
2000 May 19
5
Philips Semiconductors
Preliminary specification
Sensor Conditioning Electronic
UZZ9000
handbook, full pagewidth
MHB694
ADC1
DECIMATION
FILTER
ALU
DAC
output
angle range
offset
DATA-CLK
SMODE
CONTROL
OSCILLATOR
+
VO1
VO1
ADC2
RESET
UZZ9000
reset
DECIMATION
FILTER
+
VO2
VO2
Fig.1 Block diagram.
The following list gives a short description of the relevant
block functions:
1.
The ADC block contains two Sigma Delta AD
converters, sensor offset correction circuitry and the
circuitry required for the sensitivity and offset
adjustment of the chip output voltage curve.
The decimation filter block comprises two digital low
pass decimation filters convert the low resolution high
speed bit stream output from the ADC’s into a low
speed digital word.
The ALU block derives an angle value from the two
digital inputs using the CORDIC algorithm.
The DAC converts the output of the ALU block to an
analog signal.
The CONTROL block provides the clock and the
control signals for the chip.
The RESET block supplies a reset signal during
power-up and power-down when the power supply is
below a certain value.
The Oscillator generates the master clock.
2.
3.
4.
5.
6.
7.
Angle range selection
In order to accommodate varying applications, both the
mechanical input angular range of the UZZ9000 and the
zeropointoftheoutputcurveareuserprogrammable.This
section describes how to select a desired mode.
The output curve is adjusted by changing the angular
range as shown in Fig.2. Without any zero point offset, the
ramp-up starts at mechanical 0
°
(
α
1 = 0
°
). When using a
KMZ41 sensor, the maximum angular range
α
is 0
°
to 180
°
. For the UZZ9000, smaller angular ranges
can be set. In this case,
α
2 becomes smaller than 180
°
and the output curve is clipped at this position. The
location of discontinuity X
D
(change from lower to upper
clipping area) depends on the adjusted range and can be
calculated as follows:
In order to compensate for tolerances, the zero point of the
output curve can be shifted by
±
5 in steps of 0.5
°
. The
effect of this measure is shown in Fig.3. Now
α
1 is no
longer identical with mechanical 0, but with the zero point
shift X
off
. Consequently, the location of discontinuity X
D
can be calculated as follows:
X
D
α
°
180
α
–
2
+
=
X
D
x
off
α
+
°
180
α
–
2
+
=