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DAC1280

Current Output

Differential DAC

Synchronization

CLK

SYNC

PWDN

DGND AVSSGAIN[2:0]

DVDD AVDD

DAC1280

VREF

Bitstream

Source

OUT

External I/V Converter

DAC1280

www.ti.com

SBAS432A –APRIL 2010–REVISED SEPTEMBER 2010

Low Distortion Digital-to-Analog Converter for Seismic Monitoring

Check for Samples: DAC1280

FEATURES

DESCRIPTION

• Outstanding Performance:

The DAC1280 is a very low distortion digital-to-analog

converter (DAC) suited for performance testing of

– THD: –125dB

seismic equipment. The DAC1280 provides a

– SNR: 120dB (413Hz BW, Gain = 1/1)

high-accuracy output signal from a bitstream input.

– Gain Error: 0.1%

The device achieves very high linearity in a small

• Pin Operation: No Registers to Program package while dissipating only 18mW. Together with

the high-performance ADS1281 and ADS1282

• Gain: 1/1 to 1/64

analog-to-digital converters (ADCs), these devices

• SYNC Input for Phase Control

create a test and measurement system that meets

• Power-Down Mode

the exacting demands of energy exploration and

seismic monitoring equipment.

• Low Power: 18mW

• Analog Supply: +5V or ±2.5V The DAC1280 is designed to match the system

components (power supply, clock and reference

• Digital Supply: 1.8V to 3.3V

voltage) of the companion ADCs, the ADS1281 and

• Small 16-Pin TSSOP Package

ADS1282. The input to the DAC1280 is a 1s density

• Temperature Range: –40°C to +85°C

modulated bitstream. The DAC1280 output is a

differential current intended for use with an active I/V

converter. The I/V converter provides a voltage output

APPLICATIONS

suitable for performance testing of sensors and

• Energy Exploration Equipment

ADCs.

• Seismic Monitoring Systems

Three gain control pins set the output range in 6dB

steps from 0dB to –36db (±2.5V to ±0.039V

differential). The attenuation ranges match the gains

of the ADS1282 for testing at all gains. The DAC

uses a reference voltage and bias resistor to set the

full-scale output. The resistor can be adjusted to

fine-trim the DAC full-scale.

The SYNC pin aligns the input data sampling to the

CLK phase. A power-down pin shuts down the device

when not in use. The DAC1280 is available in a

small, 16-pin TSSOP package and is fully specified

for operation over –40°C to +85°C temperature range

with a maximum operating temperature of +125°C.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas

Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (24 pages)

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DA C1 DAC1280 280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 Low Distortion Digital-to-Analog Converter for Seismic Monitoring Check for Samples: DAC1280 FEATURES DESCRIPTION • The DAC1280 is a very low distortion digital-to-analog converter (DAC) suited for performance testing of seismic equipment. The DAC1280 provides a high-accuracy output signal from a bitstream input. The device achieves very high linearity in a small package while dissipating only 18mW.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure.
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 ELECTRICAL CHARACTERISTICS Minimum/maximum specifications at –40°C to +85°C, typical specifications at +25°C, AVDD = +2.5V, AVSS = –2.5V, DVDD = 3.3V, CLK = 4.096MHz, VREF = 5V, and RREF = 30kΩ, unless otherwise noted. Refer to circuit configuration shown in Figure 35.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com ELECTRICAL CHARACTERISTICS (continued) Minimum/maximum specifications at –40°C to +85°C, typical specifications at +25°C, AVDD = +2.5V, AVSS = –2.5V, DVDD = 3.3V, CLK = 4.096MHz, VREF = 5V, and RREF = 30kΩ, unless otherwise noted. Refer to circuit configuration shown in Figure 35. DAC1280 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 28 30 60 kΩ REFERENCE RESISTOR (RREF) Reference resistor DIGITAL INPUTS (DVDD = 1.65V to 3.
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 TIMING CHARACTERISTICS space tCLK tTDATA tTCSU tCPW 1 CLK 2 3 4 5 6 7 8 21 9 Next TDATA Sample TDATA Sample tCPW TDATA tSCSU tCTHD SYNC tSTDAT tSYLW DAC OUTPUT tTSOP Output Hold Output Update Figure 1. TIMING REQUIREMENTS At TA = –40°C to +85°C and DVDD = 1.65V to 3.6V.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com DEVICE INFORMATION PW PACKAGE TSSOP-16 (TOP VIEW) CLK 1 16 PWDN TDATA 2 15 IOUTP SYNC 3 14 IOUTN DGND 4 13 NC DAC1280 DVDD 5 12 AVDD GAIN0 6 11 AVSS GAIN1 7 10 RREF GAIN2 8 9 VREF TERMINAL FUNCTIONS TERMINAL 6 NAME NO. I/O CLK 1 Digital Input 4.
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 TYPICAL CHARACTERISTICS At TA = +25°C, AVDD = +2.5V, AVSS = +2.5V, DVDD = +3.3V, CLK = 4.096MHz, VREF = +5V, and RREF = 30kΩ, unless otherwise noted. Data acquired using circuit configuration shown in Figure 35. THD and SNR measured by ADS1282 (1ms sampling and complement gain setting). OUTPUT SPECTRUM OUTPUT SPECTRUM 0 0 Amplitude (dB) -40 -60 -80 -100 -120 -140 Gain = 1/2 4k FFT VOUT = -0.5dBFS, 31.25Hz THD = -128.9dB SNR = 119.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = +2.5V, AVSS = +2.5V, DVDD = +3.3V, CLK = 4.096MHz, VREF = +5V, and RREF = 30kΩ, unless otherwise noted. Data acquired using circuit configuration shown in Figure 35. THD and SNR measured by ADS1282 (1ms sampling and complement gain setting).
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = +2.5V, AVSS = +2.5V, DVDD = +3.3V, CLK = 4.096MHz, VREF = +5V, and RREF = 30kΩ, unless otherwise noted. Data acquired using circuit configuration shown in Figure 35. THD and SNR measured by ADS1282 (1ms sampling and complement gain setting).
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = +2.5V, AVSS = +2.5V, DVDD = +3.3V, CLK = 4.096MHz, VREF = +5V, and RREF = 30kΩ, unless otherwise noted. Data acquired using circuit configuration shown in Figure 35. THD and SNR measured by ADS1282 (1ms sampling and complement gain setting).
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 DAC1280 OVERVIEW The DAC1280 is a high-accuracy digital-to-analog converter (DAC) that provides outstanding THD performance together with low noise. The DAC1280 is suitable for the demanding requirements of energy exploration and precision instrumentation where a low-distortion test signal is needed. Figure 26 shows the DAC1280 block diagram. The DAC provides a signal output proportional to a 1s density input.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com DAC1280 Basics Output Scaling The basic requirements of DAC1280 operation are a clock, a bitstream input, an external current-to-voltage converter, and a reference voltage. The bitstream originates either from an FPGA-based digital modulator or playback from a ROM device holding a stored bitstream file. The external reference voltage is +5V and should be precision (low drift and low noise).
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DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 Table 1. DAC1280 Ideal Output Scaling (1) (1) TDATA 1s DENSITY (%) IOUTP – IOUTN (mA) VP – VN (V) 25 –1250 ● Gain –2.5 ● Gain 37.5 –625 ● Gain –1.25 ● Gain 50 0 0 62.5 +625 ● Gain +1.25 ● Gain 75 +1250 ● Gain +2.5 ● Gain VREF = 5V, RREF = 30kΩ, external current-to-voltage converter resistors = 2kΩ. Output current and voltage are differential.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com Pin Descriptions GAIN[2:0] Pins The DAC1280 output range can be set in 6dB steps, controlled by three digital inputs. The ranges match the gains of the ADS1282 for testing at all gains. Table 2 shows the output range versus gain settings for the DAC1280.
PAGE 15
DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 Table 3. DAC1280 Power Consumption Power Supplies The DAC1280 has two power supplies, analog and digital. The analog supply is 5V and can be configured for bipolar operation (with AVDD = 2.5V and AVSS = –2.5V), or configured for unipolar operation (with AVDD = 5V and AVSS grounded). The common-mode voltage of the external I/V converter is normally set to the DAC1280 midsupply.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com If desired, SNR can be improved by decreasing the 2kΩ I/V feedback resistors and then applying correspondingly higher DAC1280 gains. Decreasing the resistor values results in a decrease of the maximum output amplitude as shown in Figure 31, SNR versus output amplitude for I/V resistor values of 2kΩ, 1kΩ, and 500Ω.
PAGE 17
DAC1280 www.ti.com SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 Seismic System Figure 34 illustrates an example of a three-channel seismic measurement system that consists of the DAC1280 and three ADS1282s. geophone or routed through an external switch network. The DAC input signal is sourced from a bitstream pattern stored in the device flash memory (as shown here), or supplied directly from a bitstream modulator implemented in an FPGA.
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DAC1280 SBAS432A – APRIL 2010 – REVISED SEPTEMBER 2010 www.ti.com Basic Connection reference bias resistor is a 31.6kΩ precision resistor. Increasing the resistor value (from 30kΩ nominal) reduces the DAC full-scale output by –0.5db, to avoid clipping of the ADC. The filter series resistance and the VREF input impedance interaction results in a gain error of –0.5% Figure 35 shows a basic connection of the DAC1280, with an external op amp current-to-voltage converter.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device DAC1280IPWR Package Package Pins Type Drawing TSSOP PW 16 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2000 330.0 12.4 Pack Materials-Page 1 6.9 B0 (mm) K0 (mm) P1 (mm) 5.6 1.6 8.0 W Pin1 (mm) Quadrant 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) DAC1280IPWR TSSOP PW 16 2000 367.0 367.0 35.
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