SBAS721A December   2015  – January 2016 DAC60096

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics: DAC DC
    6. 6.6  Electrical Characteristics: Square-Wave Output
    7. 6.7  Electrical Characteristics: General
    8. 6.8  Timing Requirements
    9. 6.9  Typical Characteristics: DC Mode
    10. 6.10 Typical Characteristics: Toggle Mode
    11. 6.11 Typical Characteristics, General
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Digital-to-Analog Converters (DACs)
        1. 7.3.1.1 DAC Transfer Function
        2. 7.3.1.2 DAC Register Structure
      2. 7.3.2 Reference Specifications
    4. 7.4 Device Functional Modes
      1. 7.4.1 Toggle Mode
      2. 7.4.2 DC Mode
    5. 7.5 Programming
      1. 7.5.1 Frame Error Checking
    6. 7.6 Register Maps
      1. 7.6.1 8.5.1 BUFA Register (address = 0x0) [reset = 0x0000]
      2. 7.6.2 BUFB Register (address = 0x1) [reset = 0x0000]
      3. 7.6.3 CON Register (address = 0x4) [reset = 0x0555]
      4. 7.6.4 CRC Register (address = 0x5) [reset = 0xFFF]
      5. 7.6.5 PTR Register (address = 0x6) [reset = 0x0000]
      6. 7.6.6 SWR Register (address = 0x7) [reset = 0x0000]
      7. 7.6.7 PWRM Register (address = 0x6) [reset = 0xCAFE]
      8. 7.6.8 SDIV Register (address = 0x9) [reset = 0x0000]
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Power-Supply Bypassing
        2. 8.2.2.2 Reference Input
        3. 8.2.2.3 TRIGG/Signal Conditioning
        4. 8.2.2.4 External Amplifier Selection
        5. 8.2.2.5 Unbuffered Settling Response
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Device Reset Options
      1. 9.1.1 Power-on-Reset (POR)
      2. 9.1.2 Hardware Reset
      3. 9.1.3 Software Reset
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
      1. 10.2.1 Optimal Layout Example
      2. 10.2.2 Standard Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

The DAC60096 is a low-power, 96-channel, 12-bit, digital-to-analog converter (DAC). The device provides unbuffered bipolar voltage outputs up to ±10.5 V.

This device is suitable for many applications involving multichannel bipolar DACs. Such applications include multichannel variable optical attenuators, MEMS mirror control, and ATE level drivers.

8.2 Typical Application

An example schematic incorporating the DAC60096 device is shown in Figure 49.

DAC60096 typ_app_schem_sbas721.gif Figure 49. Example Schematic

8.2.1 Design Requirements

Figure 49 uses the parameters shown in Table 12.

Table 12. Design Parameters

PARAMETER VALUE
AVCC 12 V
DVDD 5 V
AVSS –12 V
REF1 2.5 V
REF2 2.5 V

8.2.2 Detailed Design Procedure

The following sections display components and applications that may facilitate the design process.

8.2.2.1 Power-Supply Bypassing

For accurate, high-resolution performance, all power supply pins should be bypassed to ground with low ESR ceramic bypass capacitors. For additional noise filtering, use a 10-µF capacitor in parallel with a 0.1-µF capacitor.

8.2.2.2 Reference Input

The internal reference buffers of the DAC60096 device require an external 2.5-V reference voltage source, which can be driven externally through a precision voltage source or generated from a high precision voltage IC. One such integrated circuit is the REF5025, which is a low-noise, low-drift, high precision voltage reference. The basic connections are listed in Figure 50. A supply bypass capacitor ranging between 1 µF to 10 µF is recommended. A 1-µF to 50-µF output capacitor must be connected from VOUT to GND. The ESR value of the output capacitor must be less than or equal to 1.5 Ω to ensure output stability. To help minimize noise, an additional 1-µF capacitor is connected from TRIM/NR to GND.

Figure 50. External Reference

8.2.2.3 TRIGG/Signal Conditioning

The TRIGG input signal provides the square waveform required for the DAC60096 device to operate as a square-wave generator. The DAC registers are prepared for square wave operation on a TRIGG rising edge and the outputs toggle on the falling edge. The Timing Requirements table specifies the timing parameters required for proper operation.

The TRIGG input signal can be supplied from a waveform generator or voltage-to-frequency converter. An example device with schematic is provided in Figure 51. The device highlighted is the LM231, a precision voltage-to-frequency converter with wide range of full-scale frequency (1 Hz to 100 kHz). In Figure 51 the device is configured to display 0.05% linearity over an output frequency range of 10 Hz to 4 kHz with and input range of 25 mV to 12.5 V. For more information, refer to the Typical Applications section of the LM231 datasheet (SNOSBI2).

DAC60096 ext_precision_sbas721.gif Figure 51. External Precision Voltage-to-Frequency Converter for TRIGG Signal

8.2.2.4 External Amplifier Selection

The outputs of the DAC60096 are unbuffered. The output impedance is specified as 41 kΩ. In applications requiring an external buffer, the selected amplifier should exhibit both low-offset voltage and input bias current. The input bias current of the amplifier creates a potential across the DAC output impedance. This voltage error is equivalent to the input bias current multiplied by the DAC output impedance value. For fast settling, the slew rate of the operational amplifier should not impede the settling time of the DAC. Output impedance of the DAC is constant and code-independent, but in order to minimize gain errors the input impedance of the output amplifier should be as high as possible. Additionally, the amplifier adds another time constant, which increases the settling time response of the system. A higher 3-dB bandwidth amplifier effectively shortens the settling time, and additionally increases the bandwidth of the system.

Figure 52. DAC Output With External Amplifier in Voltage-Follower Configuration

8.2.2.5 Unbuffered Settling Response

For applications that use the unbuffered output, the typical settling response for different capacitive loads is displayed in Figure 53.

8.2.3 Application Curves

DAC60096 C012_SBAS721_Settling.png
Figure 53. DAC Settling Time vs Capacitive Load