AS5130ATST AMSCO [austriamicrosystems AG], AS5130ATST Datasheet - Page 30

• Manufacturer Part Number: AS5130ATST
• Description: 8 Bit Programmable Magnetic Rotary Encoder with Motion Detection & Multiturn
• Manufacturer: AMSCO [austriamicrosystems AG]

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 (<10Ω). 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
turned off. Special registers will be buffered by the low power supply and will keep the actual settings. After a t
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.
Due to the internal POR level of the IC, t
power consumption in this pulsed mode depends on the supply current in active mode and the duty cycle of the on/off
pulse:
Example: Sampling period = one measurement every 100ms. System constants = I
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:
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100n
+5V
AS5130
AS5130
I
avg
S
AV
on
V
SS
DD
=
starts after V
N
------------------------------------------
250μs
I
19mA ∗ 250μs
avg
=
+
Revision 1.00
I
------------------------ -
99.75ms
active
t
on
CS
CLK
DIO
DD
+
10k
∗ t
has reached 4.3V (worst case POR level).The average
t
off
on
= 47.5µA
>1µF
Cx
t
on
t
off
on/off
controller
micro
V
V
DD
SS
active
AV
= 19mA, t
+5V
V
SS
DD
on
(min) = 250µs:
on
(EQ 10)
(EQ 11)
of min.
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