• DOS series
  • DOS series

DOS series

Fast Response Four-Quadrant Bipolar Power Supply

  • Max Voltage: ±60V
  • Max Current: ±100A
  • Max Power: 2kW
  • Fast response

Fast response four-quadrant bipolar power supply

DOS series are four-quadrant bipolar power supply with high-speed response of DC to 200 kHz (CV mode). It shall output various waveforms including sinusoidal, triangular, saw-tooth, rectangular and more with combination with a function generator. As DOS series amplifies any waveform, it is suitable for all sorts of simulation tests.
Sourcing and sinking of electrical power with four-quadrant operation as well as 2 operation modes of CV and CC is possible. Compact size for such various function and ultra high-speed response power supply. In addition, the features of large meters with high visibility and superior operability make the DOS series versatile four quadrant bipolar power supply which can be used a wide variety of occasion from in laboratory to production line.


Fast response
Suitable for transient response test because of its ultra high-speed response DC to 200 kHz and high power, maximum 2000 W.
Four-quadrant action
DOS Series can be used both as a high speed response DC power supply and as a DC electronic load.
DC bias
10-turn potentiometer to be used as the output setting volume when used as the DC power supply and as the bias setting dial at outputting AC waveform is equipped.
Constant voltage (CV)/Constant current(CV)
A single switch selects between CV and CC modes.
Compact & light weight
For maximum compactness and light weight, DOS Series has been improved for small footprint and handiness.
DC output meter equipped
3-digit digital meter displays the DC value of the output voltage and current. (The option of rms indication is available.)
Complete protective functions
Protective functions against over voltage/current and against output short-circuit are completely provided.
Master/Slave control (option) for more power requirement. Both of Master unit and Slave unit are usable as individual amplifier. (Frequency response will vary in case of master/slave operation, please ask sales staff.)


  • Inductive load such as coil and transformer
  • Various motor tests
  • Evaluation test for solar panel related devices
  • Ripple test of capacitors
  • Voltage regulation tests for in-vehicle electrical component
  • For surface treatment

This product is not designed for charge and discharge of battery.
Please contact nearby sales if unit is used for charge and discharge application.


* Models with voltage, curremt or frequencies not listed here are also available. Please contact the nearest sales office.

Model Maximum Output Frequency response (-3 dB) Weight
[kg (approx.)]
Voltage [V] Current [A] Power [W] CV mode CC mode
DOS20-7.5 ±20 ±7.5 150 DC to 200 kHz DC to 100 kHz 11
DOS20-15 ±20 ±15 300 17
DOS20-30 ±20 ±30 600 23
DOS20-60 ±20 ±60 1200 40
DOS20-100 ±20 ±100 2000 47
DOS25-6 ±25 ±6 150 11
DOS25-12 ±25 ±12 300 17
DOS25-24 ±25 ±24 600 23
DOS25-48 ±25 ±48 1200 40
DOS25-80 ±25 ±80 2000 47
DOS45-3.3 ±45 ±3.3 150 12
DOS45-6.6 ±45 ±6.6 300 17
DOS45-13.3 ±45 ±13.3 600 23
DOS45-16 ±45 ±16 720 23
DOS45-26.7 ±45 ±26.7 1200 40
DOS45-44.4 ±45 ±44.4 2000 47
DOS60-2.5 ±60 ±2.5 150 12
DOS60-5 ±60 ±5 300 17
DOS60-10 ±60 ±10 600 23
DOS60-20 ±60 ±20 1200 40
DOS60-33.3 ±60 ±33.3 2000 47


Protective functions

Over voltage protection (O.V.P)

DOS series is equipped with over voltage protection, which protects load by limiting voltage up to approx. 110% of the rated output voltage even at abnormal conditions.

* It is possible to set variable 0% to approx. 110% output voltage range with -LVc option.

Over current protection (O.C.P)

DOS series is also equipped with over current protection, which protects power supplies and load by limiting current up to approx. 110 % of the rated output current.

* It is possible to set variable 0% to approx. 110% output voltage range with -LCc option.

High speed over current protection

DOS series is provided with 2 types of over current protections, high speed over current protection to limit the pulse current, and standard over current protection to limit the static current. The standard over current protection limits the static current, responding at around 1m sec. Additional high speed over current protection can limit pulse current of square waveforms or from a capacitive load at approximately 2 times rated current.

High speed over current protection

Output range

DOS series is a bipolar power supply which can perform four-quadrant operation. They can supply (source) and absorb (sink) current in the field of the drawing on the right.

  • Vo max: rated output voltage
  • Io max: rated output current
This image is a legend.
This image is graph.


For details, download the datasheet below.


-LN: No protection against blackout

-LF: Floating ground (Resistant to pressure 200 Vdc)

-LMsm, -LMss: Master/Slave control (parallel operation)

Maximum 3 units including master unit are hooked. "-LMsm" for the master unit and "-LMss" for slave units.
Please order required number of units. Every master unit and slave units are exclusive use, but operating individually is also available.
When change the combination of Master/Slave, they should be readjusted in our shop.

-LPr: rms display

-LVc: Output voltage limit

Variable from 0 to approx. 110% with the dial on the front panel

-LCc: Output current limit

Variable from 0 to approx. 110% with the dial on the front panel

-L(220V): 200 Vac to 240 Vac ±10% single phase, 50/60 Hz input (150 W and 300 W models only)

How to Order

To order, please add the above following option mark to the model number.
[Example] DOS25-12-LCcDFMsmNPrSVc(220V)
(Alphabetical and input voltage order)


For details, download the datasheet below.

Tech Notes

Characteristic of amplifier

Rise time

(Stepping time): The response time is sometimes described by the rise time (as shown in the drawing on the right).
The rise time of an amplifier at a response speed of (= frequency bandwidth) Fc (Hz) is generally acquired by "tr ≒ 0.35/fc."
Fall time tf is the same as tr.
Frequency bandwidth: at 200 kHz or lower, tr = tf = around 1.8 μs, at 100 kHz or lower, tr = tf = around 3.5 μs

Rise time

Response speed

When accurate output waveforms are required, select a amplifier with a frequency bandwidth higher enough than the operating frequency.
In case of using sine waves, 3 to 5 times more frequency bandwidth is required, and around 10-times more in case of square waves in general.
Inadequate bandwidth causes not only decrease in the output amplitude but much difference between the input and output phases. Therefore operating the product while monitoring the actual output waveforms is recommended.

Response speed

Inductive load

Some inductance of inductive load may cause resonance in CC mode.
In such cases, connect a C-R series circuit between output terminals to prevent resonance.

Capacitive Load

When a capacitive load is more than 100 pF (including a stray capacitance of output wire), the resonance in the output may occur. In that case, install 100-ohm (@0.1 μF) to 1000-ohm (@1000 pF) of high voltage resistance in the output in series. Please note that the frequency band will be limited as the formula written in the right figure when an amplifier is used with a capacitive load.
In addition, when an amplifier is used for the use such as a corona discharge, the current which is higher than rating will flow and it will affect the amplifier badly. In this case, as well as the time to use an amplifier with a capacitive load, please install the output resistance and limit the current.

* Please avoid continuous inputting of high frequency signal which reduces output frequency of an amplifier. An amplifier will be broken because of increase of internal loss.

This image explains frequency band when a capacitive load is connected.

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Bipolar power supplies/High voltage Amplifiers