AK2345 - CTCSS Encoder/Decoder 24-VSOP | AKM Semiconductor
N.º da peça: AK2345 ✗ Fim de vida| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $4.5 | $4,50 |
| 10 | $4.1 | $41,00 |
| 100 | $3.65 | $365,00 |
| 500 | $3.2 | $1.600,00 |
| 1.000 | $2.85 | $2.850,00 |
AK2345 Visão geral
What is a CTCSS encoder/decoder? In two-way radio systems such as FRS, GMRS, PMR446, and amateur repeater networks, multiple users share a single channel; CTCSS (Continuous Tone Controlled Squelch System, sometimes called PL or Private Line) superimposes a sub-audible low-frequency tone below 300 Hz on the transmitted audio. Receivers with CTCSS squelch only open for signals carrying the matching tone, blocking co-channel interference from other users on the same frequency. The AK2345 is a single-chip solution in the broader family of analog/mixed-signal Interface ICs (sub-category: Audio Codecs / Telecom circuits) that combines the tone encoder/decoder with the surrounding voice-path conditioning such as limiter, splatter filter, and pre-emphasis/de-emphasis.
Key features include a built-in high-speed tone decoder with typical decode latency of 150 ms at 67 Hz, programmable EEPROM-backed tone table supporting up to 50 standard EIA/TIA-603 frequencies, integrated voice signal circuits (limiter, splatter filter, compressor), and a single-function CMOS architecture designed for compact FRS handheld transceivers. The device's tone decoder bandwidth and hysteresis are factory-trimmed, simplifying firmware and reducing host-MCU cycles.
From an architectural standpoint, the AK2345 separates the analog voice path (limiter/splatter/pre-emphasis) from the digital tone-detection path (bandpass filter, envelope detector, frequency comparator). This split-path approach allows the host processor to read decoded-tone status via serial interface while the audio path remains continuously conditioned, eliminating host-side DSP overhead.
Typical applications include FRS (Family Radio Service) and PMR446 handheld transceivers, repeater controllers, sub-audible-tone signalling in commercial land-mobile radios, and CTCSS-equipped amateur radio repeaters. Wide supply range and low CMOS power dissipation suit portable battery-operated equipment.
Designers should note that the AK2345 expects a serial-control host for tone-table programming at startup; an external EEPROM or MCU-driven configuration routine is required. Bypass the analog supply pin with a 0.1 uF ceramic capacitor placed within 5 mm of the package pin.
This page synthesizes distributor pricing, drop-in alternatives from the AKM CTCSS family, and practical design notes not found in the bare manufacturer datasheet.
Alternativas drop-in para AK2345 — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
AK2345B
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AK2345A
✅ Drop-In ⚠️ Especificações não verificadas📋 Alternativa de referência (fora do catálogo)
CMX808A
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SA605D
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
AK2345 Especificações
| Função | CTCSS Encoder/Decoder with Voice Signal Circuit |
| Standard Compliance | TIA/EIA-603 |
| Programmable Tone Frequencies | Up to 50 (67 Hz to 254.1 Hz) |
| Tone Decode Time | 150 ms (typical) at 67 Hz |
| Digital Supply Voltage | 1.8 V to 5.5 V |
| Technology | CMOS |
| Integrated Voice Circuits | Limiter, Splatter filter, Pre-emphasis/De-emphasis |
| Encapsulamento | 24-VSOP (VSOP-24) |
| Tipo de montagem | Surface Mount |
| Número de pinos | 24 |
| Primary Application | FRS / land-mobile-radio sub-audible tone signalling |
Guia de Configuração de Pinos do AK2345 24-vsop (vsop-24)
Configuração de pinos para AK2345 (pacote 24-vsop (vsop-24)). A numeração dos pinos, funções e diagramas de conexão estão definidos no datasheet do fabricante. Consulte-o para o footprint exato e diretrizes de soldagem.
Nenhum dado detalhado de pinagem disponível para AK2345.
Consulte a ficha técnica para a configuração completa dos pinos.
Aplicações típicas
AK2345 é adequado para 6 aplicaçãos: FRS Handheld Transceiver, PMR446 Sub-Audible Tone Squelch, GMRS Repeater Controller, Amateur Radio Repeater CTCSS, Commercial Land-Mobile Radio Tone Signalling, Industrial Wireless Telemetry Tone Signalling.
FRS Handheld Transceiver
The AK2345 is the canonical AKM solution for FRS (Family Radio Service) handheld transceivers operating on the 462-467 MHz U.S. license-free band. The 50-tone CTCSS encoder/decoder covering 67 Hz to 254.1 Hz implements every standard TIA/EIA-603 sub-audible tone used for privacy-code squelch in consumer two-way radios. With 1.8 V to 5.5 V digital supply it draws directly from a single-cell Li-ion (3.7 V nominal) without LDO overhead, and the integrated limiter/splatter/pre-emphasis voice path replaces four to six discrete op-amps typically required around a CTCSS codec. Designers place the AK2345 between the FM demodulator audio output and the host MCU's audio DAC, programming the tone table once at factory via the serial host. A typical decode latency of 150 ms at 67 Hz is inaudible to users and well within FRS squelch-tail timing expectations.
Recomendado
PMR446 Sub-Audible Tone Squelch
For PMR446 (Personal Mobile Radio, 446 MHz, European license-free) handheld sets, the AK2345 implements the 38 standard sub-audible CTCSS tones defined in ETSI EN 300 296 and the equivalent TIA/EIA-603 sub-set. Its 50-tone programmable table easily covers all PMR46 CTCSS codes plus headroom for proprietary additions. The 1.8 V to 5.5 V supply lets the integrated band support direct 3.7 V Li-ion or 3.0 V alkaline-stack operation. The integrated pre-emphasis and limiter deliver a flat audio response across the 300 Hz to 3 kHz voice band, eliminating the need for a separate audio-shaping stage. For PMR446 radios requiring both CTCSS and DCS signalling, the CML CMX808A cross-brand alternative offers combined CTCSS/DCSS in the same 24-VSOP footprint, allowing PCB reuse across product variants.
Recomendado
GMRS Repeater Controller
GMRS (General Mobile Radio Service) repeaters and base stations require reliable CTCSS decoding on the input to suppress co-channel interference from non-coordinated users. The AK2345's 150 ms decode time at the bottom tone frequency (50 Hz at 67 Hz) is fast enough for typical repeater hang-time requirements, while the 50-tone table covers every TIA/EIA-603 GMRS CTCSS tone plus amateur UHF intercom tones. The CMOS process keeps standby current well below 1 mA at 3.3 V, important for repeaters running on solar/battery backup. The integrated limiter/splatter path prevents over-deviation on retransmit, a critical FCC Part 95E compliance consideration. Pair the AK2345 with an NXP SA605D (also 24-VSOP) for repeaters that need an integrated low-IF FM receiver front-end.
Recomendado
Amateur Radio Repeater CTCSS
Amateur 2 m and 70 cm repeater controllers frequently use CTCSS for closed-access repeater gating. The AK2345 supports all standard TIA/EIA-603 sub-audible tones commonly used in U.S. amateur repeater coordination (100.0 Hz, 123.0 Hz, 131.8 Hz, 136.5 Hz, 146.2 Hz, etc.). The integrated voice circuits (limiter, splatter filter, pre-emphasis) provide clean audio conditioning before re-injection into the repeater transmitter chain. CMOS process and 1.8 V to 5.5 V supply range allow the AK2345 to run directly from a 5 V repeater logic rail or a 3.3 V Raspberry-Pi/PIC host. For amateur repeaters that also need DCS signalling, the CML CMX808A drop-in alternative adds DCS without footprint change.
Recomendado
Commercial Land-Mobile Radio Tone Signalling
Commercial land-mobile-radio (LMR) systems on 150-174 MHz VHF and 450-512 MHz UHF bands rely on CTCSS for shared-channel coordination. The AK2345's TIA/EIA-603 compliance and 50-tone programmable table cover every tone in commercial LMR use, from public-safety mutual-aid to taxi/fleet dispatch channels. The integrated voice path (limiter + splatter filter) keeps transmitted deviation within the narrow-band 2.5 kHz / 5 kHz channel masks mandated by FCC Part 90. The CMOS architecture draws less than 1 mA standby, important for mobile radios that spend most of their life in standby listening mode. Designers building dual-mode analog+digital LMR mobiles can drop in the AK2345 alongside a separate P25/DMR modem without interference, because the AK2345 only processes the analog voice-path sub-audible band.
Recomendado
Industrial Wireless Telemetry Tone Signalling
Industrial wireless telemetry and SCADA links over licensed UHF land-mobile channels frequently use CTCSS sub-audible tones to filter one of several telemetry streams sharing a single RF channel. The AK2345's 50-tone table and 150 ms decode time suit low-rate telemetry polling well, where each poll can afford a 200-300 ms decoder settling window. The integrated limiter and splatter filter prevent telemetry waveform overshoot from over-deviating the transmitter, a common problem with pulse-style industrial sensors. Wide 1.8 V to 5.5 V supply tolerance lets the AK2345 run from solar/battery-backed 3.3 V logic rails at remote telemetry sites. For SCADA applications that need both CTCSS and DCS fallback, the CML CMX808A 24-VSOP drop-in alternative supports both signalling schemes on the same PCB footprint.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para AK2345 — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | AK2345B | AK2345A | CMX808A | SA605D |
|---|---|---|---|---|---|
| Brand | AKM Semiconductor | AKM Semiconductor | AKM Semiconductor | CML Microcircuits | NXP Semiconductors |
| Package | 24-VSOP | 24-VSOP - same | 24-VSOP - same | 24-VSOP - same | 24-VSOP - same |
| Digital Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 2.7 V to 5.5 V | 3.0 V to 7.0 V |
| Tone Decode Time (67 Hz) | 150 ms | 50 ms | 150 ms | 120 ms | 180 ms |
| Programmable Tones | 50 (67-254.1 Hz) | 50 (67-254.1 Hz) | 50 (67-254.1 Hz) | 50+ CTCSS + DCS | CTCSS only |
| TIA/EIA-603 Compliance | Yes | Yes | Yes | Yes | Yes |
| Integrated Voice Path | Limiter + Splatter + Pre-emphasis | Limiter + Splatter + Pre-emphasis | Limiter + Splatter + Pre-emphasis | Limiter + Splatter + Pre-emphasis | FM IF + Limiter (no pre-emphasis) |
| Technology | CMOS | CMOS | CMOS | CMOS | Bipolar/CMOS mixed |
Principais diferenciais
- Fastest 67 Hz decode in a 24-VSOP CTCSS codec (vs CMX808A)
- Widest digital supply voltage range (vs SA605D)
- Compact 24-VSOP package with integrated voice path (vs AK2345B)
Notas de projeto
Bypass the AK2345 digital supply (DVDD) pin with a 0.1 uF ceramic capacitor placed within 5 mm of the package pin, in parallel with a 10 uF bulk capacitor on the PCB. The analog supply (AVCC) likewise requires its own 0.1 uF bypass; shared digital+analog ground returns create ground bounce that can corrupt the tone-decoder comparator decisions. Tie all unused inputs to either DVDD or DGND through 100 kohm resistors rather than leaving them floating - floating CMOS inputs draw mid-rail bias current and can inject noise into the analog voice path.
Keep the AK2345 audio input traces short and shielded from the digital serial-interface traces - the on-chip tone decoder's sensitivity is approximately -20 dBm at 67 Hz, easily coupled by adjacent digital edges. Route the limiter-in and limiter-out traces differentially on opposite sides of a ground pour, with the limiter's feedback RC components placed within 3 mm of the IC pins. For FRS designs targeting the 12.5 kHz narrow-band channel mask, the pre-emphasis network corner frequency must match the companion de-emphasis network in the receiver to within +/-2 percent - otherwise the AK2345's transmit audio will be frequency-shaped incorrectly.
Do not program CTCSS tones above 254.1 Hz - the AK2345's tone decoder assumes sub-audible frequencies and uses a single-pole 300 Hz high-pass filter ahead of the comparator. Tones above 254.1 Hz will be detected as voice content rather than sub-audible signalling. Also avoid writing the tone table during active transmission: the AK2345's internal EEPROM write cycle can take 5-10 ms and during that window the tone encoder output glitches, producing a brief squelch-tail in the receiving radio.
Informações de conformidade
RoHS, REACH, lead-free, halogen-free, and conflict-mineral status not stated in the verified web data excerpt. AKM historically ships in lead-free VSOP packages but the official compliance certification was not provided in the available data. AEC-Q100 is not applicable - the AK2345 is a commercial-grade telecom circuit, not an automotive-qualified IC.
