PI5A121CE Equivalent & Substitute Parts

Part Overview

The PI5A121CE is a single-circuit SPST-NO (Normally Open) analog switch manufactured by Diodes Incorporated, designed for low-impedance signal routing applications. This component features a 10Ohm on-state resistance and operates across a 2V to 6V single supply voltage range. The part is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Switch Circuit Type	SPST - NO (Single Pole Single Throw - Normally Open)
Multiplexer/Demultiplexer Configuration	1:1
Number of Circuits	1
On-State Resistance (Max)	10Ohm
Channel-to-Channel Matching (ΔRon)	200mOhm
Supply Voltage Range (Single)	2V ~ 6V
Switch Time (Ton/Toff)	15ns / 7ns
-3dB Bandwidth	326MHz
Charge Injection	1.6pC
Channel Capacitance (CS(off)/CD(off))	5.5pF / 5.5pF
Leakage Current (IS(off)) Max	200pA (Typ)
Operating Temperature Range	-40°C ~ 85°C
Package Type	SC-70-5 (5-TSSOP)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PI5A121CE is determined by strict adherence to the following electrical and mechanical criteria:

Primary Substitution Criteria:

Switch circuit topology: SPST - NO configuration
Circuit count: Single circuit (1:1 multiplexer/demultiplexer)
Package compatibility: SC-70-5 (5-TSSOP, SOT-353)
On-state resistance: Must accommodate applications designed for 10Ohm nominal performance
Supply voltage overlap: Minimum compatibility with 2V ~ 6V range or subset thereof
Operating temperature: -40°C minimum and 85°C maximum or broader range

Identified Substitute Parts:

ISL43L110IHZ-T (Renesas Electronics Corporation) — Primary substitute with superior low-voltage capability and lower on-state resistance
74HCT1G66GW-Q100H (Nexperia USA Inc.) — Alternative with automotive qualification and extended temperature range

Parameter Comparison

Parameter	PI5A121CE (Main)	ISL43L110IHZ-T	74HCT1G66GW-Q100H
Manufacturer	Diodes Incorporated	Renesas Electronics	Nexperia USA Inc.
Switch Circuit	SPST - NO	SPST - NO	SPST - NO
Multiplexer Configuration	1:1	1:1	1:1
Number of Circuits	1	1	1
On-State Resistance (Max)	10Ohm	220mOhm (Typ)	95Ohm
Supply Voltage Range	2V ~ 6V	1.1V ~ 4.5V	4.5V ~ 5.5V
Switch Time (Ton/Toff)	15ns / 7ns	15ns / 10ns	30ns / 44ns
-3dB Bandwidth	326MHz	Not specified	200MHz
Leakage Current (IS(off)) Max	200pA (Typ)	30nA	1µA
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C
Package	SC-70-5	SC-70-5	5-TSSOP
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

ISL43L110IHZ-T Selection Criteria: This substitute is recommended for applications requiring extended low-voltage operation below 2V, as it supports 1.1V minimum supply. The on-state resistance of 220mOhm (typical) is significantly lower than the PI5A121CE nominal 10Ohm specification, making it suitable for high-impedance signal paths. Switch timing characteristics (15ns/10ns) closely match the original part. The SC-70-5 package provides direct mechanical compatibility. Product status is active with ROHS3 compliance and MSL-2 moisture sensitivity rating.

74HCT1G66GW-Q100H Selection Criteria: This substitute is applicable for applications operating within the 4.5V to 5.5V supply window. The on-state resistance of 95Ohm represents a significant departure from the original 10Ohm specification and is suitable only for applications tolerant of higher impedance. Extended operating temperature range (-40°C to 125°C) and automotive qualification (AEC-Q100) provide advantages for temperature-critical or automotive environments. The 5-TSSOP package is mechanically compatible with SC-70-5 footprints. Product status is active with ROHS3 compliance and MSL-1 moisture sensitivity rating.

Frequently Asked Questions (FAQ)

Q: Can ISL43L110IHZ-T directly replace PI5A121CE in all applications? A: ISL43L110IHZ-T maintains SPST-NO topology, 1:1 configuration, and SC-70-5 package compatibility. However, the on-state resistance of 220mOhm (typical) differs substantially from the 10Ohm specification. Substitution is valid only when circuit design accommodates higher impedance. Supply voltage range (1.1V ~ 4.5V) overlaps the lower portion of the original 2V ~ 6V range.

Q: What are the package compatibility considerations? A: Both ISL43L110IHZ-T and 74HCT1G66GW-Q100H use SC-70-5 or 5-TSSOP packaging, which are mechanically and electrically equivalent designations for the same physical footprint. Direct PCB substitution is supported without layout modification.

Q: How does supply voltage range affect substitution suitability? A: The PI5A121CE operates from 2V to 6V. ISL43L110IHZ-T supports 1.1V to 4.5V, providing lower-voltage capability but limited to 4.5V maximum. The 74HCT1G66GW-Q100H operates from 4.5V to 5.5V, covering only the upper portion of the original range. Application supply voltage must fall within the substitute part's specified range.

Q: What is the significance of on-state resistance differences? A: The PI5A121CE specifies 10Ohm maximum on-state resistance. ISL43L110IHZ-T provides 220mOhm (typical), and 74HCT1G66GW-Q100H provides 95Ohm. Higher on-state resistance increases signal attenuation and power dissipation. Substitution is valid only when the application circuit design accommodates the higher impedance without performance degradation.

Q: Are there compliance or qualification differences between substitutes? A: All three parts are ROHS3 compliant and REACH unaffected. The 74HCT1G66GW-Q100H carries AEC-Q100 automotive qualification, providing additional reliability assurance for automotive applications. Moisture sensitivity levels differ: PI5A121CE and 74HCT1G66GW-Q100H are MSL-1 (unlimited), while ISL43L110IHZ-T is MSL-2 (1 year).

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