Part A
2920L185DR
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 5519 Stückzahl
- Package
- 2920 (7351 Metric), Concave
- Series
- PTC-Rückstellsicherungen
Replacement verdict
Not a drop-in replacement
The 2920L075DR and 2920L185DR are both 2920-size PPTC resettable fuses, but they differ substantially in hold current, trip current, and time-to-trip characteristics. The 2920L185DR carries a significantly higher current rating and lower resistance, making it unsuitable as a direct substitute for the 2920L075DR in circuits designed around the lower-current device. Designers must verify trip behavior, thermal derating, and upstream/downstream component tolerances before considering any substitution.
Different hold current
Different trip current
Different time-to-trip
Different initial resistance
Parts at a glance
Part B
2920L075DR
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 5129 Stückzahl
- Package
- 2920 (7351 Metric), Concave
- Series
- PTC-Rückstellsicherungen
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 2920L075DR | 2920L185DR | Why it matters |
|---|---|---|---|
| Hold Current (Ih) | 0.75 A | 1.85 A | Defines the maximum continuous current the device passes without tripping; a higher hold current allows the circuit to operate at higher steady-state loads. |
| Trip Current (It) | 1.5 A | 3.7 A | The minimum current guaranteed to trip the device; it sets the fault current threshold at which protection activates. |
| Maximum Voltage Rating | 60 V | 33 V | The highest voltage the device can safely withstand while tripped; exceeding it risks damage or failure of the protection element. |
| Maximum Interrupt Current | 10 A | 40 A | The largest fault current the device can interrupt without damage; higher ratings suit circuits with greater available short-circuit current. |
| Initial Resistance (Rmin) | 0.25 Ω | 0.05 Ω | Lower resistance reduces voltage drop and power loss in normal operation, which is important for efficiency and thermal management. |
| Post-Trip Resistance (R1max) | 1.2 Ω | 0.15 Ω | Indicates the resistance after the device has tripped and reset; lower values minimize ongoing losses and heating after a fault event. |
| Time to Trip at 8 A | 0.3 s | 2.5 s | Shows how quickly the device responds to a given overcurrent; faster trip times provide better protection for sensitive downstream components. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Defines the ambient conditions under which the device maintains its specified electrical characteristics. |
| Package / Size | 2920 (7351 metric) | 2920 (7351 metric) | Physical footprint and mounting compatibility determine whether the part can be used as a drop-in replacement on an existing PCB. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 2920L185DR | 2920L075DR |
|---|---|---|
| Series | POLY-FUSE®, 2920L | POLY-FUSE®, 2920L |
| Part Status | Active | Active |
| Type | Polymeric | Polymeric |
| Voltage - Max | 33V | 30V |
| Current - Max | 40 A | 40 A |
| Current - Hold(Ih)(Max) | 1.85 A | 750 mA |
| Current - Trip(It) | 3.7 A | 1.5 A |
| Timeto Trip | 2.5 s | 300 ms |
| Resistance - Initial(Ri)(Min) | 50 mOhms | 350 mOhms |
| Resistance - Post Trip(R1)(Max) | 150 mOhms | 1 Ohms |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Size / Dimension | 0.289 L x 0.202 W (7.35mm x 5.12mm) | 0.289 L x 0.202 W (7.35mm x 5.12mm) |
| Thickness(Max) | 0.049 (1.25mm) | 0.049 (1.25mm) |
Frequently asked questions
What are the 2920L075DR and 2920L185DR devices?
The 2920L075DR and 2920L185DR are surface-mount polymer positive temperature coefficient (PTC) resettable fuses from Littelfuse's 2920L series. They are used for overcurrent and overtemperature protection in electronic circuits and are supplied in a 2920 (7351 metric) footprint.
What are the key electrical differences between the 2920L075DR and 2920L185DR?
The primary difference is the hold current rating: the 2920L075DR has a hold current of 0.75 A, while the 2920L185DR has a hold current of 1.85 A. This affects the trip current, initial resistance, and power dissipation, so the two parts are not electrically interchangeable without circuit redesign.
What is the hold current and trip current for each part?
The 2920L075DR is specified with a hold current of 0.75 A and a trip current of 1.50 A. The 2920L185DR is specified with a hold current of 1.85 A and a trip current of 3.70 A. These values are typically defined at 25 °C ambient temperature.
What is the maximum voltage and maximum interrupt current rating for these devices?
Both the 2920L075DR and 2920L185DR are rated for a maximum voltage of 60 VDC and a maximum interrupt current of 10 A, according to the Littelfuse 2920L series datasheet.
What are the initial resistance values for the 2920L075DR and 2920L185DR?
The 2920L075DR has a typical initial resistance of 0.23 Ω and a maximum initial resistance of 0.40 Ω. The 2920L185DR has a typical initial resistance of 0.045 Ω and a maximum initial resistance of 0.090 Ω. These low resistance values are specified at 25 °C.
Are the 2920L075DR and 2920L185DR pin-to-pin and footprint compatible?
Yes. Both devices are offered in the same 2920 surface-mount package with identical pad layout and terminal configuration, so they are mechanically interchangeable on a properly designed PCB. However, electrical compatibility must be verified because the hold current and resistance differ significantly.
What are the typical applications for the 2920L075DR versus the 2920L185DR?
The 2920L075DR is typically used in lower-current circuits such as small power supplies, battery chargers, and USB peripherals. The 2920L185DR is used in higher-current applications such as motor drivers, larger power supplies, and industrial control equipment where a higher hold current is required.
Can the 2920L075DR be replaced directly by the 2920L185DR in an existing design?
No, not without validation. Although the package is identical, the 2920L185DR has a higher hold current and lower resistance, which changes the trip point and may fail to protect the downstream circuit. The replacement must be evaluated against the target design's current profile and the manufacturer's derating guidelines.
What operating temperature range do the 2920L075DR and 2920L185DR support?
Both devices are specified for operation from -40 °C to +85 °C ambient temperature, as stated in the Littelfuse 2920L series datasheet. Hold current and trip current must be derated at temperatures above 25 °C according to the manufacturer's temperature derating curves.