ADC128D818

ADC128D818 12-Bit, 8-Channel, ADC System Monitor with Temperature Sensor, Internal/ External Reference, and I2C Interface April 1, 2010 ADC128D818 12-Bit, 8-Channel, ADC System Monitor with Temperature Sensor, Internal/External Reference, and I2C Interface 1.0 General Description The ADC128D818 I2C™ system monitor is designed for maximum flexibility. The system monitor can be configured for single-ended and/or pseudo-differential inputs. An on-board temperature sensor, combined with WATCHDOG window comparators, and an interrupt output pin, INT, allow easy monitoring and out-of-range alarms for every channel. A high performance internal reference is also available to provide for a complete solution in the most difficult operating conditions. The ADC128D818’s 12-bit delta-sigma ADC supports Standard Mode (Sm, 100 kbits/s) and Fast Mode (Fm, 400kbits/s) I2C interfaces. The ADC128D818 includes a sequencer to control channel conversions and stores all converted results in independent registers for easy microprocessor retrieval. Unused channels can be shut down independently to conserve power. The ADC can use either an internal 2.56V reference or a variable external reference. An analog filter is included on the I2C digital control lines to provide improved noise immunity. The device also includes a TIMEOUT reset function on SDA and SCL to prevent I2C bus lock-up. The ADC128D818 operates from +3.0 to +5.5V power supply voltage range, –40°C to 125°C temperature range, and the device is available in a 16-pin TSSOP package. 3.0 Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 12-bit Resolution Delta-Sigma ADC Local Temperature Sensing Configurable Single-Ended and/or Pseudo-Diff. Inputs +2.56V Internal VREF or Variable External VREF WATCHDOG Window Comparators with Status and Mask Registers of All Measured Values Independent Registers for Storing Measured Values INT Output Notifies Microprocessor of Error Event I2C Serial Bus Interface Compatibility 9 Selectable Addresses TIMEOUT Reset Function to Prevent I2C Bus Lock-Up Individual Channel Shutdown to Limit Power Consumption Deep Shutdown Mode to Minimize Power Consumption TSSOP 16-Lead Package 4.0 Key Specifications ■ ADC Resolution ■ Supply Voltage Range ■ Total Unadjusted Error ■ Integral Non-Linearity ■ Differential Non-Linearity ■ Operating Current ■ Deep Shutdown Current ■ Temperature Resolution ■ Temp. Accuracy (–40°C to 125°C) ■ Temp. Accuracy (–25°C to 100°C) 12-bit +3.0V to +5.5V –0.45/+0.2% ±1LSb ±1LSb 0.56 mA 10 µA 0.5°C/LSb ± 3°C ± 2°C 2.0 Applications ■ ■ ■ ■ ■ ■ Communications Infrastructure Thermal / Hardware Server Monitors System Monitors Industrial and Medical Systems Electronic Test Equipment and Instrumentation Power Supply Monitoring / Supervision 5.0 Typical Application 30096301 I2C® is a registered trademark of the Philips Corporation. © 2010 National Semiconductor Corporation 300963 www.national.com ADC128D818 6.0 Ordering Information Temperature Range –40°C ≤ TA ≤ +125°C NS Package Number Specified Power Supply Voltage 6.0 Connection Diagram Order Number ADC128D818CIMT1 ADC128D818CIMTX 2 Device Marking ADC128D81 8CIMT MO-153 +3.0V to +5.5V Note: 1-Rail 2-Tape transport media, 61 parts per rail and reel transport media, 2500 parts per reel 30096302 7.0 Pin Descriptions Pin Number Pin Name(s) ESD Structure Type Description ADC external reference. ADC128D818 allows two choices for sourcing VREF: internal or external. If the +2.56V internal VREF is used, leave this pin unconnected. If the external VREF is used, source this pin with a voltage between +1.25V and V+. At Power-On-Reset (POR), the default setting is the internal VREF. Bypass with the parallel combination of 1 μF (electrolytic or tantalum) and 0.1 μF (ceramic) capacitors. Serial Bus Bidirectional Data. NMOS open-drain output. Requires external pull-up resistor to function properly. 1 VREF Analog Input 2 SDA Digital I/O 3 4 SCL GND Digital Input GROUND Serial Bus Clock. Requires external pull-up resistor to function properly. Internally connected to all of the circuitry. +3.0V to +5.5V power. Bypass with the parallel combination of 1 μF (electrolytic or tantalum) and 0.1 μF (ceramic) bypass capacitors. Interrupt Request. Active Low, NMOS, open-drain. Requires external pull-up resistor to function properly. 5 V+ POWER 6 INT Digital Output 7-8 A0 - A1 Tri-Level Inputs Tri-Level Serial Address pins that allow 9 devices on a single I2C bus. 9 - 16 IN7 - IN0 Analog Inputs The full scale range will be controlled by the internal or external VREF. These inputs can be assigned as singleended and/or pseudo-differential inputs. www.national.com 2 ADC128D818 8.0 Block Diagram 30096303 9.0 Product Highlights The maximum number of channels that can be enabled for each input mode are shown in the table below. Unusued channels may be disabled through software. TABLE 1. Input Modes Modes of Operation 0 1 2 3 Single-Ended Inputs Pseudo-Differential Inputs 4 2 Internal Temperature Cycle Time with Maximum Measurement Number of Channels Enabled (ms - typ). 1 1 1 88 96 52 76 7 8 4 3 www.national.com ADC128D818 TABLE 2. Conversion Modes Conversion Modes Continuous Low Power Description Enabled channels are measured continuously. Enabled channels are measured, then the device is automatically placed into shutdown mode. This cycle is repeated every 728 ms. When One-Shot Register (address 09h) is programmed while the device is in shutdown or deep shutdown mode, the device will initiate a single conversion and comparison cycle, after which the device returns to the respective mode it was in. One-Shot www.national.com 4 ADC128D818 10.0 Absolute Maximum Ratings (Note 1, Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (V+): Voltage on SCL, SDA, A0, A1, INT: Voltage on IN0-IN7, VREF: Input Current at Any Pin (Note 3): Package Input Current (Note 3): Maximum Junction Temperature (TJMAX): (Note 4) ESD Susceptibility (Note 6) Human Body Model: Machine Model: 6.0V –0.3V to 6.0V –0.3V to (V+ + 0.3)V and ≤ 6.0V ±5 mA ±30 mA 150°C 3,000V 300V Charged Device Model: 1,000V Storage Temperature –65°C to +150°C For soldering specifications, see product folder at www.national.com and www.national.com/ms/MS/MS-SOLDERING.pdf 11.0 Operating Ratings Supply Voltage (V+): Voltage on SCL, SDA, A0, A1, INT: Voltage on IN0-IN7, VREF: Temperature Range for Electrical Characteristics: Operating Temperature Range: Junction to Ambient Thermal Resistance (θJA): (Note 5) (Note 1, Note 2) 3.0V to 5.5V –0.05V to 5.5V –0.05V to (V+ + 0.05)V and ≤ 5.5V TMIN = –40°C TMAX = 125°C –40°C ≤ TA ≤ +125°C 130°C/W 12.0 DC Electrical Characteristics The following specifications apply for +3.0 VDC ≤ V+ ≤ +5.5 VDC , External VREF = +2.56V, unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C (Note 7). Symbol Parameter Conditions Min (Note 9) 3.0 1.25 Typical (Note 8) 3.3 or 5.0 2.56 2.56 23 Interface Inactive, V+ = 5.5V, Mode 2 I+ Supply Current (see the "Power Management" section for more information). Interface Inactive, V+ = 3.6V, Mode 2 Shutdown Mode, V+ = 5.5V Shutdown Mode, V+ = 3.6V Deep Shutdown Mode (Note 10). TEMPERATURE-to-DIGITAL CONVERTER CHARACTERISTICS Temperature Error Resolution ANALOG-to-DIGITAL CONVERTER CHARACTERISTICS n Resolution 12-bit with full-scale at VREF = 2.56V. External VREF = 1.25V, PseudoDifferential, V+ = 3.0V to 3.3V. (Note 10) INL Integral Non-Linearity External VREF = 2.56V, PseudoDifferential External VREF = 5.0V, PseudoDifferential, V+ = 5.0V to 5.5V. DNL Differential Non-Linearity (Note 13) –1 0.625 0.36 1 mV LSb –40°C ≤ TA ≤ +125°C –25°C ≤ TA ≤ +100°C 0.5 ±3 ±2 °C °C °C 0.74 0.56 0.65 0.48 10 Max (Note 9) 5.5 V+ Units POWER SUPPLY CHARACTERISTICS V+ VREF Supply Voltage External Reference Voltage Internal Reference Voltage V V V ppm/°C mA mA mA mA µA –2 1.58 4 LSb -1 ±0.25 1 LSb 5 www.national.com ADC128D818 Symbol Parameter Conditions Internal VREF, Single-Ended, V+ = 3.0V to 3.6V. Internal VREF, Single-Ended, V+ = 4.5V to 5.5V (Note 12). Internal VREF, Pseudo-Differential, V+ = 3.0V to 3.6V or V+ = 4.5V to 5.5V (Note 12). Min (Note 9) Typical (Note 8) Max (Note 9) Units –0.5 0.5 % of FS –0.3 0.5 % of FS TUE Total Unadjusted Error (Note 11) External VREF = 1.25V, Single-Ended, V+ = 3.0V to 3.6V. External VREF = 2.56V, Single-Ended, V+ = 3.0V to 5.5V. External VREF = 1.25V, PseudoDifferential, V+ = 3.0V to 3.6V. External VREF = 2.56V, PseudoDifferential, V+ = 3.0V to 5.5V. Internal VREF, V+ = 3.0V to 3.6V. Internal VREF, V+ = 4.5V to 5.5V (Note 12) –0.6 0.1 % of FS –0.45 0.2 % of FS –0.25 0.45 % of FS GE Gain Error External VREF = 1.25V or 2.56V, V+ = 3.0V to 3.6V. External VREF = 2.56V or 5.0V, V+ = 4.5V to 5.5V. Internal VREF, PseudoDifferential, V+ = 4.5V to 5.5V (Note 12). External VREF = 1.25V or 2.56V, Single-Ended, V+ = 3.0V to 3.6V. –0.45 0.2 % of FS –0.15 0.2 % of FS OE Offset Error External VREF = 2.56V or 5.0V, SingleEnded, V+ = 4.5V to 5.5V External VREF = 1.25V or 2.56V, Pseudo-Differential, V+ = 3.0V to 3.6V. External VREF = 2.56V or 5.0V, Pseudo-Differential, V+ = 4.5V to 5.5V –0.5 0.1 % of FS –0.2 0.15 % of FS Continuous Conversion Mode tC Low Power Conversion Mode Each Enabled Voltage Channel Internal Temperature Sensor Enabled Voltage Channel(s) and Internal Temperature Sensor 12 3.6 728 ms ms ms MULTIPLEXER / ADC INPUT CHARACTERISTICS RON ION IOFF On Resistance Input Current (On Channel Leakage Current) Off Channel Leakage Current IOUT = +5.0 mA at V+ = +4.5V, IOUT = +3.0 mA at V+ = +3.0V IOUT = +3.0 mA at V+ = +4.5V, VOUT = V+ 0.005 2 ±0.005 ±0.005 10 kΩ μA μA DIGITAL OUTPUTS: INT VOUT(0) Logical “0” Output Voltage 0.4 V OPEN DRAIN SERIAL BUS OUTPUT: SDA VOUT(0) IOH Logical “0” Output Voltage High Level Output Current 0.4 1 V μA www.national.com 6 ADC128D818 Symbol Parameter Conditions Min (Note 9) 0.90 x V+ 0.43 x V+ GND 0.05 0.7 × V+ GND 0.05 Typical (Note 8) Max (Note 9) 5.5 0.57 x V+ 0.10 x V+ Units DIGITAL INPUTS: A0 and A1 VIN(1) VIM VIN(0) Logical “1” Input Voltage Logical Middle Input Voltage Logical “0” Input Voltage V V SERIAL BUS INPUTS: SCL and SDA VIN(1) VIN(0) VHYST Logical “1” Input Voltage Logical “0” Input Voltage Hysteresis Voltage V+ = +3.3V V+ = +5.5V VIN = V+ VIN = 0 VDC −1 5.5 0.3 × V+ 0.67 1.45 – 0.005 0.005 20 1 v V V V µA µA pF ALL DIGITAL INPUTS: SCL, SDA, A0, A1 IIN(1) IIN(0) CIN Logical “1” Input Current Logical “0” Input Current Digital Input Capacitance 7 www.national.com ADC128D818 13.0 AC Electrical Characteristics The following specifications apply for +3.0 VDC ≤ V+ ≤ +5.5 VDC , unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. Symbol Parameter Conditions Min (Note 9) 2.5 100 0 100 100 25 35 Typical (Note 8) Max (Note 9) 100 Units SERIAL BUS TIMING CHARACTERISTICS t1 t2 t3 t4 t5 tTIMEOUT SCL (Clock) Period Data In Setup Time to SCL High Data Out Stable After SCL Low SDA Low Setup Time to SCL Low (start) SDA High Hold Time After SCL High (stop) SCL or SDA time low for I2C bus reset µs ns ns ns ns ms 30096326 FIGURE 1. Serial Bus Timing Diagram Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: All voltages are measured with respect to GND, unless otherwise specified. Note 3: If the input voltage at any pin exceeds the power supply ( that is, VIN < GND or VIN > V +) but is less than the absolute maximum ratings, then the current at that pin should be limited to 5mA. The 30 mA maximum package input current rating limits the number of pins that can safely exceed the power supply with an input current of 5mA to six pins. Parasitic components and/or ESD protection circuitry are shown in the Pin Descriptions table. Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA and the ambient temperature, TA. The maximum allowable power dissipation at any temperature is PD = (TJMAX − T A) / θJA. Note 5: For the given θJA, the device is on a 2-layer printed circuit board with 1 oz. copper foil and no airflow. Note 6: Human body model (HBM) is a charged 100pF capacitor discharged into a 1.5kΩ resistor. Machine model (MM) is a charged 200pF capacitor discharged directly into each pin. Charged Device Model (CDM) simulates a pin slowly acquiring charge (such as from a device sliding down the feeder in an automated assembler) then rapidly being discharged. Note 7: Each input and output is protected by an ESD structure to GND, as shown in the Pin Descriptions table. Input voltage magnitude up to 0.3V above V+ or 0.3V below GND will not damage the ADC128D818. There are diodes that exist between some inputs and the power supply rails. Errors in the ADC conversion can occur if these diodes are forward biased by more than 50mV. As an example, if V+ is 4.50 VDC, INx (where 0 ≤ x ≤ 7) must be ≤ 4.55 VDC to ensure accurate conversions. Note 8: Typicals are at TJ = TA = 25°C and represent most likely parametric norm. Note 9: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 10: Limit is guaranteed by characterization. Note 11: TUE (Total Unadjusted Error) includes Offset, Gain and Linearity errors of the ADC. Note 12: The range is up to 7/8 of full scale. Note 13: Limit is guaranteed by design. Note 14: Timing specifications are tested at the Serial Bus Input logic levels: VIN(0) = 0.3 × V+ for a falling edge and VIN(1) = 0.7 × V+ for a rising edge if the SCL and SDA edge rates are similar. —— www.national.com 8 ADC128D818 The following typical performance plots apply for the internal VREF = 2.56V, V+ = 3.3V, Pseudo-Differential connection, unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. (Note 14) TUE vs. Code TUE vs. Code (External VREF = 1.25V) 14.0 Typical Performance Characteristics 30096346 30096347 TUE vs. Code (External VREF = 2.56V) TUE vs. Code (External VREF = 5V, V+ = 5V) 30096348 30096349 INL vs. Code (External VREF = 1.25V for 1 Unit) INL vs. Code (External VREF = 1.25V for 28 Units) 30096350 30096371 9 www.national.com ADC128D818 INL vs. Code (External VREF = 2.56V for 1 Unit) INL vs. Code (External VREF = 2.56V for 28 Units) 30096351 30096372 INL vs. Code (External VREF = 5V, V+ = 5V for 1 Unit) INL vs. Code (External VREF = 5V, V+ = 5V for 28 Units) 30096352 30096373 DNL vs. Code (External VREF = 2.56V for 1 Unit) DNL vs. Code (External VREF = 2.56V for 28 Units) 30096354 30096355 www.national.com 10 ADC128D818 Offset Error vs. V+ Offset Error vs. Temperature 30096356 30096358 Gain Error vs. V+ Gain Error vs. Temperature 30096360 30096362 I+ vs. Temperature I+ vs. V+ Typical 30096364 30096365 11 www.national.com ADC128D818 I+ vs. V+ for Voltage Conversion I+ vs. V+ for Temperature Conversion 30096367 30096366 I+ vs. V+ in Shutdown Mode I+ vs. V+ in Deep Shutdown Mode 30096368 30096369 www.national.com 12 ADC128D818 15.0 Functional Description 15.1 GENERAL DESCRIPTION The ADC128D818 provides 8 analog inputs, a temperature sensor, a delta-sigma ADC, an external or internal VREF option, and WATCHDOG registers on a single chip. An I2C Serial Bus interface is also provided. The ADC128D818 can perform voltage and temperature monitoring for a variety of systems. The ADC128D818 continuously converts the voltage input to 12-bit resolution with an internal VREF of 0.625mV LSb (Least Significant bit) weighting, yielding input range of 0V to 2.56V. There is also an external VREF option that ranges from 1.25V to V+. The analog inputs are intended to be connected to several power supplies present in a variety of systems. Eight inputs can be configured for single-ended and/or pseudo-differential channels. Temperature can be converted to a 9-bit two's complement word with resolutions of 0.5°C per LSb. The ADC128D818 provides a number of internal registers. These registers are summarized in the "ADC128D818 Internal Registers" section. The ADC128D818 supports Standard Mode (Sm, 100kbits/s) and Fast Mode (Fm, 400kbits/s) I2C interface modes of operation. ADC128D818 includes an analog filter on the I2C digital control lines that allows improved noise immunity. The device also supports TIMEOUT reset function on SDA and SCL to prevent I2C bus lock-up. Two tri-level address pins allow up to 9 devices on a single I2C bus. At start-up, ADC128D818 cycles through each measurement in sequence and continuously loops through the sequence based on the Conversion Rate Register (address 07h) setting. Each measured value is compared to values stored in the Limit Registers (addresses 2Ah - 39h). When the measured value violates the programmed limit, the ADC128D818 will set a corresponding interrupt bit in the Interrupt Status Registers (address 01h). An interrupt output pin, INT, is also available and fully programmable. 15.2 SUPPLY VOLTAGE (V+) The ADC128D818 operates with a supply voltage, V+, that has a range between +3.0V to +5.5V. Care must be taken to bypass this pin with a parallel combination of 1 µF (electrolytic or tantalum) capacitor and 0.1 µF (ceramic) bypass capacitor. 15.3 VOLTAGE REFERENCES (VREF) The reference voltage (VREF) sets the analog input range. The ADC128D818 has two options for setting VREF. The first option is to use the internal VREF, which is equal to 2.56V. The second option is to source VREF externally via pin 1 of ADC128D818. In this case, the external VREF will operate in the range of 1.25V to V+. The default VREF selection is the internal VREF. If the external VREF is preferred, use the Advanced Configuration Register (address 0Bh) to change this setting. VREF source must have a low output impedance and needs to be bypassed with a minimum capacitor value of 0.1 µF. A larger capacitor value of 1 µF placed in parallel with the 0.1 µF is preferred. VREF of the ADC128D818, like all ADC converters, does not reject noise or voltage variations. Keep this in mind if VREF is derived from the power supply. Any noise and/or ripple from the supply that is not rejected by the external reference circuitry will appear in the digital results. The use of a reference source is recommended. The LM4040 and LM4050 shunt reference families as well as the LM4120 and LM4140 series reference families are excellent choices for a reference source. 15.4 ANALOG INPUTS (IN0 - IN7) The ADC128D818 allows up to 8 single-ended inputs or 4 pseudo-differential inputs as selected by the modes of operation. The input types are described in the next subsections. 15.4.1 Single-Ended Input ADC128D818 allows a maximum of 8 single-ended inputs, where the source's voltage is connected to INx (0 ≤ x ≤ 7). The source’s ground should be connected to ADC128D818’s GND pin. In theory, INx can be of any value between 0V and (VREF-3LSb/2), where LSb = VREF/212. To use the device single-endedly, refer to the "Modes of Operation" section and to bits [2:1] of the Advanced Configuration Register (address 0Bh). Figure 2 shows the appropriate configuration for a single-ended connection. 30096331 FIGURE 2. Single-Ended Configuration 15.4.2 Pseudo-Differential Input Pseudo-differential mode is defined as the positive input voltage applied differentially to the ADC128D818, as shown in Figure 3. The input that is digitized is (ΔVIN = IN+ - IN-), where (IN+ - IN-) is (IN0-IN1), (IN3-IN2), (IN4-IN5), or (IN7-IN6). Be aware of this input configuration because the order is swapped. In theory, ΔVIN can be of any value between 0V and (VREF-3LSb/2),where LSb = VREF/212. By using this pseudo-differential input, small signals common to both inputs are rejected. Thus, operation with a pseudodifferential input signal will provide better performance than with a single-ended input. Refer to the "Modes of Operation" section for more information. 30096332 FIGURE 3. Pseudo-Differential Configuration 13 www.national.com ADC128D818 15.4.3 Modes of Operation ADC128D818 allows 4 modes of operation, as summarized in the following table. Set the desired mode of operation using the Advanced Configuration Register (address 0Bh, bits [2:1]). TABLE 3. Modes of Operation Ch. 1 2 3 4 5 6 7 8 Local Temp * nc = No Connect Mode 0 IN0 IN1 IN2 IN3 IN4 IN5 IN6 nc* Yes Mode 1 IN0 IN1 IN2 IN3 IN4 IN5 IN6 IN7 No Mode 2 IN0 (+) & IN1 (-) IN3 (+) & IN2 (-) IN4 (+) & IN5 (-) IN7 (+) & IN6 (-) Mode 3 IN0 IN1 IN2 IN3 IN4 (+) & IN5 (-) IN7 (+) & IN6 (-) Yes Yes 15.5 DIGITAL OUTPUT (DOUT) The digital output code for a 12-bit ADC can be calculated as: For the above equation, ΔVIN = INx - GND, where 0 ≤ x ≤ 7, for the single-ended configuration, and ΔVIN = (IN+ - IN-) for DOUT = [ΔVIN / VREF] x 212 the pseudo-differential configuration. In theory, ΔVIN can be of any value between 0V and (VREF-3LSb/2). Any ΔVIN value outside of this range will produce a digital output code of 0 or 4095. Figure 4 shows a theoretical plot of DOUT vs. ΔVIN and some sample DOUT calculation using the equation above. 30096333 FIGURE 4. DOUT vs ΔVIN for a 12-bit ADC assuming VREF = 2.56V. www.national.com 14 ADC128D818 15.6 POWER MANAGEMENT To understand the average supply current (I+), the conversion rates must be introduced. ADC128D818 has three types of conversion rates: Continuous Conversion Mode, Low Power Conversion Mode, and One Shot Mode. In the Low Power Conversion Mode, the device converts all of the enabled channels then enters shutdown mode; this process takes approximately 728 ms to complete. (More information on the conversion rate will be discussed in the "Conversion Rate Register (address 07h)" and "One-Shot Register (address 09h)" sections). Each type of conversion produces a different average supply current. The supply current for a voltage conversion will be referred to as I+_VOLTAGE, a temperature conversion as I+_TEMP, and the shutdown mode as I+_SHUTDOWN. These values can be obtained from Typical Performance Characteristics plots. In general, I+ is the average supply current while ADC128D818 is operating in the Low Power Conversion Mode with all of the available channels enabled. Its plot can be seen in the "Typical Performance Characteristic" section and its equation is shown below. 30096345 FIGURE 5. I+ Equation Where "a" is the number of local temperature available, and "b" is the number of ENABLED voltage channel. Each mode of operation has a different "a" and "b" values. The following table shows the value for "a" and the maximum value for "b" for each mode. TABLE 4. "a" and "b" Values a Mode 0 Mode 1 Mode 2 Mode 3 1 0 1 1 b (Max) 7 8 4 6 15 www.national.com ADC128D818 15.7 INTERFACE The Serial Bus control lines include the SDA (serial data), SCL (serial clock), and A0-A1 (Serial Bus Address) pins. The ADC128D818 can only operate as a slave. The SCL line only controls the serial interface, and all of other clock functions within ADC128D818 are done with a separate asynchronous internal clock. When the Serial Bus Interface is used, a write will always consists of the ADC128D818 Serial Bus Address byte, followed by the Register Address byte, then the Data byte. Figure 6 and Figure 7 are two examples showing how to write to the ADC128D818. There are two cases for a read: 1. If the Register Address is known to be at the desired address, simply read the ADC128D818 with the Serial Bus Address byte, followed by the Data byte read from the ADC128D818. Examples of this type of read can be seen in Figure 8 and Figure 9. 2. If the Register Address value is unknown, write to the ADC128D818 with the Serial Bus Address byte, followed by the desired Register Address byte. Then restart the Serial Communication with a Read consisting of the Serial Bus Address byte, followed by the Data byte read from the ADC128D818. See Figure 10 and Figure 11 for examples of this type of read. The Serial Bus Address can be found in the next section, and the Register Address can be found in the "Register Map" section. For more information on the I2C Interface, refer to NXP's "I2C-Bus Specification and User Manual", rev. 03. 15.7.1 Serial Bus Address There are nine different configurations for the ADC128D818 Serial Bus Address, thus nine devices are allowed on a single 15.7.3 Example Writes and Reads I2C bus. Examples to set each address bit low, high, or to midscale can be found in the "Example Applications" section. The Serial Bus Address can be set as follows: TABLE 5. Serial Bus Address Table Serial Bus Address Serial Bus [A6][A5][A4]...[A0] Address (hex) 001_1101b 001_1110b 001_1111b 010_1101b 010_1110b 010_1111b 011_0101b 011_0110b 011_0111b 1Dh 1Eh 1Fh 2Dh 2Eh 2Fh 35h 36h 37h A1 LOW LOW LOW MID MID MID HIGH HIGH HIGH A0 LOW MID HIGH LOW MID HIGH LOW MID HIGH 15.7.2 Timeout The ADC128D818 I2C state machine resets to its idle state if either SCL or SDA is held low for longer than 35ms. This feature also ensures that ADC128D818 will automatically release SDA after driving it low continuously for 25-35ms, hence preventing I2C bus lock-up. The TIMEOUT feature should not be used when the device is operating in deep shutdown mode. 30096309 FIGURE 6. Serial Bus Interface Write Example 1 - Internal Address Register Set Only. www.national.com 16 ADC128D818 30096308 FIGURE 7. Serial Bus Interface Write Example 2 - Internal Address Register Set with Data Byte Write. 30096310 FIGURE 8. Serial Bus Interface Read Example 1 - Single Byte Read with Preset Internal Address Register. 30096322 FIGURE 9. Serial Bus Interface Read Example 2 - Double Byte Read with Preset Internal Address Register. 17 www.national.com ADC128D818 30096324 FIGURE 10. Serial Bus Interface Read Example 3 - Single Byte Read with Internal Address Set using a Repeat Start. 30096323 FIGURE 11. Serial Bus Interface Read Example 4 - Double Byte Read with Internal Address Set using a Repeat Start. www.national.com 18 ADC128D818 15.8 USING THE ADC128D818 15.8.1 ADC128D818 Internal Registers TABLE 6. ADC128D818 Internal Registers Read/ Write R/W R R/W R/W R/W W R/W R/W R R R/W R R Register Address (hex) 00h 01h 03h 07h 08h 09h 0Ah 0Bh 0Ch 20h - 27h 2Ah - 39h 3Eh 3Fh Default Value [7:0] 0000_1000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0010 ----0000_0001 0000_1001 Register Format 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 16-bit 8-bit 8-bit 8-bit Register Name Configuration Register Interrupt Status Register Interrupt Mask Register Conversion Rate Register Channel Disable Register One-Shot Register Deep Shutdown Register Advanced Configuration Register Busy Status Register Channel Readings Registers Limit Registers Manufacturer ID Register Revision ID Register Register Description Provides control and configuration Provides status of each WATCHDOG limit or interrupt event Masks the interrupt status from propagating to INT Controls the conversion rate Disables conversion for each voltage or temperature channel Initiates a single conversion of all enabled channels Enables deep shutdown mode Selects internal or external VREF and modes of operation Reflects the ADC128D818 'Busy' and 'Not Ready' statuses Report channels (voltage or temperature) readings Set the limits for the voltage and temperature channels Reports the manufacturer's ID Reports the revision's ID 15.8.2 Quick Start 1. Power on the device, then wait for at least 33ms. 2. Read the Busy Status Register (address 0Ch). If the 'Not Ready' bit = 1, then increase the wait time until 'Not Ready' bit = 0 before proceeding to the next step. 3. Program the Advanced Configuration Register (address 0Bh): a. Choose to use the internal or external VREF (bit 0). b. Choose the mode of operation (bits [2:1]). 4. Program the Conversion Rate Register (address 07h). 5. Choose to enable or disable the channels using the Channel Disable Register (address 08h). 6. Using the Interrupt Mask Register (address 03h), choose to mask or not to mask the interrupt status from propagating to the interrupt output pin, INT. 7. Program the Limit Registers (addresses 2Ah – 39h). 8. Set the ‘START’ bit of the Configuration Register (address 00h, bit 0) to 1. 9. Set the 'INT_Clear' bit (address 00h, bit 3) to 0. If needed, program the 'INT_Enable' bit (address 00h, bit 1) to 1 to enable the INT output. The ADC128D818 then performs a round-robin monitoring of enabled voltage and temperature channels. The sequence of items being monitored corresponds to locations in the Channel Readings Registers (except for the temperature reading). Detailed descriptions of the register map can be found at the end of this datasheet. 15.8.3 Power On Reset (POR) When power is first applied, the ADC128D818 performs a power on reset (POR) on several of its registers, which sets the registers to their default values. These default values are shown in the table above or in the "Register Map" section. Registers whose default values are not shown have power on conditions that are indeterminate. 15.8.4 Configuration Register (address 00h) The Configuration Register (address 00h) provides all control to the ADC128D818. After POR, the 'START' bit (bit 0) is set low and the 'INT_Clear' bit (bit 3) is set high. The Configuration Register has the ability to start and stop the ADC128D818, enable and disable the INT output, and set the registers to their default values. • Bit 0, ‘START’, controls the monitoring loop of the ADC128D818. After POR, set this bit high to start conversion. Setting this bit low stops the ADC128D818 monitoring loop and puts the ADC128D818 in shutdown mode; thus, reducing power consumption. Even though this bit is set low, serial bus communication is possible with any register in the ADC128D818. After an interrupt occurs, the INT pin will not be cleared if the user sets this bit low. • Bit 1, 'INT_Enable', enables the interrupt output pin, INT, when this bit is set high. • Bit 3, 'INT_Clear', clears the interrupt output pin, INT, when this bit is set high. When this bit is set high, the ADC128D818 monitoring function will stop. The content of the Interrupt Status Register (address 01h) will not be affected. • Bit 7, ‘INITIALIZATION’, accomplishes the same function as POR, that is, it initializes some of the registers to their default values. This bit automatically clears after being set high. Setting this bit high, however, does not reset the Channel Readings Registers (addresses 20h - 27h) and 19 www.national.com ADC128D818 the Limit Registers (addresses 2Ah - 39h). These registers will be indeterminate immediately after power on. If the Channel Readings Registers contain valid conversion results and/or the Limit Registers have been previously set, they will not be affected by this bit. 15.8.5 Interrupt Status Register (address 01h) Each bit in this read-only register indicates whether the voltage reading > the voltage high limit or ≤ the voltage low limit, or the temperature reading > the temperature high limit. For example, if "IN0 High Limit" register (address 2Ah) were set to 2V and if IN0 reading (address 20h) were 2.56V, then bit 'IN0 Error' would be 1, indicating that the voltage high limit has been exceeded. 15.8.6 Interrupt Mask Register (address 03h) This register masks the interrupt status from propagating to the interrupt output pin, INT. For example, if bit 'IN0 Mask' = 1, then the interrupt output pin, INT, would not be pulled low even if an error event occurs at IN0. 15.8.7 Conversion Rate Register (address 07h) There are three options for controlling the conversion rate. The first option is called the Low Power Conversion Mode, where the device converts all of the enabled channels then enters shutdown mode. This process takes approximately 728 ms to complete. The second option is the Continuous Conversion Mode, where the device continuously converts the enabled channels, thus never entering shutdown mode. A voltage conversion takes 12.2 ms, and a temperature conversion takes 3.6 ms. For example, if operating in mode 2 and three voltage channels were enabled, then each round-robin monitor would take 40.2 ms (3 x 12.2ms + 3.6ms) to complete. Use the "Channel Disable Register" (address 08h) to disable the desired channel(s). The third option is called the On-Shot mode, which will be discussed in the next subsection. 15.8.8 One-Shot Register (address 09h) The One-Shot register is used to initiate a single conversion and comparison cycle when the device is in shutdown mode or deep shutdown mode, after which the device returns to the respective mode it was in. The obvious advantage of using this mode is lower power consumption because the device is operating in shutdown or deep shutdown mode. This register is not a data register, and it is the write operation that causes the one-shot conversion. The data written to this address is irrelevant and is not stored. A zero will always be read from this register. 15.8.9 Deep Shutdown Register (address 0Ah) The ADC128D818 can be placed in deep shutdown mode, thus reducing more power consumption. The procedures for deep shutdown entrance are: 1. Enter shutdown by setting the ‘START’ bit of the “Configuration Register’ (address 00h, bit 0) to 0. 2. Enter deep shutdown by setting the ‘DEEP SHUTDOWN’ bit (address 0Ah, bit 0) to 1. 3. A one-shot conversion can be triggered by writing any values to register address 09h. Deep Shutdown Exit Procedure: 1. Set the ‘DEEP SHUTDOWN’ bit to 0. 15.8.10 Channel Readings Registers (addresses 20h 27h) The channel conversion readings are available in registers 20h to 27h. Each register is 16-bit wide to accommodate the 12-bit voltage reading or 9-bit temperature reading. Conversions can be read at any time and will provide the result of the last conversion. If a conversion is in progress while a communication is started, that conversion will be completed, and the Channel Reading Registers will not be updated until the communication is complete. www.national.com 20 ADC128D818 15.9 TEMPERATURE MEASUREMENT SYSTEM The ADC128D818 delta-VBE type temperature sensor and delta-sigma ADC perform 9-bit two's-complement conversions of the temperature. This temperature reading can be obtained at the Temperature Reading Register (address 27h). This register is 16-bit wide, and thus, all 9 bits of the temperature reading can be read using a double byte read (Figure 9 or Figure 11). The following figure and the table below it show the theoretical output code (DOUT) vs. temperature and some typical temperature-to-code conversions. 30096320 (Non-Linear Scale for Clarity) FIGURE 12. 9-bit Temperature-to-Digital Transfer Function > Thot, an interrupt occurs. How this interrupt occurs will be explained in the "Temperature Interrupt" section. Each temperature limit is represented by an 8-bit, two's complement word with an LSb (Least Significant bit) equal to 1°C. The table below shows some sample temperatures that can be programmed to the Temperature Limit Registers. In general, use the following equations to calculate the digital code that represents the desired temperature limit: If Temp Limit (°C) >= 0: Digital Code (dec) = Temp Limit(°C) If Temp Limit (°C) < 0: Digital Code (dec) = 28 - |Temp Limit (°C)| Temp Limit +125°C +25°C +1.0°C +0°C −1.0°C −25°C −40°C Digital Code Binary [MSb...LSb] 0111_1101 0001_1001 0000_0001 0000_0000 1111_1111 1110_1111 1101_1000 Decimal 125 25 1 0 255 231 216 Hex 7D 19 01 00 FF E7 D8 Temp +125°C +25°C +0.5°C +0°C −0.5°C −25°C −40°C Digital Output (DOUT) Binary [MSb...LSb] 0 _1111_1010 0_0011_0010 0_0000_0001 0_0000_0000 1_1111_1111 1_1100_1110 1_1011_0000 Decimal 250 50 1 0 511 462 432 Hex 0_FA 0_32 0_01 0_00 1_FF 1_CE 1_B0 In general, the easiest way to calculate the temperature (°C) is to use the following formulas: If DOUT[MSb] = 0: +Temp(°C) = DOUT(dec) / 2 If DOUT[MSb] = 1: –Temp(°C) = [29 - DOUT(dec)] / 2 15.9.1 Temperature Limits One of the ADC128D818 features is monitoring the temperature reading. This monitoring is accomplished by setting a temperature limit to the Temperature High Limit Register (Thot , address 38h) and Temperature Hysteresis Limit Register (Thot_hyst, address 39h). When the temperature reading 21 www.national.com ADC128D818 15.10 INTERRUPT STRUCTURE 30096318 FIGURE 13. Interrupt Structure Figure 13 shows the ADC128D818's Interrupt Structure. Note that the number next to each bit name represents its register address and bit number. For example, 'INT_Clear' (00h[3]) refers to bit 3 of register address 00h. 15.10.1 Interrupt Output (INT) ADC128D818 generates an interrupt as a result of each of its internal WATCHDOG registers on the voltage and temperature channels. In general, INT becomes active when all three scenarios, as depicted in Figure 13, occur: 1. 'INT_Clear' (00h[3]) = 0. 2. 'INT_Enable' (00h[1]) = 1 to enable interrupt output. 3. The voltage reading > the voltage high limit or ≤ the voltage low limit, or the temperature reading > Thot. 15.10.2 Interrupt Clearing Reading the Interrupt Status Register (addresses 01h) will output the contents of the register and clear the register. When the Interrupt Status Register clears, the interrupt output pin, INT, also clears until this register is updated by the roundrobin monitoring loop. Another method to clear the interrupt output pin, INT, is setting 'INT_Clear' bit (address 00h, bit 3) = 1. When this bit is high, the ADC128D818 round-robin monitoring loop will stop. 15.10.3 Temperature Interrupt One of the ADC128D818 features is monitoring the temperature reading. This monitoring is accomplished by setting a temperature limit to the Temperature High Limit Register (Thot , address 38h) and Temperature Hysteresis Limit Register (Thot_hyst, address 39h). These limit registers have an interrupt mode, shown in Figure 14, that operates the the following way: if the temperature reading > Thot, an interrupt will occur and will remain active indefinitely until reset by reading the Interrupt Status Register (address 01h) or cleared by the 'INT_Clear' bit. Once an interrupt event has occurred by crossing Thot, then reset, an interrupt will occur again once the next temperature conversion has completed. The interrupts will continue to occur in this manner until the temperature reading is ≤ Thot_hyst and a read of the Interrupt Status Register has occurred. 30096317 FIGURE 14. Temperature Response Structure (Assuming the interrupt output pin, INT, is reset before the next temperature reading) www.national.com 22 ADC128D818 15.11 EXAMPLE APPLICATIONS 15.11.1 General Voltage Monitoring 30096341 FIGURE 15. Typical Analog Input Application A typical application for ADC128D818 is voltage monitoring. In this application, the inputs would most often be connected to linear power supplies of 2.5V, 3.3V, ±5V and ±12V inputs. These inputs should be attenuated with external resistors to any desired value within the input range. The attenuation is done with resistors R1 and R2 for the positive single-ended voltage, and R3 and R4 for the positive pseudo-differential voltage. A typical single-ended application might select the input voltage divider to provide 1.9V at the analog input of the ADC128D818. This is sufficiently high for good resolution of the voltage, yet leaves headroom for upward excursions from the supply of about 25%. To simplify the process of resistor selection, set the value of R2 first. Select a value for R2 between 10 kOhm and 100 kOhm. This is low enough to avoid errors due to input leakage currents yet high enough to protect both the inputs under and overdrive conditions as well as minimize loading of the source. Finally, calculate R1 to provide a 1.9V input using simple voltage divider derived formula: R1 = [(VS1 - VIN2) / VIN2 ] x R2 Care should be taken to bypass V+ with decoupling 0.1 µF ceramic capacitor and 1 µF tantalum capacitor. If using the external reference option, VREF should be connected to a voltage reference, such as the LM4140, and should also be decoupled to the ground plane by a 0.1 µF ceramic capacitor and a 1 µF tantalum capacitor. For both supplies, the 0.1 µF capacitor should be located as close as possible to the ADC128D818. Since SDA, SCL, and INT are open-drain pins, they should have external pull-up resistors to ensure that the bus is pulled high until a master device or slave device sinks enough current to pull the bus low. A typical pull-up resistor, R, ranges from 1.1 kOhm to 10 kOhm. Refer to NXP's "I2C-Bus Specification and User Manual" for more information on sizing R. Because there are two tri-level address pins (A0 and A1), up to 9 devices can share the same I2C bus. A trick to set these serial addresses utilizes four GPO (general purpose output) pins from the master device as shown in the example diagram. A table showing how to program these GPO pins can be seen below. 23 www.national.com ADC128D818 TABLE 7. Setting Serial Bus Address using GPO A1 LOW LOW LOW MID MID MID HIGH HIGH HIGH Z = high impedance A0 LOW MID HIGH LOW MID HIGH LOW MID HIGH GPO1 GPO2 GPO3 GPO4 Z Z Z HIGH HIGH HIGH HIGH HIGH HIGH LOW LOW LOW LOW LOW LOW Z Z Z Z HIGH HIGH Z HIGH HIGH Z HIGH HIGH LOW LOW Z LOW LOW Z LOW LOW Z 15.11.2 Voltage Monitoring for Power Supplies 30096342 FIGURE 16. Power Supply Application Figure 16 shows a more complete systems application using a DC/DC converter. Such configuration can be used in a power supply application. The point to make with this example diagram is the Serial Bus Address connections. The previous example shows A0 and A1 connected to four GPOs, but this example shows a simpler A0 and A1 connection using two resistor dividers. This connection accomplishes the same goal as the GPO connection, that is, it can set A0 and A1 high, low, or to midscale. For example, to set A0 high, don't populate RB_bottom; to set A0 low, don't populate RB_top; and to set A0 to midscale, leave RB_top and RB_bottom as is and set them equal to each other. A typical RB value ranges from 1 kOhm to 10 kOhm. www.national.com 24 ADC128D818 15.11.3 Temperature Sensors 30096343 FIGURE 17. Temperature Sensor Applications An external temperature sensor can be connected to any of ADC128D818's eight single-ended input for additional temperature sensing. One such temperature sensor can be National's LM94022, a precision analog temperature sensor with selectable gains. The application diagram shows LM94022's gains (GS1 and GS0) both grounded indicating the lowest gain setting. Four possible gains can be set using these GS1 and GS0 pins. According to the LM94022 datasheet, the voltage-to-temperature output plot can be determined using the method of linear approximation as follows: V - V1 = (V2 - V1) / (T2 - T1) x (T - T1) Where V is in mV, T is in °C, V1 and T1 are the coordinates of the lowest temperature, and T2 and V2 are the coordinates of the highest temperature. For example, to determine the equation of a line over a temperature range of 20°C to 50°C, first find V1 and V2 relative to those temperatures, then use the above equation to find the transfer function. V - 925 mV = (760 mV - 925 mV) / (50C - 20°C) x (T - 20°C) V = (-5.50 mV /°C) x T + 1035 mV For more information and explanation of this example, refer to the LM94022 datasheet. 25 www.national.com ADC128D818 15.11.4 Bridge Sensors 30096344 FIGURE 18. Bridge Sensor Application ADC128D818 is perfect for transducer applications such as pressure sensors. These sensors measure pressure of gases or liquids and produce a pressure-equivalent voltage at their outputs. Figure 18 shows a typical connection of a pressure sensor, represented by the bridge sensor. Most pressure sensor has a low sensitivity characteristic, which means its output is typically in the millivolts range. Because of that reason, an op-amp, such as an instrumentation amplifier, can be used for the gain stage. The positive aspect of this configuration is its ratiometric connection. A ratiometric connection is when the ADC’s VREF and GND are connected to the bridge sensor’s voltage references. With a ratiometric configuration, external VREF accuracy can be ignored. 15.11.5 Layout and Grounding Analog inputs will provide best accuracy when referred to the GND pin or a supply with low noise. A separate, lowimpedance ground plane for analog ground, which provides a ground point for the voltage dividers and analog components, will provide best performance but is not mandatory. Analog components such as voltage dividers should be located physically as close as possible to the ADC128D818. www.national.com 26 ADC128D818 15.12 REGISTER MAP 15.12.1 ADC128D818 Internal Registers TABLE 8. ADC128D818 Internal Registers Read/ Write R/W R R/W R/W R/W W R/W R/W R R R/W R R Register Address (hex) 00h 01h 03h 07h 08h 09h 0Ah 0Bh 0Ch 20h - 27h 2Ah - 39h 3Eh 3Fh Default Value [7:0] 0000_1000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0000 0000_0010 ----0000_0001 0000_1001 Register Format 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 8-bit 16-bit 8-bit 8-bit 8-bit Register Name Configuration Register Interrupt Status Register Interrupt Mask Register Conversion Rate Register Channel Disable Register One-Shot Register Deep Shutdown Register Advanced Configuration Register Busy Status Register Channel Readings Registers Limit Registers Manufacturer ID Register Revision ID Register Register Description Provides control and configuration Provides status of each WATCHDOG limit or interrupt event Masks the interrupt status from propagating to INT Controls the conversion rate Disables conversion for each voltage or temperature channel Initiates a single conversion of all enabled channels Enables deep shutdown mode Selects internal or external VREF and modes of operation Reflects ADC128D818 'Busy' and 'Not Ready' statuses Report the channels (voltage or temperature) readings Set the limits for the voltage and temperature channels Reports the manufacturer's ID Reports the revision's ID 15.12.2 Configuration Register — Address 00h Default Value [7:0] = 0000_1000 binary Bit ALL MODES 0 1 2 3 4 5 6 Start INT_Enable Reserved INT_Clear Reserved Reserved Reserved Read/Write Read/Write Read Only Read/Write Read Only Read Only Read Only 1: Restore default values to the following registers: Configuration, Interrupt Status, Interrupt Mask, Conversion Rate, Channel Disable, One-Shot, Deep Shutdown, Advanced Configuration, Busy Status, Channel Readings, Limit, Manufacturer ID, Revision ID. This bit clears itself 1: Clear the interrupt output pin, INT, without affecting the contents of Interrupt Status Registers. When this bit is set high, the device stops the round-robin monitoring loop. 0: ADC128D818 in shutdown mode 1: Enable startup of monitoring operations 1: Enable the interrupt output pin, INT Bit Name Read/Write Bit(s) Description 7 Initialization Read/Write 27 www.national.com ADC128D818 15.12.3 Interrupt Status Register — Address 01h Default Value [7:0] = 0000_0000 binary Bit MODE 0 0 1 2 3 4 5 6 7 MODE 1 0 1 2 3 4 5 6 7 MODE 2 0 1 2 3 4 5 6 7 MODE 3 0 1 2 3 4 5 6 7 IN0 Error IN1 Error IN2 Error IN3 Error IN4(+) & IN5(-) Error IN7(+) & IN6(-) Error Reserved Hot Temperature Error Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only 1: A High limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded IN0(+) & IN1(-) Error IN3(+) & IN2(-) Error IN4(+) & IN5(-) Error IN7(+) & IN6(-) Error Reserved Reserved Reserved Hot Temperature Error Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only 1: A High limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded IN0 Error IN1 Error IN2 Error IN3 Error IN4 Error IN5 Error IN6 Error IN7 Error Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded IN0 Error IN1 Error IN2 Error IN3 Error IN4 Error IN5 Error IN6 Error Hot Temperature Error Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High or Low limit has been exceeded 1: A High limit has been exceeded Bit Name Read/Write Bit(s) Description www.national.com 28 ADC128D818 15.12.4 Interrupt Mask Register — Address 03h Default Value [7:0] = 0000_0000 binary Bit MODE 0 0 1 2 3 4 5 6 7 MODE 1 0 1 2 3 4 5 6 7 MODE 2 0 1 2 3 4 5 6 7 MODE 3 0 IN0 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 29 www.national.com Bit Name Read/Write Bit(s) Description 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT IN0 Mask IN1 Mask IN2 Mask IN3 Mask IN4 Mask IN5 Mask IN6 Mask Temperature Mask Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write IN0 Mask IN1 Mask IN2 Mask IN3 Mask IN4 Mask IN5 Mask IN6 Mask IN7 Mask Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write IN0(+) & IN1(-) Mask IN3(+) & IN2(-) Mask IN4(+) & IN5(-) Mask IN7(+) & IN6(-) Mask Reserved Reserved Reserved Temperature Mask Read/Write Read/Write Read/Write Read/Write Read Only Read Only Read Only Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT ADC128D818 Bit 1 2 3 4 5 6 7 Bit Name IN1 Mask IN2 Mask IN3 Mask IN4(+) & IN5(-) Mask IN7(+) & IN6(-) Mask Reserved Temperature Mask Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read Only Read/Write Bit(s) Description 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 1: Mask the corresponding interrupt status from propagating to the interrupt output pin, INT 15.12.5 Conversion Rate Register — Address 07h Default Value [7:0] = 0000_0000 binary Bit Bit Name Read/Write Bit(s) Description Controls the conversion rate: 0: Low Power Conversion Mode 1: Continuous Conversion Mode Note: This register must only be programmed when the device is in shutdown mode, that is, when the 'START' bit of the 'Configuration Register' (address 00h) =0 0 Conversion Rate Read/Write 1–7 Reserved Read Only www.national.com 30 ADC128D818 15.12.6 Channel Disable Register — Address 08h Default Value [7:0] = 0000_0000 binary • This register must only be programmed when the device is in shutdown mode, that is, when the ‘START’ bit of the “Configuration Register’ (address 00h) = 0. Bit MODE 0 0 1 2 3 4 5 6 7 MODE 1 0 1 2 3 4 5 6 7 MODE 2 0 1 2 3 4 5 6 7 IN0(+) & IN1(-) Disable IN3(+) & IN2(-) Disable IN4(+) & IN5(-) Disable IN7(+) & IN6(-) Disable Reserved Reserved Reserved Temperature Disable Read/Write Read/Write Read/Write Read/Write Read Only Read Only Read Only Read/Write IN0 Disable IN1 Disable IN2 Disable IN3 Disable IN4 Disable IN5 Disable IN6 Disable IN7 Disable Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write IN0 Disable IN1 Disable IN2 Disable IN3 Disable IN4 Disable IN5 Disable IN6 Disable Temperature Disable Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Bit Name Read/Write • Whenever this register is programmed, all of the values in the Channel Reading Registers and Interrupt Status Registers will return to their default values. Bit(s) Description 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 31 www.national.com ADC128D818 Bit MODE 3 0 1 2 3 4 5 6 7 Bit Name Read/Write Bit(s) Description 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. 1: Conversions are skipped and disabled, value register reading will be 0, and error events will be suppressed. IN0 Disable IN1 Disable IN2 Disable IN3 Disable IN4(+) & IN5(-) Disable IN7(+) & IN6(-) Disable Reserved Temperature Disable Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read Only Read/Write www.national.com 32 ADC128D818 15.12.7 One-Shot Register — Address 09h Default Value [7:0] = 0000_0000 binary Bit 0 1–7 Bit Name One-Shot Reserved Read/Write Write Only Read Only Bit(s) Description 1: Initiate a single conversion and comparison cycle when the device is in shutdown mode or deep shutdown mode, after which the device returns to the respective mode that it was in 15.12.8 Deep Shutdown Register — Address 0Ah Default Value [7:0] = 0000_0000 binary Bit 0 1–7 Bit Name Deep Shutdown Enable Reserved Read/Write Read/Write Read Only and Interrupt Status Registers will return to their default values. Bit(s) Description 1: When 'START' = 0 (address 00h, bit 0), setting this bit high will place the device in deep shutdown mode 15.12.9 Advanced Configuration Register — Address 0Bh Default Value [7:0] = 0000_0000 binary Note: Whenever the Advanced Configuration Register is programmed, all of the values in the Channel Reading Registers Bit 0 Bit Name External Reference Enable Read/Write Read/Write Bit(s) Description 0: Selects the 2.56V internal VREF 1: Selects the variable external VREF Mode Select [1] Mode Select [0] 0 1 0 1 Mode Mode 0 Mode 1 Mode 2 Mode 3 0 1 Mode Select [0] Read/Write 0 1 1 2 3–7 Mode Select [1] Reserved Read Only 15.12.10 Busy Status Register — Address 0Ch Default Value [7:0] = 0000_0010 binary Bit 0 1 2–7 Bit Name Busy Not Ready Reserved Read/Write Read Only Read Only Read Only Bit(s) Description 1: ADC128D818 is converting 1: Waiting for the power-up sequence to end 33 www.national.com ADC128D818 15.12.11 Channel Readings Registers — Addresses 20h – 27h Address MODE 0 20h 21h 22h 23h 24h 25h 26h 27h MODE 1 20h 21h 22h 23h 24h 25h 26h 27h MODE 2 20h 21h 22h 23h 24h 25h 26h 27h MODE 3 20h 21h 22h 23h 24h 25h 26h 27h IN0 Reading IN1 Reading IN2 Reading IN3 Reading IN4(+) & IN5(-) Reading IN7(+) & IN6(-) Reading Reserved Temperature Reading Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel IN0(+) & IN1(-) Reading IN3(+) & IN2(-) Reading IN4(+) & IN5(-) Reading IN7(+) & IN6(-) Reading Reserved Reserved Reserved Temperature Reading Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel IN0 Reading IN1 Reading IN2 Reading IN3 Reading IN4 Reading IN5 Reading IN6 Reading IN7 Reading Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel IN0 Reading IN1 Reading IN2 Reading IN3 Reading IN4 Reading IN5 Reading IN6 Reading Temperature Reading Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Reading for this perspective channel Register Name Read/Write Register Description www.national.com 34 ADC128D818 15.12.12 Limit Registers — Addresses 2Ah – 39h Address MODE 0 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h 38h 39h MODE 1 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h 38h 39h MODE 2 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h IN0(+) & IN1(-) High Limit IN0(+) & IN1(-) Low Limit IN3(+) & IN2(-) High Limit IN3(+) & IN2(-) Low Limit IN4(+) & IN5(-) High Limit IN4(+) & IN5(-) Low Limit IN7(+) & IN6(-) High Limit IN7(+) & IN6(-) Low Limit Reserved Reserved Reserved Reserved Reserved Reserved Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read Only Read Only Read Only Read Only Read Only Read Only 35 www.national.com Register Name IN0 High Limit IN0 Low Limit IN1 High Limit IN1 Low Limit IN2 High Limit IN2 Low Limit IN3 High Limit IN3 Low Limit IN4 High Limit IN4 Low Limit IN5 High Limit IN5 Low Limit IN6 High Limit IN6 Low Limit Temperature High Limit Temperature Hysteresis Limit IN0 High Limit IN0 Low Limit IN1 High Limit IN1 Low Limit IN2 High Limit IN2 Low Limit IN3 High Limit IN3 Low Limit IN4 High Limit IN4 Low Limit IN5 High Limit IN5 Low Limit IN6 High Limit IN6 Low Limit IN7 High Limit IN7 Low Limit Read/ Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Hysteresis Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit Register Description ADC128D818 Address 38h 39h MODE 3 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h 38h 39h Register Name Temperature High Limit Temperature Hysteresis Limit IN0 High Limit IN0 Low Limit IN1 High Limit IN1 Low Limit IN2 High Limit IN2 Low Limit IN3 High Limit IN3 Low Limit IN4(+) & IN5(-) High Limit IN4(+) & IN5(-) Low Limit IN7(+) & IN6(-) High Limit IN7(+) & IN6(-) Low Limit Reserved Reserved Temperature High Limit Temperature Hysteresis Limit Read/ Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read Only Read Only Read/Write Read/Write High Limit Hysteresis Limit High Limit Hysteresis Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit High Limit Low Limit Register Description 15.12.13 Manufacturer ID Register — Address 3Eh Default Value [7:0] = 0000_0001 binary Address 3Eh Register Name Manufacturer ID Read/Write Read Only Register Description Manufacturer's ID always defaults to 0000_0001. 15.12.14 Revision ID Register — Addresses 3Fh Default Value [7:0] = 0000_1001 binary Address 3Fh Register Name Revision ID Read/Write Read Only Register Description Revision's ID always defaults to 0000_1001. www.national.com 36 ADC128D818 16.0 Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Molded Plastic TSSOP Order Number ADC128D818CIMT or ADC128D818CIMTX NS Package Number MO-153 37 www.national.com ADC128D818 12-Bit, 8-Channel, ADC System Monitor with Temperature Sensor, Internal/ External Reference, and I2C Interface Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® 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