PKB4313D datasheet(18/28 Pages) FLEX

18 / 28 page

Operating information

Input Voltage

The input voltage range 36 to 75 Vdc meets the requirements

of the European Telecom Standard ETS 300 132-2 for normal

input voltage range in –48 and -60 Vdc systems, -40.5 to -57

V and -50 to -72 V respectively.

At input voltages exceeding 75 V, the power loss will be higher

than at normal input voltage and TP1 must be limited to

absolute max +125°C. The absolute maximum continuous

input voltage is 80 Vdc.

Above 42 V the product operates with normal regulation with

constant output voltage and constant maximum power. Below

42 V the output voltage starts to track the input voltage with a

fixed proportion, keeping a duty-cycle guard band for

regulation. The product operates down below 36 V before the

internal under voltage lock out turns off the product.

Short duration transient disturbances can occur on the DC

distribution and input of the product when a short circuit fault

occurs on the equipment side of a protective device (fuse or

circuit breaker). The voltage level, duration and energy of the

disturbance are dependent on the particular DC distribution

network characteristics and can be sufficient to damage the

product unless measures are taken to suppress or absorb this

energy. The transient voltage can be limited by capacitors and

other energy absorbing devices like Zener diodes connected

across the positive and negative input conductors at a number

of strategic points in the distribution network. The end-user

must secure that the transient voltage will not exceed the

value stated in the Absolute maximum ratings. ETSI TR

100 283 examines the parameters of DC distribution networks

and provides guidelines for controlling the transient and

reduce its harmful effect.

Turn-off Input Voltage

The products monitor the input voltage and will turn on and

turn off at predetermined levels. The minimum hysteresis

between turn on and turn off input voltage is 2.5 V.

Remote Control (RC)

The products are fitted

with a remote control

function referenced to the

primary negative input

connection (-In), with

negative and positive logic

options available. The RC

function allows the product

to be turned on/off by an

external device like a

semiconductor or

mechanical switch.

The RC pin has an

internal pull up resistor of 10 kΩ to +5V.

The external device must provide a minimum required sink

current to guarantee a voltage not higher than maximum

voltage on the RC pin (see Electrical characteristics table).

When the RC pin is left open, the voltage generated on the

RC pin is 5 V.

The standard product is provided with “negative logic” RC. To

turn off the product the RC pin should be left open, or

connected to a voltage higher than 4 V referenced to -In. In

situations where it is desired to have the product to power up

automatically without the need for control signals or a switch,

the RC pin can be wired directly to –In. To turn on the product

the RC pin should be lower than 1V referenced to –In.

The second option is “positive logic” remote control, which can

be ordered by adding the suffix “P” to the end of the part

number. When the RC pin is left open, the product starts up

automatically when the input voltage is applied. Turn off is

achieved by connecting the RC pin to the –In, or a voltage

lower than 1V referenced to -In. The product will restart

automatically when this connection is opened.

The RC function incorporates a short delay in order to not

trigger on glitches. Typically this filter has a settling time of

0.1-0.5 ms. This setup reduces the risk that the noise may

cause the converter to shut down or power up accidently.

See Design Note 021 for detailed information.

Input and Output Impedance

The impedance of both the input source and the load will

interact with the impedance of the product. It is important that

the input source has low characteristic impedance. The

products are designed for stable operation with a minimum of

100 uF external capacitors connected to the input. The

electrolytic capacitors will be degraded in low temperature and

the ESR value may increase. The needed input capacitance in

low temperature should be equivalent to 100 uF at 20° C. This

means that the input capacitor value may need to be

substantially larger to guarantee a stable input at low

temperatures. The performance in some applications can be

enhanced by addition of external capacitance as described

under External Decoupling Capacitors. The minimum required

capacitance value depends on the output power and the input

voltage. The higher output power the higher input capacitance

is needed.

External Decoupling Capacitors

When powering loads with significant dynamic current

requirements, the voltage regulation at the load can be

improved by addition of decoupling capacitors at the load.

The most effective technique is to locate low ESR ceramic and

electrolytic capacitors as close to the load as possible, using

several parallel capacitors to lower the effective ESR. The

ceramic capacitors will handle high-frequency dynamic load

changes while the electrolytic capacitors are used to handle

low frequency dynamic load changes. It is equally important to

use low resistance and low inductance PWB layouts and

cabling.

PKB4000D series Fully regulated DC-DC Converters

Input 36-75 V, Output up to 25 A / 300 W

28701-BMR674 01 Rev G

July 2019

Technical Speciﬁcation

PKB4313D Datasheet(PDF) 18 Page - Flex Power Modules. FLEX LTD.

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