IC-TW14 Datasheet, PDF (8/33 Pages) IC-Haus GmbH – IC-PMX Companion Chip

iC-TW14
iC-PMX Companion Chip
FUNCTIONAL BLOCK DIAGRAM
Rev A1, Page 8/33
HOP
HON
ADC
SIN_RAW
COS_RAW
SIN_OFS_COR
COS_OFS_COR
GAIN_COR
SIN
PMX_ANGLE
COS Calc.
WOFS
SIN_OFS_RES
COS_OFS_RES
SIN_PEAK
COS_PEAK
AMP
Pos.
Calc.
PMX_MT
PMX_ST
SSI_DIR
SSI_OFS
SSI_MT
SSI_ST
SSI_LENGTH
SSI_MSB
MDI
MCL
MRDY
NCS
SCK
MISO
MOSI
NPRE
TX
RX
VWP
iC-PMX
Interface
(SPI)
PRAMP
NRAMP
PMXWI
PMXBIAS
Serial
Interface
ADC
Diagnostics
Bandgap
Reference
Preset
Temp. TEMP_RAW
Diode
TEMP25
TEMP_SLOPE
VDD
VDD_MSE
TEMP
Figure 2: iC-TW14 Functional Block Diagram
The iC-TW14 performs all the functions necessary to
interface the iC-PMX to a singleturn absolute sensor
system such as iC-LG, iC-MHM, iC-MU, iC-MN, etc.
to provide a complete energy-harvesting multiturn ab-
solute encoder, as shown in Figure 2. At power-up,
the TW14 calculates the iC-PMX magnet’s absolute
position and provides this information to the singleturn
absolute sensor for initialization via the multiturn inter-
face. The signal names in Figure 2 refer to iC-TW14
registers. See Register Map on page 13 for information
on these registers.
The raw sine and cosine signal values are conditioned
to remove offsets and equalize amplitudes. The condi-
tioned signal values are available in registers SIN and
COS respectively.
Next, a calculation determines the iC-PMX magnet an-
gle (PMX_ANGLE) based on the SIN and COS values.
This angle is concatenated with the 32-bit multiturn
count read from the iC-PMX at power-up and corrected
for the Wiegand offset (WOFS) to produce the com-
plete multiturn absolute position. This mutiturn absolute
position is available in registers PMX_MT and PMX_ST.
At power-up, the iC-TW14 interrogates the iC-PMX and
reads its multiturn count. It also reads the iC-PMX’s
singleturn Hall sensors (signals HOP and HON) via
a built-in 12-bit ADC to determine the angle of the
iC-PMX magnet. The singleturn Hall sensor readings
are combined to give values proportional to the sine
and cosine of the magnet angle. See Position of the
Hall Sensors and the Sensor Signal Processing in the
iC-PMX datasheet for more information. These values
are available in registers SIN_RAW and COS_RAW
respectively.
A final calculation corrects the multiturn absolute posi-
tion as required for the singleturn absolute sensor zero
location (SSI_OFS) and rotation direction (SSI_DIR).
This corrected position is available in registers SSI_MT
and SSI_ST.
Finally, the iC-TW14 assembles the SSI data packet as
required for the singleturn absolute sensor. The length
of the data packet (SSI_LENGTH) and the starting bit of
the multiturn position (SSI_MSB) must be set to match
the requirements of the singleturn absolute sensor and