UG:309
Page 16
Programming Initial Conditions
Once the user has selected the configuration for the timing register, the burn process can be initiated.
To begin this process, the user must be ready to be able to enable and disable the PI33xx‑xx, since this
is required to enter the burn mode and actually burn the bits. The
initial conditions
to begin the burn
process are as follows:
1.
Proper input voltage should be applied to the target PI33xx‑xx.
2.
The unit can be either enabled and producing output voltage or disabled with the output voltage
at zero. The preferred method is disabled since in some cases multiple units may depend on proper
phase delay for best performance.
The user must adhere to the instructions from the GUI to
ensure proper burn results.
The burn process consumes power from the internal bias for the controller, so only a single bit can be
burned at a time. Buck GUI takes care of this for the user and will generate the appropriate number of
bus commands to ensure each bit is burned correctly. Users that write their own software or operate
from a different GUI will need to consider this. In addition, power should not be removed from the
PI33xx‑xx during the burn process. The Buck GUI will prompt the user when to enable and disable the
target. Enabling and disabling is done using the EN pin. One important note to consider is that if the
enable polarity has been changed already due to a separate operation, the new enable polarity must be
used when enabling and disabling. The procedure along with the Buck GUI commands, for changing the
SYN[3:0] register so that the synchronization polarity is falling edge and the delay is 3/4MP is as follows.
Configuration Example – Sync Delay
Type “0001” into the SYNC dialog box. Left‑click on the “BURN” button.
The first four writes and reads ensure that the three user registers are cleared. Then the test mode
register is selected at address 18h and the test mode 05h is entered. Next, the user is prompted to
disable the unit using the enable pin. The target can be enabled or disabled prior to being prompted to
disable. See Figures 20 and 21.
Figure 20
SYNC “0001” burn phase 1
while unit enabled or disabled
Figure 21
Summary of Contents for PI33 EVAL1 Series
Page 13: ...UG 309 Page 13 Figure 14 PI33xx xx SYNC 1000 timing Figure 15 PI33xx xx SYNC 1111 1 4MP ...
Page 14: ...UG 309 Page 14 Figure 16 PI33xx xx SYNC 1110 1 3MP Figure 17 PI33xx xx SYNC 1101 1 2MP ...
Page 15: ...UG 309 Page 15 Figure 18 PI33xx xx SYNC 1100 2 3MP Figure 19 PI33xx xx SYNC 1001 3 4MP ...
