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Configure the topology and deadtime using XDPP1100 GUI

Configure the topology and deadtime using XDPP1100 GUI

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Configure the topology and deadtime using XDPP1100 GUI

The XDPP1100 is versatile digital controller that can be employed in various applications, including isolated and non-isolated DC-DC brick converters, intermediate bus converters and telecom power supplies, as well as point-of-load converters. The controller provides flexibility through FW, and the same HW can be configured for various topologies.

This article introduces how users configure the topology and deadtime using the XDPP1100 GUI.

Device Topology (Topology Selection and PWM Mapping)

Using the Device Topology tool, users can configure the XDPP1100 based on power-board topology, targeted control strategy and PWM deadtimes settings.

To access this tool,
- Click the XDPP1100-Q024::i2c x10 (highlighted in yellow in Figure 1).
- Click the Design Tools and select    1. Device Topology

XDPP1100 Topology window will be opened with Topology and DeadTime tabs (Figure 2).


Figure 1   GUI Design Tools feature and Device Topology (PWM mapping and topology)

1.    Topology tab

  • Users can select their power-board topology and targeted control strategy and assign available PWMs to the switches (Figure 2a). PWM mapping enhances the compatibility of the XDPP1100 to designed power-boards and hardware. They are mapped to each power switch using the drop-down list assigned for each PWM in the Topology tab.
  • For a full-bridge to full-bridge topology, Checked the Full Bridge in the topology tab. Four PWM signals from the digital controller are expanded for the diagonal switches with onboard hardware. As shown in Figure 2a, two primary switches Q1, Q4, and two secondary synchronous rectification switches SR1, SR2 are mapped, four switches are assigned to available PWM signals (PWM1, PWM2, PWM5 and PWM6).
  • The control mode options are VMC, PCMC on secondary and PCMC on primary. Voltage mode control (VMC) is selected in this tab (Figure 2a) as the control strategy. 

2.    DeadTime tab

Dead-time is set by adding a delay to the rising edge or falling edge of each PWM output. The dead-time of PWM rise and fall time can be configured separately. The maximum dead-time can be set to 318.75 ns with a resolution of 1.25 ns. When setting dead-time, please consider the isolator delay that will be added to the primary PWMs, making the real gate waveform shift to the right.

DPWM deadtime settings can be programmed in the DeadTime tab (Figure 2b) or by PMBus command 0xCF PWM_DEADTIME(Figure 5).

1) In this tab (Figure 2b), interactive PWM waveforms associated with each switch provide visual system verification for assigned deadtimes. 








Figure 2   Device topology(PWM mapping and topology selection) tool; a) Topology b) DeadTime

3)  The deadtime unit in this module is in the nanosecond. Changing deadtime values will change switching waveforms accordingly and depict updated deadtimes. For example, the effect of increasing SR2 rising edge deadtime (DT11) from 140 ns to 200 ns is shown in Figure 3.







Figure 3  PWM deadtime configuration; a) DT11 = 140 ns, b) DT11 = 200 ns

3)  One of the critical factors for isolated bridge topologies is timing between the primary and the secondary opposite phases to avoid shoot-through. For this timing criteria, hardware propagation delays should also be considered. As a safety measure, Isolation Delay reminds users to consider propagation delays between the XDPP1100 output and the gate of the primary side switches during the configuration of the PWM rising edge of the SR switches. This is just a reminder to avoid the wrong PWM deadtime configuration to avoid shoot-through, and does not have any impact on the actual PWM deadtime timings. This setting only provides a warning message if deadtime settings violate the Isolation Delay criteria. For example, if an Isolation Delay is considered 100 ns for the primary PWMs, GUI does not allow users to configure SR rising edge delay less than 100 ns. GUI prompts a warning message if 100ns criteria is violated, and does not allow user to configure these settings (Figure 4).

MarkYu1_8-1672663716663.pngFigure 4   PWM Isolation Delay

4) Figure 5. shows using PMBus command 0xCF PWM_DEADTIME to configure dead-time. Only the active PWMs in the selected loop can be configured and they are highlighted by a different color.

MarkYu1_9-1672663765366.pngFigure 5  PWM deadtime configuration