Abstract

Smart probes are handheld, highly-integrated, ultrasound imaging equipment. Smart probes are used to obtain the images of internal organs by scanning the human body with ultrasound beams. Compared with traditional portable device, smart probe is stricter in power consumption, thermal performance, size constraint and noise immunity. This application note introduces an efficient and low quiescent loss answer for powering the transmitter in the probe based on TI’s reference design PMP40488. This design generates bipolar adjustable high voltage (HV) from ±15 V to ±75 V. The output voltage can be adjusted by FPGA. The continuous average power of each rail is 0.75 W. To meet the size limitation(< 5 mm) of smart probe, a single-ended primary inductor converter (SEPIC) topology with uncoupled inductor is applied. The quiescent power loss is reduced by changing the switching frequency to 100 kHz at standby mode while 250 kHz at normal operation. The deviation of the negative rail is ±2% with the unbalance load at 15-V output and ±1% at 75-V output. The output voltage can be linearly control by an operational amplifier (op amp) with the external signal (0 V to 2.5 V).