SN74HC688PWR from Texas Instruments, in a TSSOP-20. 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	OE	input	Active-low output enable. When held high, the P=Q output is forced to the high level regardless of the data inputs; when held low, the comparator output reflects the P vs Q comparison.
2	P0	input	Bit 0 of the P input word. Compared against Q0 by an internal XNOR stage; must be driven to a valid CMOS level (VIH/VIL per Recommended Operating Conditions).
3	Q0	input	Bit 0 of the Q input word. Compared against P0 by an internal XNOR stage.
4	P1	input	Bit 1 of the P input word. Compared against Q1.
5	Q1	input	Bit 1 of the Q input word. Compared against P1.
6	P2	input	Bit 2 of the P input word. Compared against Q2.
7	Q2	input	Bit 2 of the Q input word. Compared against P2.
8	P3	input	Bit 3 of the P input word. Compared against Q3.
9	Q3	input	Bit 3 of the Q input word. Compared against P3.
10	GND	power_in	Ground reference (0 V). Return path for VCC supply current and logic input/output reference.
11	P4	input	Bit 4 of the P input word. Compared against Q4.
12	Q4	input	Bit 4 of the Q input word. Compared against P4.
13	P5	input	Bit 5 of the P input word. Compared against Q5.
14	Q5	input	Bit 5 of the Q input word. Compared against P5.
15	P6	input	Bit 6 of the P input word. Compared against Q6.
16	Q6	input	Bit 6 of the Q input word. Compared against P6.
17	P7	input	Bit 7 (MSB) of the P input word. Compared against Q7.
18	Q7	input	Bit 7 (MSB) of the Q input word. Compared against P7.
19	P=Q	output	Active-low equality output. Drives low when all eight P bits equal the corresponding Q bits and OE is low; drives high otherwise or whenever OE is high. Rated for ±4 mA drive at 5 V (up to 10 LSTTL loads).
20	VCC	power_in	Positive supply voltage, 2 V to 6 V (5 V nominal). A 0.1-µF bypass capacitor placed close to this pin is recommended; paralleling with a 1-µF cap is common.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	TSSOP-20
Category	Op-amp/Cmp
Pins	20

Ordering variants

Same part, different packaging or reel option.

SN74HC688PWR
SN74HC688PWRE4
SN74HC688PWRPWT
SN74HC688PWRDW
SN74HC688PWRDWR
SN74HC688PWRDWRE4
SN74HC688PWRDWRG4
SN74HC688PWRN
SN74HC688PWRJ
SN74HC688PWRFK

CAD (KiCad official)

Symbol: SN74HC688PWR
Footprint: Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm
3D model: TSSOP-20 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (24 pp, sha256 d600a33f4ebb7089, 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