DG418LDY Equivalent & Substitute Parts

Part Overview

The DG418LDY is a single-circuit SPST-NO analog switch IC manufactured by Vishay Siliconix in 8-SOIC surface mount packaging. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for new designs and production continuity. The DG418LDY operates as a high-speed analog switch with 20Ohm on-state resistance and supports dual supply voltages (±3V to ±6V) or single supply (2.7V to 12V), making it suitable for signal routing and multiplexing applications in audio, instrumentation, and data acquisition systems.

Key Parameters

Parameter	DG418LDY
Switch Circuit Type	SPST - NO
Multiplexer/Demultiplexer Circuit	1:1
Number of Circuits	1
On-State Resistance (Max)	20Ohm
Voltage - Supply, Single (V+)	2.7V ~ 12V
Voltage - Supply, Dual (V±)	±3V ~ 6V
Switch Time (Ton, Toff) (Max)	43ns, 31ns
Charge Injection	1pC
Channel Capacitance (CS(off), CD(off))	5pF
Current - Leakage (IS(off)) (Max)	1nA
Crosstalk	-71dB @ 1MHz
Operating Temperature	-40°C ~ 85°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the DG418LDY is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Switch circuit topology: SPST - NO (single pole, single throw, normally open)
Multiplexer configuration: 1:1 (single channel)
Package type: 8-SOIC surface mount
Pin count and pinout: 8-pin SOIC

Allowable Parameter Variations:

On-state resistance (Ron): The DG418LDY specifies 20Ohm maximum. Substitute parts with higher Ron values (35Ohm) are acceptable when the application circuit design accommodates increased resistance without signal degradation or excessive power dissipation.
Supply voltage ranges: Substitutes may have different single and dual supply voltage specifications. The application must operate within the intersection of available supply voltages.
Switch timing (Ton, Toff): Substitutes with longer switching times are acceptable if the application does not require the original switching speed performance.
Leakage current and charge injection: Higher values in substitutes are acceptable if the application's signal integrity requirements permit.
Operating temperature range: Substitutes with narrower temperature ranges may be used if the application operates within that range.
RoHS compliance: Active substitutes with RoHS3 compliance are preferred for new designs and regulatory adherence.

Non-Substitutable Parameters:

Switch circuit type (must remain SPST - NO)
Channel configuration (must remain 1:1)
Package type (must remain 8-SOIC)

Parameter Comparison

Parameter	DG418LDY	DG418CY+	DG418DY+	DG418LDY+
Manufacturer	Vishay Siliconix	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete	Active	Active	Active
Switch Circuit	SPST - NO	SPST - NO	SPST - NO	SPST - NO
Multiplexer/Demultiplexer Circuit	1:1	1:1	1:1	1:1
Number of Circuits	1	1	1	1
On-State Resistance (Max)	20Ohm	35Ohm	35Ohm	35Ohm
Channel-to-Channel Matching (ΔRon)	—	3Ohm (Max)	3Ohm (Max)	100mOhm
Voltage - Supply, Single (V+)	2.7V ~ 12V	10V ~ 30V	10V ~ 30V	9V ~ 36V
Voltage - Supply, Dual (V±)	±3V ~ 6V	±4.5V ~ 20V	±4.5V ~ 20V	±4.5V ~ 20V
Switch Time (Ton, Toff) (Max)	43ns, 31ns	175ns, 145ns	175ns, 145ns	175ns, 185ns
Charge Injection	1pC	3pC	3pC	15pC
Channel Capacitance (CS(off), CD(off))	5pF	8pF, 8pF	8pF, 8pF	8pF, 8pF
Current - Leakage (IS(off)) (Max)	1nA	250pA	250pA	250pA
Crosstalk	-71dB @ 1MHz	-85dB @ 1MHz	-85dB @ 1MHz	—
Operating Temperature	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

DG418CY+ is suitable for applications operating within the 0°C to 70°C temperature range. This part offers ROHS3 compliance and active product status, making it appropriate for new designs with standard industrial temperature requirements. The higher on-state resistance (35Ohm) and increased switching times require circuit-level verification to ensure signal integrity and timing margins are maintained.

DG418DY+ provides the widest operating temperature range (-40°C to 85°C) among the active substitutes, matching the original DG418LDY temperature specification. ROHS3 compliance and active product status support long-term supply chain continuity. This part is recommended for applications requiring extended temperature operation and is the preferred substitute for designs with stringent temperature specifications.

DG418LDY+ extends the single supply voltage range to 9V ~ 36V and offers the tightest channel-to-channel matching (100mOhm) among available substitutes. ROHS3 compliance and active status ensure regulatory adherence. This part is suitable for applications requiring higher supply voltages or demanding matching characteristics. The increased charge injection (15pC) must be evaluated against application noise and signal integrity requirements.

All three substitute parts maintain the 8-SOIC package footprint and pinout compatibility with the original DG418LDY, enabling direct board-level replacement without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can DG418CY+, DG418DY+, or DG418LDY+ be used as direct replacements for DG418LDY?

A: Yes, all three parts are pin-compatible and functionally equivalent within their specified operating parameters. Direct PCB replacement is possible. However, the application circuit must accommodate the higher on-state resistance (35Ohm vs. 20Ohm) and longer switching times. Verify that signal attenuation and timing margins remain acceptable for your specific application.

Q: What is the primary difference between the three substitute parts?

A: DG418CY+ operates over 0°C to 70°C; DG418DY+ and DG418LDY+ both support -40°C to 85°C. DG418LDY+ offers the highest single supply voltage range (9V ~ 36V) and tightest channel matching (100mOhm). DG418DY+ provides a balanced specification across all parameters. Select based on your application's temperature, supply voltage, and matching requirements.

Q: Is the increased on-state resistance (35Ohm vs. 20Ohm) a concern?

A: The 75% increase in Ron affects signal attenuation and power dissipation. For low-impedance signal paths or high-frequency applications, this may require circuit redesign. For high-impedance signal routing or low-current switching, the difference is typically negligible. Perform circuit simulation or bench testing to confirm performance.

Q: Why do the substitute parts have longer switching times?

A: The DG418CY+, DG418DY+, and DG418LDY+ have switching times of 175ns/145ns compared to the original 43ns/31ns. This reflects different silicon process technology and design optimization. If your application requires sub-100ns switching, these substitutes may not be suitable. Verify timing requirements against your system specifications.

Q: Are all substitute parts RoHS compliant?

A: Yes. DG418CY+, DG418DY+, and DG418LDY+ are all ROHS3 compliant, whereas the original DG418LDY is RoHS non-compliant. This makes the substitutes preferable for new designs and applications subject to RoHS regulations.

Q: Can I use DG418CY+ in an application requiring -40°C operation?

A: No. DG418CY+ is rated only to 0°C minimum. For applications requiring -40°C operation, use DG418DY+ or DG418LDY+, both of which support the full -40°C to 85°C range.

Q: What is the significance of charge injection differences?

A: Charge injection (1pC for DG418LDY vs. 3pC to 15pC for substitutes) affects signal settling time and noise in precision analog applications. Higher charge injection may introduce transient errors in sample-and-hold circuits or precision data acquisition. Evaluate this parameter if your application involves high-resolution analog signal processing.

Q: Are there any supply voltage compatibility issues?

A: The original DG418LDY supports 2.7V ~ 12V single supply and ±3V ~ 6V dual supply. All substitutes require higher minimum voltages (9V ~ 30V single supply, ±4.5V ~ 20V dual supply). Verify that your power supply design can accommodate these higher voltage requirements before substitution.

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