Hot-swap connector: blind-mate power and signal connector for plug-in modules
Blind-mate hot-plug connectors for plug-in modules · staggered contact lengths, per-contact current at 30 °C rise, inrush control on the card
A hot-swap connector is the board-to-board or module-to-backplane connector that lets a power supply, drive carrier or plug-in card be inserted and withdrawn while the system stays powered. Guide posts align the halves for blind mating, and contacts of different lengths make and break in a fixed order, for example ground first, then power and signals. Ask three things first: how many mating levels the contacts give and in what order, what current each power contact carries at the stated temperature rise, and what circuit on the card limits the inrush when the contacts close.
Blind-mate power and signal connectors for hot-pluggable modules such as server power supplies, drive carriers and backplane cards, specified by contact sequencing, per-contact current, voltage spacing and mating force. Twist-on, lever and push-in splicing connectors for building wiring are covered on the Wire connectors (splicing) page. Keyboard switch hot-swap sockets, USB and other consumer cable plugs, and hot-swap controller ICs bought alone are outside this page except where compared.
CNFX editorial research · Sources checked October 12, 2026 · 3 sources
FCI's PwrBlade datasheet offers two levels of sequential mating for the power contacts and two for the signal contacts, which together support up to three levels of sequencing; it states that mating ground first, followed by power and signals, can provide hot-swap capability, and that molded guide posts on the header align the receptacle during blind mating. [1]
A VLSI Technology patent on hot docking of bus cards shows why the length difference matters. Its PCMCIA example has power pins of 0.197 ± 0.004 in and bus signal pins of 0.167 ± 0.004 in, so the worst-case difference is 0.193 − 0.171 = 0.022 in; the bus isolation circuit must act during the time the card travels that distance. With a 12 µs isolation cycle the patent calculates a corresponding speed of 153 ft/s, and with 2 µs, 917 ft/s, both high compared with normal insertion speeds. [3] Editorial calculation: 0.022 in is about 0.56 mm.
Editorial note: the order and the length steps are part of the system design, not a connector default. Give the supplier the sequence you need (for example ground, then pre-charge or main power, then presence-detect signals last) and ask for the drawing that shows each contact's mating length and tolerance.
Give the supplier the module type, number of power and signal contacts, required mating levels and their order, current per power circuit, AC or DC voltage, board mounting (vertical or right angle, press-fit or solder), mating force limit, guide and latching arrangement, and the safety approvals required.
02
Rate the power contacts and plan the inrush
In the PwrBlade datasheet, a single powered contact is rated at 48 A, de-rated to 30 A per contact when 10 adjacent contacts carry current, both for a 30 °C temperature rise in still air; 60 A per contact is stated under UL test guidelines with 10 contacts energised. Power contact spacing options are given for AC (300 V max) and DC (200 V max), and the connector is stated to meet applicable UL current interruption criteria for hot-plug use. [1]
The connector only closes the circuit; the current at the moment of contact is set on the card. Texas Instruments' application report on hot-swap design describes a hot-swap circuit placed at the input of a plug-in card to manage inrush current and protect the bus and load during faults. In its 48 V, 20 A example with 440 µF of output capacitance, a 4 V/ms output slew rate gives an inrush current of 1.76 A and a start-up time of 15 ms at a 60 V maximum input. [2]
Editorial note: a per-contact rating is tied to the stated temperature rise and to how many neighbouring contacts are loaded. Ask the supplier for the derating curve that matches your contact count and airflow, not the single-contact headline figure.
03
Power blades, signal pins, guide posts and the inrush circuit behind them
Two parts set hot-swap behaviour: the staggered contact lengths and the inrush circuit on the card.
Part
Role
Fix in the order
Power contacts
Carry module current; 48 A single, 30 A each with 10 loaded in one datasheet. [1]
Send the module, sequence and current data together
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Module: [power supply / drive carrier / card; insertion method]
Contacts: [power count; signal count; mating levels and order]
Power: [current per circuit; AC or DC voltage; airflow]
Inrush: [controller on card; output capacitance; slew rate]
Mounting: [vertical or right angle; press-fit or solder; board thickness]
Mechanical: [mating force limit; guides; latching]
Documents: [drawing with contact lengths; derating curve; approvals]
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
How does a hot-swap connector control the order of connection?
By contacts of different lengths: FCI's PwrBlade offers two mating levels for power and two for signals, with ground mating first for hot swap. [1]
How much current can one power contact carry?
It depends on the temperature rise and how many contacts are loaded; one datasheet gives 48 A for a single contact and 30 A each for 10 contacts at a 30 °C rise. [1]
Does the connector limit inrush current?
No. A hot-swap circuit on the plug-in card manages inrush; TI's example limits it to 1.76 A at a 4 V/ms slew rate with 440 µF. [2]
How large is the pin-length step?
In the PCMCIA example worked in a VLSI Technology patent, the worst-case difference between power and signal pins is 0.022 in. [3]
Sources and what still needs a direct check
Sources checked 2026-10-12. FCI (now Amphenol) describes its own connector family; Texas Instruments describes hot-swap controller design; the VLSI Technology patent works an example from the PCMCIA pin lengths. Your module and system specification governs the final values.
