UNI-T UDP3303A 3Ch Classic-Series Linear DC Power Supply
Overview
The UDP3303A is a 195W three-channel linear bench power supply built for the kind of work where you want clean DC, predictable behavior, and labels on every button. Two adjustable channels deliver 0–30V at 0–3A; a third selectable channel switches between 1.8V, 2.5V, 3.3V, and 5V at 3.2A — the four logic rails most embedded and digital prototyping work needs without leaving the supply set up for the rest of the bench.
Linear regulation keeps output ripple under 1 mVrms with no switching artifacts to chase down — exactly what analog circuits, audio work, and low-noise sensor development need. CH1 and CH2 combine in series (up to 60V) or parallel (up to 6A) at the press of a button, and CH1+CH2 can also run in master-slave tracking. OVP, OCP, OTP, keypad lock, and a Digital I/O pin pair for external interlock round out a supply that's straightforward to set up and hard to misuse. The UDP3303A is the knob-and-button entry of the UDP3000C platform — for SCPI control, see the UDP3303C; for 5A per channel, see the UDP3305C.
UDP3303A — 3Ch 195W linear bench power supply
Key Features
- Three Channels, 195W Total — CH1 and CH2: 0–30V / 0–3A adjustable. CH3: switchable 1.8V / 2.5V / 3.3V / 5V at 3.2A. Independent operation by default.
- CH3 Logic-Rail Selector — A single front-panel button cycles CH3 through the four most-used digital supply voltages. No jumpering, no menu diving, no second adjustable channel sacrificed to digital work.
- Linear Topology, ≤1 mVrms Ripple — Clean, low-noise output. Load regulation of ≤0.01% + 3 mV (rated current ≤3A) holds the rail steady when the load steps.
- 10 mV / 1 mA Resolution — Four-digit voltage and current display per channel on EBTN LCD. High-resolution adjustment knobs with push-button coarse/fine.
- Series, Parallel, and Tracking Modes — Combine CH1+CH2 for up to 60V series or 6A parallel from the front panel. Master-slave tracking keeps both channels synchronized for matched-rail testing.
- OVP / OCP / OTP Protection — Per-channel over-voltage and over-current thresholds you set yourself, plus over-temperature shutdown. Keypad lock prevents accidental reconfiguration.
- Hardware Output Disable — Two-pin Digital I/O terminal accepts a short or relay contact for emergency cutoff and interlock circuits. No PC connection required.
- Front-Panel 5V/2A USB Charging Port (CH4) — Independent 5V/2A USB-A output for charging a phone or powering a USB-powered demo board. Charging output only — not a data interface.
- Shutdown Memory + Five Preset Storage Groups — The supply restores its last settings on power-up. Five preset groups (M1–M5) keep frequently used setups one keypress away.
- 3+2 Warranty — 3+2 warranty (3 years standard + 2 years with free registration). Free firmware updates over the product lifetime.
Detailed Features
CH3 Logic-Rail Selector — One Button, Four Voltages
Most three-channel bench supplies give you two adjustable channels and a fixed 5V rail you'll resent the moment you need 3.3V. The UDP3303A's CH3 cycles between 1.8V, 2.5V, 3.3V, and 5V at 3.2A — covering CMOS logic, modern microcontroller cores, legacy TTL, and USB-class devices — at a single front-panel button press. The practical effect: CH1 and CH2 stay free for the analog work the linear topology is genuinely good at — op-amp rails, sensor bias, charge-pump references, audio circuits — while CH3 handles whatever digital subsystem the project also needs powered. One supply, two adjustable analog rails, one switchable digital rail, all labeled, all protected.
UNI-T UDP3303A — ch3 logic-rail selector
Built for Bench Work That Has to Behave Predictably
The UDP3303A is a deliberate choice for benches where the supply itself isn't supposed to be the interesting part of the experiment. There's no SCPI command set to learn, no firmware update path to get wrong before a class starts, no remote control to reconfigure between students. There's a knob, a four-digit display per channel, four protection thresholds you set once, and a Digital I/O pin pair that can kill the output from an external interlock or panic button. For teaching labs and trade-school programs running 10–30 stations, that's the entire pitch — every student gets the same instrument with the same workflow, replacement is a power cord and a rack slot, and the instrument they learn on at school is identifiably the same kind they'll see on a service-shop bench or in a small-team R&D lab.
UNI-T UDP3303A — built for bench work that has to behave predictably
Applications
Teaching Labs & Trade Schools
Per-station cost that lets a 20-bench classroom stay inside budget. Front-panel labels, hardware interlock pins, and OVP/OCP per channel survive the mistakes students are supposed to make. The CH3 logic-rail selector covers every digital-electronics curriculum from CMOS basics to USB-device powering. The 3+2 warranty covers a typical full curriculum cycle on one purchase.
Mixed-Signal Prototyping
CH1 and CH2 power analog rails — op-amp supplies, sensor bias, audio circuits — at <1 mVrms ripple. CH3 handles the digital side at the exact logic voltage the prototype needs. One supply does what most benches use two for.
Service & Repair Benches
Three independent rails, configurable protection, and shutdown memory make this a reliable everyday bench supply for board-level service work. The keypad lock keeps a known-good test condition from drifting between repair steps.
Maker & Hobbyist Workshops
Variable digital rail covers anything from a 3.3V ESP32 board to a 1.8V FPGA core to a 5V USB device. Linear output stays clean across all of it. The CH4 front-panel USB doubles as a phone charger.
Specifications
| Model | UDP3303A |
| Channels | 3 (CH1, CH2 adjustable; CH3 selectable) |
| CH1, CH2 Output Voltage | 0–30V |
| CH1, CH2 Output Current | 0–3A |
| CH3 Output Voltage | 1.8V / 2.5V / 3.3V / 5V (±3%, fine-tunable) |
| CH3 Output Current | 3.2A |
| Total Output Power | 195W |
| CH4 USB Charging Output | 5V / 2A (front-panel USB charging output) |
| Voltage Resolution | 10 mV |
| Current Resolution | 1 mA |
| Load Regulation (CV) | ≤0.01% + 3 mV (rated current ≤3A) |
| Load Regulation (CC) | ≤0.2% + 3 mA |
| Ripple & Noise (Voltage) | ≤1 mVrms (20Hz–20MHz) |
| Ripple & Noise (Current) | ≤3 mArms |
| Temperature Coefficient | ≤300 ppm/°C (V/I) |
| Series Mode (CH1+CH2) | Up to 60V (CH1+CH2) |
| Parallel Mode (CH1+CH2) | Up to 6A (CH1+CH2) |
| Display | EBTN LCD, 4-digit voltage + current per channel |
| Programmable | No (knob and button operation) |
| Interfaces | Digital I/O hardware ON/OFF (no PC interface) |
| Memory | 5 preset storage groups (M1–M5) |
| Protection | OVP, OCP (per-channel, configurable), OTP, keypad lock, shutdown memory |
| AC Input | 100 / 120 / 220 / 230V ±10%, 50/60 Hz |
| Dimensions (W × H × D) | 240 × 168 × 347 mm |
| Weight | 8.8 kg |
| Certifications | CE | cTUVus |
| Warranty | 3+2 years |
Frequently Asked Questions
Is the UDP3303A programmable?
No. The UDP3303A is a knob-and-button bench supply with a Digital I/O pin pair for hardware output ON/OFF only — no SCPI command set, no LAN, no remote programmability. If your workflow needs SCPI control, the programmable counterparts in this family are the UDP3303C (USB-Device + RS-232) and the UDP3305C (same with 5A per channel). The UDP3303A is the manual-bench variant of the same hardware platform.
What is the front-panel USB port for?
It's a 5V/2A USB-A charging output (CH4) — useful for charging a phone or powering a USB-powered demo board without occupying a banana-jack pair on CH1/CH2/CH3. It is explicitly not a data interface; the UDP3303A has no PC connection. The data ports on the back panel are limited to the Digital I/O pin pair for external hardware ON/OFF interlock.
How do CH1 and CH2 combine in series?
Press the SER button on the front panel; the SER indicator lights and the front-panel jacks repurpose as a series pair (CH1+ becomes the positive output, CH2− becomes the negative output). All settings are made on CH1 and CH2 follows automatically. Total voltage is the sum of CH1 and CH2 (up to 60V); total current equals CH1. The same pattern applies to parallel mode.
Why a linear supply instead of switching?
Linear topology produces fundamentally cleaner output — no switching frequency, no harmonic spurs, ripple under 1 mVrms. For analog bench work, audio circuits, low-noise sensor development, and any precision measurement where supply noise shows up in the result, the difference is measurable. The trade-off is lower efficiency and more heat, which at 195W bench-supply scale is not a meaningful constraint.
What's included with the UDP3303A?
The UDP3303A ships with the instrument, power cord, output cables, English user manual, and UNI-T's 3+2 warranty. Ships from authorized US dealer.
Data Sheets and Manuals
Software / Firmware Downloads
Authentic UNI-T accessories are an affordable way to extend the functionality of your instrument.
