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

CAD (KiCad official)

Symbol: D3121F
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOP-8 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Silicore datasheet (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