The AD5755-1 is a quad， voltage and current output digital-toanalog converter （DAC） that operates with a power supply range from ?26.4 V to +33 V. On-chip dynamic power control minimizes package power dissipation in current mode. This is achieved by regulating the voltage on the output driver from 7.4 V to 29.5 V using a dc-to-dc boost converter optimized for minimum on-chip power dissipation. Each channel has a corresponding CHART pin so that HART signals can be coupled onto the current output of the AD5755-1. The device uses a versatile 3-wire serial interface that operates at clock rates of up to 30 MHz and is compatible with standard SPI， QSPI?， MICROWIRE?， DSP， and microcontroller interface standards. The interface also features optional CRC-8 packet error checking， as well as a watchdog timer that monitors activity on the interface.