Question 1

There are no products with the needed output voltage in the catalog. Is there any way to get around this?

Accepted Answer

A. Below are two ways to handle this situation.

(1) Using an output voltage variable function.
The output voltage can be adjusted with products that have output voltage variable functions such as by connecting the resistance to the output voltage variable terminal TRM.
However, they do not support voltages that exceed the variable ranges stipulated in the specifications.

(2) Stacking multiple output voltages
This method may take up a lot of space with mounting but allows configurations of various kinds of output voltages by changing how they are combined. Please refer to the example below of how output voltages can be stacked and configured.

*When the power supply does not start up, please connect a diode with as low a forward voltage as possible such as a schottky barrier diode in parallel with the outputs of each of the products to bypass this (1).
Please use a diode where the reverse voltage is twice or more the voltage between the +Vout and -Vout for the bypass.
Please also use it with the output current at the rated current value of the smallest product or below.

Figure 1　When stacking output voltages of multiple units of products

*Products with ±2 outputs can be used with 2 outputs stacked by opening the COM terminals. Products with ±12 outputs can be used as single-output products with 24V outputs.

Figure 2　When stacking output voltages of products with ±2 outputs

Table 1　Configuration example

Voltages like the ones below can be created through the configuration methods above.
At 10W or below with the CC-E Series

Configuration	Output voltage (initial value)	Settable range of output voltage (variable function)
Product with 3.3V output (single item)	3.3V	3.15 to 3.60V
Product with 5V output (single item)	5.0V	4.75 to 6.00V
Using 3.3V output x 2 units	6.6V	6.30 to 7.20V
3.3V output + 5V output	8.3V	7.90 to 9.60V
Using 5V output x 2 units	10.0V	9.50 to 12.00V
Product with 12V output (single item)	12.0V	11.40 to 15.00V
3.3V output + 12V output	15.3V	14.55 to 18.60V
5V output + 12V output	17.0V	16.15 to 21.00V
3.3V output + 5V output + 12V output	20.3V	19.30 to 24.60V
±12V output (COM terminals not used)	24.0V	22.80 to 30.00V

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Question 2

Is there a way to sustain output voltages with DC-DC converters during input interruptions?

Accepted Answer

A. There is also the method of adding a high-capacity capacitor on the input side (a diode must also be added if the input voltage is to be removed).

*The power will be supplied from the external input capacitor Cin if the power supply from the input is cut off. (1). The time it takes for the DC-DC converter to drop down to the lower limit of the operable input voltage can be lengthened by increasing the capacitance value of this input capacitor.
The backflow prevention diode D₁ must also be inserted when removing the input voltage with another circuit connected to the input power supply or input side during an input interruption (2). Please be careful as losses occur in a steady state.

Figure 1

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Question 3

How do you select diodes for series operation and parallel operation (backup)?

Accepted Answer

A. The rough standards for selections are:
(1) That the peak repetitive reverse voltage is twice the output rated voltage of the power supply or above
(2) That the average output current is at the output rated voltage of the power supply or above
(3) That it is a diode with as low a forward voltage as possible (example: schottky type)
Please take sufficient care when cooling components such as radiators and make sure that the temperatures of the elements are within the ranges stipulated by the manufacturer because the elements can be thermally destroyed if diodes are used alone.
(Please use one of our products such as the backflow prevention module RP-60-20.)

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Question 4

Please provide the recommended breaker (circuit protector) capacity.

Accepted Answer

A. Please consider one with a capacity that is of the same fuse capacity shown in the manual.
Please also make your selection from among delayed types (time-lag types) as there is the flow of surge currents.

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Question 5

How do I limit the input surge current (inrush current) of the DC-DC converter?

Accepted Answer

A. 1. Method for connecting resistors in a series

(Important Points)
・Limit the input surge current by connecting resistors in a series. The required resistance value is calculated using the following formula: R (Ω) =V (V) /Ip (A).
・Since this resistor causes a voltage drop even in a steady state and continues to consume power, it is necessary to pay attention to the power rating of the
resistor and the supply capability of the input power source.

2. Method for connecting thermistors in a series

(Important Points)
・Limit the input surge current by connecting thermistors in a series instead of resistors. When the power is turned on, the thermistor shows a high resistance
value due to the low temperature and limits the input surge current. After that, due to self-heating, the resistance value decreases as the temperature rises, so
the steady-state loss can be reduced compared to when a resistor is used.
・The circuit configuration is simple yet effective. Therefore, it is necessary to carefully consider the usage conditions at the time of selection. In particular, when
used at low temperatures, it is possible that the resistance value may not decrease even if self-heating is applied. On the other hand, when used at high
temperatures, the resistance value is low from the initial state, and it is possible that the expected limiting effect may not be obtained.
・Even if the power source is turned off and then immediately turned on again, the resistance value is low from the initial state and the limiting effect cannot be
obtained.

3. Methods for using resistors and semiconductor switches

(Important Points)
・Input surge current is limited by connecting resistors in a series and a semiconductor switch such as a FET or thyristor in parallel with the resistors. When
the power is turned on, the semiconductor switch is opened and the input surge current is limited by the resistor. After that, the input voltage, etc., is detected
and the semiconductor switch is short-circuited to suppress steady-state loss.
・Input surge current characteristics can be set relatively freely compared to other methods; however, the circuit configuration becomes complicated.

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Question 6

How do I add an external OVP (latch cutoff type) to a DC-DC converter that does not have the overvoltage protection (OVP) function?

Accepted Answer

A. *Applicable product
Products without OVP function or products with OVP (when setting OVP with high accuracy below the standard value)

1. Example circuit
Excess voltage is detected on the output side. The detection value is determined by the voltage of the Zener diode (ZD1) and the light-emitting side
forward voltage VF of the photocoupler (PC1).
The circuit in Figure 1 uses a phototriac coupler and the coupler itself has a latch function (breaker retention). However, since it is difficult to obtain such
components recently, an example circuit using a general-purpose photocoupler is also presented in Figure 2 as an alternative circuit.

2. Explanation of OVP action
When the input is turned on or in the steady state, Q1 is ON and the RC terminal is short-circuited to -Vin. This means that the DC-DC converter is also in
the ON state and the rated output voltage is generated. When, for some reason, an excess voltage condition occurs in the output and the output reaches
a voltage equal to the VZ (ZD1) + VF (PC1) voltage, PC1 turns ON and the RC pin of DC-DC turns OFF. Since this OFF state is retained (latched),
it is necessary to temporarily drop the input voltage in order to release the latch.

3. Important points when setting the constant number of products
1) An accurate OVP detection level can be obtained by setting the Zener diode (ZD1) current during OVP operation to near the ZD1 rated value
(example: 5mA).
2) If chattering occurs when turning on the input, the OVP may malfunction. Therefore, insert a bypass capacitor (Cin) in the input line as necessary.
3) The input capacitor (C1) of the thyristor circuit prevents malfunction when the input is turned on. Therefore, please be sure to attach an input capacitor.
4) Please optimize the power rating of the resistor being used and the pressure resistance of the capacitor according to the applied circuit.

*A portion of the circuit described above is configured via theoretical review. Therefore, in order to confirm that no problems exist, please be sure to
evaluate the actual device before applying it to the machine.

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Question 7

Can an appropriate housing for the connectors be purchased?

Accepted Answer

A. The housing is not sold. An optional harness described in the product information website (TDK Product Center) is available.Appropriate housing models are described in the power supply product catalog, outline drawing, and instruction manual.

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Question 8

I want to purchase a terminal cover separately.

Accepted Answer

A. Terminal covers are not sold separately.

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