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AS5130

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

Application Example IV: Polling mode

Figure 25. Polling Mode

Once powered up for at least 2.5ms, the AS5130 can be operated in a pulsed mode, where it is periodically turned on/

off by a high side FET (PMOS) switching transistor with a low Ron (<10

Ω). The on-time is at least 250µs in order to

perform one measurement. A valid measurement result can be verified by checking the lock bit (ADC is locked) in the

serial data stream.

After startup an OTP reset has to be performed in order to read out valid trimming information. Then a special SSI

command (STORE REF) copies the actual angle into a buffered reference angle register. Now the AS5130 can be

250 us, the actual angle is compared with the stored reference angle. If the angle difference is larger than a threshold

value (wlsb, SSI command WRITE CUST), the AS5130 will send an interrupt request to an external device via the

WAKE pin.

power consumption in this pulsed mode depends on the supply current in active mode and the duty cycle of the on/off

pulse:

(EQ 10)

= 47.5µA

(EQ 11)

Accuracy of the Encoder system

This section enlightens on the individual factors that influence the accuracy of the encoder system, and provides

techniques to improve them. Accuracy is defined as the difference between measured angle and actual angle. This is

not to be confused with resolution, which is the smallest step that the system can resolve. The two parameters are not

necessarily linked together. A high resolution encoder may not necessarily be highly accurate as well.

Quantization Error

There is however a direct link between resolution and accuracy, which is the quantization error:

micro

controller

AS5130

100n

+5V

CS

CLK

DIO

AS5130

S

N

on/off

10k

Cx

>1µF

+5V

+

-------------------------

19mA∗250

μs

250

μs 99.75ms

+

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