HT1621BQ from HGSEMI, in a LQFP-48(7x7). 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	/CS	input	Chip-select input, active low, with internal pull-up. When /CS is high, data/command transfers are inhibited and the serial interface is reset. When /CS is low, the host can transfer data and commands.
2	/RD	input	READ clock input with internal pull-up. RAM data is shifted out onto DATA on the falling edge of /RD; the host latches the data on the following rising edge.
3	/WR	input	WRITE clock input with internal pull-up. Data on DATA is latched into the HT1621B on the rising edge of /WR.
4	DATA	bidirectional	Serial data I/O for addresses, commands, and RAM data, with internal pull-up. Driven by the host during writes/commands and by the HT1621B during reads.
5	VSS	power_in	Ground reference (0 V).
6	OSCO	output	Crystal / external clock oscillator output. Connect a 32.768 kHz crystal between OSCI and OSCO, or leave OSCO floating when using the internal 256 kHz RC oscillator or an external clock on OSCI.
7	OSCI	input	Crystal / external clock input. Connects to a 32.768 kHz crystal (with OSCO) or accepts an external 256 kHz clock; leave floating if the internal RC oscillator is used.
8	VLCD	power_in	LCD bias-voltage input. Sets the LCD drive amplitude; VLCD must be less than or equal to VDD.
9	VDD	power_in	Main supply, 2.4 V to 5.2 V.
10	/IRQ	output	Time base / WDT overflow flag output, N-channel open-drain. Requires an external pull-up to VDD; goes low on overflow after IRQ_EN.
11	/BZ	output	Complementary buzzer drive output. Provides an anti-phase 2 kHz or 4 kHz square wave (selected by TONE2k/TONE4k, enabled by TONE ON) for driving a piezo buzzer differentially with BZ.
12	BZ	output	Buzzer drive output. Provides a 2 kHz or 4 kHz square wave (selected by TONE2k/TONE4k, enabled by TONE ON) for driving a piezo buzzer differentially with /BZ.
13	COM0	output	LCD common (backplane) driver output 0.
14	COM1	output	LCD common (backplane) driver output 1.
15	COM2	output	LCD common (backplane) driver output 2.
16	COM3	output	LCD common (backplane) driver output 3.
17	SEG31	output	LCD segment driver output 31.
18	SEG30	output	LCD segment driver output 30.
19	SEG29	output	LCD segment driver output 29.
20	SEG28	output	LCD segment driver output 28. Datasheet notes that on the 48-pin LQFP the SEG27/SEG28 pin ordering is non-standard; verify against silkscreen before layout.
21	SEG27	output	LCD segment driver output 27. Datasheet notes that on the 48-pin LQFP the SEG27/SEG28 pin ordering is non-standard; verify against silkscreen before layout.
22	SEG26	output	LCD segment driver output 26.
23	SEG25	output	LCD segment driver output 25.
24	SEG24	output	LCD segment driver output 24.
25	SEG23	output	LCD segment driver output 23.
26	SEG22	output	LCD segment driver output 22.
27	SEG21	output	LCD segment driver output 21.
28	SEG20	output	LCD segment driver output 20.
29	SEG19	output	LCD segment driver output 19.
30	SEG18	output	LCD segment driver output 18.
31	SEG17	output	LCD segment driver output 17.
32	SEG16	output	LCD segment driver output 16.
33	SEG15	output	LCD segment driver output 15.
34	SEG14	output	LCD segment driver output 14.
35	SEG13	output	LCD segment driver output 13.
36	SEG12	output	LCD segment driver output 12.
37	SEG11	output	LCD segment driver output 11.
38	SEG10	output	LCD segment driver output 10.
39	SEG9	output	LCD segment driver output 9.
40	SEG8	output	LCD segment driver output 8.
41	SEG7	output	LCD segment driver output 7.
42	SEG6	output	LCD segment driver output 6.
43	SEG5	output	LCD segment driver output 5.
44	SEG4	output	LCD segment driver output 4.
45	SEG3	output	LCD segment driver output 3.
46	SEG2	output	LCD segment driver output 2.
47	SEG1	output	LCD segment driver output 1.
48	SEG0	output	LCD segment driver output 0.

Key specifications

Parameter	Value
Manufacturer	HGSEMI
Package	LQFP-48(7x7)
Category	LED-drv
Pins	48

Ordering variants

Same part, different packaging or reel option.

HT1621BQQ
HT1621BQ
HT1621BQDQ
HT1621BDQ
HT1621BQM/TR
HT1621BM/TR
HT1621BQMS/TR
HT1621BMS/TR
HT1621BQDM/TR
HT1621BDM/TR

CAD (KiCad official)

Symbol: HT1621BQ
Footprint: Package_QFP:LQFP-48_7x7mm_P0.5mm
3D model: LQFP-48(7x7) (KiCad packages3D, STEP)

Provenance

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

Datasheet: HGSEMI datasheet (19 pp, sha256 38800fa307b08f96, 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