iC-HO
GENERAL PURPOSE SENSOR INTERFACE
iC-HO suits for various applications: mass flow metering, gas
sensing and pressure sensing. Besides the IC only a few exter-
nal components are required: a cost effective microcontroller
and/or an EEPROM, and the sensor itself. iC-HO is completely
controllable and monitorable by the microcontroller via SPI.
Alternatively, stand-alone applications can boot from the CRC-
secured external SPI EEPROM.
Instrumentation PGA inputs allow gain and offset calibration,
and temperature stabilization. An integrated look-up table (LUT)
featuring 9 breakpoints can be used to correct nonlinear sensor
characterstics directly within the sensor interface IC.
A digital PI-controller is available to drive a wide range of
MEMS heater resistors with up to 115 mW in an absolute or
relative temperature range from -25 °C to + 660 °C. A fixed set
point or sequence controller mode can be selected.
Matching constant current sources are available to bias up to
three sensor resistors. The analog ratiometric differential output
signal is implemented with a 10-bit D/A converter.
Applications
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Flow Sensors
Pressure Sensors
Gas Sensors
Features
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•
•
•
•
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•
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Ultra-low
offset and low-noise PGA inputs
11-bit analog to digital conversion
Signal offset correction
Configurable temperature drift compensation
Linearization of sensor characteristic by look-up table
Measurement data output digital and analog (10-bit D/A)
Differential output of ratiometric voltage
Adjustable PI
heater control
Signal and system monitoring functions
Fault indication at open-drain
error output
Sensor resistor bias by adjustable current sources
Integrated 8-bit temperature sensing
SPI-master (for EEPROM) and SPI-slave interfaces for
device configuration and controller operation
5 V supply voltage
Operating temperature range of -20 °C to 105 °C
VAMP
VDD
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VDDA
VDDAS
SUS3
SUS2
SUS1
GNDAS
VREF
Configurable Sensor
Supply
Bandgap
Reference
Osillator
Error Monitor
NERR
PGA Input
SPIN
SNIN
+
A
D
Look Up Table
Analog Output
-
A
D
+
OUTP
OUTN
-
iC-HO
Heater Control
RBP
RBN
NCS_S
I/O Interface
A
D
PI
RAM
Main Control
Chip Temp.
SCK_S
MOSI_S
MISO_S
SPI Slave
HEATP
HEATN
A
D
D
A
Power-Down
Reset
NCS_M
IHEAT
GNDHS
EEPROM
Interface
SPI Master
SCK_M
MOSI_M
MISO_M
GNDA
GND
Am Kuemmerling 18 • D-55294 Bodenheim, Germany
Tel. +49 61 35 / 92 92-30 0 • Fax +49 61 35 / 92 92-19 2 • http://www.ichaus.com
iC-HO
GENERAL PURPOSE SENSOR INTERFACE
Applications
FLOW
SENSOR
VDDAS
SUS3
SUS2
SUS1
GNDAS
Configurable Sensor
Supply
GAS
SENSOR
VDDA
VDDAS
SUS3
SUS2
Configurable Sensor
Supply
PRESSURE
SENSOR
VDDAS
SUS3
SUS2
Configurable Sensor
Supply
SUS1
SUS1
GNDAS
GNDAS
PGA Input
SPIN
+
SNIN
Rs
A
D
PGA Input
SPIN
+
SNIN
A
D
PGA Input
SPIN
+
SNIN
A
D
-
-
-
Rup
Rdown
iC-HO
Rb
Heater Control
RBP
RBN
iC-HO
Heater Control
RBP
iC-HO
Rb
Heater Control
RBP
RBN
A
D
PI
Rb
RBN
A
D
A
D
PI
PI
HEATP
HEATN
HEATP
HEATN
HEATP
A
D
D
A
Rh
HEATN
A
D
D
A
D
D
A
Rh
IHEAT
GNDHS
IHEAT
GNDHS
IHEAT
GNDHS
A
Pin Functions
No.
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
Name
VDDAS
IHEAT
SPIN
SNIN
GNDAS
GNDHS
HEATN
HEATP
RBN
n.c.
RBP
n.c.
VDD
GND
NCS_M
SCK_M
MOSI_M
MISO_M
NCS_S
SCK_S
MOSI_S
MISO_S
NERR
OUTP
OUTN
GNDA
VDDA
VAMP
VREF
SUS3
SUS2
SUS1
TP
Function
Switched Sensor Supply Output
Heater DAC Output Current
Positive Sensor Input
Negative Sensor Input
Switched Sensor Ground
Switched Heater Ground
Heater R ADC Negative Port
Heater R ADC Positive Port
Bulk R ADC Negative Port
not connected
Bulk R ADC Positive Port
not connected
+5 V Digital Supply Voltage
Digital Ground
SPI Master (EEPROM), chip select
SPI Master (EEPROM), clock line
SPI Master (EEPROM), data output
SPI Master (EEPROM), data input
SPI Slave, chip select
SPI Slave, clock line
SPI Slave, data input
SPI Slave, data output
Error Message Output (low active)
Positive Analog Output
Negative Analog Output
Analog Ground
+5 V Analog Supply Voltage
ADC Voltage Range Reference I/O
ADC Center Voltage Reference I/O
Sensor Bias Output 3
Sensor Bias Output 2
Sensor Bias Output 1
Thermal Pad
Key Specifications
General
Supply Voltage
+5 V +/- 10 %
Operating Temperature Range -25 °C to 105 °C
Heater Driver
Heater Driver Current
Heater Voltage
Resistor Temp. Coefficient
Differential Analog Output
Differential Output Voltage
DAC Resolution
Linearization Look-Up Table
Number of Breakpoints
Breakpoint Resolution
Correction Value
SPI Interfaces
SPI Slave
SPI Master
to master MCU (host)
to slave EEPROM
9
8 bit (address)
11 bit
+/- 80 % of VDDA
10 bit
up to 35 mA
up to 3300 mV max.
1953 … 3902 ppm/°K
PI Control Sampling Frequency 10 kHz
Pin Configuration QFN28 5x5 mm²
32 31 30 29 28 27 26 25
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
24
23
22
21
20
19
18
17
This preliminary information is not tantamount to a guarantee of device characteristics. All rights to technical changes reserved.
Am Kuemmerling 18 • D-55294 Bodenheim, Germany
Tel. +49 61 35 / 92 92-30 0 • Fax +49 61 35 / 92 92-19 2 • http://www.ichaus.com
Rev. 1.0