PC817 Reference Tables, Pins & Specifications

Pin reference

Signal names, electrical functions and connection guidance

DIP-4

Physical pin numbers4 pins

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PC817 pin functions and connections
Signal	Type	Function & connection
A	LED anode	Positive terminal of the internal infrared emitter. Forward current produces the light that controls the output transistor. Connection guidance Drive through a current-limiting resistor from the input circuit. Select resistance from the input voltage and forward voltage; never connect directly across a voltage source.
K	LED cathode	Negative terminal of the infrared emitter. Connection guidance Return to the input-side ground or input driver. This is not internally connected to the output emitter or its ground.
E	Phototransistor emitter	Emitter of the isolated NPN phototransistor. Connection guidance For the common-emitter example, return to the output-side ground. There is no base pin. Light from the input emitter controls collector current.
C	Phototransistor collector	Collector of the isolated NPN phototransistor. Connection guidance Connect a pull-up resistor to the output-side supply; take the output signal from this node. Light increases collector conduction and pulls the common-emitter output low. The output needs its own supply.

Selected devices and pinout

One gain grade · two lead forms

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Through-hole part	PC817X1NSZ1B	Rank A · four-pin DIP
SMD part	PC817X1NIP1B	Rank A · SMT gullwing DIP, not SOP-4
Pin 1 / pin 2	Anode / cathode	Input infrared LED
Pin 4 / pin 3	Collector / emitter	Output phototransistor
CTR for selected rank A	80–160%	Calculated from 4–8 mA collector current at IF = 5 mA, VCE = 5 V, 25°C
Isolation test	5 kVrms for 1 minute	40–60% RH; not a continuous working-voltage rating

Confirm the complete order code. PC817 variants and manufacturers need not have identical gain or limits.

Electrical characteristics

Sharp test conditions · 25°C

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
LED forward voltage	1.2 V typical; 1.4 V maximum	IF = 20 mA
LED reverse current	10 µA maximum	VR = 4 V
Collector dark current	100 nA maximum	VCE = 50 V; IF = 0
Collector saturation voltage	0.1 V typical; 0.2 V maximum	IF = 20 mA; IC = 1 mA
Input capacitance	30 pF typical; 250 pF maximum	V = 0; f = 1 kHz
Input-output capacitance	0.6 pF typical; 1.0 pF maximum	V = 0; f = 1 MHz

Forward voltage varies with current and temperature. CTR measured at VCE = 5 V does not guarantee the same transfer in saturation.

Response and loading

Load-dependent phototransistor response

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Rise time	4 µs typical; 18 µs maximum	VCE = 2 V; IC = 2 mA; RL = 100 Ω
Fall time	3 µs typical; 18 µs maximum	Same response-time test
Cut-off frequency	80 kHz typical	VCE = 5 V; IC = 2 mA; RL = 100 Ω; −3 dB
Output pull-up	Lower resistance demands more collector current	Higher resistance increases sensitivity to leakage and capacitance
Deep saturation	Can slow turn-off	Account for stored charge in switching designs
High-speed protocols	Use a suitable logic-output isolator when needed	The 80 kHz test is not a guaranteed digital data rate

The example uses a 10 kΩ pull-up and therefore does not inherit the 100 Ω switching-time test results.

Isolated logic input

5 V input side · separate 3.3 V output side

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Input resistance	750 Ω	Example assumes an approximately 1.2 V LED drop
Estimated LED current	5.07 mA	(5 − 1.2) / 750
Input resistor dissipation	Approximately 19.3 mW	IF² × R; 0.125 W or greater nominal rating provides margin
Output pull-up	10 kΩ to +3.3 V_B	Collector pin 4 is the output node
Low-state pull-up current	Up to approximately 0.33 mA	3.3 V / 10 kΩ, ignoring VCE(sat)
Grounds	GND_A and GND_B stay separate	No conductive link across the optocoupler

Illustrative low-voltage circuit: verify CTR across temperature and life, logic thresholds, drive capability and switching speed for the actual design.

Absolute maximum ratings

Stress limits at 25°C unless specified

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
Continuous LED current	50 mA	Derate with ambient temperature
LED reverse voltage	6 V	Avoid reverse stress in normal operation
Collector-emitter voltage	80 V	LED off
Emitter-collector voltage	6 V	Reverse output polarity limit
Collector current	50 mA	Also limited by power dissipation and temperature
LED / collector / total dissipation	70 / 150 / 200 mW	At 25°C; derating required
Operating / storage temperature	−30–100°C / −55–125°C	Ambient operation / unpowered storage

These are stress limits, not recommended continuous operating targets. Isolation-system design also depends on spacing, insulation and applicable standards.

Package and PCB geometry

Same electrical numbering in both packages

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Moulded body	6.5 × 4.6 mm nominal	3.5 mm nominal body height
Lead pitch	2.54 mm	Along each two-pin row
DIP footprint	7.62 mm row spacing	TEP pattern: 1.00 mm holes and 1.80 mm pads
SMD footprint	8.20 mm pad-row centres	Sharp reference pads: 2.20 × 1.70 mm
Pin 1 identification	Anode mark on body	Square through-hole pad / top-left SMD mark
Board routing	Preserve separation across the barrier	Avoid copper that bypasses the intended isolation

Dimensions follow Sharp’s mechanical drawings; check the ordered lead form and your fabricator’s tolerances.