AS5043

Data Sheet – Programming the AS5043

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Revision 1.80

17 – 36

Internal or external reference

The default DAC reference is the voltage at pin #16 (VDD5V) divided by 2 (see Figure 13). Using this reference, a system

that has an output voltage ratiometric to the supply voltage can be built.

Optionally, an external reference source, applied at pin#9 (DACref) can be used. This programming option is useful for

applications requiring a precise output voltage that is independent of supply fluctuations, for current sink outputs or for

applications with a dynamic reference, e.g. attenuation of audio signals.

0-100% or 10-90% full scale range

The reference voltage for the DAC is buffered internally. The recommended range for the external reference voltage is

0.2V to (VDD3V3 -0.2)V.

The DAC output voltage will be switched to 0V, when the magnetic field is out of range, when the MagInc and MagDec

indicators are both =1 and the MagRngn-pin (#1) will go low.

The default full scale output voltage range is 0-100%*VDD5V. Due to limitations in the output stage of an OP-Amp buffer,

it cannot drive the output voltage from 0-100% rail-to-rail. Without load, the minimum output voltage at 0° will be a few

millivolts higher than 0V and the maximum output voltage will be slightly lower than VDD5V. With increasing load, the

voltage drops will increase accordingly.

As a programming option, an output range of 10-90%*VDD5V can be selected. In this mode, there is no saturation at the

upper and lower output voltage limits like in the 0-100% mode and it allows failure detection as the output voltage will be

The unbuffered output of the DAC is accessible at pin #10 (DACout). This output must not be loaded.

12.6 OP-AMP Stage

The DAC output is buffered by a non-inverting Op-Amp stage. The amplifier is supplied by VDD5V (pin #16) and can

hence provide output voltages up to 5V.

By allowing access to the inverting input of the Op-Amp and with the addition of a few discrete components it can be

configured in many ways, like high current buffer, current sink output, adjustable angle range, etc...

Per default, the gain of the Op-Amp must be set by two external resistors (see Figure 13). Optionally, the fixed internal

gain setting (2x) may be programmed by OTP, eliminating the need for external resistors.

12.6.1 Output Noise

The Noise level at the analog output depends on two states of the digital angular output:

a) the digital angular output value is stable

for the default gain of 2x For other gains, it must be scaled accordingly.

b) the digital output is at the edge of a step

In this case, the digital output may jitter between two adjacent values. The rate of jitter is specified as transition

noise (parameter TN in paragraph 19.5). The resulting output noise is calculated by:

OPAMP

noise

Vout

noise

V

V

VDD

TN

V

,

,

360

5

+

∗

=

where:

= noise level at pin Vout in Vrms

TN

= transition noise (in °rms; see 19.5)

VDD5V

= Supply voltage VDD5V in V

= noise level of OPAMP

(paragraph 19.3.6) in Vrms

12.7 Application Examples

See Application Note AN5043-10 for AS5043 Application Examples.