Infineon XDPP1100, Technical Reference Manual

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User Manual 42 of 562 V 1.0
2021-08-25
XDPP1100 technical reference manual
Digital power controller
Current sense (IS)
based gain stage or IPS. All other applications require the reference level to be ground, except IPS. High-gain
mode refers to smaller LSB size and finer resolution. This implies higher noise susceptibility, whereas low-gain
mode means higher LSB size and lower noise sensitivity.
Depending on the application current level and other requirements, the proper method for the current sensing
should be selected.
Table 5 summarizes possible current sensing methods for different applications and the
corresponding current gain modes.
Table 5 Current sense method vs. gain mode selection
Application Current sense method Current gain mode
High current PCB trace High-gain mode (1)
PCB trace with external amplifier Low-gain mode (2)
Small shunt resistor with external
amplifier Low-gain mode (2)
Low and medium current Small shunt High-gain mode (1)
Small shunt with external
amplifier Low-gain mode (2)
Larger shunt resistor Low-gain mode (2)
Primary-side current sensing Current transformer Low-gain mode (2)
Non-isolated buck with IPS Integrated current sense Low-gain mode (3)
The second sub-block, the 9.25-bit DAC, has 640 quantization levels. However, some of the bits are used for
offset correction and the effective bits are less, depending on the OTA gain setting as shown in
Table 4 . The
input voltage range per LSB weight is shown in Table 6 .
Table 6 Input voltage range as a function of LSB weight
ADC LSB Min. Max. Units
100 µV -22 22 mV
1.45 mV -280 395 mV
The last two sub-blocks have the following functionality:
•
The summing node subtracts the DAC current from the OTA output current and converts to voltage for use
by the quantizer.
•
The quantizer consists of five comparators, which generate a 6-level (±1, ±3, ±5) error tracking signal used by
the CE to correct current estimation.
3.2.2 Current estimator
The CE provides a digital reconstruction of the secondary-side inductor current or the primary-side current,
depending on the current sense input pin configuration. The shape of this current is obtained through slope
estimation function. For that purpose, the following application-related information is required:
•
Output inductor value
•
Primary-side magnetizing inductance
•
Measured values of V
OUT
and V
RECT
•
Tracking error feedback from the AFE