PS9121-AX Equivalent & Substitute Parts

Part Overview

The PS9121-AX is a logic output optoisolator manufactured by CEL, designed for high-speed signal isolation applications. This component features a 3.75kV isolation voltage, 15Mbps data rate, and open collector output in a 5-SO surface mount package. The PS9121-AX is discontinued at DiGi Electronics, making the identification of functionally equivalent alternatives essential for ongoing system designs and maintenance.

Substiute Parts

PS9121-AX

CELIn Stock: 772PS9121-AX Datasheet

Current PartRFQ

HCPL-M611-560E

Broadcom LimitedIn Stock: 4062HCPL-M611-560E Datasheet

SimilarRFQ

PS9122-F3-AX

Renesas Electronics CorporationIn Stock: 18447PS9122-F3-AX Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the PS9121-AX is determined by strict alignment with critical electrical and mechanical parameters. The following parameters form the basis for substitution analysis:

• Isolation Voltage: Must equal 3750Vrms
• Package Configuration: Must be 6-SOIC (0.173", 4.40mm Width), 5 Leads
• Output Type: Must be open collector or functionally compatible derivative
• Number of Channels: Must be 1
• Input Type: Must be DC
• Mounting Type: Must be surface mount
• Environmental Compliance: Must maintain ROHS3 compliance and MSL 1 rating

The substitute parts identified (HCPL-M611-560E and PS9122-F3-AX) meet the primary isolation voltage, package, and channel requirements. However, they exhibit variations in data rate, supply voltage range, and propagation delay characteristics that must be evaluated for specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

HCPL-M611-560E (Broadcom Limited): This component is actively manufactured and maintained, offering superior output current capability (50 mA versus 25 mA). The supply voltage range (4.5V ~ 5.5V) differs from the PS9121-AX, requiring power supply design considerations. Common mode transient immunity is rated at 10kV/µs, below the original specification of 15kV/µs. Propagation delays match the original specification. Full ROHS3 compliance and MSL 1 rating are maintained. This substitute is suitable for applications where higher output current is beneficial and supply voltage alignment can be accommodated.

PS9122-F3-AX (Renesas Electronics): This component is actively manufactured by Renesas Electronics Corporation with extensive inventory availability. The supply voltage specification (7V fixed) differs from the PS9121-AX operating range. The data rate is significantly reduced (1Mbps versus 15Mbps), and propagation delays are substantially longer (700ns/500ns versus 75ns/75ns). Common mode transient immunity matches the original 15kV/µs specification. The extended operating temperature range (-40°C ~ 100°C) provides improved thermal margin. Full ROHS3 compliance and MSL 1 rating are maintained. This substitute is applicable only to low-speed data rate applications where timing margins are not critical.

Frequently Asked Questions (FAQ)

Q: Can the HCPL-M611-560E directly replace the PS9121-AX in existing designs?

A: Mechanical compatibility is ensured (identical package), and isolation voltage specifications match. However, the supply voltage range differs: HCPL-M611-560E requires 4.5V ~ 5.5V, while the original operates at 2.7V ~ 3.6V. This requires power supply circuit modification. Additionally, CMTI is 10kV/µs versus 15kV/µs. Pin-for-pin functionality is maintained.

Q: Under what conditions is the PS9122-F3-AX suitable as a substitute?

A: The PS9122-F3-AX substitution is appropriate exclusively for applications where data rate requirements do not exceed 1Mbps. The propagation delay is approximately 10 times longer than the original part. If timing-critical circuits or high-speed signal paths depend on the 15Mbps capability, this substitute is not appropriate. The fixed 7V supply voltage requirement must also be accommodated in the circuit design.

Q: Are both substitute parts form-factor compatible with the PS9121-AX?

A: Both substitute parts share the identical package configuration: 6-SOIC (0.173", 4.40mm Width) with 5 leads. PCB footprint compatibility is assured. Pin numbering and functional pin assignments require verification against individual datasheets to ensure correct circuit connections.

Q: What compliance considerations apply to these substitute parts?

A: All three components—the PS9121-AX and both substitute parts—are ROHS3 compliant and rated at MSL 1 (Unlimited moisture sensitivity level). No degradation in environmental compliance or handling requirements occurs with either substitute. All components are EAR99 ECCN classified and have REACH Unaffected status.

Q: Why does data rate differ among these optoisolators?

A: Data rate capability is an intrinsic design characteristic of the optoisolator architecture and internal circuitry. The PS9121-AX operates at 15Mbps, HCPL-M611-560E at 10MBd, and PS9122-F3-AX at 1Mbps. These differences reflect different silicon designs and are not interchangeable without circuit-level analysis of timing requirements.

Q: What inventory considerations should influence part selection?

A: The PS9121-AX is discontinued at DiGi Electronics. The HCPL-M611-560E has 4,017 pieces in stock, and the PS9122-F3-AX has 18,342 pieces in stock with packaging in Cut Tape and Digi-Reel formats. Long-term design decisions should prioritize the actively manufactured substitutes to ensure supply chain continuity.