• DOP series
  • DOP series

DOP series

Four-quadrant Fast Response Bipolar Power Supply

High speed bipolar power amplifier

  • Max Voltage: ±300V
  • Max Current: ±120A
  • Max Power: 2kW
  • Fast Response

Available for expanding to 6 kW with master-slave connection

DOP series are four-quadrant bipolar power supplies which source and sink electric power. They can be used in 2 modes of a CV (constant voltage) or a CV (constant current). The weight is half of the conventional units by adopting the aluminum frame.
They are compact and high speed, driving output proportional to the input waveform such as a sine wave, triangular wave, saw wave, and square wave.
DOP series is most appropriate for inductive load including coil and transformer, capacitive load like capacitor, test of DC servo motor or automobile electric appliances, and surface treatment.
All the models are completely solid-state with output voltage between ±5 V and ±300 V.

Even faster models or the models with function generator are also available. Contact to local sales office for details.


Response speed
Newly developed DOP Series is the most appropriate for transient response test with such high power and broad bandwidth.
Wide lineup
Select a model fitting for your applications from the lineup of various output voltage and current.
DC bias
10-turn potentiometer to be used for the output setting volume when used as the DC power supply and for the bias setting when used as AC power suppluy is equipped.
Silent operation
Operating noise bacame quiet by having employed the silent fan, and also it became easy-to-use.
DC output meter
3-digit digital meter displays the DC value of the output voltage and current. (The option of rms indication is available.)
Four-quadrant action
DOP Series can be used both as a high speed response DC power supply and as a DC electronic load.
Constant voltage (CV)/Constant current (CC)
A single switch selects between CV and CC modes.
Compact & light weight
For maximum compactness and light weight, DOP Series has been improved for small footprint and easy carry.
Complete protective function
Protective function against over voltage/current and protective measures against output short-circuit are completely provided.
The option of Master-slave control will resolve power shortages.


  • Inductive load such as coil and transformer
  • Capacitive load such as electric double-layer capacitor
  • Voltage regulation tests for in-vehicle electrical component
  • Evaluation test for solar panel related devices
  • Various motor tests
  • 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,current or frequencies not listed here are also avaliable.Please contact the nearest sales office.

Model Maximum output Frequency response (-3 dB)
Voltage [V] Current [A] Power [W]
DOP5-30 ±5 ±30 150 DC to 20 kHz
DOP5-60 ±5 ±60 300 DC to 20 kHz
DOP6-120 ±6 ±120 720 DC to 20 kHz
DOP10-15 ±10 ±15 150 DC to 20 kHz
DOP10-30 ±10 ±30 300 DC to 20 kHz
DOP10-60 ±10 ±60 600 DC to 20 kHz
DOP20-7.5 ±20 ±7.5 150 DC to 20 kHz
DOP20-15 ±20 ±15 300 DC to 20 kHz
DOP20-30 ±20 ±30 600 DC to 20 kHz
DOP20-60 ±20 ±60 1200 DC to 20 kHz
DOP20-100 ±20 ±100 2000 DC to 20 kHz
DOP25-6 ±25 ±6 150 DC to 30 kHz
DOP25-12 ±25 ±12 300 DC to 30 kHz
DOP25-24 ±25 ±24 600 DC to 20 kHz
DOP25-48 ±25 ±48 1200 DC to 20 kHz
DOP25-80 ±25 ±80 2000 DC to 20 kHz
DOP30-40 ±30 ±40 1200 DC to 20kHz
DOP45-3.3 ±45 ±3.3 150 DC to 20 kHz
DOP45-6.6 ±45 ±6.6 300 DC to 20 kHz
DOP45-13.3 ±45 ±13.3 600 DC to 20 kHz
DOP45-16 ±45 ±16 720 DC to 20 kHz
DOP45-26.7 ±45 ±26.7 1200 DC to 20 kHz
DOP45-44.4 ±45 ±44.4 2000 DC to 20 kHz
DOP60-2.5 ±60 ±2.5 150 DC to 20 kHz
DOP60-5 ±60 ±5 300 DC to 20kHz
DOP60-10 ±60 ±10 600 DC to 20 kHz
DOP60-20 ±60 ±20 1200 DC to 20 kHz
DOP60-33.3 ±60 ±33.3 2000 DC to 20 kHz
DOP70-17 ±70 ±17 1200 DC to 20 kHz
DOP80-25 ±80 ±25 2000 DC to 20kHz
DOP120-2.5 ±120 ±2.5 300 DC to 20 kHz
DOP120-5 ±120 ±5 600 DC to 20 kHz
DOP120-10 ±120 ±10 1200 DC to 20 kHz
DOP150-2 ±150 ±2 300 DC to 20kHz
DOP150-4 ±150 ±4 600 DC to 20 kHz
DOP150-8 ±150 ±8 1200 DC to 20 kHz
DOP200-1.5 ±200 ±1.5 300 DC to 20 kHz
DOP200-1.75 ±200 ±1.75 350 DC to 20 kHz
DOP200-3 ±200 ±3 600 DC to 20 kHz
DOP200-3.5 ±200 ±3. 700 DC to 20 kHz
DOP200-6 ±200 ±6 1200 DC to 20 kHz
DOP300-1 ±300 ±1 300 DC to 20 kHz
DOP300-2 ±300 ±2 600 DC to 20 kHz
DOP300-4 ±300 ±4 1200 DC to 20 kHz



OVP (Over voltage protection)

DOP 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.

* -LVc option (output voltage limitter) enable to control the output in 0 to approx. 110% range.

OCP (Over current protection)

DOP 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.

* -LCc option (output current limitter) enable to control the output in 0 to approx. 110% range.

High speed over current protection

DOP 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 1 ms. Additional high speed over current protection can limit pulse current of square waveforms or from capacitor at approx. 2 times more current of rating.

Amplifier DOP Series Over current protection

Output range

DOP 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.

CV/CC setting selection

Inputting voltage via Vcon-in enables the control of output voltage V when CV control is selected and output current A when CC control is selected.

in CV mode in CC mode
Vcon Output voltage Output current
-10 V -Rating -Rating
0 V 0 V 0 A
+10 V +Rating +Rating

Use of BIAS

When the "BIAS ON/OFF switch" is flipped to ON, bias can be changed with the "BIAS setting dial." Bias of the voltage can be set when CV control is selected, and that of the current can be when CC control is selected.

in CV mode in CC mode
Scale Output voltage Output current
000 (ccw) -Rating -Rating
500 0 V 0 A
1000 (cw) +Rating +Rating


For details, download the datasheet below.


-LN: No protection against blackout

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

-LMs( ): Master/slave control*

-LPr: rms display

-LVc: Output voltage limit

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

-LCc: Output current limit

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

-L(220V): 200 Vac to 240 Vac ±10% single phase, 50/60 Hz input

(Only for 150 W models and 300 W to 350 W models)

* ( ) shall be "m" for Master unit, or "s" for Slave unit. -LMsm for Master, -LMss for Slave. Order required quantity for each unit. Master unit or slave unit are to be set at the factory, and if master to slave change is required after shipment, adjustment at the factory will be needed. Slave unit will also be able to operate by itself. Maximum 3 units including master unit can be connected.

How to Order

When ordering, suffix the following option mark to the model number.

[Example] DOP25-12-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 30 kHz or lower, tr = tf = around 12 μs
: at 20 kHz or lower, tr = tf = around 18 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 times 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.

Read more


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Bipolar power supplies/High voltage Amplifiers