Professional Selection Guides & Technical Insights
Short answer: Choose in four steps: voltage and current inside the power envelope, channel count, ripple budget, then interface. Default lab pick: CPX400DP (2 x 60 V/20 A, 420 W). Need three or four rails, take MX; one high-power rail, take QPX; tight budget with simple loads, EX-R still works.
AIM-TTI builds a compact range of bench DC supplies, and almost every wrong buy comes from misreading one of four specifications: the voltage/current power envelope, the channel count, the ripple and noise figure, and the programming interface. Each one maps to a real decision. This guide walks through all four using AIM-TTI's current families, MX, CPX, QPX and EX-R, with figures straight from the official data sheets, so you can check them against the catalog before ordering.
AIM-TTI rates supplies as, for example, "60 V/20 A, 420 W". That does not mean you can have 60 V and 20 A at the same time. 60 V x 20 A would be 1,200 W. The 420 W figure is the real limit, and the supply delivers any voltage and current combination that stays inside that power envelope. On the CPX400, 20 A is available up to about 21 V; at 60 V the current limit is about 7 A. The same logic runs through every PowerFlex and Multi-Range model.
So the correct first question is not "how many volts do you want" but "what is the maximum power your device draws, at what voltage". A 12 V device pulling 15 A needs 180 W and is fine on a CPX200 (180 W envelope) but out of reach for a 35 V/3 A output that only makes about 105 W. Write down the worst case: voltage, current, and the product of the two, then compare against the envelope of the candidate supply.
AIM-TTI uses two names for this behaviour. PowerFlex appears on CPX and QPX series; Multi-Range on MX series. Both mean the same thing: the supply re-allocates voltage against current within a fixed power limit, and range switching keeps setting resolution high across the whole envelope.
Count your rails before you count watts. A single output is fine for powering one device at a time, but most lab work means powering a circuit and its reference, or two rails of a split supply, or several boards at once. That is where the series split happens.
| Series | Outputs | Representative models | Power per unit |
|---|---|---|---|
| MX | 3 or 4 fully functional outputs | MX100T / MX100TP (3 x 35 V/3 A); MX103QP S2 (4 x 35 V/3 A) | 315 W / 420 W |
| CPX | 1 or 2 outputs | CPX200D/DP (2 x 60 V/10 A); CPX400D/DP (2 x 60 V/20 A); CPX400S/SP (1 x 60 V/20 A) | 180 W / 420 W |
| QPX | 1 output (dual model also exists) | QPX1200S/SP (60 V/50 A); QPX600DP (dual) | up to 1200 W |
| EX-R | 1, 2 or 3 outputs, analogue controls | single 35 V/5 A, 18 V/10 A, 42 V/10 A, 20 V/20 A; dual/triple 35 V/4 A | 175–420 W |
Two practical notes on channels. First, isolated outputs can be wired in series or parallel on the CPX and MX families, so a dual 60 V unit becomes a single 120 V unit when you need it, or doubles the current in parallel mode. Second, the MX series adds a shared power mode that routes the full unit power to a single output, which is how a 3 x 35 V/3 A (315 W) unit can deliver more than 3 A from one rail when the other rails are idle. If your test rig occasionally needs one heavy rail and several light ones, that flexibility is worth paying for.
For most digital circuits, a few mV of ripple is irrelevant. For ADC references, audio, precision sensors and RF bias, it is the whole game. AIM-TTI specifies ripple and noise at 20 MHz bandwidth in CV mode, so compare like with like:
| Series | Ripple & noise (CV mode, 20 MHz BW) | Notes |
|---|---|---|
| MX | Typically < 0.5 mVrms, < 5 mV pk-pk; 1 mVrms max (main ranges) | Linear final regulation keeps noise low across outputs |
| CPX | Typically < 1 mVrms, < 15 mV pk-pk; 3 mVrms max | Full PowerFlex envelope |
| TSX | Typically < 1 mVrms; < 3 mVrms max | Silent single-output design |
| EX-R | Typically < 1 mVrms | Mixed-mode regulation |
| QPX | Typically < 3 mVrms, < 20 mV pk-pk (front terminals) | 1 mV setting resolution, front and rear terminals |
Rule of thumb: if your circuit's supply rejection is poor or you are feeding an ADC front end, put the quietest supply on the sensitive rail. The MX family's linear final stage and sub-millivolt typical ripple make it the pick for measurement-heavy benches; a switcher-based unit would need external filtering to get close.
The model suffix tells you the interface story. Plain models (CPX400D, MX100T) are front-panel only. Models with a P (CPX400DP, MX100TP, TSX3510P) add USB, RS232 and LAN with LXI compliance, and most accept an optional GPIB card. The extra cost buys you remote control, readback and automated test loops.
Decide early, because retrofitting is not a firmware update. If the supply will sit under a bench and you will touch it by hand, save the money. If it will live in a rack running scripts, get the P version and check three things: USB and LAN are standard, GPIB is an optional card on many models, and analogue control is available on specific models such as the CPX400SA for simple external voltage programming.
| Factor | MX | CPX | QPX | EX-R |
|---|---|---|---|---|
| Channel philosophy | 3–4 independent rails | 1–2 rails, up to 420 W | Single high-power rail | 1–3 rails, analogue |
| Max voltage / current (per output) | 35 V/3 A (3 or 4 outputs) | 60 V/20 A (dual, 420 W) | 60 V/50 A (1200 W) | 35 V/5 A single; 35 V/4 A dual/triple |
| Ripple (CV, 20 MHz) | < 0.5 mVrms typ | < 1 mVrms typ | < 3 mVrms typ | < 1 mVrms typ |
| Interfaces | USB/RS232/LAN (P); GPIB opt. | USB/RS232/LAN (P); GPIB opt.; analogue on SA | USB/RS232/LAN (P); GPIB opt. | RS232/USB on selected models |
| Best for | Multi-rail test benches, sensitive measurement | General dual-rail lab use, ATE | One heavy rail, power testing | Budget benches, simple loads |
| Your situation | Pick | Why |
|---|---|---|
| One general bench supply for daily board testing | CPX400DP | Dual 60 V/20 A rails in a 420 W envelope, USB/LAN ready, series/parallel when needed |
| Lab bench feeding several independent circuits or split supplies | MX100TP or MX103QP | 3–4 fully independent outputs, quietest ripple in the range, shared power mode for a heavy single rail |
| Testing power amplifiers, motors or batteries needing one big rail | QPX1200SP | 1200 W single output with 1 mV resolution and front/rear terminals |
| Simple bench, manual use, tight budget | EX-R (e.g. 35 V/5 A single or 35 V/4 A dual) | Mixed-mode regulation, typically < 1 mVrms, silent fan-free cooling on most models |
| Automated test scripts with GPIB instruments | Any P model + GPIB option | LXI LAN, USB and RS232 standard; GPIB optional to match legacy racks |
The letters after a series name are meaningful. In CPX400DP: D is dual output, P is the programmable/interface version. In MX100TP the T stands for triple output and P again means interfaces. Check the letter against your need before comparing prices between a plain unit and a P unit; they are different products.
When you order, make sure the unit is genuine and the firmware and accessories match the current AIM-TTI specification. Ruilianxin Technology supplies genuine AIM-TTI instruments sourced from the manufacturers or their first-tier distributors, with original packaging and traceable documentation. Send the series, model letter and your interface needs, and we will quote the correct part with lead time. Single-unit orders are fine.
It means the maximum voltage is 60 V, the maximum current is 20 A, and the supply can deliver any combination inside the 420 W power envelope. You cannot draw 60 V and 20 A together, because that would be 1,200 W. At 60 V the current limit is about 7 A; 20 A is available only at lower voltages. Always size against the power envelope.
Power one device and you need one rail; power a circuit with two supply voltages, or a split-rail amplifier, and two independent rails save you from buying two boxes. If you routinely run several boards or references at once, a 3 or 4 output MX unit replaces several single supplies on one bench footprint. Outputs that can be wired in series or parallel add flexibility without extra hardware.
No. If the powered circuit has decent supply rejection, a few mVrms of ripple is invisible. Invest in the quietest supply only where it matters: ADC references, precision analog front ends, audio and RF bias. On the AIM-TTI range, MX series specifies the lowest typical ripple (under 0.5 mVrms on main ranges), which is why it suits measurement-heavy benches.
Only if you will control the supply remotely. Front-panel models are cheaper and fine for manual bench work. If the supply will run automated tests or sit in a rack, the P version adds USB, RS232 and LAN (LXI) with bus readback, and GPIB is optional on most. Retrofitting interfaces later is not practical, so decide before you order.
Ruilianxin Technology supplies genuine AIM-TTI instruments sourced from the manufacturers or first-tier distributors, with original packaging and traceable documentation. Send the series and model letters you need, and we will quote the correct part and lead time. Single-unit orders are supported. Just send an inquiry.
Tell us the worst-case voltage, current and load type. The Ruilianxin technical team will match the series and model letter, then quote it with lead time.
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