MEAN WELL MSP-300-3.3 is a single-output enclosed medical-type AC/DC power supply rated 3.3 VDC, 60 A and 198 W. It combines active PFC, MOOP-level isolation, controlled fan cooling, remote sense, remote ON/OFF, a DC-OK signal and a separate 5 V standby output. Apply the model-specific input, leakage and derating limits below.
Product Datasheet
Download MEAN WELL MSP-300 Datasheet (PDF)
The MSP-300 section is on PDF pages 6, 7, 8, 9. Refer to the complete mechanical drawings and notes when planning installation.
Exact Model and Output Ratings
Complete model
MSP-300-3.3: MSP-300 single-output enclosed medical-type AC/DC power supply; -3.3 identifies the nominal 3.3 VDC output. Catalogue revision 2026-02-09.
Rated output
3.3 VDC; 60 A; 198 W. Current range: 0–60 A. These are the exact model ratings, subject to the derating limits below.
Output voltage adjustment
2.8–3.8 V using SVR. Observe the rated current and rated power limits when adjusting output voltage.
Ripple and noise
80 mVp-p maximum; measured with 20 MHz bandwidth, a 12-inch twisted pair and 0.1 µF + 47 µF parallel capacitors.
Voltage accuracy
Voltage tolerance ±2.5%; line regulation ±0.5%; load regulation ±1.0%. Tolerance includes setup, line and load regulation.
Typical efficiency
80%, at the catalogue default test conditions.
Unless otherwise stated, specifications are measured at 230 VAC input, rated load and 25°C ambient. The family name is not a substitute for this exact model’s output rating.
Input and Timing
Normal input range
85–264 VAC or 120–370 VDC; AC frequency 47–63 Hz. Apply low-input derating.
Active PFC
Typical PF >0.95 at 230 VAC and >0.99 at 115 VAC, both at full load.
Typical AC current
4.5 A at 115 VAC; 2.25 A at 230 VAC.
Inrush / surge withstand
Typical inrush 35 A at 115 VAC and 70 A at 230 VAC. Active inrush-current limiting is shown in the block diagram. Withstands 300 VAC surge input for 5 seconds; 300 VAC is not the continuous input rating.
Setup / rise time
1000 ms / 50 ms at 230 VAC; 2500 ms / 50 ms at 115 VAC, at full load.
Hold-up time
16 ms typical at 230 VAC and 16 ms typical at 115 VAC, at full load.
No-load consumption
No-load input power below 0.5 W with the main output remotely OFF: RC+ to RC− at 0–0.8 V or shorted.
Medical Isolation, Leakage and Approval Scope
Medical isolation level
Primary-to-secondary: 2 × MOOP; primary-to-earth: 1 × MOOP. MOOP stands for means of operator protection.
Leakage at 264 VAC
Earth leakage <450 µA; touch leakage <100 µA.
Listed safety approvals
IEC60601-1:2005+A1+A2; ANSI/AAMI ES60601-1:2005+A2; CAN/CSA C22.2 No.60601-1:2014+A2; EAC TP TC004.
Design references by request
BS EN/EN60335-1 and BS EN/EN62368-1 are listed as design references, by request.
Withstand voltage
Input-to-output: 4 kVAC; input-to-FG: 2 kVAC; output-to-FG: 0.5 kVAC.
Insulation resistance
100 MΩ minimum for input/output, input/FG and output/FG, tested at 500 VDC, 25°C and 70% RH.
The stated insulation classification is MOOP. These pages do not establish a MOPP patient-protection rating or certify the completed medical equipment. Match the required insulation, leakage, grounding and final-system safety evaluation to the intended application.
Protection and Cooling
Short circuit / overload
Short-circuit protection is listed. Overload threshold: 105–135% of rated output power, using constant-current limiting; automatic recovery after the fault is removed.
Overvoltage
3.96–4.62 V threshold for this model; shuts down the output, with re-powering required to recover.
Overtemperature
Shuts down the output; automatic recovery after temperature falls.
Controlled cooling fan
Built-in fan ON/OFF control: fan turns on at a typical load threshold of 35 ±15%, or when internal thermistor RTH2 reaches at least 50°C. RTH2 is not the ambient-temperature rating.
Ambient derating
Horizontal mounting: 100% load from −40°C to +50°C, decreasing linearly to 50% at +70°C. The operating range is −40°C to +70°C, subject to this curve.
Input-voltage derating
At 60 Hz, the curve rises from 80% load at 85 VAC to 100% at 100 VAC, then remains at 100% through 264 VAC.
Altitude derating
For this fan-cooled model, reduce the allowed ambient temperature by 5°C per additional 1000 m above 2000 m.
Apply input-voltage, temperature and output-rating limits together. Keep the indicated fan inlet/outlet and surrounding airflow path unobstructed; verify cooling in the final enclosure. No numerical mounting-clearance distance is specified in these catalogue pages.
Standby, Remote Control and DC OK
Standby output
5 V, 0.3 A maximum; tolerance ±5% (4.75–5.25 V), ripple 50 mVp-p maximum. AUX is not switched by the main-output remote ON/OFF control.
Standby reference
AUX pin 1 returns to AUXG pin 2. AUXG is isolated from the main +V/−V terminals; do not substitute the DC-OK ground.
Remote ON/OFF
Between RC+ pin 6 and RC− pin 4: 4–10 V or open contact = power ON; 0–0.8 V or short contact = power OFF.
DC-OK signal
DC-OK pin 3 is referenced to GND pin 5, which connects to main −V. TTL high when the PSU is ON: 3.3–5.6 V; OFF: 0–1 V.
Remote sense
Connect +S pin 7 to the positive load terminal and −S pin 8 to the negative load terminal. Twist +S and −S together; maximum line-drop compensation is 0.5 V.
Use the complete function and connection drawings on PDF pages 8–9. DC-OK is a TTL status output, not a dry relay contact; no additional contact-current or sourcing-current rating is specified here.
The documented functions for this family are standby, remote ON/OFF, DC OK and remote sense. No active current-sharing or parallel-unit count is specified for these models.
Power Terminals and CN100 Pin Assignment
Power terminals 1 / 2 / 3
AC/L / AC/N / FG (frame ground), respectively.
Power terminals 4–5 / 6–7
4 and 5: DC −V; 6 and 7: DC +V.
CN100 pin 1 — AUX
4.75–5.25 V auxiliary output, maximum 0.3 A, referenced to AUXG pin 2; remains available independently of remote ON/OFF control.
CN100 pin 2 — AUXG
Auxiliary return, isolated from the main +V and −V output terminals.
CN100 pin 3 — DC-OK
TTL status output referenced to GND pin 5; high when the PSU turns on.
CN100 pin 4 — RC-
Remote-control ground.
CN100 pin 5 — GND
DC-OK signal return; connected to the main −V output.
CN100 pin 6 — RC+
Remote ON/OFF control input relative to RC− pin 4; an open contact enables the main output and a short disables it.
CN100 pin 7 — +S
Positive remote-sense lead to the positive load terminal; use a twisted pair with −S.
CN100 pin 8 — -S
Negative remote-sense lead to the negative load terminal; use a twisted pair with +S.
Pin numbers refer to the actual connector orientation shown on PDF page 7. Verify polarity and the separate return functions before wiring.
Mating Connector and Installation Parts
Board connector
CN100: HRS DF11-8DP-2DS or equivalent, as printed in the catalogue.
Mating housing
HRS DF11-8DS or equivalent, as printed.
Contact reference
HRS DF11-**SC or equivalent. The asterisks are a contact-family placeholder, not a complete orderable contact suffix.
Confirm the complete mating-housing/contact variant, wire size and crimp tooling with the connector supplier before ordering. The catalogue does not specify an included harness quantity, a complete contact suffix or an accessory-kit order code; no inclusion is implied by the drawing.
Dimensions, Mounting and Weight
Body dimensions
Case 980A; 199 × 105 × 41 mm (L × W × H), general drawing tolerance ±1 mm.
Threaded mounting points
The base drawing marks 4-M4 L=5, with 120 × 75 mm hole spacing. Each side drawing marks 4-M4 L=6; the two side-view longitudinal spacings are 168.5 mm and 167.5 mm as drawn. Follow each view and datum separately.
Terminal and service clearance
The power-terminal projection is 17 mm maximum. The drawing shows a 125 mm overall mounting-ear width outside the 105 mm body. Leave access to the input/output terminals, CN100 and SVR, and keep the fan airflow path clear.
Local indication / adjustment
LED and output-voltage adjustment SVR are identified on the mechanical drawing.
Catalogue unit weight
950 g (0.95 kg), catalogue packing reference per unit from the PACKING row; not a measured net or shipping weight.
Packing reference
15 pieces / 15.3 kg / 0.83 CUFT. This bulk packing reference is not the quantity supplied with an individual product.
Use the complete dimension drawing on PDF page 7 for hole placement, connector orientation and installation envelope. The threaded-hole L markings must be respected; the diagram does not establish included screw quantities or tightening torques.
Environment, EMC and Reliability
Humidity / storage
Operating humidity 20–90% RH, non-condensing. Storage −40°C to +85°C, 10–95% RH, non-condensing.
Temperature coefficient
±0.03%/°C over 0–50°C.
Vibration
10–500 Hz, 5G, 10 minutes per cycle, 60 minutes along each X, Y and Z axis.
EMC emissions
BS EN/EN55011 (CISPR11) Class B; BS EN/EN61000-3-2 and -3; EAC TP TC020.
EMC immunity
BS EN/EN61000-4-2,3,4,5,6,8,11; BS EN/EN55035; BS EN/EN60601-1-2; EAC TP TC020.
EMC test arrangement
The catalogue EMC tests mount the supply on a 360 × 360 mm metal plate, 1 mm thick. The completed equipment must be reconfirmed against the applicable EMC requirements.
MTBF reference
1337.5 K hours minimum, Telcordia SR-332 (Bellcore); 175.8 K hours minimum, MIL-HDBK-217F at 25°C. These are reliability estimates, not a guaranteed operating life.
Switching reference
PWM oscillator frequency: 70 kHz, as shown in the block diagram.
Manufacturer warranty statement
The manufacturer catalogue lists a five-year warranty; applicable manufacturer terms govern.
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