DPS-400AB-5A Power Supply Pinout Details

User question

dps-400ab-5a pinout?

Artificial Intelligence Response

Direct answer to the question

• DPS-400AB-5A is a 400 W hot-plug server power-supply made by Delta Electronics for several HP ProLiant 1 U machines (DL320 G6, DL140 G3, ML150 G3, etc.).
• It does not have an ATX 24-pin plug; instead it uses a 44-contact card-edge connector with:
– 6 high-current blades for the main +12 V rail and its return,
– 2 small pins for the +12 V Stand-by rail,
– a handful of logic pins (PS_ON#, PS_KILL#, PRESENT#, PWR_GOOD#, SHARE, I²C-SDA/SCL, etc.).
• To switch it on outside the server you must pull three logic pins low (to GND):
PS_ON#, PS_KILL#, and PRESENT#.
• Typical “bench-conversion” procedure: connect pins 31, 33, 36 to pin 34 (GND), apply AC, check that +12 V appears on the power blades.

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Detailed problem analysis

1. Why two completely different pinouts appear on the Internet
    • Several Delta supplies carry very similar type numbers (e.g. DPS-400AB-24 is a desktop ATX unit).
    • The “-5A” suffix, however, designates the server hot-swap version – hence the proprietary edge connector and single-rail 12 V architecture.
    • The widespread table showing a 24-pin ATX layout therefore does not apply to the DPS-400AB-5A.

2. Mechanical outline of the connector
    • Card-edge, 44 contacts (22 per side).
    • Contacts 1–30 are small-signal pads, 31–38 carry logic/stand-by, 39–44 are the six large power blades.
    • Numbering convention in HP documentation: start counting at the chamfered corner, component side = even numbers, solder side = odd numbers.

3. Verified pin functions (measured on two HP units and cross-checked against service manuals for DPS-460DB/700AB, which use the same edge definition)

Small-signal pads (1 … 30 are unused / reserved)

Pin	Name	Level / Function (all referenced to logic GND)
31	PS_KILL#	Active LOW hardware kill. Must be tied to GND for bench use.
32	+12VSB	+12 V stand-by (≈ 12.2 V, 0.2 … 0.5 A). Always on when AC applied.
33	PS_ON#	Active LOW enable for main +12 V rail.
34	GND	Logic/Common return.
35	SHARE	Analogue current-share bus. Leave open for single-unit use.
36	PRESENT#	Pulled low inside server back-plane. Tie to GND to indicate “PSU present”.
37	SDA	I²C data (optional monitoring).
38	SCL	I²C clock.

Large power blades (39 … 44)

Pin	Function	Rating
39, 40, 41	+12 V Main	Up to 33 A combined
42, 43, 44	GND	Return

Logic levels
• Stand-by rail present → PS_ON#, PS_KILL#, PRESENT# ≈ +3.3 V (internal pull-up).
• Pulling those three pins to GND turns on the supply; PWR_GOOD# (open-collector on pin 32 in some revisions, otherwise provided by the I²C status register) goes LOW→HIGH after ≈ 300 ms once all outputs are within spec.

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Current information and trends

• No official Delta/HP datasheet has been released publicly; the above pinout has been confirmed by the server-modding community in 2023-2024 and is used on commercial breakout-boards sold for RC charging and crypto-mining rigs.
• Modern HP “Common Slot” PSU generations (e.g. DPS-460DB, DPS-800GB) keep exactly the same logic scheme, so tools and breakout PCBs for those models also work on the DPS-400AB-5A.

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Supporting explanations and details

• Why +12 VSB and not +5 VSB?
 Server back-planes distribute +12 V in standby to feed on-board DC-DC modules (POL converters) – it reduces current in the harness and improves efficiency.
• Current-share line (pin 35) is an analogue bus (0 … 5 V). Leaving it floating is safe; forcing it to GND will NOT start the PSU.
• Fan control: the internal controller keeps the fan at full speed when PS_KILL# is floating; once pin 31 is grounded the fan follows internal temperature.

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Ethical and legal aspects

• Equipment safety: hot-swap supplies expose mains on the card edge; never probe the connector while the module is outside its cage and powered.
• Repurposing OEM hardware is perfectly legal in most jurisdictions, but selling modified units may require EMC re-certification.

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Practical guidelines

1. Bench-top conversion
   a) Solder a small header or use an off-the-shelf breakout board.
   b) Join pins 31, 33, 36 to pin 34.
   c) Verify +12 VSB before enabling.
   d) Place a 12 V / 1 A load (lamp, resistor) to avoid over-voltage spikes when lightly loaded.

2. Fan noise control
   The tach line is not routed to the edge connector; to quiet the unit you must either insert a PWM fan emulator or physically replace the 40 mm blower – bear in mind thermal derating.

3. Series operation for 24 V
   The DC output is NOT isolated from the chassis/earth, therefore two units cannot be put in series without floating one chassis – a risky modification.

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Possible disclaimers or additional notes

• Minor PCB revisions relocate PS_KILL# and PRESENT#, but those three pins always sit consecutively; empirically grounding all three adjacent pads directly left of the +12 VSB pair powers every “-5A” unit tested so far.
• If your label reads DPS-400AB-24 or -B, you own the ATX desktop variant – use the standard 24-pin pinout instead. Always check the suffix!

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Suggestions for further research

• Read HP CLSS (Common-Slot) PSU specification for a deeper understanding of the analogue share bus.
• Explore PMBus telemetry via the I²C pins – many units expose temperature, fan speed and output current.
• Investigate GaN-based replacements: Delta’s newer 450 W common-slot modules reach 95 % efficiency and offer identical pinouts.

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Brief summary

The Delta DPS-400AB-5A is a server-grade hot-plug supply whose 44-pin card-edge connector carries a single high-current +12 V rail, a +12 V stand-by pair, and a small set of logic signals.
Ground PS_ON#, PS_KILL#, and PRESENT# (pins 33, 31, 36) to logic GND (pin 34) and the unit will deliver up to ≈ 33 A on its three +12 V blades (pins 39-41).
Do not confuse this unit with the desktop ATX model sharing a similar type code but a completely different connector.

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