SMD code P20
Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables.
P20 on a chip capacitor
0.2 pF
0.2 pF capacitor
The p is both the decimal point and the unit: 0.2 pF.
Check it with a meter
Lift one end and measure it on a capacitance range. A good one reads close to 0.2 pF. In circuit the meter also sees everything connected across it, so the reading means little until it is out. A failed one usually reads near 0 Ω, or a steady low resistance, on the ohms range, often from a crack. On the board a shorted capacitor shorts its whole rail. A failed reading does not change what to fit: the marking still says 0.2 pF.
On a transistor or diode body (SMA, SOT-23, SOT-323), P20 is a part code instead. Those parts are listed below.
The only part printed P20 in our tables
DDTA144EUA
- What it is
- Digital transistor (PNP, resistors built in)
- Maker
- Diodes Incorporated
- Package
- SOT-323
- Pins
- 3
- Pinout
- 1 base
- 2 emitter
- 3 collector
- Details
- PNP pre-biased (resistor-equipped) transistor; R1 = R2 = 47k
- Source
- From the manufacturer's datasheet
Is it dead?
Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.
Working, it reads
Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.
Dead, it reads
- Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
- From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
- Base to emitter near 0 Ω: failed short.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
- Watch for:
- On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Codes that begin with P20
For a marking with its end worn or burnt off. Each code has a page of its own.
Open this in the search to correct a character or try another package.