ZSPM2000 datasheet(20/42 Pages) IDT

20 / 42 page

ZSPM2000 Datasheet

January 27, 2016

Figure 3.4

Inductor Current Sensing Using the DCR Method

Alternatively, a simple shunt resistor can be used to measure the inductor current. The value of this resistor

should be selected so that the voltage range between the pins is within the specifications given in section 1.

End-of-line calibration is supported so that the ZSPM2000 can achieve improved accuracy over the full output

current range. The full calibration method is detailed in ZSPM2000 Application Note—Programming and

Calibration (see section 9). This allows the user to correct mismatches between the nominal DCR value used to

configure the device and the actual DCR value in the application caused by effects such as manufacturing

variations. The calibration range is limited to +/- 50% of the nominal DCR.

Additionally, in order to improve the accuracy of the current measurement challenged by the temperature coeffi-

cient of the inductor’s DCR, the ZSPM2000 features temperature compensation via external temperature sensing.

The temperature of the inductors is measured with an external temperature sense element placed close to the

inductor. This information is used to adapt the gain of the current sense path to compensate for the increase in

actual DCR.

3.3.8.

Temperature Measurement

The ZSPM2000 features two independent temperature measurement units for internal and external temperature.

The internal temperature sensing measures the temperatures inside the ZSPM2000. The external temperature

sense element should be placed close to the inductor to measure its temperature. A PN-junction is used as an

external temperature sense element. Small-signal transistors, such the 3904, are widely used for this application.

The configuration of the sensitivity and the offset is required in the Pink Power Designer™ GUI. A temperature

calibration via the Pink Power Designer™ or as part of the end-of-line calibration during production is highly

recommended.

ZSPM2000

+Vout

ISNSP

ISNSN

DCR

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