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ADP1046A 100Watt
Evaluation board
PWM AND SR SETTINGS
The switches on the primary and the synchronous rectifier timings are controlled in this window. This window programs the
switching frequency, timings of the synchronous rectifier, the type of modulating edge (rising or falling), modulation type
(positive or negative), and duty cycle.
The Pulse Skipping Mode is activated when the controller requires a duty cycle less than the modulation low limit to maintain
output regulation.
Note 1: All the signals shown below represent the gate drive signals at the output pins of the IC.
Note 2: Although the switching frequency can be increased, the software does not account for the dead times and these have
to be programmed manually by measuring the propagation delays between the output of the ADP1046A and the gate of the
MOSFET. A 200ns delay is conservative for the evaluation board.
Things to try:
a)
Referring to the schematic, turning on QA and QB for the entire period of Ts/2 (with appropriate dead times) and
modulating only the bottom MOSFETs.
b)
Enabling/Disabling Pulse Skipping Mode and measuring standby power (by disabling the LEDs on the board
additional power can be saved).
c)
Doubling the switching frequency. Note: The board is designed to operate at switching frequencies of up to 200kHz
with air flow cooling (i.e. a fan). Beyond this point, switching losses may be dominant.
d)
Programming an imbalance in the ON times of the MOSFETs of each branch and evaluating Volt-Second Balance.
e)
Run the software in simulation mode and program the PWM settings for a different topology such as two switch
forward.
f)
Align all SR edges to OUTA-D and adjust the primary-secondary propagation delay by using the dedicated SR delay.
Figure 21 - PWM settings window for the evaluation board
Rev. 1.3 | Page 15 of 55
PRD1386
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