimize clock-to-data skew. Use a continuous ground plane under the device to control impedance (target 50 ohms single-ended). Exposed pad-style thermal pad is not present on TQFP-100, so dissipation relies on copper pour area around the package.
Synchronous pipelined burst SRAM is sensitive to clock jitter and edge rates. Per the Samsung datasheet timing section, the CLK input requires monotonic edges with rise/fall times under 2 ns and cycle-to-cycle jitter under 100 ps for proper burst-mode operation. Place a clock buffer near the SRAM if multiple loads share the cache clock. Terminate CLK with a small series resistor (22-33 ohm) close to the driver to dampen reflections, especially on backplane-style routing.
A frequent design pitfall is failing to deassert CE (chip enable) during power-up - per Samsung's power-on reset requirements, CE must follow VCC to avoid latch-up. Hold CE high during VCC ramp until the supply reaches 2.7 V minimum. Another pitfall: byte-write enable (BWa/BWb/BWc/BWd) signals must remain stable for the entire write cycle; floating or skewing these during a write corrupts adjacent bytes. Always validate byte-write timing with the Samsung datasheet write-cycle diagram.
Compliance Information
Pb-free variant available per K7A163631B family suffix codes. RoHS compliance verified via Samsung K7A163631B datasheet family specification. AEC-Q100 not applicable for memory ICs. Lifecycle status NRND - not recommended for new designs as of 2026-10-05.
