PCF7936AS/3851/C,1 - HITAG2 256-Bit Security Transponder | NXP
料号： PCF7936AS-3851-C1 ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.65 | $16.50 |
| 100 | $1.42 | $142.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $0.95 | $950.00 |
| 5,000 | $0.78 | $3,900.00 |
PCF7936AS-3851-C1 概述
A security transponder is a passive contactless memory device that powers itself from the inductive coupling of an external reader's 125 kHz magnetic field. The HITAG2 family from NXP is widely used in automotive immobilizer systems, building access control, and industrial asset tracking, where robust mutual-authentication and replay-attack resistance are required. The transponder category sits hierarchically inside NFC/RFID tags → RFID transponders → security/authentication ICs → wired/wireless identification semiconductors.
Key features include HITAG2 protocol operation, a 39 ms typical read/write transaction time, 32-byte user EEPROM with bit-level access granularity, and an operating temperature range of -40 °C to +85 °C suitable for automotive under-hood and outdoor industrial deployments. The device is supplied in tape-and-reel packaging to support high-volume injection molding of transponder keys.
Internally, the IC uses a tuned LC resonant front-end, a low-power analog front-end for demodulation/load modulation, a deterministic HITAG2 cryptographic state machine, and a serial EEPROM array. The protocol includes rolling-code mutual authentication, making it suitable for systems where a static UID alone would be insufficient to defeat unauthorized cloning.
Typical applications include automotive vehicle immobilizers, RFID key fobs, building access control tokens, and industrial equipment authentication modules. The 256-bit memory and HITAG2 cipher make it appropriate where cloned-readers and replay attacks are realistic threat models. Compared with 1-Wire or 13.56 MHz ISO14443 credentials, 125 kHz HITAG2 offers longer read range in metal-rich environments and lower reader BOM cost.
When designing with this device, ensure the transponder coil inductance and matching capacitor are tuned for 125 kHz resonance (typical Q > 10) to achieve the rated 39 ms transaction time at the target read distance. Pair the transponder with an HITAG2-compatible reader IC such as the NXP HTRC110 or derivative, and verify EMC compliance of the complete reader system to EN 300 330 or local equivalents.
This page synthesizes distributor pricing, same-family NXP alternatives, and practical HITAG2 integration notes not found in the manufacturer datasheet. Cross-reference data is sourced from Mouser, NXP datasheet portals, and authorized NXP distributor listings as of 2026-10-05.
直接替换替代料： PCF7936AS-3851-C1 ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
PCF7936AS/3851/C,1-CT
✅ 直接替换📋 参考替代料（不在目录中）
PCF7937AS
✅ 直接替换📋 参考替代料（不在目录中）
PCF7935AS
✅ 直接替换📋 参考替代料（不在目录中）
PCF7936AS/3851
✅ 直接替换📋 参考替代料（不在目录中）
PCF7936AS-3851-C1 规格参数（制造商发布）
| Product Type | HITAG2 Security Transponder (RFID/NFC Tag) |
| Manufacturer | NXP Semiconductors |
| Carrier Frequency | 125 kHz |
| 存储容量 | 256 bit (32 byte × 8 bit) EEPROM |
| Protocol | HITAG2 (mutual authentication) |
| Read/Write Time (typical) | 39 ms |
| 工作温度范围 | -40 °C to +85 °C |
| 封装 | SOT-385-1 (transponder module) |
| 安装类型 | Embedded in transponder housing |
| Power Source | Passive (inductively coupled from reader field) |
| Authentication | Mutual authentication with rolling code |
| Tape and Reel Packaging | Yes |
| Application Domain | Automotive immobilizer / access control |
PCF7936AS-3851-C1 引脚配置
| 引脚 1 | ANT1 — Antenna coil terminal 1 (125 kHz LC resonant input) |
| 引脚 2 | ANT2 — Antenna coil terminal 2 (125 kHz LC resonant input) |
功率与热特性
| 工作温度 | -40 °C to +85 °C |
PCF7936AS-3851-C1 的功率输入和热参数（由制造商发布）。
典型应用
PCF7936AS-3851-C1 适用于 6 应用s: Automotive Vehicle Immobilizer, RFID Key Fob / Credential, Building Access Control Token, Industrial Equipment Authentication, Fleet Management / Asset Tracking, Replacement Key / Aftermarket Immobilizer.
Automotive Vehicle Immobilizer
The PCF7936AS/3851/C,1 is embedded in vehicle ignition keys to provide HITAG2 mutual authentication with the engine ECU's reader basestation. At 125 kHz carrier and 39 ms typical transaction, it reliably authenticates within the short window between key insertion and crank, while the rolling-code cipher prevents replay and cloning attacks. The -40 °C to +85 °C range covers under-hood and exterior-mounted key-slot environments.
推荐
RFID Key Fob / Credential
Used inside plastic key fobs for residential and commercial access, the PCF7936AS/3851/C,1 powers itself from the reader's 125 kHz field, eliminating battery maintenance. Its 256-bit EEPROM stores site codes and user identifiers, while HITAG2 mutual authentication prevents card cloning. Long LF read range makes it tolerant of metal-rich wallets and key rings that would shield higher-frequency credentials.
推荐
Building Access Control Token
The PCF7936AS/3851/C,1 serves as a passive contactless credential for door readers in medium-security office and apartment buildings. HITAG2 mutual authentication with 256-bit storage supports per-user keys, audit logs, and revocable access lists. Its SOT-385-1 module is small enough to embed in ISO card or token form factors without affecting reader read range.
推荐
Industrial Equipment Authentication
For industrial machinery requiring operator-presence authentication (e.g., forklift, lift, or tool authorization), the PCF7936AS/3851/C,1 is embedded in operator badges. HITAG2 authentication prevents unauthorized equipment use, and the rugged -40 °C to +85 °C operating range tolerates factory and outdoor environments. The SOT-385-1 package withstands injection molding encapsulation used in industrial-grade credentials.
推荐
Fleet Management / Asset Tracking
Mounted in trailers, containers, or high-value mobile assets, the PCF7936AS/3851/C,1 enables HF/LF RFID reader portals to authenticate asset identity without line-of-sight. Its passive operation means zero maintenance over the asset's service life, and HITAG2 security prevents tag spoofing by unauthorized readers. Long LF read range is advantageous for portal-reader installations.
推荐
Replacement Key / Aftermarket Immobilizer
The PCF7936AS/3851/C,1 is widely stocked by automotive locksmiths and aftermarket key-programming services to replace lost or damaged immobilizer keys for European vehicles. Its 256-bit EEPROM accommodates transponder-specific codes, and HITAG2 compatibility with major OEM reader basestations (VW, BMW, Mercedes, PSA generations) makes it a generic fit. Tape-and-reel packaging supports custom key blank assembly.
推荐
推荐产品汇总
工程参考数据： PCF7936AS-3851-C1 ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | PCF7936AS/3851/C,1-CT | PCF7937AS | PCF7935AS | PCF7936AS/3851 |
|---|---|---|---|---|---|
| Package | SOT-385-1 | SOT-385-1 - same | SOT-385-1 - same | SOT-385-1 - same | SOT-385-1 - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Carrier Frequency | 125 kHz | 125 kHz | 125 kHz | 125 kHz | 125 kHz |
| Protocol | HITAG2 | HITAG2 | HITAG2 extended | HITAG2 | HITAG2 |
| Read/Write Time | 39 ms (typical) | 39 ms | 39 ms | 39 ms | 39 ms |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Authentication | Mutual + rolling code | Mutual + rolling code | Mutual + rolling code (extended) | Mutual + rolling code | Mutual + rolling code |
| Package Suffix Variant | Reel (C1 customer code) | Cut Tape (C1-CT) | Standard reel | Standard reel | Reel (no C1 suffix) |
关键差异点
- Mutual-authentication HITAG2 cipher （对比 PCF7935AS)
- Extended HITAG2 command set upgrade path （对比 PCF7937AS)
- Customer-specific C1 suffix code （对比 PCF7936AS/3851)
设计说明
The PCF7936AS/3851/C,1 is supplied as a SOT-385-1 transponder module, not a discrete IC, and is typically molded into a key-head or fob housing rather than soldered onto a PCB. Design the external antenna coil with inductance tuned to resonate at 125 kHz with the IC's internal capacitor, targeting a Q > 10 for the rated 39 ms transaction at the desired read distance (typically 5-10 cm). Place a matching capacitor within 1% tolerance across the coil terminals.
Do not substitute the PCF7936AS/3851/C,1 with non-HITAG2 LF transponders (e.g., EM4100, TIRIS) - the reader basestation implements HITAG2 mutual authentication and will reject incompatible tags. When sourcing replacements, verify the HITAG2 protocol support and rolling-code cipher compatibility on the reader side before considering cross-brand parts. Cross-brand LF substitutes require firmware changes and are not drop-in.
Inside the fob housing, keep the antenna coil at least 5 mm from any ferrous or aluminum components (springs, battery contacts) to avoid Q-factor degradation and read-range loss. Orient the coil axis to align with the reader basestation's magnetic field during typical use orientation (e.g., key inserted vertically). Avoid routing the transponder module near high-frequency digital traces that could couple noise into the LC tank.
合规信息
RoHS, REACH, AEC-Q100, lead-free, halogen-free, and conflict-mineral status for PCF7936AS/3851/C,1 were not present in the verified web data; marked [DATA_NEEDED] in specs. NXP HITAG2 family typically supports EN 300 330 EMC compliance of the complete reader system.
