HTA20003R3SSLASHEM datasheet(7/14 Pages) IRF

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HTA-SERIES

This feature is available only for single output models.

Connection of the + Sense and - Sense leads at a remotely

located load permits compensation for resistive voltage drop

between the converter output and the load when they are

physically separated by a significant distance. This

connection allows regulation to the placard voltage at the

point of application. When the remote sensing features is

not used, the sense leads should be connected to their

respective output terminals at the converter. A combination

of the compensation voltage drop and output voltage

adjustment (described below in the ‘Output Voltage

Adjustment’ section) is limited to 10% of the nominal output

voltage.

Technical Notes:

Remote Sensing

As an alternative to application and removal of the DC voltage

to the input, the user can control the converter output by

providing TTL compatible, positive logic signal to Enable pin

(pin 4) and to Input Return (pin 2). Enable signal is internally

pulled “high” so that when not used, an open connection on

the Enable pin permits normal converter operation. When

its use is desired, a logical “low” on this port will shut the

converter down.

Inhibiting Converter Output

Synchronization of Multiple Converters

When operating multiple converters, system requirements

often may require operation of the converters at a common

frequency. To accommodate this requirement, the HTA

series of converters provide both a synchronization input

and output.

The Sync Input port permits synchronization of a HTA

connverter to any compatible external frequency source

operating between 500KHz and 650KHz. This input signal

should be referenced to the Input Return and have a 10%

to 90% duty cycle. Compatibility requires transition times

less than100ns, maximum low level of +0.8V and a minimum

high level of +2.0V. The Sync Output of another converter

which has been designated as the master oscillator provides

a convenient frequency source for this mode of operation.

When external synchronization is not required, the Sync In

pin should be left unconnected thereby permitting the

converter to operate at its own internally set frequency.

The sync output signal is a continuous pulse train set at

550

± 50KHz, with a duty cycle of 15 ± 5.0%. This signal is

referenced to the Input Return and has been tailored to be

compatible with the HTA Sync Input port. Transition times

are less than 100ns and the low level output impedance is

less than 50

Ω. This signal is active when the DC input

voltage is within the specified operating range and the

converter is not inhibited. This output has adequate drive

reserve to synchronize at least five additional converters.

Output Voltage Adjust - Single Output Models

In addition to permitting close voltage regulation of remotely

located loads, it is possible to utilize the converter sense

pins to incrementally increase the output voltage. The

increased output voltage is limited to 10% maximum. The

adjustments made possible by this method are intended as

a means to “trim” the output to a voltage setting for certain

design application, but are not intended to create an

adjustable output converter. These output voltage setting

variations are obtained by connecting a resistor with an

appropriate value between the +Sense and -Sense pins

while connecting the -Sense pin to the Output Return pin as

shown in Fig IV below. The resistance value for a desired

output voltage can be determined by use of the equation

presented below.

= 100

-.025

adj

NOM

OUT

NOM

•

⎧

⎨

⎩

⎫

⎬

⎭

Where V

NOM = device nominal output voltage, and

OUT = desired output voltage

Finding a resistor value for a particular output voltage, is

simply a matter of substituting the desired output voltage

and the nominal device voltage into the equation and solving

for the corresponding resistor value. Under no circumstance

should R

ADJ be less than 500Ω.

Fig IV. Connection for V

OUT Adjustment

N/C

Trim

+ Sense

- Sense

Output Return

+ Output

Load

RADJ

HTA200XXS

HTA20003R3S/EM Datasheet(PDF) 7 Page - International Rectifier

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