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U4082BG-2
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UTC Unisonic Tech Audio Amplifiers, SOP-28. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
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Symbol & Footprint
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Datasheet
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README
markdownU4082BG-2
UTC Unisonic Tech · Audio Amplifiers · SOP-28
U4082BG-2 from UTC Unisonic Tech, in a SOP-28. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | FO | output | Output of the filter, with an output impedance of less than 50Ω. |
| 2 | FI | input | Input of the filter, with an input impedance of less than 1MΩ. |
| 3 | CD | input | Chip disable input: logic low (below 0.8V) selects normal operation and logic high (above 2V) disables the IC, with about 90kΩ nominal input impedance. |
| 4 | VCC | power_in | Supply pin requiring +2.8V to +6.5V at 5mA; when VCC falls below 3.5V in receive mode, the AGC reduces the receive attenuator gain by 25dB. |
| 5 | HTO+ | output | Output of the second hybrid amplifier, whose gain is internally fixed at -1. |
| 6 | HTO- | output | Output of the first hybrid amplifier, whose gain is set by external resistors. |
| 7 | HTI | input | Input and summing node of the first hybrid amplifier, with DC level about equal to VB. |
| 8 | TXO | output | Output of the transmit attenuator, with DC level about VB. |
| 9 | TXI | input | Input of the transmit attenuator, with a maximum signal level of 350 mVrms and 10kΩ input impedance. |
| 10 | MCO | output | Output of the microphone amplifier, whose gain is set by external resistors and which is limited to ±1 mA load current. |
| 11 | MCI | input | Summing node of the microphone amplifier input, with DC level VB. |
| 12 | MUT | input | Mute input: logic low (below 0.8V) gives normal operation and logic high (above 2V) mutes the microphone amplifier only, with 90kΩ input impedance. |
| 13 | VLC | input | Volume control input: VLC=VB gives maximum receive attenuator gain, the receive gain is down 35dB at VLC=0.3×VB, and it does not affect transmit modes. |
| 14 | CT | passive | Mode-switching timing node whose external RC sets the circuit response time. |
| 15 | VB | power_out | Output at about Vcc/2 that serves as the system AC ground and bias for the volume control, and requires a filter capacitor. |
| 16 | CPT | passive | Pin where the RC sets the time constant of the transmit background noise monitor. |
| 17 | TLI2 | input | Input to the transmit level detector on the microphone/speaker side. |
| 18 | TLO2 | output | Output of the transmit level detector on the microphone/speaker side, which is also the input to the transmit background monitor. |
| 19 | RLO2 | output | Output of the receive level detector on the microphone/speaker side. |
| 20 | RLI2 | input | Input to the receive level detector on the microphone/speaker side. |
| 21 | RXI | input | Input to the receive attenuator and dial tone detector, with a maximum input level of 350 mVrms and 10kΩ input impedance. |
| 22 | RXO | output | Output of the receive attenuator, with DC level at VB. |
| 23 | TLI1 | input | Input to the transmit level detector on the line side. |
| 24 | TLO1 | output | Output of the transmit level detector on the line side, which is also the input to the transmit background monitor. |
| 25 | RLO1 | output | Output of the receive level detector on the line side. |
| 26 | RLI1 | input | Input to the receive level detector on the line side. |
| 27 | CPR | passive | Pin where the RC sets the time constant of the receive background noise monitor. |
| 28 | GND | power_in | Ground. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | UTC Unisonic Tech |
| Package | SOP-28 |
| Category | Amplifiers/Comparators |
| Pins | 28 |
Electrical characteristics
Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).
| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Supply Voltage | VCC | -1 | 7 | V | TA=25°C; voltages referred to pin 22 | 4 | |
| Voltage at Pin 3 | V3 | -1 | V | TA=25°C; referred to pin 22; max printed as VCC+1 | 4 | ||
| Voltage at Pin 12 (mute) | V12 | -1 | V | TA=25°C; referred to pin 22; max printed as VCC+1 | 4 | ||
| Voltage at Pin 13 (VLC) | V13 | -1 | V | TA=25°C; referred to pin 22; max printed as VCC+0.5 | 4 | ||
| Voltage at Pin 9, Pin 21, and Pin 2 | V9, 21, 2 | -0.5 | V | TA=25°C; referred to pin 22; max printed as VCC+0.5 | 4 | ||
| Storage Temperature | TSTR | -65 | 150 | °C | TA=25°C; referred to pin 22 | 4 | |
| Supply Voltage | V4 | 3.5 | 6.5 | V | 4 | ||
| Voltage at Pin 3 | V3 | 0 | V | max printed as VCC | 4 | ||
| Voltage at Pin 12 (MUTE) | V12 | 0 | V | max printed as VCC | 4 | ||
| IVB Current (Pin 15) | IVB | 500 | µA | 4 | |||
| Attenuator Input Signal Voltage at Pin 9, Pin 21 | V9, V21 | 350 | mVrms | 4 | |||
| Load Current RXO, TXO (Pin8, Pin 22) | -2 | 2 | mA | printed as 0~±2 mA | 4 | ||
| Load Current MCO (Pin 10) | -1 | 1 | mA | printed as 0~±1 mA | 4 | ||
| Load Current HTO-, HTO+ (Pin 6, Pin 5) | -0.5 | 0.5 | mA | printed as 0~±0.5 mA | 4 | ||
| Ambient Operating Temperature | TOPR | -20 | 60 | °C | 4 | ||
| V+ Supply Current | ICC | 5.5 | 8 | mA | VCC=6.5V, CD=0.8V | 5 | |
| V+ Supply Current | ICC | 600 | 800 | μA | VCC=6.5V, CD=2V | 5 | |
| CD Input Resistance | RCD | 50 | 90 | kΩ | VCC=VCD=6.5V | 5 | |
| CD Input Voltage High | VCDH | 2 | V | max printed as VCC | 5 | ||
| CD Input Voltage Low | VCDL | 0.8 | V | 5 | |||
| VB Output Voltage | VB | 1.3 | V | VCC=3.5V | 5 | ||
| VB Output Voltage | VB | 1.8 | 2.1 | 2.4 | V | VCC=5V | 5 |
| VB Output Resistance | ROVB | 400 | Ω | IVB=1mA | 5 | ||
| VB Power Supply Rejection Ratio | PSRR | 54 | dB | CVB=220µF, f=1kHz | 5 | ||
| Receive Attenuator Gain | GRX | 4 | 6 | 8 | dB | RX Mode, RXI=150mVrms, VCC=5V, f=1kHz, VLC=VB | 5 |
| Gain Change | ΔGRX1 | -0.5 | 0 | 0.5 | dB | VCC=3.5V vs. VCC=5V | 5 |
| AGC Gain Change | ΔGRX2 | -25 | -15 | dB | VCC=3.5V vs. VCC=5V | 5 | |
| Idle Mode Receive Gain | GRXI | -22 | -20 | -17 | dB | Idle Mode, RXI=150mVrms | 5 |
| RX to TX Mode Range | ΔGRX3 | 49 | 52 | 54 | dB | 5 | |
| Volume Control Range | VCR | 27 | 35 | dB | 5 | ||
| ΔRXO DC Voltage | ΔVRXO | -150 | 150 | mV | RX to TX Mode | 5 | |
| RXO High Voltage | VRXOH | 3.7 | V | IOUT=-1mA, RXI=VB+1.5V | 5 | ||
| RXI Input Resistance | RRXI | 7 | 10 | 14 | kΩ | RXI<350mVrms | 5 |
| Transmit Attenuator Gain | GTX | 4 | 6 | 8 | dB | TX Mode, TXI=150mVrms, f=1kHz | 5 |
| Idle Mode Transmit Gain | GTXI | -22 | -20 | -17 | dB | Idle Mode, TXI=150mVrms | 5 |
| TX to Rx Mode Range | ΔGTXI | 49 | 52 | 54 | dB | 5 | |
| TXO High Voltage | VTXOH | 3.7 | V | IOUT=-1mA, TXI=VB+1.5V | 5 | ||
| TXI Input Resistance | RTXI | 7 | 10 | 14 | kΩ | TXI<350mVrms | 5 |
| Gain Tracking | GTR | -0.1 | 0.1 | dB | GRX+GTX, @TX, IDIE, RX | 5 | |
| CT Source Current | ICTR | -85 | -60 | -40 | µA | Switching to RX Mode | 5 |
| CT Sink Current | ICTT | 40 | 60 | 85 | µA | Switching to TX Mode | 5 |
| CT Fast Idle Internal Resistance | RFI | 1.5 | 2 | 3.6 | kΩ | 5 | |
| Dial Tone Detector Threshold | VDT | 10 | 15 | 20 | mV | 5 | |
| Microphone Amplifier Output Offset | MCOVOS | -50 | 0 | 50 | mV | VMCO-VB, RF=180 kΩ | 6 |
| Microphone Output High Voltage | VMCOH | 3.7 | V | IOUT=1mA, VCC=5V | 6 | ||
| Microphone Output Low Voltage | VMCOL | 200 | mV | IOUT=1mA | 6 | ||
| MUT Input Resistance | RMUT | 50 | 90 | kΩ | VCC=VMUT=6.5V | 6 | |
| MUT High Input Voltage | VMUTH | 2 | V | max printed as Vcc | 6 | ||
| MUT Low Input Voltage | VMUTL | 0 | 0.8 | V | 6 | ||
| HTO- Offset | HVOS | -20 | 0 | 20 | mV | VHTO-~VB, RF=51kΩ | 6 |
| HTO- High Voltage | VHT-H | 3.7 | V | IOUT=-5mA | 6 | ||
| HTO- Low Voltage | VHT-L | 250 | mV | IOUT=+5mA | 6 | ||
| HTO+ High Voltage | VHT+H | 3.7 | V | IOUT=-5mA | 6 | ||
| HTO+ Low Voltage | VHT+L | 450 | mV | IOUT=+5mA | 6 | ||
| Filter Voltage Offset at FO | FOVOS | -200 | -90 | 0 | mV | VFO-VB, 220kΩ from VB to FI | 6 |
| FO Sink Current | IFO | 150 | 260 | 400 | µA | 6 | |
| System Distortion RX Mode | THDR | 0.5 | 3 | % | f=1kHz; from FI to RXO, FO connected to RXI | 6 | |
| System Distortion TX Mode | THD | 0.8 | 3 | % | f=1kHz; from MCI to HTO-/HTO+, includes TX attenuator | 6 |
CAD (KiCad official)
- Symbol:
U4082BG-2 - Footprint:
Package_SO:SOP-28_8.4x18.16mm_P1.27mm - 3D model: SOP-28 (KiCad packages3D, STEP)
- 3D model files:
u4082bg-2-etched.step/u4082bg-2-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);u4082bg-2.step/u4082bg-2.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: UTC Unisonic Tech datasheet (13 pp, sha256
d61b3165690b111e, retrieved 2026-10-18, tier: lcsc) - Extractor: parts-factory
2.0.0/extract_pins 0.3, primaryclaude-haiku-5-5(text), consensusclaude-sonnet-5-5(agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish. - CAD: KiCad official libraries (CC-BY-SA 4.0).