Performance Curves
Quarter
Brick
48Vin 15Vout 6.7A
Figure 15
10
µ
H
source
impedance
Figure 14
Figure 16
i
S
V
SOURCE
i
C
DC/DC
Converter
1
µ
F
V
OUT
10 µF,
47 µF,
<1Ω ESR
electrolytic
capacitor
ceramic
100mΩ ESR
capacitor
tantalum
capacitor
Figure 13:
Test set-up diagram showing measurement points for Input
Terminal Ripple Current (Figure 14), Input Reflected Ripple Current
(Figure 15) and Output Voltage Ripple (Figure 16).
Figure 14:
Input Terminal Ripple Current, ic, at full rated output cur-
rent and nominal input voltage with 10
µ
H source impedance and 47
µ
F
electrolytic capacitor (200 mA/div). See Figure 13.
Figure 15:
Input reflected ripple current, is, through a 10
µ
H source
inductor at nominal input voltage and rated load current (10 mA/div).
See Figure 13.
18.0
16.0
14.0
Output Voltage
(V)
12.0
10.0
8.0
6.0
4.0
2.0
0.0
0
Figure 16:
Output voltage ripple at nominal input voltage and rated
load current (50 mV/div). Load capacitance: 1
µ
F ceramic capacitor
and 10
µ
F tantalum capacitor. Bandwidth: 20 MHz. See Figure 13.
36 V
48 V
75 V
1
2
3
4
5
6
7
8
9
10
Load Current
(A)
Figure 17:
Output voltage vs. load current showing typical current limit
curves and converter shutdown points.
Product # PQ48150QGA07
Phone 1-888-567-9596
Figure 18:
Load current (5A/div) as a function of time when the con-
verter attempts to turn on into a 10 mΩshort circuit. Top trace
(2.5ms/div) is an expansion of the on-time portion of the bottom trace.
Doc.# 005-2QG415D Rev. D
8/16/02
Page 7
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