UNI-T DC Linear Power Supply — Buyer's Guide
Why Linear?
A linear regulator dissipates the difference between input and output voltage as heat. The result: extremely low output noise, no switching artifacts, fast transient response, and clean transient behavior that drops as the output voltage drops. The cost: weight, heat, efficiency, and a practical power ceiling around a few hundred watts per channel.
You want linear when the supply is feeding a circuit that will measure what the supply does — noise-sensitive analog, RF receivers, audio amplifiers, biomedical sensors, education benches, and precision instrumentation. If you need power above a few hundred watts, or high voltage above 250 V, or wide constant-power flexibility, switching is the right answer instead. See DC Switching Power Supplies.
What Every UNI-T Linear PSU Shares
Topology
Linear pass-element regulation — no switching frequency in the output, no high-frequency ripple
Ripple & noise
Sub-millivolt ripple, microvolt-class noise floor — ideal for sensitive analog
Regulation
CV / CC crossover with automatic mode indication, load and line regulation in the 0.01% class
Protections
OVP, OCP, OTP — full protection suite standard across the line
Display
High-contrast V/I readout, dual-display on multi-channel models
Warranty
3+2 years — parts, labor, return shipping
Decision 1: How Many Channels?
Single-channel
1Ch
Best for: dedicated bench supply for a single rail or one device under test. Compact footprint, simple front panel.
UDP1306C (192W, 32V/6A) and the
UTP3000 family (90–150W, single-channel value picks) anchor this tier.
Triple-channel
3Ch
Best for: R&D bench work powering multiple rails on the same DUT — analog, digital, and a reference together. Two independent 0–30V channels plus a fixed-output third (typically 2.5 V / 3.3 V / 5 V). Series and parallel modes combine channels for higher voltage or current. Anchored by
UDP3000C.
Four-channel
4Ch
Best for: production test, complex multi-rail prototypes, education labs running multiple students per bench. Three programmable channels plus one fixed reference output. Anchored by
UDP3000S and
UDP4303S.
Decision 2: Programmable or Manual?
Programmable supplies accept SCPI commands over USB, RS-232, or LAN — for automated test stations, scripted ramp profiles, captured V/I logs, and integration with LabVIEW or Python. Manual supplies have knobs and a front panel only.
| Use case |
Pick |
Why |
| Automated test, scripted profiles, list-mode sequencing |
Programmable |
USB/LAN/SCPI control built in; channel state captured by ATE software |
| R&D bench, prototyping, occasional captured measurements |
Programmable |
USB logging while you work; reach for the bus when you need it |
| Education, training labs, repair, hobbyist work |
Manual is fine |
Knob-and-display workflow; lower price point per station |
| Production line with fixed setpoints |
Programmable |
Recall stored profiles instead of re-entering on every shift |
UNI-T's catalog leans programmable — all UDP-series models have SCPI control; only the entry-tier UDP3303A and the UTP3000 family are manual-only.
Decision 3: Power, Voltage, and Current
Linear supplies in this category top out around 335 W total power and 32 V per channel. Beyond that envelope, switching is the only practical topology. Within the envelope:
| Series |
Channels |
V/A per programmable channel |
Total power |
Best for |
| UDP1306C |
1Ch |
32V / 6A |
192W |
Single-rail bench, compact footprint, programmable |
| UDP3303A |
3Ch |
30V / 3A |
195W |
Education and basic R&D, manual front panel |
| UDP3303C |
3Ch |
30V / 3A |
195W |
Triple-output programmable, education and value R&D |
| UDP3305C |
3Ch |
30V / 5A |
315W |
Triple-output programmable, higher current per channel |
| UDP3305S |
4Ch |
30V / 5A |
328W |
Four-output programmable, R&D and production |
| UDP3305S-E |
4Ch |
30V / 5A |
328W |
Education variant of UDP3305S at education-tier pricing |
| UDP4303S |
4Ch |
32V / 10A |
297W |
4-channel high-current programmable bench |
| UTP3300/3313/3315 |
1–3Ch |
30–32V / 3–5A |
90–335W |
Manual value-pick benches, single- or triple-channel |
Recommended Configurations
Noise-sensitive analog R&D
Pick: UDP3305S or UDP3305C — clean linear supply for op-amp front-ends, RF receivers, audio amplifiers, sensor electronics. Triple- or four-channel lets you power analog (+/−15V), digital (3.3V), and a reference rail from one chassis.
Education lab bench
Pick: UDP3305S-E or UDP3303A — UDP3305S-E is the education-priced 4-channel; UDP3303A is the manual 3-channel for stations that don't need SCPI. Both cover the full undergraduate electronics curriculum.
Production test station
Pick: UDP4303S or UDP3305S — programmable, scriptable, 4-channel. UDP4303S delivers 10A per channel for higher-current DUTs; UDP3305S is the standard 5A choice.
Single-rail dedicated bench supply
Pick: UDP1306C — 192W single-channel programmable, compact, USB control. The right pick when you only need one supply on this bench.
Repair shop / hobbyist / training
Pick: UTP3000 family — manual front-panel value picks from 90W single-channel to 335W triple-channel. Knob-and-display workflow at the lowest price points in the linear line.
Why Choose UNI-T Linear PSUs?
Sub-millivolt ripple
Linear pass-element regulation produces no switching frequency in the output. Ripple stays in the microvolt-class noise floor that RF receivers, audio front-ends, and precision analog circuits need.
Fast transient response
Linear topology delivers tens-of-microsecond recovery from load steps — faster than switching supplies in the same class. Driving switching loads from a linear supply gives you a clean source impedance to test against.
Channel coupling options
Series and parallel modes on UDP3000C/S combine two channels for double voltage (0–60V) or double current. Tracking and independent modes covered by a single front-panel switch.
3+2 year warranty
Three-year base warranty, two additional years on registration. Parts, labor, return shipping included.
FAQ
How much cleaner is linear than switching?
UNI-T linear supplies hold output ripple in the sub-millivolt range and noise in the microvolt range. UNI-T switching supplies hold ripple in the tens-of-millivolts range, well-filtered but visibly present in spectrum-analyzer plots above the linear noise floor. For RF receivers, precision instrumentation, and audio gear measuring below −60 dBc, the difference is the difference between a clean measurement and chasing supply artifacts.
Can I parallel two channels for higher current?
Yes — UDP3000C and UDP3000S triple-output models support parallel mode that combines channels 1 and 2 for double the current at the same voltage. Series mode combines them for double the voltage at the same current. Switching modes is a single front-panel control.
Why does the third channel on triple-output supplies have a fixed output?
The fixed channel (typically selectable among 2.5 V, 3.3 V, 5 V) is the logic-rail reference for the DUT — you wire it to the digital section while channels 1 and 2 power the programmable analog. Most embedded DUTs have a fixed logic supply, so dedicating one channel saves you a front-panel input on every setup.
Linear or switching for testing a battery?
Switching — battery test rarely cares about supply ripple at the microvolt level (the battery's own internal resistance dominates) and benefits from switching's wide voltage envelope and high power. The UDP5000 family (including the 800V UDP5800 SKUs) is purpose-built for battery validation. Pick linear for the front-end electronics; pick switching for the cells themselves.
Linear or switching for an RF receiver?
Linear, every time. Switching supplies inject their switching frequency into anything they power; an RF receiver with a 10 MHz IF and a switching supply at 250 kHz spurs all the way through the analog chain. Linear supplies have no switching frequency to inject.
What's the difference between UDP3303A and UDP3303C?
UDP3303A is manual-only; UDP3303C adds USB-Device for SCPI control and PC logging. Same chassis, same channels, same V/A capabilities — you're paying for the programmability bus. Pick C if you'll ever run scripted profiles or capture data; pick A if the supply will live next to a workbench and never see a PC.
Linear for noise-sensitive analog. Match channels to your DUT rail count. Programmable for automation.
