Is there a pin-compatible replacement for TLP521GB(UMW)?

Parts like the MSKSEMI PC817B-MS and PC817C-MS share the same DIP-4/SOP-4 package and pinout. However, they are not electrically identical, featuring a lower collector-emitter voltage (35V vs 55V), which requires careful engineering review before use.

What risks should I check before replacing TLP521GB(UMW)?

Key risks include: 1) Collector-Emitter Voltage (VCEO), as many substitutes have a lower rating than the target's 55V. 2) Isolation Voltage, ensuring the replacement meets the 5000Vrms requirement. 3) Current Transfer Ratio (CTR), as different bins can affect circuit timing and gain.

TLP521GB(UMW) Alternatives, Datasheet & Cross Reference | UMW

Finding a substitute for the TLP521GB(UMW) optocoupler requires careful matching of its 5kV isolation, 55V collector voltage, and 100% minimum CTR. Several alternatives exist but often involve compromises in voltage ratings.

AI replacement insight

Electrical riskhigh

Many alternatives have lower VCEO or isolation voltage.

Package risklow

The DIP-4/SOP-4 package is very common.

Sourcing riskmedium

The target is from a smaller manufacturer; alternatives from larger vendors are plentiful but have parametric differences.

Can it be replaced directly?

No direct, 1-to-1 replacement has been identified. All candidates require review due to parametric differences, primarily in voltage ratings.

Best replacement path

Cross-reference to another vendor's '521' or '817' type optocoupler, then verify VCEO, Isolation Voltage, and CTR bin.

Main risk

The main risk is substituting a part with a lower Collector-Emitter Voltage (VCEO), which could lead to device failure under normal operating conditions.

Recommended alternatives

Similar package and CTR, but lower voltage and current ratings require review.

View details

Alternative comparison matrix

Feature / factor	TLP521GB(UMW)	PC817B-MS	PC817C-MS	VOS617A-8T	Compatibility / risk
Package	DIP-4 / SOP-4	DIP-4 / SOP-4	DIP-4 / SOP-4	4-SOIC	DIP-4 / SOP-4 / 4-SOIC — Package matches, enabling form-fit compatibility.; PC817C-MS: Package matches, enabling form-fit compatibility.; VOS617A-8T: Likely compatible with SOP-4 variant of target.
Voltage	5000 Vrms	5000 Vrms	35 V	80V (from datasheet)	5000 Vrms / 35 V / 80V (from datasheet) — Isolation voltage matches.; PC817C-MS: VCEO is significantly lower, a critical downgrade.; VOS617A-8T: VCEO is higher, providing more margin.
Ctr	100% min	130% - 260%	200-400%	130% - 260%	130% - 260% / 200-400% — CTR range is higher and narrower than target's minimum.; PC817C-MS: Higher CTR bin may alter circuit performance.; VOS617A-8T: CTR range is a good match.
Current	70 mA	50 mA	50 mA	-	50 mA — Max forward current is lower.; PC817C-MS: Max forward current is lower.
Pinout	4	-	-	Missing	Missing — Pin count is missing from source data, requires verification.

Application & sourcing insights

Questions & answers

The PC817 series (like PC817B/C) is functionally similar but has a lower 35V collector-emitter voltage. The VOS617A series has a higher 80V rating but lower 3.75kV isolation. The best choice depends on which parameter is most critical for your application.