●The STHV800 is an octal, monolithic, high-voltage and high-speed pulse generator. It is designed for medical ultrasound applications, but can be used for other piezoelectric, capacitive or MEMS transducers.
●The device integrates a controller logic interface circuit (compatible with both 1.8 V and 3.3 V input signals), level translators, MOSFET gate drivers, noise blocking diodes, and high power P-channel and N-channel MOSFETs as the output stage for each channel. These MOSFETs are capable of providing more than 2 A of peak output current. Each channel has a dedicated bridge in order to reduce power dissipation and jitter during continuous wave mode (peak current is limited to 0.3 A). This CW bridge has dedicated power supplies (HV_CW) which are fully independent on the main HV supplies.
●These HV_CW supplies can be shorted to the HV supplies. The fundamental structure of each channel also consists of active clamping to ground circuitry, anti-leakage and anti-memory block, a thermal sensor to protect the device and an integrated TR-switch (just 8 Ω as equivalent resistor ) to connect the HV output to its LV output, guaranteeing strong decoupling during the transmission phase.
●The eight independent T/R switches can be used in both a dedicated RX chain per channel or in a multiplexing configuration.
●The clamp circuit has a current capability up to 2 A and works directly on the output pin, carrying this node exactly to zero. This feature allows minimized injection change during the transition from clamp to RX state.
●In addition, the STHV800 includes self-biasing circuitry which allows very low power consumption during the RX phase (down to 200 µW global power dissipation) and thermal shutdown block sensing by an external dedicated pin (THSD).
●One of the main benefits of this device is that it requires very few external components: only decoupling capacitors on the HV and LV supplies, and a resistor to pull up the THSD pin (moreover, this resistor can be shared by many devices).
●Each channel is driven independently by only 2 digital bits, which in CW mode become one bit. An external clock can be used with the STHV800 to synchronize all the input signals. This feature, however, is optional: if the CK pin is tied to ground the device works in asynchronous mode.
●Key Features
● High-density ultrasound transmitter
● Two independent half-bridges per channel
● 0 to ±90 V output voltage
● Power-up free
● Synchronization of the input signals (selectable) by an external clock
● Up to 20 MHz operating frequency
● Low-power, high-voltage, high-speed drivers
● 2 independently-supplied half bridges (shorted-option) for each channel, one dedicated to continuous wave (CW) mode
● Main half bridge: ±2 A source and sink currentDown to 20 ps jitterLow 2nd harmonic distortion
● CW half bridge:±0.3 A source and sink currentDown to 10 ps jitterVery low power consumption
● Fully integrated real clamping-to-ground function
● 8 Ω synchronous active clamp
● ±2 A source and sink current
● Fully integrated TR switch
● 8 Ω ON resistance
● Up to 300 MHz BW
● Current consumption down to 10 μA in RX phase
● Receiver multiplexing function
● 1.8 V to 3.6 V CMOS logic interface
● Auxiliary integrated circuits
● Noise blocking diodes
● Anti-leakage on output node
● Fully self-biasing architecture
● Thermal protection
● Latch-up free due to HV SOI technology
● Very few external passive components or supplies needed
