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 external 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 CRCsecured external SPI EEPROM. Applications • • • Features • • • • • • • • • • • • • • • 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. VDDA VDDAS VREF Configurable Sensor Supply SUS3 Flow Sensors Pressure Sensors Gas Sensors 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 VDD VAMP Bandgap Error Monitor NERR Reference Osillator SUS2 SUS1 GNDAS PGA Input SPIN + SNIN Look Up Table A - Analog Output A D OUTP + D OUTN - iC-HO NCS_S Heater Control RBP RBN A PI D MOSI_S MISO_S A D D IHEAT GNDHS SPI Slave SCK_S Chip Temp. HEATP HEATN I/O Interface RAM Main Control Power-Down Reset NCS_M EEPROM Interface SPI Master A GNDA SCK_M MOSI_M MISO_M 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 GAS SENSOR Configurable Sensor Supply SUS3 VDDA VDDAS SUS2 PRESSURE SENSOR Configurable Sensor Supply SUS3 VDDAS Configurable Sensor Supply SUS3 SUS2 SUS2 SUS1 SUS1 GNDAS GNDAS SUS1 GNDAS PGA Input SPIN + Rs A + iC-HO RBP PI Rb HEATP HEATN RBN A iC-HO Rb RBP RBN PI D HEATN D GNDHS A HEATN A A D D IHEAT D IHEAT A GNDHS A Rh Pin Functions GNDHS PI D HEATP D D IHEAT D Heater Control HEATP A A - Heater Control RBP A D Rh + D iC-HO Heater Control RBN SPIN SNIN - D Rdown Rb PGA Input A SNIN - Rup PGA Input SPIN SNIN A Key Specifications General No. Name Function 1 VDDAS Switched Sensor Supply Output Supply Voltage 2 IHEAT Heater DAC Output Current Operating Temperature Range -25 °C to 105 °C 3 SPIN Positive Sensor Input 4 SNIN Negative Sensor Input 5 GNDAS Switched Sensor Ground Heater Driver Current up to 35 mA up to 3300 mV max. +5 V +/- 10 % Heater Driver 6 GNDHS Switched Heater Ground Heater Voltage 7 HEATN Heater R ADC Negative Port PI Control Sampling Frequency 10 kHz 8 HEATP Heater R ADC Positive Port Resistor Temp. Coefficient 9 RBN Bulk R ADC Negative Port 10 n.c. not connected 11 RBP Bulk R ADC Positive Port 12 n.c. not connected 13 VDD +5 V Digital Supply Voltage 14 GND Digital Ground 15 NCS_M SPI Master (EEPROM), chip select 16 SCK_M SPI Master (EEPROM), clock line 17 MOSI_M SPI Master (EEPROM), data output 18 MISO_M SPI Master (EEPROM), data input 19 NCS_S SPI Slave, chip select 20 SCK_S SPI Slave, clock line 21 MOSI_S SPI Slave, data input 22 MISO_S SPI Slave, data output 23 NERR Error Message Output (low active) 24 OUTP Positive Analog Output 25 OUTN Negative Analog Output 26 GNDA Analog Ground 27 VDDA +5 V Analog Supply Voltage 28 VAMP ADC Voltage Range Reference I/O 29 VREF ADC Center Voltage Reference I/O 30 SUS3 Sensor Bias Output 3 31 SUS2 Sensor Bias Output 2 32 SUS1 Sensor Bias Output 1 TP Thermal Pad 1953 … 3902 ppm/°K Differential Analog Output Differential Output Voltage +/- 80 % of VDDA DAC Resolution 10 bit Linearization Look-Up Table Number of Breakpoints 9 Breakpoint Resolution 8 bit (address) Correction Value 11 bit SPI Interfaces SPI Slave to master MCU (host) SPI Master to slave EEPROM Pin Configuration QFN28 5x5 mm² 32 31 30 29 28 27 26 25 1 2 3 4 5 6 7 8 24 23 22 21 20 19 18 17 9 10 11 12 13 14 15 16 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