| Key Input Parameter | Key Output Signal | Recommended Device |
|---|---|---|
|
Supply Voltage: 11.5 V to 12 V Efficiency: ≥ 90% | Output Voltage: ±24 V at 500 mA |
DAC81416, DAC81404, DAC61416, DAC61402, LM51571, LM25776 |
Objective:Design a power-supply solution to optimize the output of DAC81416 high-voltage output.
This application note describes how to design a power supply to power the high voltage output of the DAC81416 using a single 12-V input. The proposed power supply is capable of providing 500 mA of current for a high-voltage output from the DAC. The DAC81416, DAC71416, and DAC61416 (DACx1416) are a pin-compatible family of 16-channel, buffered, high-voltage output digital-to analog converters (DACs) with 16-bit, 14-bit, and 12-bit resolution. A user-selectable output configuration enables full-scale bipolar output voltages of ±20 V, ±10 V, ±5 V or ±2.5 V, and full-scale unipolar output voltages of 40 V, 20 V, 10 V or 5 V.
The DACx1416 requires five power-supply inputs: VIO, VDD, VAA, VCC, and VSS. VDD and VAA should be at the same level. For high-voltage output options like ±20 V, VCC and VSS should be ±24 V to account for the headroom and footroom requirements for the output buffer of the DAC81416. For unipolar output voltage (0 V to 40 V), the minimum VCC supply required is 42 V.
To generate the 24-V VCC supply, use LM51571 in boost configuration. The LM5157x-Q1 device is a wide input range, non-synchronous boost converter with integrated 50-V, 6.5-A (LM5157-Q1) or 50-V, 4.33-A (LM51571-Q1) power switch. The device can be used in boost, SEPIC, and flyback topologies.
The –24-V VSS supply is generated by using the LM25576 in an inverting buck boost configuration. Operating with an input voltage range of 6 V to 42 V, the LM25576 delivers 3 A of continuous output current with an integrated 170-mΩ N-Channel MOSFET