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AS5130

Data Sheet - D e ta i l e d D e s c r i p t i o n

Figure 13. Magnetic Field Strength Indicator

High Speed Operation

The AS5130 is using a fast tracking ADC (TADC) to determine the angle of the magnet. The TADC has a tracking rate

of 1.15µs (typ).

Once the TADC is synchronized with the angle, it sets the LOCK bit in the status register (see Table 8). In worst case,

usually at start-up, the TADC requires a maximum of 127 steps (127 * 1.15µS = 146,05µs) to lock. Once it is locked, it

requires only one cycle (1.15µs) to track the moving magnet.

The AS5130 can operate in locked mode at rotational speeds up to 30,000 rpm.

In Low Power Mode, the position of the TADC is frozen. It will continue from the frozen position once it is powered up

again. If the magnet has moved during the power down phase, several cycles will be required before the TADC is

locked again. The tracking time to lock in with the new magnet angle can be roughly calculated as:

(EQ 3)

Where:

OldPos = Angle position when one of the reduced power modes is activated [º]

NewPos = Angle position after resuming from reduced power mode [º]

Propagation Delay

The Propagation delay is the time required from reading the magnetic field by the Hall sensors to calculating the angle

and making it available on the serial or PWM interface. While the propagation delay is usually negligible on low

speeds, it is an important parameter at high speeds. The longer the propagation delay, the larger becomes the angle

error for a rotating magnet as the magnet is moving while the angle is calculated. The position error increases linearly

with speed. The main factors that contribute to the propagation delay are discussed in detail further in this document.

Sampling Rate

For high speed applications, fast ADC’s are essential. The ADC sampling rate directly influences the propagation

delay. The fast tracking ADC used in the AS5130 with a tracking rate of only 1.15µs (typ) is a perfect fit for both high

speed and high performance.

Chip Internal Lowpass Filtering

A commonplace practice for systems using analog-to-digital converters is to filter the input signal by an anti-aliasing

filter. The filter characteristic must be chosen carefully to balance propagation delay and noise. The lowpass filter in the

AS5130 has a cutoff frequency of typ. 23.8kHz and the overall propagation delay in the analog signal path is typ.

15.6µs.

AS5130

100n

+5V

CS

DCLK

DIO

AS5130

C1

I/O

Output

Output

CAO

1k

LED1