GC1307 from Gcore, 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	X1	input	Oscillator input. Connect to a standard 32.768 kHz crystal with a 12.5 pF load capacitance (CL). May alternatively be driven by an external 32.768 kHz oscillator, in which case X2 must be left floating.
2	X2	output	Oscillator output. Connect to the 32.768 kHz crystal opposite X1. Leave floating when X1 is driven by an external oscillator.
3	VBAT	power_in	Backup supply input for a standard 3 V lithium cell or other backup source (2.0 V to 3.5 V typical). Must be within the min/max limits for correct operation; tie to GND if backup is not used. RTC/RAM access is disabled below the power-fail trip point VPF = 1.25 x VBAT. A >48 mAh Li cell provides >10 years of backup at +25 C.
4	GND	power_in	Ground reference for all supplies and I/O.
5	SDA	bidirectional	I2C serial data input/output. Open-drain; requires an external pull-up resistor. The pull-up voltage may be as high as 5.5 V regardless of VCC.
6	SCL	input	I2C serial clock input used to synchronise data transfers on SDA. The pull-up voltage may be as high as 5.5 V regardless of VCC. Standard-mode 100 kHz only.
7	SQW/OUT	output	Square-wave / output driver. When enabled (SQWE=1) drives one of four frequencies (1 Hz, 4.096 kHz, 8.192 kHz, 32.768 kHz). Open-drain; requires an external pull-up (up to 5.5 V). Powered from VCC or VBAT. Leave floating if unused.
8	VCC	power_in	Main supply (4.5 V to 5.5 V, 5.0 V typical). Full device access when VCC is in range. When VBAT is present and VCC falls below VTP (~1.25 x VBAT), read/write is inhibited; timekeeping continues on VBAT.

Key specifications

Parameter	Value
Manufacturer	Gcore
Package	SOP-8
Category	RTC
Pins	8

CAD (KiCad official)

Symbol: GC1307
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOP-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`gc1307.step`	122 KB	You want the bare part, or you mark your own boards.
`gc1307-etched.step`	1.5 MB	You want the part with `GC1307` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 375 faces against 147 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: Gcore datasheet (13 pp, sha256 03896c33df3fb5e7, 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