PQ60260HTB10 Datasheet, PDF (11/13 Pages) SynQor Worldwide Headquarters – Half-brick DC/DC Converter

Technical Specification
Input: 35-75 V
Output: 26 V
Current: 9.6 A (250W)
Package: Half-brick
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 below provides a typicalcircuit
diagram which details the input filtering and voltage trimming.
Input Filtering and External Capacitance: Figure E below
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 Specifications
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 200ms when it is
shut down for any reason. When an output short is present, this
generates a 5Hz “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 (not present in Quarter-brick)
• 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:
Before time t₀, when the input voltage is below the UVL threshold,
the unit is disabled by the Input Under-Voltage Lockout feature.
When the input voltage rises above the UVL threshold, the Input
Under-Voltage Lockout is released, and a Startup Inhibit Period is
initiated.At the end of this delay, the ON/OFF pin is evaluated,
and since it is active, the unit turns on.
At time t₁, the unit is disabled by the ON/OFF pin, and it cannot be
enabled again until the Startup Inhibit Period has elapsed.
When the ON/OFF pin goes high after t₂, the Startup Inhibit Period
has elapsed, and the output turns on within the typical Turn-On
Time.
Vin(+)
Vout(+)
Electrolytic
Vsense(+)
Vin
External
Input
Capacitor
47µF
ON/OFF
R_trim-up
Trim
or
Filter
Vsense(^_)
R_trim-down C_load
I_load
Vin(^_)
Vout(^_)
Figure D: Typical application circuit (negative logic unit, permanently enabled).
L
Vin(+)
C₁
C₂
Vin(^_)
Figure E: Internal Input Filter Diagram (component values listed on page 3).
Product # PQ60260HTB10
Phone [phone]
www.synqor.com
Doc.# 005-2HTB26F Rev. H
10/10/08
Page 11