AS5247 datasheet(9/37 Pages) AMSCO

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ams Datasheet: 2014-Jun-20 [v1-02]

AS5247 – 9

Detaile d Desc rip t ion

The AS5547 is a Hall-effect magnetic sensor using a CMOS

lateral technology. The lateral Hall sensors convert the

magnetic field component perpendicular to the surface of the

chip into a voltage.

The signals from the Hall sensors are amplified and filtered by

the analog front-end (AFE) before being converted by the

analog-to-digital converter (ADC). The output of the ADC is

processed by the hardwired CORDIC (coordinate rotating

digital computer) block to compute the angle and magnitude

of the magnetic vector. The intensity of the magnetic field

(magnitude) is used by the automatic gain control (AGC) to

adjust the amplification level for compensation of the

temperature and magnetic field variations.

The internal 14-bit resolution is available by reading a register

through the SPI interface. The resolution on the ABI output can

be programmed for 10 or 11bits.

The Dynamic Angle Error Compensation block corrects the

calculated angle for latency using a linear prediction

calculation algorithm. At constant rotation speed the latency

time is internally compensated by the AS5247, reducing the

dynamic angle error at the SPI, ABI and UVW outputs. The

AS5247 allows selecting between a UVW / ABI output and a

PWM-encoded interface on the W-pin or the I-pin

At higher speeds, the interpolator fills in missing ABI pulses and

generates the UVW signals with no loss of resolution. The

non-volatile settings in the AS5247can be programmed

through the SPI interface without any dedicated programmer.

Power Management

The AS5247 can be either powered from a 5.0V supply using the

on-chip low-dropout regulator or from a 3.3V voltage supply.

The LDO regulator is not intended to power any other loads,

and it needs a 1 μF capacitor to ground located close to the chip

for decoupling as shown in Figure 11.

In 3.3V operation, VDD and VREG must be tied together. In this

configuration, normal noise performance (ONL) is available at

reduced maximum temperature (125°C) by clearing NOISESET

to 0. When NOISESET is set to 1, the full temperature range is

available with reduced noise performance (ONH).

Figure 10:

Temperature Range and Output Nosie in 3.3V and 5.0V Mode

VDD (V)

NOISESET

Temperature Range (°C)

RMS Output Noise (degree)

5.0

-40 ~ 150

0.068

3.3

-40 ~ 125

0.068

3.3

-40 ~ 150

0.082

Detailed Description

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