MAX9814ETD+T - Mic Amplifier with AGC | Analog Devices
料号： MAX9814ETD+T ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $1.13 | $1.13 |
| 10 | $1.05 | $10.50 |
| 100 | $0.96 | $96.00 |
| 500 | $0.85 | $425.00 |
| 1,000 | $0.75 | $750.00 |
MAX9814ETD+T 概述
A microphone preamplifier is the front-end analog stage that boosts a microphone's small output signal to a usable line level before ADC or codec digitization. In the signal-chain hierarchy, it sits between the transducer (electret or MEMS microphone) and the ADC or audio codec. By integrating AGC and bias generation, the MAX9814ETD+T removes two external ICs and several discrete components, simplifying the BOM while keeping the dynamic range high enough for speech and music capture.
Key features include a low-noise preamp with selectable gain settings (40 dB, 50 dB, 60 dB), a low-noise 2.5V microphone bias generator with PSRR above 100 dB, integrated AGC with selectable attack/release ratios, a low 3.7 mA supply current, and a <1 uA shutdown mode. The TDFN-14 3x3 mm package gives a small PCB footprint with an exposed thermal pad that must be soldered to the ground plane for rated thermal performance.
The architecture chains the low-noise preamp into the VGA, which is driven by an envelope detector that sets the gain based on the output amplitude. The internal bias generator rails the electret capsule cleanly so even budget microphones achieve >100 dB dynamic range. Typical THD+N at 1 kHz is well below 1% at rated output, sufficient for voice and high-quality portable recording.
Typical applications include Bluetooth headsets, digital still and video cameras, IP phones and teleconferencing units, portable recorders, PDAs, and karaoke/entertainment systems. The wide 2.7V-5.5V input range covers a single Li-ion cell (3.0V-4.2V) plus USB-powered 5V designs.
When laying out the PCB, tie the exposed pad to a solid ground pour for thermal relief and lowest noise. Place the bypass and bias capacitors within a few millimetres of the IC and route microphone traces away from switching converters to preserve SNR.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, helping audio engineers shorten their BOM evaluation and speed time-to-market.
直接替换替代料： MAX9814ETD+T ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： MAX9814ETD+T （相同外形与封装尺寸） ——差异在于 Package, Product Type.
快速对比工具——选择替代料号进行并排对比：
MAX9814ETD+
✅ 直接替换📋 参考替代料（不在目录中）
MAX9814ETD+T
✅ 直接替换✓ 有现货
$0.75 / 个
查看数据手册 →MAX9814ETD+G45
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
MAX9814ETD+T 最大额定值与电气特性
| Product Type | Microphone Preamplifier with AGC |
| 输出类型 | 1-Channel (Mono), Class AB |
| 电源电压 | 2.7 V to 5.5 V |
| 电源电流 | 3.7 mA (typ) |
| 关断电流 | <1 uA |
| Preamplifier Gain Settings | 40 dB / 50 dB / 60 dB (selectable) |
| AGC Attack/Release Ratios | Selectable |
| Microphone Bias Voltage | 2.5 V (low-noise, integrated) |
| Bias PSRR | >100 dB |
| 输出类型 | Differential / Single-ended (configurable) |
| 工作温度 | -40 C to +85 C |
| 封装 | 14-pin TDFN (3x3 mm) with exposed pad |
| 安装类型 | Surface Mount |
| RoHS 状态 | Compliant |
MAX9814ETD+T 引脚配置
| 引脚 1 | MIC+ — Microphone non-inverting input |
| 引脚 2 | MIC- — Microphone inverting input |
| 引脚 3 | BIAS — Microphone bias voltage output (2.5 V) |
| 引脚 4 | GAIN1 — Gain select input 1 |
| 引脚 5 | GAIN0 — Gain select input 0 |
| 引脚 6 | CT — AGC attack/release timing capacitor |
| 引脚 7 | SHDN — Shutdown input (active low) |
| 引脚 8 | GND — Ground |
| 引脚 9 | OUT+ — Non-inverting output |
| 引脚 10 | OUT- — Inverting output |
| 引脚 11 | VDD — Supply voltage (2.7 V to 5.5 V) |
| 引脚 12 | C1P — Charge pump flying capacitor positive |
| 引脚 13 | C1N — Charge pump flying capacitor negative |
| 引脚 14 | EP — Exposed pad - connect to GND |
典型应用
MAX9814ETD+T 适用于 6 应用s: Bluetooth Headset Microphone Front-End, Digital Still and Video Camera Audio Capture, IP Phone and Teleconferencing Speakerphone, Portable Digital Voice Recorder, Karaoke and Entertainment System Microphone Input, Two-Way Radio and Walkie-Talkie Mic Preamp.
Bluetooth Headset Microphone Front-End
The MAX9814ETD+T is a strong fit for Bluetooth headsets because it combines a low-noise preamplifier, integrated AGC, and a 2.5V low-noise bias generator in a single IC that runs from a single Li-ion cell (3.0V-4.2V). The 40/50/60 dB selectable gain stages let the designer match sensitivity to the electret or MEMS capsule, while the AGC prevents clipping when the user speaks loudly or moves the headset close to the mouth. The <1 uA shutdown mode preserves headset standby battery life when the call is ended, and the 3x3 mm TDFN footprint fits inside a typical earbud PCB.
推荐
Digital Still and Video Camera Audio Capture
In digital still cameras (DSC) and camcorders, the MAX9814ETD+T provides a clean, AGC-controlled microphone input directly to the camera's audio codec or DSP. The integrated low-noise 2.5V bias generator (>100 dB PSRR) keeps supply noise from a switching LCD backlight or image processor out of the capsule rail, preserving the wide dynamic range required for music and outdoor recording. The wide 2.7V-5.5V supply tolerates a single Li-ion cell, while the small 14-pin TDFN package fits inside the cramped camera PCB.
推荐
IP Phone and Teleconferencing Speakerphone
The MAX9814ETD+T is recommended by Analog Devices for IP phones and conference speakerphones where participants may speak at unpredictable levels and at varying distances from the microphone. The integrated AGC with selectable attack and release times keeps the outgoing audio level constant whether the speaker whispers or raises their voice, eliminating the need for software gain riding in the VoIP DSP. The 14-pin TDFN package and 2.7V-5.5V supply simplify designs powered from USB, PoE-derived rails, or 3.3V logic supplies.
推荐
Portable Digital Voice Recorder
For handheld dictation devices and portable music recorders, the MAX9814ETD+T delivers studio-grade dynamic range from a tiny footprint. The integrated low-noise bias generator with >100 dB PSRR supports a wide range of electret capsules, and the selectable 40/50/60 dB gain lets the designer tune sensitivity to high-SPL musical sources without overloading the ADC. The <1 uA shutdown current is critical for battery-powered recorders that spend most of their time in standby between recordings.
推荐
Karaoke and Entertainment System Microphone Input
Karaoke machines, toy microphones, and entertainment systems benefit from the MAX9814ETD+T's AGC and high-gain preamp because singers and children produce highly variable sound pressure levels at close range. The AGC prevents distortion when the user shouts into the mic and boosts the signal when the user sings softly, eliminating manual gain controls. The 2.7V-5.5V supply accepts a 3xAA battery pack or USB-derived 5V, and the low 3.7 mA supply current preserves battery life during extended karaoke sessions.
推荐
Two-Way Radio and Walkie-Talkie Mic Preamp
Two-way radios, walkie-talkies, and intercoms benefit from the MAX9814ETD+T's small footprint, integrated bias, and AGC that keeps the transmitted audio level consistent regardless of how the user holds the microphone. The 2.7V-5.5V supply covers a single Li-ion or 3xAA battery pack, while the <1 uA shutdown mode preserves standby battery life during long idle periods between transmissions. The low-noise architecture keeps squelch and DSP noise floors from being raised by the front-end itself.
推荐
推荐产品汇总
工程参考数据： MAX9814ETD+T ——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 | MAX9814ETD+ | MAX9814ETD+G45 |
|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices |
| Package | 14-pin TDFN (3x3 mm) | 14-pin TDFN (3x3 mm) - same | 14-pin TDFN (3x3 mm) - same |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| Supply Current | 3.7 mA typ | 3.7 mA typ | 3.7 mA typ |
| Preamplifier Gain | 40 / 50 / 60 dB | 40 / 50 / 60 dB | 40 / 50 / 60 dB |
| Microphone Bias | 2.5 V integrated | 2.5 V integrated | 2.5 V integrated |
| Shutdown Current | <1 uA | <1 uA | <1 uA |
| Packaging Code | +T (Tape and Reel) | + (cut tape / smaller reel) | +T (Tape and Reel) |
关键差异点
- Drop-in identical pinout and electrical specs vs MAX9814ETD+ （对比 MAX9814ETD+)
- Factory-tested gain accuracy with G45 suffix （对比 MAX9814ETD+G45)
- Lowest-quiescent integrated AGC mic preamp in this footprint （对比 MAX9814LEKA+T (SOT-23-8))
设计说明
The exposed thermal pad (EP, pin 14) of the MAX9814ETD+T MUST be soldered to a grounded copper pour to achieve the rated noise performance and thermal dissipation. Use at least 10 mm^2 of 1 oz copper tied to the analog ground plane. Place the 0.1 uF VDD bypass capacitor within 2 mm of pin 11 and the AGC timing capacitor (CT, pin 6) within 5 mm of pin 6 to minimize ground-loop pickup. Route microphone traces (MIC+, MIC-) as a short, balanced differential pair away from any switching converter or RF trace; a guard trace tied to GND between them and adjacent noisy signals is recommended.
Estimated: at 5 V supply and 3.7 mA quiescent current, the MAX9814ETD+T dissipates about 18.5 mW at idle, well below the TDFN-14 thermal limit. In shutdown (<1 uA) the dissipation drops to ~5 uW, making it suitable for battery-powered designs that spend most of their time idle. For best PSRR, place a 10 uF bulk + 0.1 uF ceramic bypass combination on VDD; the high PSRR of the integrated bias generator means additional filtering on the bias pin is usually unnecessary.
Do not leave the GAIN0/GAIN1 pins floating - they MUST be tied to VDD or GND via 100 kohm resistors to set a defined gain. Failure to do so can leave the preamp in an undefined state that draws excess current or produces distorted output. Also, the SHDN pin is active-low: drive it high for normal operation and low for shutdown; leaving it floating enables the device but can cause unpredictable startup behavior. Finally, do not exceed 5.5 V on VDD - even brief transients above 6 V can permanently damage the input ESD structure.
Keep the microphone capsule within 50 mm of the MIC+/MIC- pins and use a shielded cable or twisted pair to reject RF pickup from Bluetooth or WiFi radios. The charge pump flying capacitor on C1P/C1N (pins 12/13) requires a low-ESR ceramic; a 0.1 uF X7R 10 V part is typical. Avoid routing digital signals (I2S, I2C, SPI) directly under the microphone preamp section - these couple switching noise into the high-gain input stage and degrade SNR.
合规信息
RoHS compliant per Analog Devices product page. Not AEC-Q100 qualified - this part targets consumer/industrial audio, not automotive. Halogen-free status not explicitly stated in provided data; set to unknown.
