NS4165B from Shenzhen Nsiway Tech, in a ESOP-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	SD	input	Shutdown control input. High level puts the amplifier into power-down; low level enables normal operation. Internal pull-down means the part is ON when the pin is left floating. Logic thresholds: VIH ≥ 0.7·VDD, VIL ≤ 0.7 V.
2	Bypass	passive	Internal reference voltage (VDD/2) bypass node. Connect an external decoupling capacitor (typically 1 µF) to GND to stabilize the mid-rail bias and minimize pop/click noise at start-up.
3	AB/D	input	Class-AB / Class-D mode select input. High level selects Class-D operation; low level selects Class-AB. Internal pull-up defaults to Class-D when the pin is left floating. Logic thresholds: VIH ≥ 0.7·VDD, VIL ≤ 0.7 V.
4	INN	input	Inverting analog audio signal input. AC-coupled through a series input capacitor Ci and gain-setting resistor Ri. Closed-loop gain Av = 300 kΩ / Ri (internal feedback resistor 300 kΩ, ±10%).
5	VON	output	Negative BTL speaker output. Drives one terminal of the loudspeaker directly (filterless in Class-D). Delivers up to 5.4 W into 2Ω (Class-D, 10% THD, VDD=5V) together with VOP.
6	VDD	power_in	Supply voltage input. Recommended operating range 3.0 V to 5.5 V (absolute maximum 6.5 V). Bypass locally with 100 µF in parallel with a 1 µF ceramic capacitor as close to the pin as possible.
7	GND	power_in	Device ground / power return. Also serves as the thermal path together with the ESOP-8 exposed pad; connect to a solid ground plane using a star topology for the power/ground routing.
8	VOP	output	Positive BTL speaker output. Drives the opposite terminal of the loudspeaker from VON. Together the differential pair supplies up to 5.4 W into 2Ω at VDD=5V with 90% peak efficiency in Class-D mode.

Key specifications

Parameter	Value
Manufacturer	Shenzhen Nsiway Tech
Package	ESOP-8
Category	Op-amp/Cmp
Pins	8

CAD (KiCad official)

Symbol: NS4165B
Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm
3D model: ESOP-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`ns4165b.step`	193 KB	You want the bare part, or you mark your own boards.
`ns4165b-etched.step`	1.4 MB	You want the part with `NS4165B` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 358 faces against 63 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: Shenzhen Nsiway Tech datasheet (10 pp, sha256 ebcb3f8ca7f9c49d, 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