as5134 austriamicrosystems, as5134 Datasheet - Page 20

• Manufacturer Part Number: as5134
• Description: 360?programmable High Speed Bldc Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5134
Data Sheet - D e t a i l e d D e s c r i p t i o n
Digital Readout Rate
Aside from the chip-internal propagation delay, the time required to read and process the angle data must also be
considered. Due to its nature, a PWM signal is not very usable at high speeds, as you get only one reading per PWM
period. Increasing the PWM frequency may improve the situation but causes problems for the receiving controller to
resolve the PWM steps. The frequency on the AS5134 PWM output is typ. 1.95kHz with a resolution of 2µs/step. A
more suitable approach for high speed absolute angle measurement is using the serial interface. With a clock rate of
up to 6MHz, a complete set of data (21bits) can be read in >3.5µs.
Total Propagation Delay of the AS5134
The total propagation delay of the AS5134 is the delay in the analog signal path and the tracking rate of the ADC:
If only the SIN-/COS-outputs are used, the propagation delay is the analog signal path delay only (typ. 15.6µs).
Position Error Over Speed:
The angle error over speed caused by the propagation delay is calculated as:
In addition, the anti-aliasing filter causes an angle error calculated as:
Table 9. Examples of the Overall Position Error caused by Speed (includes both propagation delay and filter delay)
Reduced Power Modes
The AS5134 can be operated in two reduced power modes. Both these modes have in common that they switch off or
freeze parts of the chip during intervals between measurements. In Low Power Mode or Ultra Low Power Mode, the
AS5134 is not operational, but due to the fast start-up, an angle measurement can be accomplished very quickly and
the chip can be switched to reduced power immediately after a valid measurement has been taken. Depending on the
intervals between measurements, very low average power consumption can be achieved using such a strobed
measurement mode.
Low/Mid Power Mode
The AS5134 can be put in Low/Mid Power Mode by simple serial commands, using the regular connection for 2-wire or
3-wire serial data transmission.
www.austriamicrosystems.com
Low/Mid Power Mode: Reduced current consumption, very fast start-up. Ideal for short sampling intervals (<3ms).
Power Cycling mode: Zero power consumption (externally switched off) during sampling intervals. Ideal for sam-
pling intervals 200ms.
Speed (rpm)
10000
1000
100
Δθ
pd
Δ
θ
= rpm * 6 * 17 * E
lpf
15.6µs + 1.4µs = 17µs
= ArcTan [rpm / (60 * f0)]
Revision 1.6
-6
in degrees
Total Position Error (Δθ
0,0175º
0,175º
1,75º
pd +
Δ
θ
lpf
)
20 - 29
(EQ 2)
(EQ 3)
(EQ 4)