.ut-cat{color:#333;font-family:Arial,Helvetica,sans-serif;line-height:1.5;} .ut-cat h4{color:#1a1a1a;font-size:1.15em;margin:1.5em 0 .5em;padding-bottom:.25em;border-bottom:2px solid #ccc;} .ut-cat h2{color:#1a1a1a;font-size:1.25em;margin:1.2em 0 .4em;} .ut-cat h3{color:#222;font-size:1.05em;margin:1em 0 .3em;} .ut-cat p{margin:.6em 0;} .ut-cat ul{margin:.5em 0;padding-left:1.4em;}.ut-cat li{margin:.25em 0;} .ut-cat img{max-width:100%;height:auto;} .ut-cat table{border-collapse:collapse;width:100%;margin:.5em 0;} .ut-cat th,.ut-cat td{border:1px solid #ddd;padding:6px 10px;text-align:left;vertical-align:top;} .ut-cat td strong{color:#222;} 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. 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. 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 × UNI-T UDP3303A — ch3 logic-rail selector UNI-T UDP3303A — built for bench work that has to behave predictably 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. Mixed-Signal Prototyping CH1 and CH2 power analog rails — op-amp supplies, sensor bias, audio circuits — at
