Quick Start Procedure - Linear Technology DC1793A Demo Manual

DEMO MANUAL DC1793A

QUICK START PROCEDURE

3. Slowly increase the load on LDO– to –50mA and
observe how the output ripple on V
how the burst frequency increases. When the load
is large enough, the charge pump will run constant
frequency to keep V
OUT
4. Slowly increase the load on LDO+ to 50mA and observe
the output ripple and the output voltage on LDO+.
5. Set the LDO+ load and the LDO– load to 0mA and
turn off PS1.
NOTE: To avoid applying an overvoltage to the ADJ±
pins, power must be turned off before changing the
LDO+ or LDO– jumpers.
6. Set the JP5 LDO+ jumper to the 3.3V position and JP6
LDO– to the –3.3V position.
7. Repeat steps 2 through 5.
8. Set the JP5 LDO+ jumper to the 12V position and JP6
LDO– to the –12V position.
9. Turn on and set PS1 to 15V.
10. Repeat steps 3 through 5.
11. Set the JP5 LDO+ jumper to the 24V position and JP6
LDO– to the –24V position.
2
changes and
OUT
in regulation.
0-50mA
Figure 1. Proper Measurement Equipment Setup for DC1793A
12. Turn on and set PS1 to 32V.
13. Repeat steps 3 through 6.
14. Turn on and set PS1 to 12V.
15. Slowly increase the load on V
observe the output ripple and output voltage on V
16. Set the load on V
OUT
17. Change the JP3 MODE jumper from Burst Mode op-
eration to constant-frequency mode and repeat steps
14 and 15.
18. Change the JP4 FREQ jumper from 500kHz to 200kHz,
then slowly increase the load on V
–50mA and observe the output ripple and output volt-
age on V .
OUT
19. Set the load on V
OUT
20. Change the JP4 FREQ jumper from 200kHz to
50kHz. Slowly increase the load on V
to –10mA and observe the output ripple and output
voltage on V .
OUT
Figures 4 and 5 illustrate how the efficiency varies with
load current in Burst Mode operation and in constant-
frequency mode operation.
0-50mA
to –100mA and
OUT
to 0mA.
from 0mA to
OUT
to 0mA.
from 0mA
OUT
.
OUT
dc1793afa