IQ18-HPC Ver la hoja de datos (PDF) - SynQor Worldwide Headquarters

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componentes Descripción

Fabricante

IQ18-HPC

Half-brick DC-DC Converter

SynQor Worldwide Headquarters 

Technical

Specification

IQ18-HPC Family

APPLICATION CONSIDERATIONS

Input system Instability: This condition can occur because

any dc-dc converter appears incrementally as a negative

resistance load. A detailed application note titled “Input

System Instability” is available on the SynQor website which

provides an understanding of why this instability arises, and

shows the preferred solution for correcting it.

Application Circuits: Figure D provides a typical circuit

diagram which details the input filtering and voltage trimming.

Input Filtering and external Capacitance: Figure E provides

a diagram showing the internal input filter components. This filter

dramatically reduces input terminal ripple current, which otherwise

could exceed the rating of an external electrolytic input capacitor.

The recommended external input capacitance is specified in the

Input Characteristics section on the Electrical Characteristics

page. More detailed information is available in the application

note titled “EMI Characteristics” on the SynQor website.

startup Inhibit Period: The Startup Inhibit Period ensures that

the converter will remain off for approximately 200 ms when it is

shut down for any reason. When an output short is present, this

generates a 5 Hz “hiccup mode,” which prevents the converter

from overheating. In all, there are seven ways that the converter

can be shut down, initiating a Startup Inhibit Period:

• Input Under-Voltage Lockout

• Input Over-Voltage Shutdown

• Output Over-Voltage Protection

• Over Temperature Shutdown

• Current Limit

• Short Circuit Protection

• Turned off by the ON/OFF input

Figure F shows three turn-on scenarios, where a Startup Inhibit

Period is initiated at t0, t1, and t2:

Vin(+)

Vout(+)

Electrolytic

Vsense(+)

External

Capacitor

Rtrim-up

Vin

Input

ON/OFF

Trim

or

Filter

Vsense(_)

Rtrim-down Cload

Iload

Vin(_)

Vout(_)

Figure D: Typical application circuit (negative logic unit, permanently enabled).

L

Vin(+)

C

Vin(_)

Figure E: Internal Input Filter Diagram (component values listed on the specifications page).

Product # IQ18xxxHPCxx

Phone 1-888-567-9596

www.synqor.com

Doc.# 005-005029 Rev. B

04/13/09

Page 26

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