ad7294nbsp Analog Devices, Inc., ad7294nbsp Datasheet
ad7294nbsp
Related parts for ad7294nbsp
ad7294nbsp Summary of contents
Page 1
... One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 Fax: 781.461.3113 AVDD AGND 12-BIT VOUTA DAC OFFSET IN A 12-BIT VOUTB DAC OFFSET IN B 12-BIT VOUTC DAC OFFSET IN C 12-BIT VOUTD DAC OFFSET IN D ©2007 Analog Devices, Inc. All rights reserved. AD7294 www.analog.com ...
Page 2
AD7294 TABLE OF CONTENTS Features .............................................................................................. 1 Applications.................................. Error! Bookmark not defined. General Description ......................................................................... 1 Revision History ............................................................................... 2 Functional Block Diagram ......... Error! Bookmark not defined. Specifications..................................................................................... 3 DAC Specifications....................................................................... 3 ADC Specifications ...................................................................... 4 General Specifications ................................................................. ...
Page 3
Preliminary Technical Data SPECIFICATIONS DAC SPECIFICATIONS 4 5.5 V, AGND = DGND = 0 V, internal 2.5 V reference version: −40°C to +105°C. All specifications T from ...
Page 4
AD7294 ADC SPECIFICATIONS 4 5.5 V, AGND = DGND = 0 V, internal 2.5 V reference version: −40°C to +105°C. All specifications T characterization, not subject to production test. Parameter ...
Page 5
Preliminary Technical Data Parameter Medium Level Output Current Source High Level Output Current Source Maximum Series Resistance for External Diode CURRENT SENSE Supply Range Gain RS(+) and RS(−) Input Bias Current CMRR/PSRR Accuracy Offset Error Offset Drift Amplifier Peak-To-Peak Noise ...
Page 6
AD7294 GENERAL SPECIFICATIONS 4 5.5 V, AGND = DGND internal 2.5 V reference version: −40°C to +105°C. All specifications T characterization, not subject to production test. Parameter LOGIC ...
Page 7
Preliminary Technical Data TIMING CHARACTERISTICS Serial Interface 4 5.5 V, AGND = DGND = noted. Specifications guaranteed by design and characterization, not subject to production test. ...
Page 8
AD7294 ABSOLUTE MAXIMUM RATINGS 25°C, unless otherwise noted. A Table 3. Parameter Rating V to AGND −0 + AGND −0 V(+) to AGND −0 ...
Page 9
Preliminary Technical Data PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REFOUT / REFIN DAC CONNECT NC RS2(-) RS2(+) NC AVDD1 AGND1 AGND2 AVDD2 D2(-) D2(+) D1(+) D1(-) AGND3 AVDD3 REFOUT / REFIN DAC NC RS2 (-) 1 RS2(+) ...
Page 10
AD7294 Table 4. Pin Function Descriptions LFCSP Pin No. TQFP Pin No. Mnemonic RS2(−), RS1(− RS2(+), RS1(+) 16, 17, 32, NC 33, 59 13, 22, ...
Page 11
Preliminary Technical Data LFCSP Pin No. TQFP Pin No. Mnemonic N/A 48 DAC High 49, 50, 51, 52 VIN3 to VIN0 47 53 REFOUT/REFIN ADC 48 54 DCAP 55, 56 62, 63 VPP1, VPP2 Description High Impedance ...
Page 12
AD7294 TERMINOLOGY DAC TERMINOLOGY Relative Accuracy For the DAC, relative accuracy or integral nonlinearity (INL measure of the maximum deviation, in LSBs, from a straight line passing through the endpoints of the DAC transfer func tion. Differential Nonlinearity ...
Page 13
Preliminary Technical Data Differential Nonlinearity The difference between the measured and the ideal 1 LSB change between any two adjacent codes in the ADC. Offset Error The deviation of the first code transition (00…000) to (00…001) from the ideal—that is, ...
Page 14
AD7294 THEORY OF OPERATION ADC OVERVIEW The AD7294 consists of a successive approximation ADC based around a capacitive DAC. The analog input range for the part can be selected input × ...
Page 15
Preliminary Technical Data +2.5V R +1.25V –1.25V R 1 ADDITIONAL PINS OMITTED FOR CLARITY. Figure 8. Single-Ended Mode Connection Diagram Differential Mode The AD7294 can have two differential analog input pairs. Differential signals have ...
Page 16
AD7294 An op amp pair can be used to directly couple a differential signal to one of the analog input pairs of the AD7294. The circuit con figurations illustrated in Figure 12 and Figure 13 show how a dual op ...
Page 17
Preliminary Technical Data V REF p-p DC INPUT VOLTAGE 1 ADDITIONAL PINS OMITTED FOR CLARITY. Figure 16. Pseudo Differential Mode Connection Diagram CURRENT SENSOR Two bidirectional high-side current sense amplifiers are provided, which can accurately amplify small differential current shunt ...
Page 18
AD7294 SENSE RESISTOR CURRENT FLOW FROM SUPPLY KELVIN SENSE TRACES RSX(+) RSX(–) AD7294 Figure 19. Kelvin Sense Connections ANALOG COMPARATOR LOOP The AD7294 consists of two setpoint comparators that are used for independent analog control. The advantage of using analog ...
Page 19
Preliminary Technical Data AD7294 2N3904 D+ NPN 10pF D– Figure 21. Measuring Temperature Using an NPN Transistor AD7294 D+ 10pF 2N3906 D– PNP Figure 22. Measuring Temperature Using a PNP Transistor Series Resistance Cancellation Parasitic resistance to the D+ and ...
Page 20
AD7294 OUTPUT R AMPLIFIER R R Figure 24. Resistor String Structure Output Amplifier Referring to Figure 23, the purpose buffer the DAC output range from The second amplifier, ...
Page 21
Preliminary Technical Data REGISTER SETTING The AD7294 contains internal registers (see Figure 25) that are used to store conversion results, high and low conversion limits, and information to configure and control the device. COMMAND REGISTER RESULT REGISTER DAC REGISTERS T ...
Page 22
AD7294 COMMAND REGISTER (0x00) Writing in the command register puts the part into command mode. When in command mode, the part cycles through the selected channels on each subsequent read. If the external T channels are selected in the command ...
Page 23
Preliminary Technical Data ADC Channel Allocation These nine channel address bits select which analog input channel is to convert using the multiplexer, see Table 11. Choosing Channel 1 to Channel 4 selects the standard analog voltage inputs. Channel 5 and ...
Page 24
AD7294 DAC4 REGISTER (0x04) Writing to this register address sets the DAC4 output code. Bits[D11:D0] in the result register are the data bits sent to DAC4. Bits[D14:D12] are ignored and the MSB, D15, is reserved as an Alert_Flag bit. Table ...
Page 25
Preliminary Technical Data Table 25. Configuration Register Bit Function Description D15 to D8 Channel Bit D15 D14 Function Reserved Enable noise- delayed sampling. Use to delay critical sample intervals from occurring when there is when there is activity on 2 ...
Page 26
AD7294 Channel 7 to Channel and T SENSE SENSE to 3FF and 400 for the DATA and DATA HIGH are in twos complement 10-bit format. Differential mode is not available for Channel 7 to Channel ...
Page 27
Preliminary Technical Data INTERFACE 2 GENERAL I C TIMING Figure 26 shows the timing diagram for general read and write 2 operations using an I C-compliant interface. 2 The I C bus uses open-drain drivers, therefore, when ...
Page 28
AD7294 SERIAL BUS ADDRESS BYTE The first byte the user writes to the device is the slave address 2 Similar to all I C-compatible devices, the AD7294 has a byte. 7-bit serial address. The 5 LSBs are user programmable by ...
Page 29
Preliminary Technical Data Table 36, H means tie the pin to VDRIVE, L means tie the pin to GND, and NC refers to a pin left floating. Note that in this final case, the stray capacitance on the pin must ...
Page 30
AD7294 INTERFACE PROTOCOL 2 The AD7294 uses the following I C protocols. Writing a Single Byte of Data to an 8-Bit Register The alert registers (0x05, 0x06, 0x07), power down register (0x0A), channel sequence register (0x08), temperature offset registers (0x26, ...
Page 31
Preliminary Technical Data Writing Two Bytes of Data to a 16-Bit Register The limit and hysteresis registers (0x0B to 0x25), the result registers (0x01 ~ 0x04), and the configuration register (0x09) are 16-bit registers; therefore, two bytes of data are ...
Page 32
AD7294 Writing to Multiple Registers Writing to multiple address registers consists of the following: 1. The master device asserts a start condition on SDA. 2. The master sends the 7-bit slave address followed by the write bit (low). 3. The ...
Page 33
Preliminary Technical Data Reading Data from an 8-Bit Register Reading the contents from any of the 8-bit registers is a single- byte read operation, as shown in Figure 30. In this protocol, the first part of the transaction writes to ...
Page 34
AD7294 Reading Two Bytes of Data from a 16-Bit Register In this example, the master device reads three lots of two-byte data from a slave device. This protocol assumes that the particular register address has been set ...
Page 35
Preliminary Technical Data MODES OF OPERATION There are two different methods of initiating a conversion on the AD7294. COMMAND MODE In command mode, the AD7294 ADC converts on demand on either a single channel or a sequence of channels. To ...
Page 36
AD7294 AUTOCYCLE MODE The AD7294 can be configured to convert continuously on a programmable sequence of channels. These conversions take place in the background approximately every 45 µs, and are transparent to the master. Reads and writes can still be ...
Page 37
Preliminary Technical Data ALERTS AND LIMITS THEORY ALERT_FLAG BIT The Alert_Flag bit indicates whether the conversion result being read or any other channel result has violated the limit registers associated with it alert occurs and the Alert_Flag bit ...
Page 38
AD7294 contain a value of 8 LSB for nontemperature result registers and 8° LSB, for the T registers different hysteresis SENSE value is required, that value must be written to the hysteresis register for the channel ...
Page 39
... RF IN signal is switched off by the comparator. By measuring the transmitted power (Tx) and the received power (Rx), the device can dynamically change the drivers and PA signal to optimize performance. This application requires a logarithmic detector/controller, such as Analog Devices, Inc. AD8317. R SENSE R SENSE RS2(– ...
Page 40
AD7294 GAIN CONTROL OF POWER AMPLIFIER In gain control mode, a setpoint voltage, proportional the desired output power, is applied to a power detector such as the AD8362. A sample of the output power from the power ...
Page 41
Preliminary Technical Data LAYOUT AND CONFIGURATION POWER SUPPLY BYPASSING AND GROUNDING When accuracy is important in a circuit, carefully consider the power supply and ground return layout on the board. The printed circuit board containing the AD7294 should have separate ...
Page 42
AD7294 EVALUATION BOARD FOR THE AD7294 The AD7294 evaluation board consists of the AD7294 LFCSP package along with two R resistors and a number of SMB SENSE sockets and jumpers to allow access to the various on-chip functionalities of the ...
Page 43
Preliminary Technical Data Figure 38. Evaluation Board Schematic Rev. PrD | Page AD7294 ...
Page 44
AD7294 Figure 39. Component Side Artwork Figure 40. Component Side SilkScreen Rev. PrD | Page Preliminary Technical Data ...
Page 45
Preliminary Technical Data Figure 41. Solder Side Artwork Rev. PrD | Page AD7294 ...
Page 46
... Temperature Range AD7294BCPZ 1 −40°C to +105°C 1 AD7294BSUZ −40°C to +105°C 1 EVAL-AD7294EBZ RoHS Compliant Part. ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR05747-0-10/07(PrD) 8.00 BSC SQ 0.60 MAX 43 42 TOP 7.75 VIEW BSC SQ 0 ...