I am observing an AD5144 (actually 6 devices tested) not loading its configuration on power-up. On consecutive power-ups the configuration was sometimes loaded sometimes not.
The screenshot of the oscilloscope shows the measured supply voltages during power-up.
VDD = VLOGIC = RESET = DIS = WPN = LRDAC = 2.5 V
ADDR0 = ADDR1 = 0V
VSS = EXP = -2.5 V
SCL = SDA = floating
Has anyone of you an idea on how to solve this?
May i know what the three scope shots represent? I'm assuming the pink one is the VDD/VLOGIC and the three others are the terminals?
Also take note that because there are diodes to limit the voltage compliance at Terminal A, Terminal B, and Terminal W (see Figure 48 of the AD5144 data sheet), it is important to power up VDD first before applying any voltage to Terminal A, Terminal B, and Terminal W. Otherwise, the diode is forward-biased such that VDD is powered unintentionally. The ideal power-up sequence is VSS, VDD, VLOGIC, digital inputs, and VA, VB, and VW. The order of powering VA, VB, VW, and digital inputs is not important as long as they are powered after VSS, VDD, and VLOGIC