ADP1071-1EVALZ
User Guide
UG-1384
Rev. 0 | Page 5 of 13
EVALUATING THE ADP1071-1EVALZ BOARD
Test points on the evaluation board allow the user to monitor
output signals. The following sections provide descriptions of
the typical results when evaluating the device in a multiflyback
topology. The user can modify the operation of the device
according to the
ADP1071-1
/
ADP1071-2
data sheet as needed.
STARTUP
When the supply voltage is on, the output voltages ramp up
smoothly. For details about two-stage soft start, refer to the
ADP1071-1
/
ADP1071-2
data sheet. Figure 4 shows the startup
under a no load condition, and Figure 5 shows the startup of a
full load condition.
CH1
10.0V
CH2 10.0V
M40.0ms
A CH1 9.60V
T
9.0000ms
B
W
B
W
CH3
10.0V
B
W
1
17050-
004
+24V
+5.5V
–15V
Figure 4. Startup at No Load
CH1
10.0V
CH2 10.0V
M40.0ms
A CH1 9.60V
T
9.0000ms
B
W
B
W
CH3
10.0V
B
W
1
17050-
005
+24V
+5.5V
–15V
Figure 5. Startup at Full Load
To experiment with different soft start timings, see more details
in the soft start section in the
ADP1071-1
/
ADP1071-2
data
sheet.
CROSS REGULATION
On the secondary side, the output voltage information of the
5.5 V rail and the 24 V rail are sensed by a voltage divider
network and sent to the FB pin. These two voltages (5.5 V and
24 V) are partially regulated by a weightage ratio of 6:4. The
−15 V rail is left quasi regulated due to its relatively low load
current rating. The user can adjust the feedback weightage ratio
according to the regulation requirement and load rating to
achieve the most optimal cross regulation among the three
outputs. Figure 6 through Figure 9 show the cross regulation
performance under different load conditions.
CH1
500mA
CH2 1.00V
A CH1 270mA
1
4
3
CH3
5.00V
CH4 5.00V
5.5V LOAD STEP
0mA TO 500mA
+24V
AT FULL
LOAD
+5.5V
–15V
AT FULL
LOAD
17050-
006
Figure 6. Cross Regulation with Load Step at a +5.5 V Rail When +24 V and
−15 V Rails at Full Load
CH1
500mA
CH2 1.00V
A CH1 135mA
1
4
3
CH3
5.00V
CH4 5.00V
5.5V LOAD STEP
0mA TO 500mA
+24V
+5.5V
AT FULL
LOAD
–15V
AT FULL
LOAD
17050-
007
Figure 7. Cross Regulation with Load Step at a +24 V Rail When +5.5 V and
−15 V Rails at Full Load
CH1
500mA
CH2 1.00V
A CH1 270mA
1
4
3
CH3
5.00V
CH4 5.00V
5.5V LOAD STEP
0mA TO 500mA
+5.5V
+24V
AT NO
LOAD
–15V
AT NO
LOAD
17050-
008
Figure 8. Cross Regulation with Load Step at a +5.5 V Rail When +24 V and
−15 V Rails at No Load
