FEB 14, 2006 revised to MAY 17, 2006 Page 8 of 14 www.power-one.com
HKS48T30120 DC-DC Series Data Sheet
Half-Brick with 48VDC Input; 12VDC @ 32A Output
Noise Measurement Methods
To improve the accuracy and repeatability of ripple
and noise measurements, Power-One utilizes the
test setups shown in Figure 9 & 10 below.
DUT
LOAD1
1uF
ceramic
SCOPE
COPPER STRIPS (2 to 3 inches)
+Vo1
-Vo1
10uF
Tantalum
Figure 9. Output Ripple and Noise Measurement Test Setup
A BNC connector is used for measurements to
eliminate noise pickup associated with long ground
leads of conventional scope probes. The connector,
a 0.1 μF ceramic, a 10 μF tantalum capacitor, and
the load are located 2-3” away from the converter.
For output decoupling, we recommend using a 10μF
low ESR tantalum (AVX TPSC106M025R0500 is
used in Power-One test setup) and a 0.1μF ceramic
capacitor. Note that the capacitors do not substitute
for filtering required by the load.
BATTERY
Cs 220 uF
ESR < 0.1 OHM
@ 20 ºC, 100 kHz
Ltest
12 uH
220 uF
ESR < 0.1 OHM
@ 20 ºC, 100 kHz
Vi(+)
Vi(-)
TO OSCILLOSCOPE
Figure 10. Input Reflected Ripple Current Measurement Setup
Note: Measure input reflected-ripple current with a simulated
inductance (Ltest) of 12 µH. Capacitors offset possible battery
impedance. Measure current as shown above
Overcurrent Protection
To provide protection from an output overload or short
circuit condition, the HKS is equipped with current
limiting circuitry and can endure the fault condition for
an unlimited duration. At the point of current-limit
inception, the converter enters hiccup mode, causing
the output current to be limited in both peak and
duration. While in the hiccup mode, the converter
attempts to restart approximately once every 150 ms
as shown in Figure 11. Because of very low duty
cycle the RMS value of output current is limited to
only 8 A
RMS
max..
Figure 11. Short Circuit Behavior (typ)
Condition: Vin = 75 VDC
Channel 1 - Short circuit current, 6.22A
RMS
(measured)
Scale: 20 Amperes/division.
Once the output current is brought back into its
specified range, the converter automatically exits the
hiccup mode and continues normal operation.
Back Driving
The HKS DC-DC converter uses a control driven
synchronous rectification technique. Applying an
external voltage on the output of a unit that is shut
down will not cause damage.
