The PLCC-20 package is the 20-lead member of the JEDEC MO-047 family — a square plastic leaded chip carrier with a 7.37–8.38 mm (0.290–0.330 in) lead-tip span and the standard 1.27 mm PLCC lead pitch. It’s the package Atmel/Microchip used for the ATF16V8B PLD family and a handful of other 20-pin-equivalent logic parts. This page gives the verified outline dimensions, a real pin-configuration table, and the sockets that actually fit it.

Key takeaways

• JEDEC outline MO-047-AA. Lead-tip span 7.37–8.38 mm (0.290–0.330 in) square, lead pitch 1.27 mm (0.05 in) fixed.
• Lead width runs 0.33–0.53 mm — use that to size solder pads if hand-soldering directly to the board.
• There is no single fixed “PLCC-20 pinout” — pin function depends on the specific IC. Below is the verified pinout for the ATF16V8B PLD family as a worked example.
• The classic through-hole PLCC-20 socket (Adam Tech PLCC-20-AT) is marked Obsolete at DigiKey; ASSMANN WSW’s A-CCS 020-Z-SM is an active, electrically equivalent alternative.
• Standard commercial PLCC-20 sockets are rated 1 A per contact — check that figure before routing shared current through more than one pin.

PLCC-20 Dimensions

The PLCC-20 is registered under JEDEC MO-047, variant AA. The package outline drawing gives a lead-tip-to-lead-tip body span of 7.37–8.38 mm (0.290–0.330 in) on each side, with leads on all four edges at the fixed 1.27 mm PLCC pitch. Lead width is specified at 0.33–0.53 mm (0.013–0.021 in).

Parameter	Value	Source
JEDEC outline	MO-047-AA	JEDEC / Analog Devices P-20 package drawing
Lead count	20	JEDEC / Analog Devices P-20 package drawing
Lead-tip span (body)	7.37–8.38 mm (0.290–0.330 in), square	Analog Devices P-20 package drawing
Lead pitch	1.27 mm (0.05 in) BSC	Analog Devices P-20 package drawing
Lead width	0.33–0.53 mm (0.013–0.021 in)	Analog Devices P-20 package drawing
Standoff (min.)	0.51 mm (0.021 in) approx., per lead detail	Analog Devices P-20 package drawing

Worked example: at the fixed 1.27 mm pitch, a 0.53 mm maximum lead width leaves a minimum 0.74 mm gap between adjacent lead edges (1.27 mm − 0.53 mm). A solder pad drawn to roughly 0.6–0.7 mm keeps the joint inspectable without bridging the next pad — the same margin applies whether you’re soldering the IC directly to the board or laying out pads under a socket footprint.

PLCC-20 Pinout

PLCC-20 doesn’t have one universal pinout the way a 555 timer’s DIP-8 does — pin function is defined per IC, not per package. The clearest documented example is the Microchip/Atmel ATF16V8B family of programmable logic devices, which datasheets a full pin-configuration table across TSSOP, DIP/SOIC, and PLCC in a single numbering scheme:

Pin	Function	Pin	Function
1	I/CLK (clock input)	11	I9/OE (output enable)
2	I1 (logic input)	12	I/O
3	I2 (logic input)	13	I/O
4	I3 (logic input)	14	I/O
5	I4 (logic input)	15	I/O
6	I5 (logic input)	16	I/O
7	I6 (logic input)	17	I/O
8	I7 (logic input)	18	I/O
9	I8 (logic input)	19	I/O
10	GND	20	VCC (+5 V supply)

The ATF16V8B datasheet notes that pin 1 and pin 11 are permanently configured as CLK and OE respectively in registered mode, and that the same pin numbering is used across the TSSOP, DIP/SOIC, and PLCC package options for this device family — a detail worth checking before assuming a PLCC part drops into a DIP-numbered schematic symbol unchanged. For any other PLCC-20 part, pull the pin-configuration table from that specific datasheet; don’t reuse this one.

PLCC-20 Sockets

Sockets for the PLCC-20 come in through-hole and surface-mount styles, both built around the same 1.27 mm mating pitch. Two real parts show the range and the lifecycle risk that comes with an older package size:

Parameter	Adam Tech PLCC-20-AT (THT)	ASSMANN WSW A-CCS 020-Z-SM (SMT)
Mounting	Through hole, 0.100 in (2.54 mm) post pitch	Surface mount
Mating pitch	0.050 in (1.27 mm)	1.27 mm
Contact material / plating	Phosphor bronze, tin, 80 µin thick	Phosphor bronze, tin over nickel
Current rating	1 A	1.0 A
Voltage rating	not stated by this distributor listing	100 V
Contact resistance	30 mΩ	not stated by this distributor listing
Operating temperature	−55 °C to +105 °C	not stated by this distributor listing
Housing material	PBT, glass filled, UL94V-0	Nylon
Lifecycle status	Obsolete (per DigiKey)	Active

The lifecycle line is the one to check first: if a BOM still calls out the Adam Tech PLCC-20-AT, it needs a substitute before the next build — DigiKey lists it Obsolete with stock depleting. The ASSMANN part is electrically equivalent (same pitch, same current rating, same phosphor-bronze-with-tin-plating contact approach) but is a surface-mount part, so it isn’t a drop-in mechanical replacement on a board laid out for through-hole pads.

If the socket is for test or programming rather than a permanent board position, Aries Electronics’ Series 537 “live bug” ZIF test socket accepts JEDEC MO-047AA–AH PLCCs — including the 20-lead AA variant — through interchangeable insert plates, at a suggested PCB hole size of 0.032 in ± 0.002 in (0.81 mm ± 0.05 mm). That hole dimension is specific to that socket’s solder tails; it is not a JEDEC package dimension, so don’t reuse it for a different socket vendor’s PLCC-20 part.

Choosing Between Direct Solder and a Socket

• Production board, part won’t be swapped after assembly → solder the PLCC-20 directly; skip the socket’s added height and contact resistance.
• Bring-up board, or the part is a field-programmable PLD/EEPROM that gets reprogrammed by hand → through-hole or SMT commercial socket, sized to your board’s mounting style.
• Test, burn-in, or programmer fixture → ZIF test socket rated for a stated mating-cycle count, not a board-mount part with no cycle rating.

FAQ

What are the dimensions of a PLCC-20 package?

Per JEDEC MO-047-AA, the PLCC-20 has a square lead-tip span of 7.37–8.38 mm (0.290–0.330 in) with 20 leads at 1.27 mm (0.05 in) pitch and a lead width of 0.33–0.53 mm.

Does PLCC-20 have a standard pinout?

No — pin function is defined per IC, not by the package. The ATF16V8B PLD family is a documented example with pin 1 as clock input, pin 10 as ground, pin 11 as output enable, and pin 20 as VCC; other PLCC-20 parts assign pins differently.

What socket fits a PLCC-20 package?

Any socket built to JEDEC MO-047-AA at 1.27 mm pitch, in through-hole or surface-mount styles. The Adam Tech PLCC-20-AT (through-hole) is now marked Obsolete; ASSMANN WSW’s A-CCS 020-Z-SM (surface-mount) is an active alternative with equivalent current rating.

What is the lead pitch on a PLCC-20?

1.27 mm (0.05 in), the same fixed pitch used across every JEDEC PLCC size from 20 to 84 leads.

Can a PLCC-20 be hand-soldered without a socket?

Yes. With a 0.53 mm maximum lead width at 1.27 mm pitch, a 0.6–0.7 mm solder pad leaves enough clearance to hand-solder and inspect each joint without bridging adjacent pads.

The Decision

For a new design, treat the PLCC-20 as a known-good footprint with an unknown pinout: get the outline dimensions from JEDEC MO-047-AA, but pull the pin assignment from the specific part’s own datasheet every time. For sourcing, check socket lifecycle status before you commit a BOM — the Adam Tech through-hole part that’s been the default choice for years is now Obsolete, and the surface-mount ASSMANN equivalent isn’t a mechanical drop-in if your board is laid out for through-hole pads.