AD7812 Analog Devices, AD7812 Datasheet
AD7812
Specifications of AD7812
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AD7812 Summary of contents
Page 1
... Small Outline IC (SOIC) and in a 20-lead, Thin Shrink Small Outline Package (TSSOP). PRODUCT HIGHLIGHTS 1. Low Power, Single Supply Operation Both the AD7811 and AD7812 operate from a single 2 5.5 V supply and typically consume only power. The power dissipation can be significantly reduced at lower throughput rates by using the automatic power- down mode e.g., 315 µ ...
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... AD7811/AD7812–SPECIFICATIONS Parameter DYNAMIC PERFORMANCE Signal to (Noise + Distortion) Ratio Total Harmonic Distortion (THD) 1 Peak Harmonic or Spurious Noise 1, 2 Intermodulation Distortion Second Order Terms Third Order Terms 1, 2 Channel-to-Channel Isolation DC ACCURACY Resolution Minimum Resolution for Which No Missing Codes are Guaranteed 1 Relative Accuracy ...
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... [EXT] unless otherwise noted) DD REF DD Unit Conditions/Comments µs (max) Power-Up Time of AD7811/AD7812 after Rising Edge of CONVST µs (max) Conversion Time CONVST Pulsewidth ns (min) ns (min) SCLK High Pulsewidth ns (min) SCLK Low Pulsewidth ns (min) RFS Rising Edge to SCLK Rising Edge Setup Time ...
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... IN Analog Inputs V –V (AD7811 –0 IN1 IN4 V –V (AD7812 –0 IN1 IN8 Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 150°C Plastic DIP Package, Power Dissipation . . . . . . . . . . 450 mW θ Thermal Impedance . . . . . . . . . . . . . . . . . . . . 105°C/W JA Lead Temperature, (Soldering 10 sec 260°C ...
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... For example a twelve channel solution can be achieved by using the AD7811 and the AD7812 on the same serial bus. Digital Ground. Ground reference for digital circuitry. ...
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... The AD7811 and AD7812 are tested using the CCIF standard where two input frequencies near the top end of the input bandwidth are used. In this case, the second and third order terms are of different significance ...
Page 7
... This is the package address bit used in conjunction with the package address pin to allow two AD7811s to share the same serial bus. The AD7811 can also share the same serial bus with the AD7812. When a control word is written to the control register of the AD7811 the control word is ignored if the package address bit in the con- trol byte does not match how the package address pin is hardwired ...
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... The Control Register is a 10-bit-wide, write only register. The Control Register is written to when the AD7812 receives a falling edge on its TFS pin. The AD7812 will maintain the same configuration until a new control byte is written to the part. The control register can be written to at the same time data is being read. This latter feature enhances throughput rates when software control is being used or when the analog input channels are being changed frequently. The power-up default register contents are all zeros ...
Page 9
... V (+) Pseudo Differential with Respect to V IN1 1 V (+) Pseudo Differential with Respect to V IN3 0 Internal Test. SAR Input Equal Internal Test. SAR Input Equal to V Table II. AD7812 Channel Configurations CH1 CH0 Description Single-Ended with Respect to AGND IN1 Single-Ended with Respect to AGND ...
Page 10
... OSC Analog Input Figure 5 shows an equivalent circuit of the analog input struc- ture of the AD7811 and AD7812. The two diodes D1 and D2 provide ESD protection for the analog inputs. Care must be taken to ensure that the analog input signal never exceeds the supply rails by more than 200 mV. This will cause these diodes to become forward biased and start conducting current into the substrate ...
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... External 1 nF capacitor on V ON-CHIP REFERENCE The AD7811 and AD7812 have an on-chip 2.5 V reference circuit. The schematic in Figure 9 shows how the reference circuit is implemented. A 1.23 V bandgap reference is gained up to provide a 2.5 V ± 2% reference voltage. The on-chip refer- ence is not available externally (SW2 is open) ...
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... The AD7811 and AD7812 have a 1.5 µs power-up time when using an external reference or when powering up from partial power-down. When V AD7812 are in a low current mode of operation. In order to carry out a conversion the AD7811 and AD7812 must first be powered up by writing to the control register of each ADC to set the power-down bits (i ...
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... FREQUENCY – kHz QUICK EVALUATION SETUP The schematic shown in Figure 14 shows a suggested configura- tion of the AD7812 for a first look evaluation of the part. No external reference circuit is needed as the V connected to V and RFS to enable the serial port. Also by selecting Mode 2 operation (see Operating Modes section) the power performance of the AD7812 can be evaluated ...
Page 14
... The CONVST signal should be logic high at the end of the conversion to prevent the part from powering down. The serial port on the AD7811 and AD7812 is enabled on the rising edge of the first SCLK after the rising edge of the RFS signal—see Serial Interface section. As explained earlier, this rising edge ...
Page 15
... DB9 DB8 (Point “B”), whichever occurs latest before initiating a serial read. The serial port of the AD7811 and AD7812 is still func- tional even though the devices have been powered down. Because it is possible serial read from the part while it is ...
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... The serial interface on the AD7811 and AD7812 allows the parts to be directly connected to a range of many different microprocessors. This section explains how to interface the AD7811 and AD7812 with some of the more common micro- controller and DSP serial interface protocols. AD7811/AD7812 to PIC16C6x/7x The PIC16C6x Synchronous Serial Port (SSP) is configured as an SPI Master with the Clock Polarity bit = 0 ...
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... AD7811/AD7812 ADDITIONAL PINS OMITTED FOR CLARITY AD7811/AD7812 to DSP56xxx The connection diagram in Figure 25 shows how the AD7811 and AD7812 can be connected to the SSI (Synchronous Serial Interface) of the DSP56xxx family of DSPs from Motorola. The TMS320C5x SSI is operated in Synchronous Mode (SYN bit in CRB =1) CLKX with internally generated 1-bit clock period frame sync for both Tx and Rx (FSL1 and FSL0 bits in CRB = 1 and 0 respectively) ...
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... AD7811/AD7812 0.210 (5.33) 0.160 (4.06) 0.115 (2.93) 0.006 (0.15) 0.002 (0.05) SEATING PLANE OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 16-Lead Plastic DIP (N-16) 0.840 (21.33) 0.745 (18.93 0.280 (7.11) 0.240 (6.10 PIN 1 0.060 (1.52) 0.015 (0.38) MAX 0.130 (3.30) MIN 0.100 0.070 (1.77) SEATING 0.022 (0.558) PLANE (2.54) 0.045 (1.15) 0.014 (0.356) BSC 16-Lead Small Outline Package (SOIC) (R-16A) 0 ...
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... PIN 1 0.002 (0.05) 0.0433 (1.10) MAX 0.0118 (0.30) 0.0256 (0.65) SEATING 0.0079 (0.20) BSC 0.0075 (0.19) PLANE 0.0035 (0.090) AD7811/AD7812 0.325 (8.25) 0.195 (4.95) 0.300 (7.62) 0.115 (2.93) 0.130 (3.30) MIN 0.015 (0.381) 0.008 (0.204) 0.0291 (0.74) x 45° 0.0098 (0.25) 0.0500 (1.27) 8° 0° 0.0157 (0.40) 0.028 (0.70) 8° 0° 0.020 (0.50) ...