PQ60012EGL20 Datasheet, PDF (11/13 Pages) SynQor Worldwide Headquarters – Input under-voltage lockout disables converter at low

Technical Specification
Input: 35-75 V
Output: 1.2 V
Current: 20 A
Package: Eighth-brick
Output Current Limit: The maximum current limit remains con-
stant as the output voltage drops. However, once the impedance
of the short across the output is small enough to make the output
voltage drop below the specified Output DC Current-Limit
Shutdown Voltage, the converter turns off.
The converter then enters a “hiccup mode” where it repeatedly
turns on and off at a 5 Hz (nominal) frequency with a 5% duty
cycle until the short circuit condition is removed. This prevents
excessive heating of the converter or the load board.
Output Over-Voltage Limit: If the voltage across the output
pins exceeds the Output Over-Voltage Protection threshold, the
converter will immediately stop switching. This prevents damage
to the load circuit due to 1) excessive series resistance in output
current path from converter output pins to sense point, 2) a
release of a short-circuit condition, or 3) a release of a current
limit condition. Load capacitance determines exactly how high
the output voltage will rise in response to these conditions. After
200 ms the converter will automatically restart.
Over-Temperature Shutdown: A temperature sensor on the
converter senses the average temperature of the module. The ther-
mal shutdown circuit is designed to turn the converter off when the
temperature at the sensed location reaches the Over-Temperature
Shutdown value. It will allow the converter to turn on again when
the temperature of the sensed location falls by the amount of the
Over-Temperature Shutdown Restart Hysteresis value.
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” available on the SynQor website which provides an
understanding of why this instability arises, and shows the pre-
ferred solution for correcting it.
Application Circuits: Figure E below provides a typical circuit
diagram which details the input filtering and voltage trimming.
Input Filtering and External Capacitance: Figure F 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 spec-
ified in the “Input Characteristics” section. More detailed infor-
mation is available in the application note titled “EMI
Characteristics” on the SynQor website.
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 E: Typical application circuit (negative logic unit, permanently enabled).
L
Vin(+)
C
Vin(^_)
Figure F: Internal Input Filter Diagram (component values listed on the specifications page).
Product # PQ60012EGL20
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www.synqor.com
Doc.# 005-2EG621G Rev. D 04/09/10
Page 11