Name: MEAN WELL N78-2 series: Non-isolated DC-DC regulator for negative output - N78025-2C
Brand: MEAN WELL
SKU: N78025-2C
Price: 24.64 USD
Availability: InStock

MEAN WELL N78-2 series: Non-isolated DC-DC regulator for negative output - N78025-2C

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Description

N78025-2C — Non-isolated DC-DC switching regulator for negative output

MEAN WELL N78025-2C is a non-isolated DC-DC switching regulator for a negative −2.5 V output application, with output-current magnitude up to 1000 mA. This cased type for vertical mounting operates from 8–32 V DC. Connect it using the specified negative-output pin assignment and observe the load and temperature limits below.

Download MEAN WELL N78-2 Datasheet (PDF)
Download MEAN WELL EMI Testing Guidance (PDF)

Model section: datasheet PDF pages 9–16. Follow the table and connection drawing for this output application.

Model and output application

Manufacturer model	N78025-2C
Output application	Negative output: −2.5 V
Package and model code	C: cased type for vertical mounting. The 2A designation identifies the series; the selected application current below is the applicable limit.
Other output applications	The same ordering code also has a positive application at 2.5 V, with 4.5–32 V DC input and a 2000 mA output-current magnitude limit. Use the corresponding pin assignment. One module does not provide both output rails simultaneously.
Typical uses	Negative-rail generation and point-of-load regulation in distributed power systems, industrial PCs, digital set-top boxes, data communications and microcontroller circuits. Pin-out compatibility with LM78xx/LM79xx linear regulators is specified; verify the chosen polarity, pin orientation and operating limits before substitution.

Electrical specifications

Input voltage	8–32 V DC; catalogue normal input: 12, 24 V DC.
Input current	No load: 1 mA; full load: 363 mA. Note 3 specifies minimum input voltage for the full-load input-current measurement; the 1 mA value remains the separate no-load column.
Output voltage	−2.5 V DC in the selected application.
Output current range	0–1000 mA in the catalogue; output-current magnitude up to 1000 mA in the negative-voltage application.
Calculated output power	2.5 W, calculated from the selected output-voltage magnitude and maximum output-current magnitude; subject to the stated input, load and temperature limits. This is a calculation from the application table, not a separately specified power rating.
Series power range	3.6–30 W is the series-wide catalogue range. Use this application’s output voltage, current and derating limits; the series upper value is not a rating for every model or polarity.
Series capability reference	The N78-2 series offers efficiency up to 96% and input capability up to 32 V DC across its models and applications. Use the selected application's efficiency, input range, load and temperature limits stated here; these series maxima are not individual ratings.
Efficiency	86% at minimum input voltage and full load (Note 3).
Maximum capacitive load	1000 µF.
Voltage accuracy	±3.0% maximum.
Ripple and noise	100 mVp-p maximum; measured at 20 MHz bandwidth with a 12-inch twisted pair terminated by 0.1 µF and 47 µF capacitors connected in parallel.
Line regulation	The catalogue gives ±0.5% for 1.8–3.3 V outputs and ±0.4% for other outputs, measured from low to high input at rated load. It does not explicitly assign the negative 2.5 V / 3.3 V applications to these groups; confirm the applicable tolerance with MEAN WELL.
Load regulation	The catalogue gives ±1.5% for 1.8–3.3 V outputs and ±1.0% for other outputs, measured from 10% to 100% rated load. Confirm which tolerance applies to this negative-output application.
Switching frequency	400 kHz typical.
Internal power dissipation	1250 mW as listed in the specification.
General test conditions	Normal input, rated load, 25°C ambient and 70% RH unless a particular parameter states another condition. The input-current no-load column retains its stated no-load condition.

Protection and operating conditions

Input filter and fuse	Capacitor input filter. An external 3000 mA slow-blow input fuse is recommended for all models in this series.
Input surge voltage	36 V maximum for 100 ms maximum; this transient limit does not extend the continuous input-voltage range.
Short-circuit protection	Continuous short-circuit protection; automatic recovery after the short-circuit condition is removed.
Overload protection	150–300% as specified; recovers automatically after the fault condition is removed.
Overtemperature protection	Shuts down the output voltage; automatic recovery after the unit cools.
Cooling and load derating	Free-air / natural convection; no additional heatsink is required within the specified operating and load limits. The curve permits 100% load from −40°C through +60°C, then derates to 50% at +85°C. Follow the intervening curve.
Operating and case temperature	Ambient −40 to +85°C subject to derating; case temperature +110°C maximum.
Humidity and storage	Operating humidity: 5–95% RH, non-condensing. Storage: −55 to +125°C and 10–95% RH, non-condensing.
Temperature coefficient	0.03%/°C over 0–60°C.
Soldering temperature	265°C maximum for 3–5 seconds, measured 1.5 mm from the case.
Vibration	10–500 Hz, 2 G; 10 minutes per cycle, for 60 minutes along each X, Y and Z axis.

Dimensions and connection

Dimensions	Cased body: 11.5 × 9.0 × 17.5 mm (L × W × H).
Mechanical drawing details	C drawing: 3.81 mm lead extension, separate 0.50 mm body stand-off, 2.54 mm pitch and 2.1 mm pin-axis offset from the case edge in the bottom view. Pins are 0.75 × 0.25 mm, ±0.1 mm; general dimensional tolerance ±0.5 mm.
PCB / connection orientation	Top-view footprint: 2.54 mm grid, Ø1 mm holes (+0.2/−0), illustrated pin order 1, 2, 3 from left to right. Use the drawing for the selected C or CH mounting form.
Pin assignment	Pin 1: +Vin; pin 2: −Vout; pin 3: GND. This is the negative-output application pin assignment.

Typical application and installation

External capacitors	The typical application table specifies MLCC capacitors: input Ci = 10 µF / 50 V; output Co = 22 µF / 10 V. For this application above 30 V DC input, Note 2 requires a 22 µF / 50 V input capacitor; the typical 10 µF table value does not remove that requirement.
Application circuit connections	In the negative application, the output capacitor connects between pin 2 (−Vout) and pin 3 (GND). The schematic marks its positive side at GND and negative side at −Vout. The input capacitor connects between +Vin and GND.
Combined positive and negative rails	The illustrated combined application uses two separate modules, one wired for positive output and one for negative output, with a common ground. Select an input voltage valid for both applications. A 10 µH LDM component is recommended in the negative-module input branch to reduce interference; the diagram does not establish same-rail current sharing.
Accessories and assembly	No dedicated accessory ordering code is specified in this series datasheet. External fuses, capacitors and the application-dependent inductor are circuit components selected for the system, not stated as items supplied with the regulator.

Compliance, reliability and packing

Isolation and safety	Non-isolated input/output. EAC TP TC 020/2011 approved as listed in the catalogue.
EMC emission	BS EN/EN55032 (CISPR32): conducted emission is listed as N/A; radiated Class B is specified without additional EMC components. Observe the application-circuit and input-capacitor requirements and verify the completed system.
EMC immunity	BS EN/EN61000-4-2: Level 3, ±8 kV air-discharge ESD; BS EN/EN61000-4-3: Level 2, 3 V/m; BS EN/EN61000-4-4: Level 1, 0.5 kV; BS EN/EN61000-4-5: Level 1, 0.5 kV line-to-line; BS EN/EN61000-4-6: Level 2, 3 Vrms.
MTBF	1600 K hours, MIL-HDBK-217F at 25°C.
Construction	Non-conductive plastic case rated UL 94V-0.
Single-unit weight reference	4 g, catalog packing reference per unit; not a measured net-weight or parcel-weight claim.
Standard packing	42 pieces per tube / 200 g tube gross weight; 3,360 pieces per carton (80 tubes) / 17 kg carton gross weight. Tube length: 520 mm; its packaging cross-section is marked 10.56, 5, 19.76 and 25.06 mm. Standard carton: 620 × 230 × 230 mm. These are manufacturer bulk-packing references, not a statement of the quantity included with an individual purchase.
Manufacturer warranty	3 years as stated in the series datasheet.

System installation and EMC

Complete-system EMC verification	Verify EMC with the regulator installed in the final equipment and connected to a representative load. Wiring, assembly and the application affect the result. Follow the model's specified EMC conditions and any required external components; the linked EMI testing guidance does not certify the finished equipment.