BU4051BC Equivalent & Substitute Parts

Part Overview

The BU4051BC is a single-circuit 8:1 multiplexer/demultiplexer IC manufactured by Rohm Semiconductor, housed in a 16-DIP package with 160Ohm on-state resistance. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production support. The BU4051BC operates across a single supply voltage range of 3V to 18V and is suitable for analog signal switching applications requiring low on-state resistance and minimal leakage current.

Key Parameters

Parameter	BU4051BC
Multiplexer/Demultiplexer Circuit	8:1
Number of Circuits	1
On-State Resistance (Max)	160Ohm
Voltage - Supply, Single (V+)	3V ~ 18V
Channel Capacitance (CS(off), CD(off))	10pF
Current - Leakage (IS(off)) (Max)	300nA
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	16-DIP (0.300", 7.62mm)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the BU4051BC is determined by the following critical parameters:

Circuit Configuration: 8:1 multiplexer/demultiplexer with single circuit
Package Type: 16-DIP (0.300", 7.62mm) through-hole mounting
On-State Resistance: Maximum 160Ohm (primary electrical constraint)
Supply Voltage Compatibility: Single supply operation within overlapping voltage ranges
Leakage Current: Maximum 300nA (off-state performance)
Operating Temperature Range: -40°C to 85°C minimum coverage

Three substitute parts meet these criteria: CD4051BE, CD4051BEE4, and MAX4558EPE+. All three maintain the 8:1 multiplexer configuration, 16-DIP package, and compatible supply voltage ranges. The CD4051 variants feature 240Ohm on-state resistance with extended temperature range and dual supply capability. The MAX4558EPE+ matches the 160Ohm on-state resistance specification and provides superior performance characteristics including lower leakage current and faster switching times.

Parameter Comparison

Parameter	BU4051BC	CD4051BE	CD4051BEE4	MAX4558EPE+
Multiplexer/Demultiplexer Circuit	8:1	8:1	8:1	8:1
Number of Circuits	1	1	1	1
On-State Resistance (Max)	160Ohm	240Ohm	240Ohm	160Ohm
Voltage - Supply, Single (V+)	3V ~ 18V	3V ~ 20V	3V ~ 20V	2V ~ 12V
Current - Leakage (IS(off)) (Max)	300nA	100nA	100nA	1nA
Operating Temperature	-40°C ~ 85°C	-55°C ~ 125°C	-55°C ~ 125°C	-40°C ~ 85°C
Package / Case	16-DIP (0.300", 7.62mm)	16-DIP (0.300", 7.62mm)	16-DIP (0.300", 7.62mm)	16-DIP (0.300", 7.62mm)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

MAX4558EPE+ (Recommended Primary Substitute)

The MAX4558EPE+ is an active product from Analog Devices Inc./Maxim Integrated and provides the closest electrical match to the BU4051BC. It maintains identical 160Ohm on-state resistance, operates within the -40°C to 85°C temperature range, and exceeds performance specifications with 1nA leakage current and 2Ohm channel-to-channel matching. This part is ROHS3 compliant and currently in active production with 3400 units in stock.

CD4051BE (Secondary Substitute)

The CD4051BE from Texas Instruments is an active product offering extended supply voltage range (3V to 20V) and superior temperature coverage (-55°C to 125°C). On-state resistance is specified at 240Ohm, which represents a 50% increase from the BU4051BC specification. This part is suitable for applications where the higher on-state resistance is acceptable and extended operating temperature range is required. ROHS3 compliant with 20300 units in stock.

CD4051BEE4 (Tertiary Substitute)

The CD4051BEE4 is classified as obsolete but shares identical electrical specifications with the CD4051BE. This part is ROHS3 compliant with 2100 units available. Selection of this part should be limited to legacy system maintenance where supply continuity is critical.

Frequently Asked Questions (FAQ)

Q: Can the CD4051BE replace the BU4051BC directly?

A: Yes, with design consideration. The CD4051BE maintains the same 8:1 multiplexer configuration and 16-DIP package. The primary difference is on-state resistance: 240Ohm versus 160Ohm. Applications sensitive to signal attenuation or requiring low impedance paths must evaluate this 50% increase. Supply voltage range is compatible (3V to 20V overlap).

Q: What is the advantage of MAX4558EPE+ over CD4051BE?

A: The MAX4558EPE+ matches the original 160Ohm on-state resistance specification and provides superior leakage current performance (1nA versus 100nA). It also offers faster switching times (150ns Ton, 120ns Toff) and lower charge injection (2.4pC). These characteristics make it suitable for high-speed analog switching applications. However, the MAX4558EPE+ has a narrower single supply voltage range (2V to 12V) compared to CD4051BE (3V to 20V).

Q: Are all substitute parts pin-compatible with the BU4051BC?

A: All three substitute parts use the 16-DIP (0.300", 7.62mm) package. Pin compatibility must be verified against the specific application schematic, as multiplexer pin assignments may vary between manufacturers. Consult individual datasheets for pin configuration details.

Q: Which substitute part has the best availability?

A: The CD4051BE has the highest inventory level at 20300 units in stock. The MAX4558EPE+ has 3400 units available, and the CD4051BEE4 has 2100 units. All three parts are currently available for procurement.

Q: Can I use these substitutes in applications requiring extended temperature range?

A: The CD4051BE and CD4051BEE4 support -55°C to 125°C operating temperature, exceeding the BU4051BC specification of -40°C to 85°C. The MAX4558EPE+ matches the original -40°C to 85°C range. For applications requiring temperatures below -40°C or above 85°C, the CD4051 variants are required.

Q: Are all substitute parts RoHS compliant?

A: Yes. The BU4051BC, CD4051BE, CD4051BEE4, and MAX4558EPE+ are all ROHS3 compliant. All parts are REACH unaffected and classified under ECCN EAR99.

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