MC44BS374T1AEF - PLL-Tuned UHF/VHF A/V Modulator | NXP
MPN： MC44BS374T1AEF ✗ 停產MC44BS374T1AEF 概覽
An RF modulator is a transmitter IC that converts a baseband audio and video signal into a vestigial-sideband or double-sideband RF carrier suitable for connection to a television's antenna input. Within the broader product hierarchy, the MC44BS374 sits at: modulator -> RF transmitter -> specialized consumer IC -> integrated circuit -> semiconductor. It is the direct descendant of the legacy MC44BS373/4 family and is functionally superseded by the newer MC44CC373/MC44CC374 CMOS family while retaining the same footprint and electrical interface to ease migration.
Key features include programmable UHF/VHF output frequency via the high-speed I2C-compatible bus, a Logic Output Port pin (pin 3) for status or switching functions, 5 V and 3.3 V compatible I2C logic levels, and a TV output level of 82 dBuV (typical, MC44BS374T1A variant) or 75 dBuV (MC44BS374T1 variant). The PLL architecture provides fine channel selection across the broadcast TV band, allowing the modulator to replace traditional saw filters and discrete modulator circuits in cost-sensitive consumer designs.
The IC uses a CMOS process with an integrated VCO and PLL loop filter, reducing external component count compared with older bipolar modulator designs. Typical DC supply is 5 V, and the high-speed I2C bus allows full register configuration of audio deviation, video modulation depth, RF output frequency, and power-down mode. The 16-SOIC package is industry-standard and footprint-compatible with the newer MC44CC374 family, simplifying in-place upgrades.
Typical applications include set-top box RF outputs, DVD/VCR combo outputs to legacy televisions, video game console A/V-to-RF adapters, security camera RF modulators, and PC TV-capture cards. The Logic Output Port pin can be used to drive an external LED indicator or switch a relay on channel change. The combination of low external parts count and I2C programmability makes this part attractive for high-volume consumer products.
When designing with this modulator, pay close attention to the RF output network - use a proper 75 ohm matching network and shielding to meet FCC/CE radiated emissions limits. Decouple VCC with a 10 uF bulk and 100 nF ceramic capacitor placed as close to the IC as possible; inadequate bypassing produces visible hum bars on the modulated video output.
This page synthesizes distributor pricing, drop-in alternatives from the same NXP family (MC44BS373T1AEF, MC44CC373T1AEF, MC44CC374T1AEF), and practical design notes that are not aggregated on DigiKey, Mouser, or Octopart product pages.
直接替換替代品，適用於 MC44BS374T1AEF — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： MC44BS374T1AEF （相同外形與佔位） — 差異在於 Function, Modulation Standards, Package, Supply Voltage.
MC44BS373T1AEF
✅ 直接替換📋 參考替代品（不在目錄中）
MC44CC373T1AEF
✅ 直接替換📋 參考替代品（不在目錄中）
MC44CC374T1AEF
✅ 直接替換📋 參考替代品（不在目錄中）
MC44BS374CA
✅ 直接替換📋 參考替代品（不在目錄中）
MC44BS374T1AEF 規格
| 功能 | PLL-Tuned UHF/VHF Audio/Video RF Modulator |
| Modulation Standards | NTSC, PAL |
| Output Frequency Bands | UHF, VHF |
| TV Output Level (MC44BS374T1A variant) | 82 dBuV typical |
| TV Output Level (MC44BS374T1 variant) | 75 dBuV typical |
| 供應電壓 | 5 V (3.3 V compatible I2C logic) |
| I2C Bus Compatibility | High-Speed I2C, 5 V and 3.3 V compatible |
| Logic Output Port | Yes (pin 3) |
| Process Technology | CMOS |
| 封裝 | 16-SOIC (Small Outline IC) |
| 腳位數 | 16 |
| 安裝類型 | Surface Mount |
| Terminal Form | GULL WING |
| Temperature Grade | COMMERCIAL |
| Package Outline Code | SOP |
| Package Shape | RECTANGULAR |
MC44BS374T1AEF 腳位配置
| 腳位 1 | VCC — 5 V supply input |
| 腳位 2 | GND — Ground |
| 腳位 3 | LOP — Logic Output Port (programmable CMOS output) |
| 腳位 4 | SDA — I2C-compatible serial data |
| 腳位 5 | SCL — I2C-compatible serial clock |
| 腳位 6 | ADDR — I2C address selection |
| 腳位 7 | AUDIO IN — Analog audio input |
| 腳位 8 | VIDEO IN — Composite video input |
| 腳位 9 | NC — Not connected (per datasheet) |
| 腳位 10 | GND — Ground |
| 腳位 11 | RF OUT — Modulated RF output to antenna |
| 腳位 12 | VCC — 5 V supply for RF output stage |
| 腳位 13 | PLL LF — PLL loop filter |
| 腳位 14 | GND — Ground |
| 腳位 15 | XTAL — Reference crystal or oscillator input |
| 腳位 16 | NC — Not connected (per datasheet) |
典型應用
MC44BS374T1AEF 適用於 6 應用s: Set-Top Box RF Output, DVD/VCR Combo A/V to RF Modulator, Video Surveillance RF Modulator, Video Game Console A/V-to-RF Adapter, PC TV-Capture Card Output Stage, Broadcast Test Pattern Generator.
Set-Top Box RF Output
The MC44BS374T1AEF is a textbook fit for set-top box (STB) RF outputs that drive legacy television antenna inputs. Its 5 V supply rails match STB power-tree rails, and the high-speed I2C-compatible bus at 3.3 V logic lets a host Media Processor or SoC directly configure output channel, audio deviation, and video modulation depth without glue logic. With UHF coverage of US channels 14-83 and European Band IV/V, a single PCB configuration can ship to NTSC (82 dBuV output) and PAL markets by firmware alone. The 16-SOIC package keeps the modulator footprint compact, leaving board area for HDMI, Ethernet, and tuner sections.
推薦
DVD/VCR Combo A/V to RF Modulator
The MC44BS374T1AEF accepts analog composite video and analog audio from a DVD player's encoder or a VCR's playback head and modulates the pair into a single-channel RF carrier for the TV's antenna input. The Logic Output Port on pin 3 can be programmed to drive an LED that lights when the PLL achieves lock, giving end users a visual status indicator. Programmable video modulation depth via the I2C bus lets designers match the modulator's output level to typical TV sensitivity (75-82 dBuV) without external attenuators, reducing manufacturing calibration steps.
推薦
Video Surveillance RF Modulator
For analog CCTV and security camera applications, the MC44BS374T1AEF converts a camera's composite video output to a UHF channel that can be distributed over existing coax to multiple TV monitors. The PLL's frequency stability eliminates channel drift seen with older LC-tank modulators, giving stable picture quality across long cable runs. The 16-SOIC's wide commercial temperature grade supports indoor cabinet installations, and the I2C bus allows remote channel selection when paired with an RS-232-to-I2C bridge in matrix-switcher systems. The Logic Output Port can drive a relay that switches backup cameras on demand.
推薦
Video Game Console A/V-to-RF Adapter
Classic video game consoles and retro-computing adapters use the MC44BS374T1AEF to deliver composite video plus stereo audio onto a single RF channel for connection to period-correct CRT televisions. The CMOS process keeps quiescent current low, important for line-powered adapter enclosures with no active cooling. Programmable audio FM deviation lets adapters match NTSC-B/M, PAL-B/G, and SECAM sound subcarrier standards. The 16-SOIC's small footprint is well-suited to dongle-form-factor enclosures.
推薦
PC TV-Capture Card Output Stage
PCIe and USB TV-capture cards can use the MC44BS374T1AEF to provide a passthrough RF output that lets users continue watching live TV on a secondary display while recording on the host PC. The modulator's low external parts count and single 5 V rail simplify the card's power tree. The I2C bus integrates with the capture-card controller to blank the RF output during recording and avoid interference with the host monitor. The 82 dBuV output level matches typical consumer TV sensitivity without external amplification.
推薦
Broadcast Test Pattern Generator
Test equipment manufacturers use the MC44BS374T1AEF as a compact low-cost RF output stage for bench-top test pattern generators and NTSC/PAL signal sources. The PLL's fine channel resolution permits precise channel selection across the broadcast band, useful for verifying TV tuner sensitivity and adjacent-channel rejection. The high-speed I2C-compatible bus allows scripted test automation to step through channels and modulation depths without manual intervention. The 16-SOIC package's industrial temperature characteristics suit lab environments.
推薦
推薦產品摘要
工程參考資料，適用於 MC44BS374T1AEF — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MC44BS373T1AEF | MC44CC373T1AEF | MC44CC374T1AEF | MC44BS374CA |
|---|---|---|---|---|---|
| Package | 16-SOIC | 16-SOIC - same | 16-SOIC - same | 16-SOIC - same | 16-SOIC - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Family | MC44BS373/4 legacy | MC44BS373/4 legacy (sibling) | MC44CC373/4 next-generation | MC44CC373/4 next-generation | MC44BS373/4 legacy (CA variant) |
| Generation | Legacy (Rev. 1.2, 04/2004) | Legacy (sibling) | Next-generation successor | Next-generation successor | Legacy (CA variant) |
| Output Frequency Bands | UHF, VHF | UHF, VHF | UHF, VHF (enhanced PLL) | UHF, VHF (enhanced PLL) | UHF, VHF |
| Supply Voltage | 5 V | 5 V | 5 V (3.3 V I2C) | 5 V (3.3 V I2C) | 5 V |
| I2C Bus Compatibility | High-Speed I2C, 5 V / 3.3 V | High-Speed I2C, 5 V / 3.3 V | High-Speed I2C, 5 V / 3.3 V | High-Speed I2C, 5 V / 3.3 V | High-Speed I2C, 5 V / 3.3 V |
| Standards Supported | NTSC, PAL | NTSC, PAL | NTSC, PAL | NTSC, PAL | NTSC, PAL |
| Pin Count | 16 | 16 | 16 | 16 | 16 |
主要差異化特點
- Backwards-compatible drop-in for legacy STB and VCR designs (對比MC44BS373T1AEF)
- Designed as latest-generation upgrade path (對比MC44CC374T1AEF)
- Combines audio FM and video modulator in one CMOS die (對比MC44CC373T1AEF)
設計說明
The MC44BS374T1AEF requires a clean 5 V supply rail. Place a 10 uF bulk tantalum or aluminum-polymer capacitor and a 100 nF ceramic decoupling capacitor within 5 mm of the VCC pin. Use a ferrite bead on VCC if the modulator shares a rail with digital switching circuitry; switching noise on VCC manifests as visible hum bars and audio buzz on the modulated RF output.
Keep the RF OUT trace on the top layer, 75 ohm characteristic impedance, and as short as possible. Stitch a continuous ground pour around the RF output and PLL loop filter trace to provide a low-impedance return path. Avoid routing digital I2C traces under the RF output network - coupling can inject I2C clock spurs into the RF spectrum, causing visible beat patterns on adjacent TV channels.
Do not omit the reference crystal on pin 15. The PLL requires a stable reference frequency to lock; mechanical vibrations or temperature drift in a missing external crystal will cause channel drift on the modulated RF output. When replacing the legacy MC44BS374 with the newer MC44CC374, re-verify the I2C register map - register addresses and bit fields differ between the two families even though the bus is electrically compatible.
合規資訊
RoHS compliance status not specified in the verified source data. AEC-Q100 not applicable - this part is commercial-grade for consumer video and STB applications. Verify compliance directly with NXP's product page or distributor documentation before use in regulated designs.
