Evaluating The Adp1055; Pwm And Sr Window - Analog Devices ADP1055-EVALZ User Manual

ADP1055-EVALZ User Guide
EVALUATING THE ADP1055
The goal of this user guide is to familiarize you with the GUI
and to describe the flexibility available with the extensive
programming options provided by the ADP1055. Several test
points on the evaluation board allow easy monitoring of the
various signals. You can use the GUI software to program
multiple responses for the various fault conditions. The
following sections provides a description of the typical features
and results realized when evaluating this device.

PWM AND SR WINDOW

The PWM and SR window shows the PWM settings for the
switches on the primary side and the synchronous rectifier
in the General tab at the top left corner of the window. Other
tabs program the Modulating Edges, prevent transformer
saturation (Volt Second Balance), and perform other functions
as described in this section of the user guide (Sync, Snubber,
and Adaptive Dead Time). This tab programs the switching
frequency, SR phase in speed, pulse skipping, maximum duty
cycle, and so on.
Figure 17. PWM and SR Window (Full Bridge Hard Switching)
Note the following:

All the signals shown in Figure 17 represent the signals at
the output pins of the IC.

Although the switching frequency can be increased, the
software does not account for the dead times; these have
to be programmed manually by measuring the propagation
delays between the output of the
of the MOSFET. A 200 ns delay is conservative for the
evaluation board.
In Figure 17, a typical PWM configuration for a full bridge hard
switching topology is provided with modulation on the falling
edges of OUTA to OUTD and on the rising edge of SR1 and
SR2. The synchronous rectifiers in light load mode (LLM) have
an independent setting as shown in Figure 18.
ADP1055 and the gate
Rev. B | Page 9 of 43
Figure 18. SR1 and SR2 in Light Load Mode (LLM)
The PWM window can be used to set up several different
topologies, notably the full bridge phase shifted topology whose
PWM settings are shown in Figure 19.
Figure 19. PWM and SR Window (Full Bridge Phase Shifted)
The PWM settings can be changed in a simple drag-and-drop
fashion or by checking/unchecking the respective function.
The Apply Settings button is highlighted in red whenever a
change is made. Changes take place after Apply Settings is
clicked and are stored in the RAM of the IC, but need to be
saved to EEPROM for permanent storage.
Figure 20. PWM Example Under 10 A Load
Top 2 Waveforms: SR1 and SR2
Bottom 2 Waveforms: OUTB and OUTD
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