40G QSFP+ Passive DAC Cable Specifications
| Link role | A same-speed QSFP+ short-reach copper link for in-rack switch, server, storage, or adapter connections where passive reach is sufficient. |
|---|---|
| Endpoint form factor | QSFP+ at both cable ends |
| Aggregate data rate | 40G |
| Lane / channel detail | 40G aggregate link |
| Length guidance | Up to 7 m |
| Power approach | Passive cable assembly; no active optical engine |
| Standards / management | Compliant with QSFP+ MSA and SFF-8436; Compliant with IEEE 802.3ba / InfiniBand QDR |
| Cable construction | 30 AWG to 24 AWG cable sizes available; copper twinax assembly |
| Operating temperature | :0°C to 70°C (Commercial) |
| Configuration status | Standard and custom options must be confirmed in the quotation and approved BOM |
Search terminology for this configuration includes 40G passive DAC, QSFP+ direct attach copper, 40G DAC cable data center, QSFP+ twinax cable. These phrases describe the same purchase task only when the endpoint form factor, link mode, and ordered length match this page.
Standards context: IEEE 802 standards catalog · SNIA SFF technology affiliates.
When to Use This 40G Passive DAC
- Use it for direct links between QSFP+ endpoints when the routed path stays within up to 7 m.
- Choose passive copper when low cable power and simple installation matter more than reach or cable diameter.
- Confirm both ports operate at the same link mode and the exact cable code is accepted by the host systems.
Compatibility and Acceptance Checklist
- Confirm the connector at each end: QSFP+.
- Confirm the required aggregate rate and host lane mode: 40G aggregate link.
- Measure the routed path, not the straight-line rack distance; the current datasheet states up to 7 m.
- Send switch/NIC part numbers and firmware versions for coding review; no platform-specific compatibility is assumed without validation.
- Check cable gauge, bend radius, and port-side mechanical clearance for the selected length.
- Specify commercial or industrial temperature requirements and the requested jacket/label/packaging details.
- At receipt, verify labels and part numbers, inspect latches and cable jackets, then test the complete link at the intended data rate.
1 Differential Insertion Loss (SDD21 Max.)
| AWG / Length | 600 MHz | 1.25 GHz | 2.5 GHz | 5.0 GHz |
|---|---|---|---|---|
| 30 AWG (1 m) | >= -3.0 dB | >= -4.0 dB | >= -5.5 dB | >= -8.0 dB |
| 28 AWG (3 m) | >= -5.0 dB | >= -6.5 dB | >= -9.5 dB | >= -14.0 dB |
| 26 AWG (5 m) | >= -6.0 dB | >= -8.0 dB | >= -11.0 dB | >= -16.0 dB |
| 24 AWG (10 m) | — | — | — | — |
Ordering Options
| Part Number | Description | Length | Jacket | Wire Gauge |
|---|---|---|---|---|
| BWN-DAC-QSFP+-40G-01M | 40G QSFP+ Passive DAC | 1 m | PVC or LSZH | 30 AWG |
| BWN-DAC-QSFP+-40G-03M | 40G QSFP+ Passive DAC | 3 m | PVC or LSZH | 28 AWG |
| BWN-DAC-QSFP+-40G-05M | 40G QSFP+ Passive DAC | 5 m | PVC or LSZH | 26 AWG |
| BWN-DAC-QSFP+-40G-07M | 40G QSFP+ Passive DAC | 7 m | PVC or LSZH | 24 AWG |
| BWN-DAC-QSFP+-40G-10M | 40G QSFP+ Passive DAC | 10 m | PVC or LSZH | 24 AWG |
| BWN-DAC-QSFP+-40G-xxM | 40G QSFP+ Passive DAC | Custom | PVC or LSZH | Custom |
Common Procurement Objections
Will it work in my switch or NIC?
Form factor and standards alignment are necessary but not sufficient. Send the exact host model, firmware, port mode, length, and coding requirement for a compatibility review.
Which length should I order?
The current datasheet lists up to 7 m. Measure the routed path, include a controlled service loop, and avoid ordering unnecessary slack.
Should I use AOC instead?
Use an ACC when a copper route exceeds the practical passive budget but remains short. Use an AOC when the route needs more distance, a lighter cable body, or EMI immunity.
Can BWNFiber customize the assembly?
Datasheet ordering tables include standard and/or custom entries. Submit the endpoint, length, label, jacket, coding, temperature, packaging, and quantity requirements for feasibility confirmation.
Related High-Speed Cable Options
Request a Configuration Review
Send endpoint models, firmware, port mode, length, quantity, temperature, labeling, packaging, and acceptance requirements. BWNFiber can return a proposed cable code and BOM for review.
