User Manual
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V 1.0
2021-08-25
XDPP1100 technical reference manual
Digital power controller
Current sense (IS)
Sensing method
Advantages
Disadvantages
Applications
•
Improved current
sensing accuracy
non-isolated buck
topology
A shunt resistor is suitable for all applications, whereas the PCB trace sensing is recommended only for high-
current applications. If PCB trace sensing is applied in low-current applications, there could be various
drawbacks:
•
Increased noise due to longer PCB trace that is needed for sufficient resistance
•
High-gain amplifier stage, which might impose bandwidth (BW) limitations
Current transformer is the simplest method to transfer primary current information to the controller on the
secondary side. In non-isolated topologies it is possible to sense the primary current as long as the current
sense voltage is referenced to the supported reference levels (GND or 1.2 V), as will be described later in this
chapter. The main requirement for using the integrated current sensing of IPS is to have 1.2 V reference voltage
for current sense. An example of supported integrated power stage is
Infineon’s IR3555A
.
Depending on the selected sensing method, the IADC resolution as well as the reference level need to be
adjusted, as will be discussed in the following sections.
3.2
Current sense analog to digital converter
The IADC is a tracking ADC, and the two IADCs in the current sense module are identical. They comprise two
main sub-blocks:
•
AFE
•
CE
A simplified block diagram of the IADC is shown in
, where the submodules are emphasized as dashed
lines. This ADC has configurable LSB weight and effective conversion rate of 25 MHz. The subsections that
follow describe the ADC resolution configuration depending on the sensing method utilized as well as the CE
functionality in more detail.