FDS7779Z Equivalent & Substitute Parts

Part Overview

The FDS7779Z is a P-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 16A continuous drain current at 25°C. This device is packaged in an 8-SOIC surface mount configuration and is part of the PowerTrench® series. The FDS7779Z is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support, production continuity, and component sourcing.

Key Parameters

Parameter	Value	Unit
FET Type	P-Channel	—
Drain to Source Voltage (Vdss)	30	V
Current - Continuous Drain (Id) @ 25°C	16	A
Rds On (Max) @ Id, Vgs	7.2 mOhm @ 16A, 10V	—
Power Dissipation (Max)	2.5	W
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	8-SOIC (0.154", 3.90mm Width)	—

Substitute Part Grouping Explanation

Substitution of the FDS7779Z is determined by the following critical parameters:

Electrical Compatibility Requirements:

FET Type: P-Channel topology must be maintained
Drain to Source Voltage (Vdss): Minimum 30V rating required
Continuous Drain Current (Id): Minimum 14A at 25°C acceptable for applications with reduced current margin
Rds On (Max): Maximum 7.8 mOhm at rated current and 10V gate voltage
Power Dissipation: Minimum 650mW acceptable for thermal design considerations
Operating Temperature Range: Minimum -55°C to 150°C required

Physical Compatibility Requirements:

Mounting Type: Surface Mount only
Package Type: 8-SOIC or 8-SOP footprint compatibility

Compliance and Status:

RoHS and REACH compliance preferred for new production
Product status considered for long-term availability

The substitute parts FDS6673BZ and RRH140P03GZETB meet these criteria with trade-offs in current rating, gate charge, and power dissipation characteristics.

Parameter Comparison

Parameter	FDS7779Z (Main)	FDS6673BZ (Substitute)	RRH140P03GZETB (Substitute)
Manufacturer	onsemi	onsemi	Rohm Semiconductor
FET Type	P-Channel	P-Channel	P-Channel
Vdss (V)	30	30	30
Id @ 25°C (A)	16	14.5	14
Rds On (Max) @ Id, Vgs (mOhm)	7.2 @ 16A, 10V	7.8 @ 14.5A, 10V	7 @ 14A, 10V
Vgs(th) (Max) @ Id (V)	3 @ 250µA	3 @ 250µA	2.5 @ 1mA
Gate Charge (Qg) (Max) @ Vgs (nC)	98 @ 10V	124 @ 10V	150 @ 10V
Vgs (Max) (V)	±25	±25	±20
Input Capacitance (Ciss) (Max) @ Vds (pF)	3800 @ 15V	4700 @ 15V	8000 @ 10V
Power Dissipation (Max) (W)	2.5	2.5	0.65
Operating Temperature (°C)	-55 to 150	-55 to 150	—
Package / Case	8-SOIC	8-SOIC	8-SOP
Product Status	Obsolete	Active	Not For New Designs
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

FDS6673BZ (onsemi): This substitute is the primary equivalent for the FDS7779Z. Both devices are manufactured by onsemi within the PowerTrench® series and share identical voltage ratings, power dissipation, and operating temperature ranges. The FDS6673BZ is currently in active production status, ensuring long-term availability. The continuous drain current is reduced from 16A to 14.5A, representing a 9.4% reduction in current capacity. Gate charge increases from 98 nC to 124 nC, resulting in slightly slower switching characteristics. Input capacitance increases from 3800 pF to 4700 pF. The FDS6673BZ is ROHS3 compliant and available in higher inventory quantities (50,400 pieces). This part is suitable for applications where the reduced current margin is acceptable within the thermal and electrical design constraints.

RRH140P03GZETB (Rohm Semiconductor): This substitute provides an alternative from a different manufacturer with comparable electrical characteristics. The continuous drain current is 14A, representing a 12.5% reduction from the FDS7779Z. The Rds On is lower at 7 mOhm compared to 7.2 mOhm, providing improved on-state performance. However, the power dissipation rating is significantly reduced to 650mW, limiting thermal headroom. Gate charge is higher at 150 nC, and input capacitance is substantially higher at 8000 pF, indicating slower switching performance. The maximum gate voltage is ±20V compared to ±25V. The RRH140P03GZETB is classified as "Not For New Designs," indicating limited future support. This part is suitable only for legacy system maintenance or where existing designs have been validated with this device. The 8-SOP package differs from the 8-SOIC footprint, requiring PCB layout verification.

Frequently Asked Questions (FAQ)

Q: Can the FDS6673BZ directly replace the FDS7779Z without circuit modifications?

A: The FDS6673BZ is pin-compatible and functionally equivalent for most applications. Both devices share the same 8-SOIC package, voltage ratings, and operating temperature range. The reduced continuous drain current (14.5A vs. 16A) and increased gate charge (124 nC vs. 98 nC) require verification that the application's current demands and gate drive circuit remain within acceptable operating margins. No circuit modifications are necessary if these parameters are within design tolerances.

Q: What are the key differences between FDS6673BZ and RRH140P03GZETB?

A: Both substitutes reduce the continuous drain current to approximately 14A. The FDS6673BZ maintains the 2.5W power dissipation rating and 8-SOIC package, while the RRH140P03GZETB reduces power dissipation to 650mW and uses an 8-SOP package. The RRH140P03GZETB has lower Rds On (7 mOhm) but higher gate charge (150 nC) and input capacitance (8000 pF). The RRH140P03GZETB is marked "Not For New Designs," limiting its suitability for ongoing production.

Q: Is the FDS6673BZ suitable for high-frequency switching applications?

A: The FDS6673BZ has increased gate charge (124 nC vs. 98 nC) and input capacitance (4700 pF vs. 3800 pF) compared to the FDS7779Z. These parameters result in slower switching transitions. Applications requiring high-frequency operation must verify that the increased switching losses and gate drive requirements remain within design specifications.

Q: Can the RRH140P03GZETB be used in new product designs?

A: The RRH140P03GZETB is classified as "Not For New Designs" by the manufacturer. This designation indicates limited long-term availability and support. New product designs should prioritize the FDS6673BZ, which is in active production status and ROHS3 compliant.

Q: What is the impact of the reduced power dissipation rating in the RRH140P03GZETB?

A: The RRH140P03GZETB has a maximum power dissipation of 650mW compared to 2.5W in the FDS7779Z and FDS6673BZ. This 73% reduction in thermal capacity limits the device's ability to handle sustained high-current or high-frequency operation. Thermal design calculations must account for this reduced headroom to prevent junction temperature violations.

Q: Are there package compatibility issues between the substitutes?

A: The FDS6673BZ uses the 8-SOIC package, identical to the FDS7779Z. The RRH140P03GZETB uses an 8-SOP package, which has a different footprint. While both are surface mount packages with similar pin counts, PCB layout and footprint verification is required before substituting the RRH140P03GZETB.

Q: What is the significance of the gate voltage rating difference (±25V vs. ±20V)?

A: The FDS7779Z and FDS6673BZ are rated for ±25V maximum gate voltage, while the RRH140P03GZETB is rated for ±20V. Gate drive circuits must not exceed ±20V when using the RRH140P03GZETB. This difference may require gate drive circuit modifications if the original design uses the full ±25V range.

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