PDF AD7418 Data sheet ( Hoja de datos )

Número de pieza	AD7418
Descripción	10-Bit Digital Temperature Sensor (AD7416) and Single/Four-Channel ADC (AD7417/AD7418)
Fabricantes	Analog Devices
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No Preview Available ! a10-Bit Digital Temperature Sensor (AD7416) and Single/Four-Channel ADC (AD7417/AD7418) AD7416/AD7417/AD7418 FEATURES 10-Bit ADC with 15 ␮s and 30 ␮s Conversion Times Single and Four Single-Ended Analog Input Channels On-Chip Temperature Sensor: –55؇C to +125؇C On-Chip Track/Hold Over-Temperature Indicator Automatic Power Down at the End of a Conversion Wide Operating Supply Range: +2.7 V to +5.5 V I2C® Compatible Serial Interface Selectable Serial Bus Address Allows Connection of Up to Eight AD7416/AD7417s to a Single Bus AD7416 is a Superior Replacement for LM75 APPLICATIONS Data Acquisition with Ambient Temperature Monitoring Industrial Process Control Automotive Battery Charging Applications Personal Computers FUNCTIONAL BLOCK DIAGRAMS BANDGAP TEMPERATURE SENSOR 10-BIT ANALOG-DIGITAL CONVERTER ADDRESS POINTER REGISTER A0 A1 A2 TEMPERATURE VALUE REGISTER TOTI SETPOINT REGISTER THYST SETPOINT REGISTER CONFIGURATION REGISTER SERIAL BUS INTERFACE AD7416 SETPOINT COMPARATOR FAULT QUEUE COUNTER REFIN VDD +VS OTI GND SDA SCL GENERAL DESCRIPTION The AD7417 and AD7418 are 10-bit, single- and 4-channel A/D converter with an on-chip temperature sensor that can operate from a single +2.7 V to +5.5 V power supply. The de- vices contain a 15 µs successive-approximation converter, a 5-channel multiplexer, a temperature sensor, a clock oscillator, a track/hold, and a reference (+2.5 V). The AD7416 is a tem- perature-monitoring-only device in an 8-lead package. The temperature sensor on the parts can be accessed via multi- plexer Channel 0. When Channel 0 is selected and a conversion is initiated, the resulting ADC code at the end of the conversion gives a measurement of the ambient temperature (± 1°C @ +25°C). On-chip registers can be programmed with high and low temperature limits, and an open drain Over-Temperature Indicator output (OTI) is provided, which becomes active when a programmed limit is exceeded. A configuration register allows programming of the sense of the OTI output (active high or active low) and its operating mode (comparator or interrupt). A programmable fault queue counter allows the number of out of limit measurements that must occur before triggering the OTI output to be set, to prevent spurious triggering of the OTI output in noisy environments. (continued on page 7) I2C is a registered trademark of Philips Corporation. REV. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. TEMP SENSOR REF 2.5V OVER-TEMP REG B A>B A CHARGE DISTRIBUTION DAC DATA OUT VIN1 VIN2 VIN3 VIN4 MUX SAMPLING CAPACITOR CLOCK + CONTROL LOGIC I2C INTERFACE VBALANCE NC NC GND CONVST NC = NO CONNECT AD7417 A0 A1 A2 VDD REFIN TEMP SENSOR REF 2.5V OVER-TEMP REG B A>B A CHARGE DISTRIBUTION DAC DATA OUT VIN1 MUX SAMPLING CAPACITOR CLOCK + CONTROL LOGIC I2C INTERFACE AGND VBALANCE CONVST AD7418 OTI SCL SDA OTI SCL SDA One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 1999 1 page Pin No. 1 2 3 4 5 6 7 8 Pin No. 1 2 3 4 5 6 7 8 AD7416/AD7417/AD7418 Mnemonic SDA SCL OTI GND A2 A1 A0 VDD Mnemonic SDA SCL OTI GND AIN REFIN VDD CONVST AD7416 PIN FUNCTION DESCRIPTION Description Digital I/O. Serial Bus Bidirectional Data. Push-pull output. Digital Input. Serial Bus Clock. This is a logic output. The Over-Temperature Indicator (OTI) is set if the result of a conversion on Channel 0 (Temperature Sensor) is greater that an 8-bit word in the Over-Temperature Register (OTR). The signal is reset at the end of a serial read operation. Open-drain output. Ground reference for track/hold, comparator and capacitor DAC, and digital circuitry. Digital Input. The highest programmable bit of the Serial Bus Address. Digital Input. The middle programmable bit of the Serial Bus Address. Digital Input. The lowest programmable bit of the Serial Bus Address. Positive Supply Voltage, +2.7 V to +5.5 V. AD7418 PIN FUNCTION DESCRIPTION Description Digital I/O. Serial Bus Bidirectional Data. Push-pull output. Digital Input. Serial Bus Clock. This is a logic output. The Over-Temperature Indicator (OTI) is set if the result of a conversion on Channel 0 (Temperature Sensor) is greater that an 8-bit word in the Over-Temperature Register (OTR). The signal is reset at the end of a serial read operation. Open-drain output. Ground reference for track/hold, comparator and capacitor DAC, and digital circuitry. Analog Input Channel. The input channel is single-ended with respect to GND. The input channel can convert voltage signals in the range 0 V to VREF. The analog input channel is selected by writing to the configuration register of the AD7418 and choosing Channel 4. (See Control Byte section.) Reference Input. An external 2.5 V reference can be connected to the AD7418 at this pin. To en- able the on-chip reference the REFIN pin should be tied to GND. If an external reference is con- nected to the AD7418, the internal reference will shut down. Positive Supply Voltage, +2.7 V to +5.5 V. Logic Input Signal. Convert Start Signal. The rising edge of this signal fully powers up the part. The power-up time for the part is 4 µs. If the CONVST pulse is greater than 4 µs, the falling edge of CONVST places the track/hold mode into hold mode and initiates a conversion. If the pulse is less than 4 µs, an internal timer ensures that the track/hold does not go into hold and conversion is not initiated until the power-up time has elapsed. The track/hold goes into track mode again at the end of conversion. (See Operating Mode section.) AD7416 PIN CONFIGURATION SOIC/␮SOIC SDA 1 8 VDD SCL 2 AD7416 7 A0 TOP VIEW OTI 3 (Not to Scale) 6 A1 GND 4 5 A2 AD7418 PIN CONFIGURATION SOIC/␮SOIC SDA 1 8 CONVST SCL 2 AD7418 7 VDD TOP VIEW OTI 3 (Not to Scale) 6 REFIN GND 4 5 AIN REV. B –5– 5 Page AD7416/AD7417/AD7418 the selected device waits for data to be read from or written to it. If the R/W bit is a 0 then the master will write to the slave device. If the R/W bit is a 1 the master will read from the slave device. 2. Data is sent over the serial bus in sequences of nine clock pulses, eight bits of data followed by an Acknowledge Bit from the receiver of data. Transitions on the data line must occur during the low period of the clock signal and remain stable during the high period, as a low-to-high transition when the clock is high may be interpreted as a STOP signal. 3. When all data bytes have been read or written, stop condi- tions are established. In WRITE mode, the master will pull the data line high during the 10th clock pulse to assert a STOP condition. In READ mode, the master device will pull the data line high during the low period before the 9th clock pulse. This is known as No Acknowledge. The master will then take the data line low during the low period before the 10th clock pulse, then high during the 10th clock pulse to assert a STOP condition. Any number of bytes of data may be transferred over the serial bus in one operation, but it is not possible to mix read and write in one operation, because the type of operation is determined at the beginning and cannot subsequently be changed without starting a new operation. WRITING TO THE AD7416/AD7417/AD7418 Depending on the register being written to, there are three dif- ferent writes for the AD7416/AD7417/AD7418. 1. Writing to the Address Pointer Register for a subsequent read. In order to read data from a particular register, the Address Pointer Register must contain the address of that register. If it does not, the correct address must be written to the Ad- dress Pointer register by performing a single-byte write operation, as shown in Figure 7. The write operation consists of the serial bus address followed by the address pointer byte. No data is written to any of the data registers. 2. Writing a single byte of data to the Configuration Registers or TOTI, THYST Registers. The Configuration Register is an 8-bit register, so only one byte of data can be written to it. If only 8-bit temperature comparisons are required, the temperature LSB can be ig- nored in TOTI and THYST, and only eight bits need be written to the TOTI and THYST registers. Writing a single byte of data to one of these registers consists of the serial bus address, the data register address, written to the Address Pointer Register, followed by the data byte, written to the selected data register. This is illustrated in Figure 8. SCL 1 91 9 SDA 10 0 1 A2 A1 A0 R/W P7 P6 P5 P4 P3 P2 P1 P0 START BY MASTER FRAME 1 SERIAL BUS ADDRESS BYTE ACK. BY AD7416 FRAME 2 ADDRESS POINTER REGISTER BYTE ACK. BY STOP BY AD7416 MASTER Figure 7. Writing to the Address Pointer Register to Select a Data Register for a Subsequent Read Operation SCL 1 91 9 SDA START BY MASTER 1 0 0 1 A2 A1 A0 R/W P7 FRAME 1 SERIAL BUS ADDRESS BYTE ACK. BY AD7416 P6 P5 P4 P3 P2 P1 P0 FRAME 2 ADDRESS POINTER REGISTER BYTE ACK. BY AD7416 SCL (CONTINUED) 1 9 SDA (CONTINUED) D7 D6 D5 D4 D3 D2 D1 D0 FRAME 3 DATA BYTE ACK. BY STOP BY AD7416 MASTER Figure 8. Writing to the Address Pointer Register Followed by a Single Byte of Data to the Selected Data Register REV. B –11– 11 Page

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