# D3121F

**Silicore** · Isolation Amplifiers · SOP-8

D3121F from Silicore, in a SOP-8. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | OUT1 | output | Channel 1 audio output. AC-coupled (typ. 4.7 uF) to the downstream power amplifier stage. Output is inverted with unity voltage gain (Gv = -0.04 dB typical) relative to IN1. |
| 2 | Vm1 | passive | Channel 1 mid-bias / ripple-filter node. An external electrolytic capacitor (typ. 22 uF) is connected from this pin to GND to set the internal bias reference and stabilize ripple rejection. The Vm1:Vm2 external cap ratio should be kept at 2:1 for stable ripple rejection. |
| 3 | IN1 | input | Channel 1 audio signal input from the tape deck / tuner. AC-coupled through an external electrolytic capacitor (typ. 4.7 uF). Input resistance RIN = 55 kΩ typical (44-66 kΩ). |
| 4 | GND | power_in | Signal / device ground reference. Connected to the car-body / chassis ground at the source-end (tape deck / tuner) side, exploiting the on-chip op-amp CMRR to cancel body-noise voltage between the two ground references. |
| 5 | IN2 | input | Channel 2 audio signal input from the tape deck / tuner. AC-coupled through an external electrolytic capacitor (typ. 4.7 uF). Input resistance RIN = 55 kΩ typical (44-66 kΩ). |
| 6 | Vm2 | passive | Channel 2 mid-bias / ripple-filter node. An external electrolytic capacitor (typ. 10 uF) is connected from this pin to GND. The Vm1:Vm2 external cap ratio should be kept at 2:1 (e.g. 22 uF : 10 uF) for stable ripple rejection. |
| 7 | OUT2 | output | Channel 2 audio output. AC-coupled (typ. 4.7 uF) to the downstream power amplifier stage. Output is inverted with unity voltage gain (Gv = -0.04 dB typical) relative to IN2. |
| 8 | Vcc | power_in | Positive supply voltage. Recommended operating range 4-18 V (typ. 12 V); absolute maximum 18 V. Quiescent current IQ = 9 mA typ. (5.6-14 mA). Bypass with a 47 Ω series resistor and 220 uF electrolytic per the test/application circuit. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Silicore |
| Package | SOP-8 |
| Category | Op-amp/Cmp |
| Pins | 8 |

## Ordering variants

Same part, different packaging or reel option.

- `D3121FF`
- `D3121F`
- `D3121FN`

## 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 |  |  | 18 | V |  | 3 |
| Power dissipation (D3121F) | PD |  |  | 450 | mW | Ta=25C; reduce 4.5mW per C above 25C | 3 |
| Operating temperature | Topr | -30 |  | 85 | C |  | 3 |
| Storage temperature | Tstg | -55 |  | 125 | C |  | 3 |
| Supply voltage | Vcc | 4 | 12 | 18 | V | Ta=25C | 3 |
| Quiescent current | IQ | 5.6 | 9 | 14 | mA | VIN=0Vrms | 3 |
| Output noise voltage | VNO |  | 3.5 | 8 | μVrms | BPF=20Hz～20KHz | 3 |
| Voltage gain | GV | -1.5 | -0.04 | 1.5 | dB | Vo=-10dBm,Rg=0Ω | 3 |
| Maximum output voltage | VOM | 1.8 | 2 |  | Vrms | THD=0.1%,Vcc=8V | 3 |
| Total harmonic distortion | THD |  | 0.002 | 0.02 | % | Vo=0.7Vrms | 3 |
| Common mode rejection ratio | CMRR | 41 | 57 |  | dB |  | 3 |
| Common mode voltage | VCM | 2.5 | 3.75 |  | Vrms | Vcc=8V,CMRR=40dB | 3 |
| Ripple rejection ratio | RR | 72 | 80 |  | dB | fRR=100Hz, Rg=0Ω, VRR=-10dBm | 3 |
| Input resistance | RIN | 44 | 55 | 66 | KΩ |  | 3 |
| Channel separation | CS |  | 82 |  | dB | VIN=-10dBm, Rg=1.8KΩ/OPEN | 3 |
| Slew rate | SR |  | 2 |  | V/μs |  | 3 |

## CAD (KiCad official)

- Symbol: `D3121F`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `d3121f-etched.step` / `d3121f-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `d3121f.step` / `d3121f.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Silicore datasheet](docs/d3121f-datasheet.pdf) (None pp, sha256 `c9d5278c4698f7d7`, retrieved 2026-08-17, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/d3121f-datasheet.pdf)