BA3123F-E2 from ROHM, 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 electrolytic) to the power amplifier input. Maximum output swing V_OM ~2.0 Vrms at V_CC = 8 V, THD = 0.1 %.
2	VM1	passive	Channel 1 common-mode reference / noise-cancel input. External electrolytic capacitor (typ. 4.7 uF) to the source (tape deck/tuner) ground so the op-amp can subtract the car-body noise voltage from IN1. Larger caps here improve low-frequency CMRR (see Figure 10).
3	IN1	input	Channel 1 audio input. AC-coupled (typ. 4.7 uF electrolytic) from the tuner/tape-deck output. Input resistance R_IN typ. 55 kOhm (44-66 kOhm).
4	GND	power_in	Ground reference for the IC. Tied to the local (power-amplifier / car body) ground; the isolation topology intentionally references the IC ground separately from the source ground.
5	IN2	input	Channel 2 audio input. AC-coupled (typ. 4.7 uF electrolytic) from the tuner/tape-deck output. Input resistance R_IN typ. 55 kOhm (44-66 kOhm).
6	VM2	passive	Channel 2 common-mode reference / noise-cancel input. External electrolytic capacitor (typ. 10 uF in the front-page circuit) to the source ground so the op-amp can subtract the car-body noise voltage from IN2. Cap value trades off low-frequency CMRR vs. board area.
7	OUT2	output	Channel 2 audio output. AC-coupled (typ. 4.7 uF electrolytic) to the power amplifier input. Maximum output swing V_OM ~2.0 Vrms at V_CC = 8 V, THD = 0.1 %.
8	VCC	power_in	Positive supply. Recommended operating range 4 V to 18 V (typ. 12 V), absolute maximum 18 V. Quiescent current I_Q typ. 9.0 mA (max 14 mA). Bypass locally to GND.

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

BA3123F-E2

CAD (KiCad official)

Symbol: BA3123F-E2
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: ROHM datasheet (15 pp, sha256 7d7f8f0e50bbea12, retrieved 2026-08-17, tier: manufacturer)
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