The DAC1282 is a fully-integrated digital-to-analog converter (DAC) providing low distortion, digital synthesized voltage output suitable for testing of seismic equipment

DAC1282

Manufacturer Part NumberDAC1282
DescriptionThe DAC1282 is a fully-integrated digital-to-analog converter (DAC) providing low distortion, digital synthesized voltage output suitable for testing of seismic equipment
ManufacturerTexas Instruments
DAC1282 datasheet
 


Specifications of DAC1282

Dac: Channels1InterfaceSerial SPI
Output TypeVoltageSettling Time(µs)25
Reference: TypeExtPower Consumption(typ)(mw)38
Pin/package24TSSOP  
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LOW DISTORTION DIGITAL-TO-ANALOG CONVERTER FOR SEISMIC
FEATURES
1
• Single-Chip Test Signal Generator
23
Buffered Voltage Output
High Performance:
– THD: –125 dB (G = 1/1 to 1/8)
– SNR: 120 dB (413 Hz BW, G = 1/1)
Analog and Digital Gain Control
Output Frequency: 0.488 Hz to 250 Hz
Sine, Pulse, and DC Modes
Digital Data Input Mode
Low On-Resistance Signal Switch
Sync Input
Power-Down Mode
Analog Supply: 5 V or ±2.5 V
Digital Supply: 1.8 V to 3.3 V
Power: 38 mW
Package: TSSOP-24
Operating Range: –50°C to +125°C
APPLICATIONS
Energy Exploration
Seismic Monitoring Systems
High-Accuracy Instrumentation
SYNC
DOUT
SCLK
RESET/
PWDN
SW/TD
1
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.
SPI is a trademark of Motorola.
2
All other trademarks are the property of their respective owners.
3
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.
Check for Samples:
DAC1282
DESCRIPTION
The DAC1282 is a fully-integrated digital-to-analog
converter (DAC) providing low distortion, digital
synthesized voltage output suitable for testing of
seismic equipment. The DAC1282 achieves very high
performance in a small package with low power.
Together, with the high-performance
ADS1282
devices create a measurement system that meets the
exacting
equipment.
The DAC1282 integrates a digital signal generator, a
DAC, and an output amplifier providing sine wave, dc,
and pulse output voltages.
The output frequency is programmable from 0.5 Hz to
250 Hz and the magnitude is scaled by both analog
and digital control. The analog gain is adjustable in
6-dB steps and the digital gain in 0.5-dB steps. The
analog gain settings match those of the ADS1282 for
testing at all gains with high resolution.
The DAC1282 also provides pulse outputs. The pulse
amplitude is user-programmed and then selected by
the pin for precise timing. Custom output signals can
be generated by applying an external bitstream
pattern.
A signal switch can be used to connect the DAC
output to sensors for THD and impulse testing. The
switch timing is controlled by pin and by command.
A SYNC pin synchronizes the DAC output to the
analog-to-digital converter (ADC) sample interval. A
power-down input disables the device, reducing
power consumption to microwatts.
DVDD
DAC1282
CLK
CS
Digital
DIN
Serial
Signal
Interface
Generator
Optional Bitstream Input
DGND
SBAS490 – DECEMBER 2011
ADS1281
analog-to-digital converters (ADCs), these
demands
of
seismic
data
VREF
AVDD
VOUTP
Voltage
Output
DAC
VOUTN
Switch In
Switch Out
AVSS
Copyright © 2011, Texas Instruments Incorporated
DAC1282
and
acquisition

DAC1282 Summary of contents

  • Page 1

    ... The analog gain settings match those of the ADS1282 for testing at all gains with high resolution. The DAC1282 also provides pulse outputs. The pulse amplitude is user-programmed and then selected by the pin for precise timing. Custom output signals can be generated by applying an external bitstream pattern ...

  • Page 2

    ... Submit Documentation Feedback ORDERING INFORMATION RELATED PRODUCTS (1) JEDEC standard 22, test method A114-C.01, all pins JEDEC standard 22, test method C101, all pins Product Folder Link(s): DAC1282 www.ti.com DEVICE ADS1281 ADS1282 REF5050 DAC1282 MIN MAX UNIT –0.3 +5.5 V –2.8 +0.3 V –0.3 +3.6 V –10 +10 mA AVSS – 0.3 AVDD + 0 ...

  • Page 3

    ... VOUTN) = ±V /2 × Gain. Gain is the DAC analog gain. REF = 0.48 × (AVDD – AVSS) + AVSS. COM Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 = +25°C, AVDD = +2 Figure 50. DAC1282 MIN TYP MAX UNIT ±V /2 × gain V REF –0.1 V Ω 1.6 ...

  • Page 4

    ... SWIN SWOUT T = +25° +85° Product Folder Link(s): DAC1282 www.ti.com = +25°C, AVDD = +2 Figure 50. DAC1282 MIN TYP MAX UNIT ±0.0195 ±2.5 ±0.1 ±0.75 3 ppm/°C ±0.5 ±3 3 µV/°C 1.5 µV 5 V/µ 100 1.3 µ ...

  • Page 5

    ... AVDD = +2 Figure 50. DAC1282 MIN TYP MAX UNIT –2 AVSS + 5.25 V 1.65 3.6 V (11) 7.4 8 µA 180 300 µ µ µW –40 +85 °C –50 +125 °C –65 +150 °C DAC1282IPW PW (TSSOP) UNITS 24 PINS 78.3 12.1 33.8 °C/W 0.3 33.5 N/A Submit Documentation Feedback 5 ...

  • Page 6

    ... CAPN DGND 11 14 AVSS 13 VREF 12 AVDD DAC1282 Terminal Functions DESCRIPTION Analog positive power supply Analog negative power supply, reference ground Analog negative power supply External capacitor connected to VOUTN External capacitor connected to VOUTP Serial port chip select Master clock 4.096 MHz Key digital ground ...

  • Page 7

    ... DOUT load = 100 kΩ to DGND. Copyright © 2011, Texas Instruments Incorporated t SPWH t SPWL Figure 1. Serial Interface Timing DESCRIPTION (1) (3) (3) Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 t CSH t SCCS B0 t DOPD DOHD CSDOZ MIN MAX UNIT 30 ...

  • Page 8

    ... G000 Product Folder Link(s): DAC1282 www.ti.com = 5 V, unless otherwise noted. REF Gain = 1/2 4k FFT Vo = 31.25 Hz, −0.5 dBFS THD = −125.6 dB SNR = 119.0 dB 100 150 200 250 300 350 400 450 500 Frequency (Hz) G000 Figure 3 ...

  • Page 9

    ... G000 25 Gain = 1/1 Gain = 1/64 30 units Pulse Mode 105 125 G000 Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 = 5 V, unless otherwise noted. REF GAIN ERROR vs TEMPERATURE Gain = 1/1 Gain = 1/8 Gain = 1/64 Gain = 1/2 Gain = 1/16 Pulse Mode Gain = 1/4 Gain = 1/32 − ...

  • Page 10

    ... Gain = 1/1 Gain = 1/2 100 Gain = 1/4 Gain = 1/8 Gain = 1/16 80 Gain = 1/32 Gain = 1/ −40 −20 0 −120 G000 Product Folder Link(s): DAC1282 www.ti.com = 5 V, unless otherwise noted. REF SNR vs TEMPERATURE Gain = 1/1 Gain = 1/8 Gain = 1/64 Gain = 1/2 Gain = 1/16 Gain = 1/4 Gain = 1/32 − 105 125 Temperature (°C) Figure 15 ...

  • Page 11

    ... POWER-SUPPLY CURRENT vs TEMPERATURE 8 30 Units Gain = 1/1 2 Gain = 1/2 Gain = 1 −110 −105 −55 −35 G000 Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 = 5 V, unless otherwise noted. REF Gain = 1/8 Gain = 1/64 Gain = 1/16 Gain = 1/32 2 2.5 3 3.5 4 4.5 Clock (MHz) G000 Figure 21. Gain = 1/8 Gain = 1/64 Gain = 1/16 Gain = 1/32 3 ...

  • Page 12

    ... G000 SWITCH ON-RESISTANCE MATCH vs TEMPERATURE 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 −55 −35 G000 Product Folder Link(s): DAC1282 www.ti.com = 5 V, unless otherwise noted. REF SWITCH THD vs RESISTIVE LOAD Gain = 1/1 Gain = 1/2 Gain = 1/4 Gain = 1/8 Gain = 1/16 Gain = 1/32 Gain = 1/64 100 1000 10000 100000 1000000 Switch Output Load Resistance ( ) Figure 27. ...

  • Page 13

    ... An SPI™-compatible serial interface is used to access the DAC1282 registers for device configuration and control. The configuration registers can be read back by clocking the data out on the DOUT pin. The DAC1282 voltage output is fully differential and is taken out on the VOUTP/VOUTN pins. The CAPP/CAPN pins connect to external filter capacitors to reduce the output noise ...

  • Page 14

    ... The SYNC input synchronizes the output signal to a known time reference. In sine mode, SYNC resets the sine wave to the zero crossing. In Pulse mode, SYNC selects one of two user-programmed dc levels. The RESET/PWDN pin powers down the device when low. When RESET/PWDN is released high, the DAC1282 is reset. ...

  • Page 15

    ... ADC and does not affect system performance. DAC MODES The DAC1282 has four operational modes of: sine, dc, pulse, and external digital data input. These modes are programmed by the MODE[1:0] bits in the GANMOD register, as shown in MODE[1:0] BITS ...

  • Page 16

    ... DIFFERENTIAL RANGE (V) ±2.5 0 –6 ±1.25 –12 ±0.625 –18 ±0.312 –24 ±0.156 –30 ±0.078 –36 ±0.039 Product Folder Link(s): DAC1282 www.ti.com FREQ BIT 1111 1111 1 1111 1111 0 0111 1111 0 0011 1111 0 0001 1111 0 0000 1111 0 0000 0111 ...

  • Page 17

    ... Full mute Full mute Full mute DC Mode The DAC1282 provides a dc output mode with 24-bit available resolution. The output level is determined by the analog gain and the 24-bit dc registers. The GAIN[2:0] register bits set the analog gain (see over the selected analog range. ...

  • Page 18

    ... Arbitrary DAC output waveforms can be generated by application of custom digital data patterns. The data format in this mode is ones-density modulated input at CLK/16 data rate (256 kHz). The input is applied to the SW/TD input pin. The DAC1282 output in digital data mode is defined in Digital Data Mode Differential Output = VOUTP – VOUTN = V ...

  • Page 19

    ... REFERENCE VOLTAGE (V ) REF The DAC1282 requires an external reference for operation. Although reference voltage as low as 2.5 V can be used, best SNR is achieved with a 5-V reference. The reference input is defined as the voltage difference between VREF and AVSS (that is, V reference noise or drift appears on the DAC output. Excessive reference noise may lead to degraded SNR. A low-drift and low-noise reference is recommended ...

  • Page 20

    ... Submit Documentation Feedback Figure 46. In pulse mode, the filter is internally disabled, yielding shorter CAPP 2 k VOUTP Current Output Amplifier DAC VOUTN 2 k CAPN Figure 36. Output Filter Product Folder Link(s): DAC1282 www.ti.com Copyright © 2011, Texas Instruments Incorporated ...

  • Page 21

    ... OUTPUT SWITCH (SWINP, SWINN, SWOUTP, SWOUTN) The DAC1282 has an integrated output switch. The switch can be used to route the DAC output signal to a sensor for pulse, THD, and common-mode testing. The switch has low on-resistance and matched elements to minimize signal distortion. The switch input voltage range extends to the analog power supply. ...

  • Page 22

    ... When the ones-density is 50% (on average, an equal number of '0's and '1's), the differential output is zero. SW/TD is sampled by the DAC1282 at the rate of CLK/16. Therefore, the sampling can have ±8 CLK periods of uncertainty. SYNC can be used to eliminate the uncertainty by synchronizing the phase of SW/TD to the desired CLK cycle. Synchronizing the digital input results in a consistent phase of the output signal ...

  • Page 23

    ... SYNC SYNC is a digital input used to synchronize the DAC1282 output. In the digital data mode, the DAC input is a ones-density bitstream. In this mode, the SYNC pin synchronizes the sampling of SW/TD digital data to the desired master clock cycle (CLK). When SYNC is low or high, the DAC operates normally ...

  • Page 24

    ... SYLO Figure 40. Sine Mode Synchronization Figure 40 DESCRIPTION SYNC pulse width low Figure 41. When the SYNC pin is changed, the DAC output PULSA PULSB PULSA Output SYNC Product Folder Link(s): DAC1282 www.ti.com Figure 40. That is, the SYNC t SCSU t CSHD (1) MIN UNIT 2 t CLK ...

  • Page 25

    ... The signal output and digital pin DOUT enters 3-state and the output switch is driven off. Note that the digital inputs must remain defined as either logic low or logic high; do not float the inputs. Disable the CLK input to minimize leakage. To exit the power-down state, take the pin high. The DAC1282 is reset after power-down mode is exited. ...

  • Page 26

    ... V and V REF Offset and Gain Error The DAC1282 features a low offset error ( ±7/Gain + 50 ppm FS typical) and low gain error (0.1 % typical). Offset and gain drift are also very low for the DAC1282. Drift is calculated using the box calculation method of Equation 4: Drift Calculation = (Max – ...

  • Page 27

    ... DAC gain for each output range. The noise is the standard deviation of 4096-point ADC acquisition record (RMS noise, referred-to-output). Total Harmonic Distortion (THD) The DAC1282 achieves excellent THD performance. The THD data are obtained using the DAC circuit of Figure 50 and captured by the ADS1282. The ADC gain is set to the complement of the DAC gain for each output range. THD is measured with a – ...

  • Page 28

    ... SYNC pin transition −2 − 100 150 200 250 300 350 400 450 Time (µs) Figure 46. DC Mode Step Response Figure 47 illustrates the DAC1282 frequency response. Note that OUTPUT FREQUENCY RESPONSE 0 CLK = 4.096MHz Excludes I/V Filter Rolloff ...

  • Page 29

    ... Avoid starting new commands after this time interval to prevent an unexpected serial port reset at the next command instant. Data Input (DIN) DIN is the data input pin used to send data to the DAC. The DAC1282 latches DIN input data on the rising edge of SCLK. Data Output (DOUT) DOUT is the data output pin used to read register data out of the DAC ...

  • Page 30

    ... The commands summarized in Table 14 commands are two-byte command arguments plus additional data bytes while the reset command is a one-byte command. The DAC1282 serial port chip select (CS) can be taken high or held low between commands but must remain low for the entire command operation. COMMAND ...

  • Page 31

    ... Description: This command resets the DAC. The registers are set to power-on default the value; see the RESET/PWDN section. Copyright © 2011, Texas Instruments Incorporated 9 17 OPCODE 1 OPCODE 2 REG DATA 1 Don’t Care Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 25 REG DATA 2 Submit Documentation Feedback 31 ...

  • Page 32

    ... DAC1282 SBAS490 – DECEMBER 2011 REGISTER MAP DAC1282 operation is controlled through a set of 8-bit registers. Collectively, the registers contain all the information needed to configure the DAC, such as output frequency and amplitude, output pulse levels, etc. Table 15 shows the register map. The default state of the device at power-up, after the RESET pin is taken high or after a RESET command is as follows: Sine mode, frequency = 31.25 Hz, – ...

  • Page 33

    ... Common-mode positive SWINP to SWOUTP and SWINP to SWOUTN Common-mode negative SWINN to SWOUTP and SWINN to SWOUTN Single-ended positive SWINP to SWOUTP only Single-ended negative SWINN to SWOUTN only Short SWOUTP to SWOUTN Product Folder Link(s): DAC1282 DAC1282 SBAS490 – DECEMBER 2011 SINEG2 SINEG1 SINEG0 Table 17 ...

  • Page 34

    ... Table 6. Note that the pulse level value is independent of the PULSB4 PULSB3 PULSB2 Table 6. Note that the pulse level value is independent of the RANGE[2:0] Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): DAC1282 www.ti.com DCG1 DCG0 1 0 DCG9 ...

  • Page 35

    ... BASIC CONNECTION Figure 50 shows the basic DAC1282 connection. Bipolar analog supplies are shown (±2.5 V). Single-supply operation is also possible with AVDD = 5 V and AVSS = GND. The digital supply range low-noise, low-drift reference is recommended for best performance, such as the REF5050 (+5 V) and REF5045 (+4 ...

  • Page 36

    ... The DAC1282 is used to test both the ADC and geophone. The DAC1282 connects directly to channel 1 of the ADC. Tests of the ADC include THD, pulse, input noise, common-mode, etc. The DAC output and ADC sample timing are controlled by the SYNC input pins ...

  • Page 37

    ... FOUR-CHANNEL SEISMIC SYSTEM Figure 52 illustrates a four-channel system. The switched DAC1282 output is routed to the ADC inputs. The signal from the DAC switch is used to perform sensor impulse testing by opening the switch while digitizing the response. Geophone Geophone Geophone Geophone Figure 52. Four-Channel Seismic System Copyright © ...

  • Page 38

    ... Orderable Device (1) Package Type Package Status DAC1282IPW ACTIVE TSSOP DAC1282IPWR ACTIVE TSSOP (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. ...

  • Page 39

    ... TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Type Drawing DAC1282IPWR TSSOP PW PACKAGE MATERIALS INFORMATION Pins SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 24 2000 330.0 16.4 6.95 Pack Materials-Page 1 22-Dec-2011 Pin1 (mm) (mm) (mm) (mm) Quadrant 8.3 1.6 8.0 16.0 Q1 ...

  • Page 40

    ... Device Package Type DAC1282IPWR TSSOP PACKAGE MATERIALS INFORMATION Package Drawing Pins SPQ Length (mm 2000 Pack Materials-Page 2 22-Dec-2011 Width (mm) Height (mm) 346.0 346.0 33.0 ...

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  • Page 43

    ... Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’ ...