AD5668:  Octal, 16-Bit, SPI Voltage Output denseDAC With 5 PPM/°C On-Chip Reference

The AD5668 device is a low power, octal, 16-bit, buffered voltage-output DAC. The device operates from a single 2.7 V to 5.5 V supply and is guaranteed monotonic by design.

The AD5668 has an on-chip reference with an internal gain of 2. The AD5668-1 has an 1.25 V 5 ppm/°C reference, giving a full-scale output range of 2.5 V; the AD5668-2, -3 has a 2.5 V 5 ppm/°C reference, giving a full-scale output range of 5 V. The on-board reference is off at power-up, allowing the use of an external reference. The internal reference is enabled via a software write.

The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V (AD5668-1, -2) or midscale (AD5668-3) and remains powered up at this level until a valid write takes place. The part contains a power-down feature that reduces the current consumption of the device to 400 nA at 5 V and provides software-selectable output loads while in power-down mode for any or all DAC channels.

The outputs of all DACs can be updated simultaneously using the LDAC function, with the added functionality of user-selectable DAC channels to simultaneously update. There is also an asynchronous CLR that updates all DACs to a user-programmable code—zero scale, midscale, or full scale.

The AD5668 utilizes a versatile 3-wire serial interface that operates at clock rates of up to 50 MHz and is compatible with standard SPI®, QSPI™, MICROWIRE™, and DSP interface standards. The on-chip precision output amplifier enables rail-to-rail output swing.

The AD5668-EP supports defense and aerospace applicatons (AQEC)

1. Octal, 16-bit DAC.
2. On-chip 1.25 V/2.5 V, 5 ppm/°C reference.
3. Available in 14-lead/16-lead TSSOP.
4. Power-on reset to 0 V or midscale.
5. Power-down capability. When powered down, the DAC typically consumes 200 nA at 3 V and 400 nA at 5 V.

Applications

• Optical transceivers
• Power Amp control
• Data acquisition systems
• Digital gain and offset adjustment