ICHAUS TW3DEVAL

iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 1/24
FEATURES
APPLICATIONS
♦
♦
♦
♦
♦ Programmable general purpose
sensor interface
♦ Optical position sensors
♦ Magnetic position sensors
♦ Incremental position sensors
♦ Linear scales
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
Fully differential 3-channel signal conditioning
PGS inputs for differential and single-ended signals
Overall gain of -3 to 57 dB, adjustable in steps of 0.08 dB
Output referred offset range of ±1.2 V, adjustable in steps of
2 mV
Signal bandwidth to 1 MHz and in/out latency below 1 µs
Selectable automatic gain and offset control for encoder
applications
On-chip or off-chip temperature sensing
Temperature drift compensation for gain and offset via
programmable look-up-tables
Short-circuit-proof outputs: 1 Vpp to 100 Ω, 2 Vpp to 1 kΩ
I2 C interface to restore device setup from serial EEPROM
Bidirectional 1-wire interface for direct RAM and EEPROM
access
Optical setup link via 1-wire interface operating a photo
receiver
Single 3.0 V to 5.5 V supply
Operating temperature range of -40 to +125 °C
PACKAGES
QFN32
BLOCK DIAGRAM
Copyright © 2009 iC-Haus
http://www.ichaus.com
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 2/24
DESCRIPTION
The general purpose sensor signal conditioner iCTW3 provides highly accurate non contact trimming
of three independent sine/cosine sensor signals. The
differential output signals can be calibrated to 1 Vpp
or to 2 Vpp, alternatively.
The internal or an external temperature sensor linked
to the chip can influence the gain and offset correction by arbitrary temperature-dependent compensation parameters sourced from a look-up table.
For encoder applications an automatic gain and offset control compensates sensor offset voltages and
stabilizes the output signal level.
The direct connection of sine/cosine encoders, MR
sensor bridges or photosensor arrays is possible and
supported by a selectable input impedance.
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 3/24
PACKAGES
PIN CONFIGURATION QFN32 5 mm x 5 mm
PIN FUNCTIONS
No. Name
Function
32 31 30 29 28 27 26 25
1
24
2
23
3
22
4
TW3
code...
...
5
6
7
21
20
19
18
17
8
9
10
11 12 13 14 15 16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
PINZ
NINZ
TESTEN
CLK
NZO
ZO
GNDB
VDDB
NBO
BO
GND
SCL
SDA
VDD
GNDA
n.c.
AO
NAO
VDDA
1W
NERR
NRST
NSTORE*
n.c.
NINA
PINA
KELVIN
GNDIN
VDDIN
PINB
NINB
VC
TP TP**
Signal Input Z+
Signal Input ZTest Mode Enable Input
External Clock Input
Signal Output ZSignal Output Z+
Driver Ground
+3...+5.5 V Driver Supply Voltage
Signal Output BSignal Output B+
Digital Ground
I2C Interface, clock line
I2C interface, data line
+3...+5.5 V Digital Supply Voltage
Driver Ground
not connected
Signal Output A+
Signal Output A+3...+5.5 V Driver Supply Voltage
1-Wire Interface, bidirectional port
Error Message Output, active low
External Reset Input, active low
Coefficient Store Input, active low
not connected
Signal Input ASignal Input A+
External Temperature Sensor Input
Input Ground
+3...+5.5 V Input Supply Voltage
Signal Input B+
Signal Input B1.21 V Reference Voltage Output,
Reference Voltage Input
Thermal Pad
Notes:
*) Pin NSTORE should be wired to VDD.
**) The Thermal Pad of the QFN package (bottom side) is to be connected to a ground plane on the PCB which
must have GND potential.
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 4/24
ABSOLUTE MAXIMUM RATINGS
These ratings do not imply operating conditions; functional operation is not guaranteed. Beyond these ratings device damage may occur.
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Max.
G001 VDDx()
Voltage at VDD, VDDA, VDDB, VDDIN referenced to GND, GNDA, GNDB, GNDIN
-0.3
6.0
V
G002 V()
Voltage applied to any other pin
-0.3
VDD +
0.5
V
G003 V()
Voltage Difference VDDA, VDDB vs.
VDD
0.5
V
G004 V()
Voltage Difference VDDIN vs. VDD
0.5
V
G005 V()
Voltage Difference GNDA, GNDB vs.
GND
0.5
V
G006 V()
Voltage Difference GNDIN vs. GND
G007 Vd
ESD Susceptibility Of Signal Outputs:
AO, NAO, BO, NBO, ZO, NZO
HBM, 100 pF discharged through 1.5 kΩ
G008 Vd
ESD Susceptibility (remaining pins)
HBM, 100 pF discharged through 1.5 kΩ
G009 Tj
Junction Temperature
-40
G010 Ts
Storage Temperature
-40
150
°C
referenced to GND
0.5
V
2
kV
2
kV
150
°C
THERMAL DATA
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
T01
Ta
Operating Ambient Temperature Range
T02
Rthja
Thermal Resistance Chip To Ambient
Typ.
-40
surface mounted to PCB according
to JEDEC 51
All voltages are referenced to ground unless otherwise stated.
All currents into the device pins are positive; all currents out of the device pins are negative.
Max.
125
40
°C
K/W
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 5/24
ELECTRICAL CHARACTERISTICS
Operating conditions: VDD, VDDA, VDDB, VDDIN = 3.0...5.5 V, Tj = -40...125 °C, reference point GND unless otherwise stated
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Typ.
Max.
Total Device
001
VDDx
Permissible Supply Voltage
at VDD, VDDA, VDDB, VDDIN
3.0
5.5
V
002
I(VDDx)
Total Supply Current
VDDx = 3.3 V
VDDx = 5.5 V
15
25
mA
mA
003
Vc()hi
Clamp-Voltage hi at all pins
Vc()hi = V() - VDD; I() = 10 mA
004
Vc()lo
Clamp-Voltage lo at all pins
I() = -10 mA
0.3
1.4
V
-1.2
-0.3
V
1.4
VDD 1.2 V
V
±15
mV
Analog Signal Inputs PINA, NINA, PINB, NINB, PINZ, NINZ
101
Vin()sig
Permissible Input Voltage Range
102
Vin()os
Input Offset Voltage
103
Iin()
Input Current
ENSIGAB = 0, ENSIGZ = 0
-35
104
Rpu()
Input Pull-Up Resistor
ENSIGAB = 1, ENSIGZ = 1
2.0
105
106
fg
-3 dB Bandwidth
PGA gain of 36 dB
1.2
CMRR
Common Mode Rejection Ratio
fc < 1 MHz
fc < 1 kHz
40
60
dB
dB
107
PSRR
Power Supply Rejection Ratio
fc < 1 MHz
fc < 1 kHz
40
60
108
en
Input Voltage Noise
f = 1 kHz
f = 100 Hz
f = 0.1 to 10 Hz
dB
dB
√
V/√Hz
V/√Hz
V/ Hz
109
∆DGAIN
Dynamic Gain Step Width
0.08
dB
110
∆DOFFS
Dynamic Offset Step Width
2
mV
±5
2.5
35
nA
3
MΩ
MHz
20 n
25 n
2µ
Temperature Sensor and Analog Input KELVIN
201
Tor
Int. Temperature Sensor Operat- after calibration of ADC;
ing Range
202
Tacc
Device-To-Device Temp. Sensor
Variation
after calibration of ADC,
Tj = -40 °C to 125 °C
± 10
°C
203
Vin()low
Temperature Input Voltage
CELSIUS(7:0) = 10
CELSIUS(7:0) = 245
1.7
0.9
V
V
204
205
Iin()
Input Current at KELVIN
V(KELVIN) = 0 .. VDD
T()lo
Lo-Temperature ADC Reading,
via Register CELSIUS(7:0)
after calibration of ADC;
XCELSIUS = 0, internal sensor: Tj = -40 °C
XCELSIUS = 1, ext. sensor: V(KELVIN) = 1.7 V
19
10
Hi-Temperature ADC Reading,
via Register CELSIUS(7:0)
after calibration of ADC;
XCELSIUS = 0, internal sensor: Tj = 125 °C
XCELSIUS = 1, ext. sensor: V(KELVIN) = 0.9 V
224
245
206
T()hi
-50
150
-50
°C
50
nA
Reference Voltage Input/Output VC
301
Vout(VC)
Reference Voltage Output
302
Vin(VC)
Permissible Input Voltage Range VEXT = 1
at VC
VEXT = 0; CL = 100 nF, I() = 0 mA
303
Iin(VC)
Input Current at VC
VEXT = 1
1.10
1.35
V
0
1.21
2.21
V
-0.1
1
µA
3.0
V
Power-On Reset and Input NRST
401
VDDon
Turn-On Threshold (power-on
release)
increasing voltage at VDD
402
VDDoff
Turn-Off Threshold (power-down decreasing voltage at VDD
reset)
403
Vt()hi
Input Threshold Voltage hi
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
404
Vt()lo
Input Threshold Voltage lo
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
405
Ipu()
Input Pull-Up Current
V() = 0...VDD - 1 V
406
Vpu()
Input Pull-Up Voltage
Vpu() = VDD - V(), I() = -3 µA
2.6
V
1.5
3.3
V
V
0.8
1.0
V
V
-3
µA
700
mV
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 6/24
ELECTRICAL CHARACTERISTICS
Operating conditions: VDD, VDDA, VDDB, VDDIN = 3.0...5.5 V, Tj = -40...125 °C, reference point GND unless otherwise stated
Item
No.
Symbol
Parameter
Conditions
Oscillator CLK, TESTEN
501 Vt()hi
Input Threshold Voltage hi
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
502
Vt()lo
Input Threshold Voltage lo
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
503
Ipd()
Input Pull-Down Current
V() = 1 V...VDD
504
505
Vpd()
Input Pull-Down Voltage
I() = 3 µA
fosc
Oscillator Frequency
TEST_CLK = 1, measured at NERR;
CLKDIV = 0 (low active)
CLKDIV = 1
506
Unit
Min.
fin()
Typ.
Max.
1.5
3.3
V
V
0.8
1.0
3
V
V
µA
Permissible External Clock Frequency at CLK
700
mV
2
4
MHz
MHz
4
MHz
300
mV
1-Wire Interface 1W
601
Vs()lo
Saturation Voltage lo
602
Isc()lo
Short-Circuit Current lo
I() = 1 mA
603
Ipu()
Input Pull-Up Current
V() = 0...VDD - 1 V
604
Vpu()
Input Pull-Up Voltage
Vpu() = VDD - V(), I() = -3 µA
605
606
tr(), tf()
Rise and Fall Time (10/90%)
VDD = 3.3 V, CL = 10 pF
Vt()hi
Input Threshold Voltage hi
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
607
Vt()lo
Input Threshold Voltage lo
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
2
mA
-3
µA
700
mV
32
ns
1.5
3.3
V
V
0.8
1.0
V
V
400
mV
I2C Interface SDA, SCL
701
Vs()lo
Saturation Voltage lo
I() = 1 mA
702
Isc()lo
Short-Circuit Current lo
V() = 1V...VDD
703
Ipu()
Pull-Up Current
V() = 0...VDD - 1 V
704
705
Vpu()
Input Pull-Up Voltage
Vpu() = VDD - V(), I() = -3 µA
Vt()hi
Input Threshold Voltage hi at
SDA
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
706
Vt()lo
Input Threshold Voltage lo at
SDA
VDD = 3.3 V +/- 10 %
VDD = 5.0 V +/- 10 %
707
fclk()
Write/Read Clock Frequency at
SCL
CLKDIV = 0
708
tbusy()cfg
Duration Of Startup Configuration CLKDIV = 0, 2 LUT blocks
CLKDIV = 0, 16 LUT blocks
3
mA
-3
µA
700
mV
1.5
3.3
V
V
0.8
1.0
100
V
V
kHz
20
80
ms
ms
Digital Output NERR
901
Vs()lo
Saturation Voltage lo
I() = 1 mA
400
mV
902
Vs()hi
Saturation Voltage hi
Vs()hi = VDD - V(); I() = -1 mA
400
mV
903
Isc()lo
Short-Circuit Current lo
904
Isc()hi
Short-Circuit Current hi
3
mA
-2.5
mA
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 7/24
ELECTRICAL CHARACTERISTICS
Operating conditions: VDD, VDDA, VDDB, VDDIN = 3.0...5.5 V, Tj = -40...125 °C, reference point GND unless otherwise stated
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Typ.
Max.
Line Driver Outputs AO, NAO, BO, NBO, ZO, NZO
B01
Vpk()max
Permissible Output Amplitude
B02
Vdc()
Output DC Voltage
B03
∆Vout()
Output Voltage Load Dependency
I() = 0...5 mA
B04
Isc()lo
Short-Circuit Current lo
pin shorten to VDD/2
B05
Isc()hi
Short-Circuit Current hi
pin shorten to VDD/2
B06
B07
Isc()
Output Current Limitation hi/lo
V() = 0...VDD
SR()hi, lo
Slew Rate hi/lo
CL() = 5 nF
CL() = 50 pF
B08
B09
tS
Settling Time
CL() = 5 nF, to 0.1% of final value
dbVlin
Output Linearity
100 kHz sine and diff. 1 Vpp output voltage;
RL() > 1 kΩ
RL() = 120 Ω
B10
CLmax
Maximum Capacitive Output
Load
VDD = 3 V, RL = 50 Ω vs. VDD/2
550
mV
50
mV
12
50
mA
-50
-12
mA
VDD / 2
no sustained oscillation
40
50
3
4
mA
V / µs
V / µs
1
80
60
µs
dB
dB
100
nF
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 8/24
PROGRAMMING
Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 9
I2C INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 11
CHECKSUM: EEPROM Checksum
1-Wire Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 12
A/B Signal Path . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 14
SINGLEIN:
Single ended input functionality
ENSIGAB:
Input signal error detection control
CGAINA/B:
Coarse gain select for channel A/B
COFSA/B:
Coarse offset select for channel A/B
DGAINA/B:
Dynamic gain on channel A/B
DOFSA/B:
Dynamic offset on channel A/B
OGAIN:
Output amplifier gain select on channel A/B
FILTER:
Signal path filter select
PDA/B:
Power down control for channel A/B
Z Signal Path (Index) . . . . . . . . . . . . . . . . . . . . . . Page 16
SINGLEZ:
Single ended input functionality for index channel Z
MODEZ:
Channel Z output mode select
BYPASSZ:
Channel Z comparator bypass control
GAINZ:
Gain select for channel Z
OFSZ:
Offset select for channel Z
OGAINZ:
Output amplifier gain select on channel Z
ENSIGZ:
Input signal error detection control on
channel Z
PDZ:
Power down control for channel Z
POLARITYZ: Channel Z polarity select
Automatic Compensation . . . . . . . . . . . . . . . . . Page 18
VEXT:
Target voltage select
DYNAMIC:
Automatic compensation control
FREQ:
Automatic adaption frequency
GENTLE:
Automatic compensation update rate
Temperature Sensing . . . . . . . . . . . . . . . . . . . . . Page 19
XCELSIUS:
Temperature sensor select
FCELSIUS:
Fine temperature offset value
CCELSIUS:
Coarse temperature offset value
CELSIUS:
Current temperature value
Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . Page 20
ERR_SIG:
Signal unconnected alarm
ERR_TEMP: Temperature alarm
ERR_EE:
EEPROM error condition
Temperature Compensation . . . . . . . . . . . . . . Page 21
TEMP:
Temperature compensation control
Test Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 22
PD_CELSIUS: Power down control for internal temperature sensor
TEST_CLK:
Internal test clock oscillator control
CLKDIV:
Internal clock divider select
Typical Applications . . . . . . . . . . . . . . . . . . . . . . Page 23
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 9/24
REGISTER MAP
Adr
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Configuration Registers
0x00
0x01
0x02
ROM Device ID[7:0]
OGAIN[1:0]
SINGLEIN
VEXT
XCELSIUS
0x03
ERR_SIG
ERR_TEMP
0x04
EN_NSTORE*
0x07
MODEZ
ERR_EE
GENTLE
DYNAMIC
TEMP
BYPASSZ
SINGLEINZ
POLARITYZ
ENSIGZ
ENSIGAB
PDB
PDA
TALARM[2:0]
FILTER[1:0]
0x05
0x06
FREQ[1:0]
OGAINZ[1:0]
PDZ
CCELSIUS[3:0]
FCELSIUS[3:0]
GAINZ[2]
OFSZ[5:0]
GAINZ[1:0]
CGAINB[2:0]
0x08
CGAINA[2:0]
COFSA[7:0]
0x09
COFSB[7:0]
0x0A
DGAINA[7:0]
0x0B
DGAINB[7:0]
0x0C
DOFSA[7:0]
0x0D
DOFSB[7:0]
0x0E
VC[1:0]*
0x0F
0x10
CLKSLOW*
CLKDIV
TEST_CLK
PD_CELSIUS
VTEST0*
PD_BG*
TEST_BG*
Internal Checksum(7:0)
TEST_ADC*
TEST_VGA*
TEST_PGA*
VTEST1*
0x11
0x12
CELSIUS[7:0]
0x13
Internal State Machine Registers
0x14
INTERNAL USE
0x15
INTERNAL USE
0x16
INTERNAL USE
0x17
INTERNAL USE
0x18
INTERNAL USE
0x19
INTERNAL USE
0x1A
INTERNAL USE
0x1B
INTERNAL USE
0x1C
INTERNAL USE
0x1D
INTERNAL USE
0x1E
INTERNAL USE
0x1F
INTERNAL USE
0x20
INTERNAL USE
0x21
INTERNAL USE
0x22
INTERNAL USE
0x23
INTERNAL USE
0x24
INTERNAL USE
0x25
INTERNAL USE
0x26
INTERNAL USE
0x27
INTERNAL USE
Peripheral Registers
0x40
CELSIUSRAW[7:0]
0x41
0x42
EE_ERR
CHANNEL
OFS_P
OFS_N
GAIN_P
GAIN_N
XERR_OUT
1OUTPUT
1INPUT
XSTORE
SIG_VALID
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 10/24
REGISTER MAP
Adr
0x43
Notes
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
EE_IRQ
Bit 2
Bit 1
1INPUT_IRQ
XSTORE_IRQ
Only the configuration registers are user programmable.
*) Bits marked by an asterisk are solely intended for IC test and must be kept
on zero for normal operation.
Table 4: Register layout
Bit 0
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 11/24
I2C INTERFACE
Startup
An external I2 C 1-kbit EEPROM (e.g. 24xx01 family)
is used to store configuration parameters permanently.
On power-up and after reset is released iC-TW3 accesses the external EEPROM and reads its device
configuration according to Table 6.
EEPROM Checksum
The checksum at address 0x0F contains the 8-bit sum
of registers 0x01 to 0x0E plus the 8-bit sum of all LUT
bytes up to and including the final block with its breakpoint set to 255.
On startup iC-TW3 calculates the expected checksum
and compares it with the value stored at EEPROM
address 0x0F. If computed and stored address match
normal operation begins. Otherwise, iC-TW3 asserts
an error condition and pin NERR is pulled low.
It is the user’s responsibility to store the correct checksum in the EEPROM during production programming.
CHECKSUM(7:0)
Adr 0x0F; Bit 7:0
R/W
therefore equivalent to accessing memory location 128
via the 1-wire interface (see page 12).
EEPROM
Address
Description
Corresponding
Configuration Register
0x00
<reserved>
-
0x01
Config. 1
0x01
0x02
Config. 2
0x02
0x03
Config. 3
0x03
0x04
Config. 4
0x04
0x05
Temp. Sensing
0x05
0x06
Config. Index
0x06
0x07
Coarse Gain
0x07
0x08
COFSA
0x08
0x09
COFSB
0x09
0x0A
DGAINA
0x0A
0x0B
DGAINB
0x0B
0x0C
DOFSA
0x0C
0x0D
DOFSB
0x0D
0x0E
Test 1
0x0E
0x0F
CHECKSUM
0x0F
EEPROM
Address
Description
LUT Block Number
Code
Function
0x10
Breakpoint 0
0
...
Checksum of EEPROM contents
0x11
GAINA
0
0x12
GAINB
0
0x13
OFSA
0
0x14
OFSB
0
0x15
OFSZ
0
0x16
Breakpoint 1 (255)
1
0x17
GAINA
1
0x18
GAINB
1
0x19
OFSA
1
0x1A
OFSB
1
0x1B
OFSZ
1
.
.
.
.
.
.
.
.
.
0x6A
Breakpoint 255
15
0x6B
GAINA
15
0x6C
GAINB
15
0x6D
OFSA
15
0x6E
OFSB
15
0x6F
OFSZ
15
Table 5: Checksum
EEPROM Register Map
The 14 bytes of device configuration data are followed
by a minimum of 2 to a maximum of 16 lock-up-table
blocks (LUT). The LUT block size is 6 bytes each and
the final block is indicated by its breakpoint value of
255.
Thus, a minimum of 28 bytes are read with 2 active
LUT blocks and 112 bytes are read with 16 active LUT
blocks during the configuration phase. Note that the
checksum is only calculated up and including the last
LUT block. The last LUT block ist indicated by a breakpoint value of 255. Further descriptions on LUTs are
given in section "Temperature Compensation" on page
21.
Note that the EEPROM address space maps to the
1-wire address 128. Accessing EEPROM address 0 is
Table 6: EEPROM register map
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 12/24
1-WIRE INTERFACE
The 1-wire interface provides read and write access to
the register bank and to the external EEPROM. When
read access is not required an infrared phototransistor
can be directly connected to the pin in order to build
a cost effective wireless write-only port for in-field or
production programming.
coded as a short high followed by a long low. A one-bit
is encoded as a long high followed by a short low.
The modulated signal is independent of the receiver or
the transmitted clock frequency. Since iC-TW3 uses
a free-running oscillator it is important to implement a
robust, frequency insensitive protocol.
The communication bit stream is pulse-width modulated (PWM) as shown in Figure 1. A zero-bit is en-
1- wire timing
idle
start
tlong
1
tlong
0
tshort
tshort
delay
tlong
tshort
tdelay
idle
tidle
Figure 1: Pulse width modulation bit stream
Parameter
Description
min
tstart
Low time start condition (Master only)
1 ms
tlong
Unit time long (Master and iC-TW3)
tshort + 10 µs
400 µs
tshort
Unit time short (Master and iC-TW3)
35 µs
tlong - 10 µs
tdelay
Delay on register read (iC-TW3 only)
35 µs
tidle
Interface idle before next access
Access was write to external EEPROM
Access was not write to external EEPROM
8 ms
3 ms
Table 7: 1-Wire interface timing
max
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 13/24
Addressing
The EEPROM address 0x00 maps to the 1-wire address 128. Accessing EEPROM address 0 is therefore
equivalent to accessing memory location 128 through
the 1-wire interface. All other 1-wire addresses are
thus determined by adding 128 to the EEPROM address of interest.
Write Sequence
Figure 2 describes the write sequence of the 1-wire interface. On an idle wire, a write sequence is initiated
1-Wire Write Access
Read Sequence
A read sequence is depicted in Figure 3. After the start
condition the read command (001) is followed by the
register address. The master then releases the wire
and iC-TW3 begins to pull low while internally accessing the data. When the data is ready it is produced
while following the same PWM rules valid for the master.
Wire not driven
Wire driven by master
3-bit command word
000 = write
001 = read
Idle, wire is high
idle
by generating a start condition followed by the write
command (000) and by the address and register data.
000
start
Filler bit, value 0
address(7:0)
To initiate communication
pull low for at least tstart
0
data(7:0)
idle
Wait at least for tidle
before new access
8-bit register address:
0 to 127:
internal registers
128 to 255: external EEPROM
Figure 2: Register write sequence
1-Wire Read Access
Idle, wire is high
idle
start
Wire not driven
3 bit command word
000 = write
001 = read
001
To initiate communication
pull low for at least tstart
Wire driven by master
Master releases driver
address(7:0)
8-bit register address:
0 to 127:
internal registers
128 to 255: external EEPROM
Wire driven by iC-TW3
iC-TW3 starts returning data
(first bit is dummy)
delay
X
iC-TW3 drives low until
data is ready
Figure 3: Register read sequence
data(7:0)
idle
Wait at least for tidle
before new access
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 14/24
A/B SIGNAL PATH
iC-TW3 incorporates two analog gain paths called
channel A and B, respectively. Gain and offset of both
paths are independently controlled and temperature
compensated. Figure 4 depicts a diagram of a single
signal path, Table 8 below summarizes gain and offset
characteristics.
VDD
ENSIGAB
COFSA/B(5:0)
FILTER(1:0)
PINA/PINB
+
+
Input
NINA/NINB
-
+
CGAINA/B(2:0)
SINGLEIN
AO/BO
dynamic
FOFSA/B(7:0)
output
FGAINA/B(7:0)
NAO/NBO
OGAIN(1:0)
VDD/2
Figure 4: The A/B signal path
Input Amplifier
Dynamic Amplifier
Output Amplifier
Composite
Gain range
0..36 dB
-2..18.4 dB
-3 dB, 0 dB, 6 dB
-5..60 dB
Gain step
6.0 dB
0.08 dB
Offset range input
referred
1.24 V
gaininput
0.25 V
gaininput
Offset step input referred
40 mV
gaininput
1.49 V
gaininput
2 mV
gaininput
gaininput = 10
gain_of _input_amplifier _in_dB
20
Table 8: Overview of gain and offset characteristics
Single ended signals
Single ended input functionality is provided by connecting the negative input terminal (pins NINA and
NINB) to an internally generated voltage of VDD /2. This
is enabled by setting the control bit SINGLEIN to 1. Alternatively, an externally generated reference voltage
may be applied to the negative input terminals.
SINGLEIN
Adr 0x01; Bit 5
Code
Function
0
1
A and B inputs are differential (default)
A and B inputs are single ended
R/W
Table 9: Single ended input functionality
Input error detection
Weak input pull-up resistors are enabled by setting
control bit ENSIGAB to 1. The resistors are at minimum 2.0 MΩ. When driving the input with a high
impedance source it might be necessary to disable
the pull-up resistors to avoid excessive signal distortion. The pull-up resistors are used to sense floating
or damaged sensor connections. Any input terminal
left unconnected is pulled to VDD and triggers a sensor
error condition err_sig.
ENSIGAB
Adr 0x03; Bit 0
R/W
Code
Function
0
Pull-up resistors disconnected and error reporting
disabled (default)
1
Pull-up resistors and error reporting active on A/B
inputs
Table 10: Input signal error detection control
Gain and offset
Registers CGAINA(2:0) and CGAINB(2:0) are used to
set the coarse gain. Coarse gain is static and it is not
changed by the temperature or automatic compensation algorithm.
The highest legal value for CGAINA(2:0) and
CGAINB(2:0) is 6. Equivalently registers COFSA(5:0)
and COFSB(5:0) are used to control the static off-
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 15/24
set of the input signal. Note that COFSA(5:0) and
COFSB(5:0) are in 2’s complement format and their
value range is limited from -31 to +31.
CGAINA(2:0)
Adr 0x07; Bit 2:0
R/W
CGAINB(2:0)
Adr 0x07; Bit 5:3
R/W
Code
gain = cgain x 6 dB
0x00
0 dB (default)
0x01
6 dB
...
0x06
36 dB
Table 11: Coarse gain select for channel A/B
COFSA(7:0)
Adr 0x08; Bit 7:0
COFSB(7:0)
Adr 0x09; Bit 7:0
R/W
R/W
Code 2’K
Code 5:0, and decimal
offset = cofs x 40 mV
0xE1
...
0x21, -31
...
-1240 mV
0xFF
0x3F, -1
-40 mV
0x00
0x01
0x00, 0
0x01, +1
0 mV (default)
40 mV
...
...
0x1F
0x1F, +31
1240 mV
Adr 0x0A; Bit 7:0
DGAINB(7:0)
Adr 0x0B; Bit 7:0
gain = dgain x 0.08 dB - 2 dB
Code
0x00
Code
Adr 0x01; Bit 7:6
Function
0x00
0 dB (default)
0x01
0x02
reserved
+6 dB
0x03
-3 dB
R/W
A programmable 1st -order low-pass filter can be enabled to limit the path bandwidth. The filter cut-off frequency can be set via the FILTER(1:0) register.
-2 dB (default)
0 dB
0.08 dB
FILTER(1:0)
...
0xFF
18.4 dB
Table 13: Dynamic gain select for channel A/B
DOFSA(7:0)
Adr 0x0C; Bit 7:0
R/W
DOFSB(7:0)
Adr 0x0D; Bit 7:0
offset = cofs x 2 mV
R/W
Code
0x81
-254 mV
...
0xFF
-2 mV
0x00
0 mV (default)
0x01
...
2 mV
0x7F
254 mV
R/W
Table 15: Output amplifier gain on channel A/B
R/W
...
0x19
0x1A
Output driver
The output amplifier is capable of driving a 100 Ω differential load and is stable with capacitive loads of up
to 100 nF. Control register OGAIN(1:0) is used to select the output amplifier gain. A gain of -3 dB is useful
to accommodate input signals larger than 1 V and gain
of +6 dB will provide a 1 Vpp single-ended output. Note
that the selected output amplifier gain will influence the
automatic gain compensation. Refer to section "Automatic Compensation" on page 18 for details.
OGAIN(1:0)
Table 12: Coarse offset select for channel A/B
DGAINA(7:0)
enabled the values of FGAINA/B and FOFSA/B are
equal to the register values in DGAINA/B(7:0) and
DOFSA/B(7:0). Refer to chapter "Temperature Compensation" on page 21 for a detailed explanation of fine
gain and fine offset calculations. DGAINA/B(7:0) and
DOFSA/B(7:0) can be programmed to a fixed value or
it is automatically updated when dynamic adaption is
enabled.
Table 14: Dynamic offset select for channel A/B
Value FGAINA/B and FOFSA/B are fine gain and offset control respectively. They are calculated dynamically according to the temperature compensation algorithm. In case temperature compensation is not
Adr 0x04; Bit 4:3
Code
Function
0x00
0x01
1 MHz (default)
500 kHz
0x02
200 kHz
0x03
reserved
R/W
Table 16: Signal path filter
In order to save power the complete signal path can be
disabled using the control bits PDA and PDB respectively. When disabled the outputs are high impedance.
The dynamic adaption should be disabled when either
channel A or B is disabled.
PDA
Adr 0x04; Bit 0
R/W
PDB
Adr 0x04; Bit 1
R/W
Code
Function
0
1
Channel A/B is enabled (default)
Channel A/B is powered down
Table 17: Power down control on channel A/B
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 16/24
Z SIGNAL PATH (INDEX)
A third analog path is used for index signal processing
frequently found in encoder applications. Refer to Figure 5 for an overview. An input amplifier with a gain
range of 0 to 36 dB is used to amplify the index signal
to an intermediate level. The input amplifier employs
output referred offset correction. This is used to eliminate inherent amplifier offset as well as sensor offset.
Additionally, the same offset correction is used to skew
the comparator shift point to a desired level. The offset
correction is temperature compensated with a LUT.
VDD
ENSIGZ
OFSZ(5:0)
PINZ
+
BYPASSZ
+
+
+
output
1Vpp
NINZ
-
POLARITYZ
GAINZ(2:0)
ZO
-
-
MODEZ
OGAINZ(1:0)
NZO
SINGLEINZ
VDD/2
Figure 5: The Z signal path
Input Amplifier
Output Amplifier
Composite
Gain range
0..36 dB
-3 dB, 0 dB, 6 dB
-3..42 dB
Gain step
6 dB
Offset Range (input
referred*
1.86 V
gaininput
Offset step input referred
60 mV
gaininput
*: gaininput = 10
1.86 V
gaininput
gain_of _input_amplifier _in_dB
20
Table 18: Gain and offset characteristics for channel Z
A single ended input referenced to VDD /2 is provided
by setting bit SINGLEINZ of register 0x02. Alternatively, pin NINZ can be biased with an external voltage.
SINGLEINZ
Code
Adr 0x02; Bit 1
Function
0
channel Z input is differential (default)
1
channel Z is single ended
MODEZ
Function
0
1 Vpp out (default)
1
Rail-to-rail output
(requires OGAINZ(1:0) set to 0x2)
R/W
A zero-crossing comparator generates a 1.0 Vpeak-peak
output signal or a rail-to-rail signal depending on control bit MODEZ. The comparator can be bypassed
which allows using the Z Path as a regular amplifier
path. Bypassing can be toggled via bit BYPASSZ of
register 0x02.
R/W
Table 20: Channel Z output mode select
BYPASSZ
Table 19: Single ended input functionality
Adr 0x02; Bit 3
Code
Adr 0x02; Bit 2
Code
Function
0
1
Comparator is enabled (default)
Comparator is bypassed
Table 21: Channel Z comparator bypass
R/W
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 17/24
Gain and offset
Gain and offset selections on channel Z are made
available by providing control bits GAINZ(2:0) and
OFSZ(5:0). Note that the maximum value for gain on
channel Z is 6 which corresponds to a total gain of
36 dB.
OGAINZ(1:0)
Adr 0x02; Bit 5:4
Code
Function
0x00
0 dB (default)
0x01
0x02
reserved
+6 dB
0x03
-3 dB
R/W
Table 24: Output amplifier gain on channel Z
GAINZ(2:0) is split up amongst register 0x06 which
holds the MSB and register 0x07 holding the other two
bits. OFSZ(5:0) is the correction value to the output
of the input amplifier and is interpreted as 2’s complement. The input referred offset is therefore gain dependent.
The output gain on channel Z can be set via control bits
OGAINZ(1:0). For more details again refer to section
"A/B PATH" on page 14.
GAINZ(2:0)
Adr 0x06; Bit 7
Code
gain = gainz x 6 dB
0 dB (default)
6 dB
ENSIGZ
Adr 0x03; Bit 1
Function
0
Pull-up resistors disconnected and error reporting
disabled (default)
Pull-up resistors and error reporting active on inZ
1
Table 25: Input signal error detection control
PDZ
...
0x06
R/W
Code
R/W
Adr 0x07; Bit 1:0
0x00
0x01
Input error detection
Pull-up resistor and error detection on channel Z can
be controlled by bit ENSIGZ of register 0x03, disabling
of the complete Z path can be achieved by setting bit
PDZ of register 0x04 to 1. For more detailed information on pull-up and power control refer to section "A/B
PATH" on page 14 as the behaviour of index path and
signal path equal regarding these matters.
36 dB
Table 22: Gain select for channel Z
Adr 0x04; Bit 2
Code
Function
0
1
Channel Z is enabled (default)
Channel Z is powered down
R/W
Table 26: Power-down control on channel Z
Code 2’K
OFSZ(5:0)
Adr 0x06; Bit 5:0
Decimal
R/W
offset = cofs x 60 mV
0x21
-31
-1860 mV
...
0x3F
...
-1
-60 mV
0x00
0
0 mV (default)
POLARITYZ
0x01
+1
60 mV
Code
Function
...
0x1F
...
+31
1860 mV
0
1
Channel Z has normal polarity (default)
Channel Z has inverted polarity
Table 23: Offset select for channel Z
Polarity of channel Z
Furthermore, the polarity on channel Z can be inverted
by setting or not setting bit POLARITYZ.
Adr 0x02; Bit 0
Table 27: Channel Z polarity select
R/W
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 18/24
AUTOMATIC COMPENSATION
Automatic gain and offset correction is available for
dual sensor bridges that are 90° out of phase. These
types of sensors are used for encoder applications.
Automatic compensation removes any sensor offset
and sets the gain to achieve a fixed output voltage.
The target output voltage depends on the output gain
OGAIN(1:0) as well as on the control bit VEXT. When
using an external reference voltage, the appropriate
voltage must be applied to pin VC.
VEXT
Adr 0x02; Bit 7
DYNAMIC
Adr 0x01; Bit 1
Code
Function
0
Automatic function is disabled
1
Automatic function is enabled
Table 30: Automatic compensation enable
Note that setting FREQ(1:0) to other values than 0
does not affect the signal bandwidth of the amplifier.
It merely limits the rate of automatic adaption.
R/W
Code
Function
FREQ(1:0)
0
Internally generated 1 V or 2 V is used as output
target voltage, depending on register OGAIN(1:0).
Voltage applied to pin VC defines target output
voltage (see Table 29).
Code
Function
00
no tracking limit (default)
01
200 kHz
10
20 kHz
11
2 kHz
1
R/W
Table 28: Target voltage selection
Adr 0x01; Bit 4:3
R/W
Table 31: Automatic compensation adaption rate
OGAIN(1:0) Output Gain
VEXT
Target Output
Voltage Vppdiff
00
0 dB
0
1V
01
reserved
0
10
6 dB
0
2V
11
-3 dB
0
1V
00
0 dB
1
2.21 V - V(VC)
01
reserved
1
10
6 dB
1
(2.21 V - VC) x 2
11
-3 dB
1
2.21 V - VC
Table 29: Target output voltages
Automatic compensation is enabled by setting control
bit DYNAMIC of register 0x01 to 1. If enabled, it will
constantly alter register DOFSA/B and DGAINA/B to
maintain zero offset and the target output amplitude.
Control bits FREQ(1:0) of register 0x01 are used to
limit the tracking rate. If the input frequency increases
above the limit tracking will stop. Normally, it is not required to limit the tracking frequency although it can be
useful for certain bandwidth limited sensors.
In normal operation the compensation algorithm will
adjust both gain and offset simultaneously in order to
achieve fast convergence. If control bit GENTLE of
register 0x01 is set, gain and offset registers are updated alternately. This reduces output jumpiness at
the expense of slower convergence.
GENTLE
Adr 0x01; Bit 2
Code
Function
0
Gain and offset are updated simultaneously
1
Gain and offset are updated alternately
R/W
Table 32: Automatic compensation sequence control
Automatic compensation can be used in conjunction
with temperature compensation. Automatic compensation will then remove any residual offset or gain mismatch not corrected by the temperature correction algorithm.
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 19/24
TEMPERATURE SENSING
iC-TW3 contains an on-chip temperature sensor. Optionally, an external sensor can be used by setting bit
XCELSIUS of register 0x02 to 1. An external temperature sensor is useful for remote temperature sensing
or in situations where the internal sensor does not provide adequate accuracy. Also, device self-heating due
to heavy output loads can have an impact on the internal sensor readings. Connect the external temperature
sensor with its analog output to pin KELVIN.
CCELSIUS(3:0)
Adr 0x05; Bit 3:0
R/W
Code
Bit 3 is sign, bits 2:0 are magnitude of correction
1111
most negative correction
...
1001
...
least negative correction
1000
no correction
0000
0001
no correction (default)
least positive correction
...
...
0111
most positive correction
Table 34: Coarse offset correction
XCELSIUS
Adr 0x02; Bit 6
R/W
Code
Function
0
Select internal temperature sensor (default)
FCELSIUS(3:0)
Adr 0x05; Bit 7:4
R/W
Value added to ADC reading is FCELSIUS(3:0) - 8
Code
1
Select external temperature sensor
0000
-8 (default)
0001
...
-7
...
1111
7
Table 33: Temperature sensor select
Table 35: Fine offset correction
An ADC converts the analog temperature signal into
an 8-bit digital word. In case the on-chip sensor is used
the 8-bit value spans a temperature range of -50 °C to
150 °C. It is recommended to calibrate the ADC using
register 0x05 even when using an external temperature sensor.
CELSIUS(7:0)
Adr 0x12; Bit 7:0
R
Data
Function
0x00
Current temperature ADC value that is used for
compensation calculations. Value of this register is
0x40 + FCELSIUS(3:0) - 8
0xFF
Table 36: Temperature data
Calibrating the temperature ADC
The raw ADC value can be accessed through register
0x40. A ±2 increment hysteresis is applied to the ADC
value to remove conversion noise and the offset register 0x05 is added. The final value is stored in register
0x12 and is used for temperature compensation.
To achieve best temperature accuracy it is required to
calibrate the ADC by correctly programming register
0x05. At any known ambient temperature the register
0x05 is programmed such to read the expected ADC
value. As an example, consider the product assembly floor with an ambient temperature of 20 °C. Due to
device variation the ADC value read before calibration
can be anything between 0 °C to 40 °C. Register 0x05
is now used to tune the ADC output value to the correct
binary representation of 20 °C.
Temperature alarm
The iC-TW3 features a built-in temperature alarm system. An alarm threshold can be specified by the user
via the TALARM(2:0) bits in register 0x03. A temperature alarm is asserted once the temperature value generated by the ADC is above the defined threshold. The
alarm is indicated by the ERR_TEMP bit set to 1 as
well as by pin NERR going low.
TALARM(2:0)
Adr 0x03; Bit 4:2
Code
tempthreshold = (TALARM(2:0) x 16) + 144
000
144 (default)
001
160
...
110
...
240
111
Alarm disabled
Table 37: Temperature alarm threshold
R/W
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 20/24
ERROR CONDITIONS
iC-TW3 maintains three status bits reporting system
error conditions. These bits are ERR_EE, ERR_TEMP
and ERR_SIG of register 0x03. If any error condition is
triggered, i.e. indicated by any of these bits being set
to 1, this will also assert pin NERR pulling it low.
ERR_EE
Adr 0x03; Bit 5
Code
Error message
No error since the last reset
One of the following error conditions has occurred
since the last reset:
1. EEPROM checksum error*
2. EEPROM read error
3. EEPROM write error
Adr 0x03; Bit 6
Code
Error message
0
ADC reading is below value defined in register
TALARM(2:0)
1
ADC reading is above value defined in register
TALARM(2:0)
Notes
This error is not latched. Disabling temperature
monitoring is possible by setting TALARM(2:0) to
’111’.
R
0
1
Notes
ERR_TEMP
Table 39: Temperature alarm
ERR_SIG
Adr 0x03; Bit 7
Code
Error message
This error message can not be disabled and its bit
status is maintained until the device is reset.
0
1
All input terminals are connected
An input terminal is left unconnected
*) A permanent logic zero read at SDA does not
lead to a checksum error.
Notes
This error is not latched. To enable this alarm
ENSIGAB or ENSIGZ must be set 1.
Table 38: EEPROM data error
R
Table 40: Signal unconnected alarm
R
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 21/24
TEMPERATURE COMPENSATION
Temperature compensation is enabled by setting control bit TEMP of register 0x01. A piece-wise linear interpolation of values stored in a look-up-table (LUT) is
employed to calculate the gain and offset for a given
temperature. Figure 6 shows a sample configuration
with seven breakpoints.
TEMP
Adr 0x01; Bit 0
R/W
Code
Function
0
Temperature compensation is disabled (default)
1
Temperature compensation is enabled
Table 41: Temperature compensation enable
gain/ofs
ofsZ
ofsB
ofsA
gainB
gainA
ADC value
bp0
0
bp1
bp2
bp3
bp4
bp5
bp6
255
Figure 6: LUT with seven breakpoints
There can be a minimum of two up to a maximum
of 16 temperature breakpoints within the LUT. Each
breakpoint has five interpolation values associated to it
namely GAINA, GAINB, OFSA, OFSB and OFSZ. For
more details on the layout of the LUT refer to section
"EEPROM" on page 11.
Breakpoints can be placed freely across the temperature axis except for the first and the last breakpoint.
The first breakpoint must be located at ADC value 0
(which roughly corresponds to -50 °C when using the
internal sensor), the last breakpoint must be located at
ADC value 255 (150 °C with the internal sensor).
The LUT is stored in the off-chip EEPROM from memory location 0x10 onward. Note that the EEPROM address space maps to the 1-wire address 128. Accessing EEPROM address 0 is therefore equivalent to accessing memory location 128 through the 1-wire interface. The breakpoint entry with a value of 255 marks
the last valid LUT entry. All addresses thereafter including their data will be ignored.
Temperature dependent gain and offset is determined
by performing linear interpolation between breakpoints. Temperature dependent gain and offset are
TGAINA/B and TOFSA/B respectively.
Fine gain FGAINA/B and fine offset FOFSA/B (see figure 4 on page 14) are calculated as follows:
fgain = tgain + dgain
fofs = tofs + dofs
Whereas TGAIN and TOFS are the temperature dependent values calculated using the LUT and DGAIN
and DOFS are registers updated either manually or by
the automatic compensation function.
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 22/24
EEPROM address
16
22
28
1-wire address
16 + 128 = 144
22 + 128 = 150
28 + 128 = 156
0
gainA
gainB
ofsA
ofsB
ofsZ
1
gainA
gainB
ofsA
ofsB
ofsZ
255
gainA
gainB
ofsA
ofsB
ofsZ
3 breakpoint look-up table
EEPROM address
16
22
106
1-wire address
16 + 128 = 144
22 + 128 = 150
106 + 128 = 234
0
gainA
gainB
ofsA
ofsB
ofsZ
1
gainA
gainB
ofsA
ofsB
ofsZ
255
gainA
gainB
ofsA
ofsB
ofsZ
16 breakpoint look-up table
Figure 7: Temperature LUT memory map
TEST MODES
The iC-TW3 posses two registers 0x0E and 0x10
which provide access to basic testing functionality. The
PD_CELSIUS bit allows powering off the internal temperature sensor. If powered down, the temperature
sensor output value can be forced to a desired value
by writing to register 0x40. The user can then test the
compensation circuit without cycling the device temperature.
PD_CELSIUS
Adr 0x0E; Bit 0
Code
Function
0
1
Temperature sensor enabled (default)
Temperature sensor disabled
R/W
Table 42: Temperature sensor power control
TEST_CLK
Adr 0x0E; Bit 1
Code
Function
0
Clock is not driven on any pin (default)
1
Clock is driven on pin NERR
R/W
Table 43: Internal clock oscillator
CLKDIV
Adr 0x0E; Bit 2
Code
Function
1
fsystem = fosc (default)
0
fsystem = fosc / 2
Table 44: Internal clock divider selection
R/W
iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 23/24
TYPICAL APPLICATIONS
A typical application is shown in figure 8. Three differential MR sensor bridges are connected to the iC-
TW3. A, B and Z outputs are driving 120Ω terminated
transmission lines.
+3...5.5V
0.1μF
+3...5.5V
VDDIN/A/B
VDD
GNDIN/A/B
GND
PINA
0.1μF
termination
120 Ω
AO
Sensor
Bridge 0
R
NAO
NINA
BO
PINB
R
NBO
Sensor
Bridge 1
ZO
NINB
R
NZO
PINZ
VDD
Index
Sensor
SCL
NINZ
10k
SDA
iC-TW3
SCL
SDA
24xx01
EEPROM
Figure 8: Typical application MR Sensors
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areas of applications of the product.
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As a general rule our developments, IPs, principle circuitry and range of Integrated Circuits are suitable and specifically designed for appropriate use in technical
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We understand suitable application of our published designs to be state-of-the-art technology which can no longer be classed as inventive under the stipulations
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iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 24/24
ORDERING INFORMATION
Type
Package
Order Designation
iC-TW3
Evaluation board
32 pin QFN, 5 mm x 5 mm
iC-TW3 QFN32
TW3D EVAL
For technical support, information about prices and terms of delivery please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel.: +49 (61 35) 92 92-0
Fax: +49 (61 35) 92 92-192
Web: http://www.ichaus.com
E-Mail: [email protected]
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