Analog Devices Inc./Maxim Integrated

The MAX4805/MAX4805A are octal high-voltage-protected operational amplifiers. These devices are a fully integrated, very compact solution for in-probe amplification of echo signals coming from transducers in an ultrasound system. The use of in-probe buffering improves system signal-to-noise ratio (SNR) for transducers featuring high-output impedance. This results in greater penetration depth and sensitivity. The MAX4805/MAX4805A can be adopted in ultrasound probes without any change in the system (scanner machine). Typical applications include high-impedance piezoelectric transducers (PZT) and capacitive micromachined ultrasonic transducers (CMUT) in-probe buffering and amplification. The MAX4805 is optimized for PZT applications, and the MAX4805A is optimized for CMUT applications.The MAX4805/MAX4805A feature eight operational amplifiers configured in a noninverting configuration. The small-signal output impedance of these operational amplifiers is 65Ω (typ) for matching the typical cable impedance. The low-noise amplifier features 44MHz (typ) -3dB bandwidth and very low voltage and current noise, ensuring excellent noise figure. The output signals of these operational amplifiers are limited with diodes in an antiparallel configuration to GND.The MAX4805/MAX4805A provide HV protection for inputs and outputs of the operational amplifiers. The operational amplifiers inputs are protected by an external HV capacitor. An integrated automatic high-voltage switch protects the output of the amplifier from HV bursts. Transmitted bursts reach the transducer through a pair of integrated, antiparallel diodes. Each channel is able to sustain transmission burst up to ≤ 100V. The high-voltage (HV) protection is automatically activated as soon as the TX voltage is greater than ±2.7V (typ); no dedicated TX/RX signal is required.The MAX4805 and the MAX4805A differ in terms of input-current noise, input impedance, and voltage gain. Depending on the equivalent transducer source impedance, either the MAX4805 or the MAX4805A can be used to optimize a better noise figure.The MAX4805/MAX4805A are available in the 32-pin TQFN package. All devices are specified for the commercial 0°C to +70°C temperature range.ApplicationsUltrasound Imaging, PZT NDT ProbesUltrasound Medical Imaging, CMUT ProbesUltrasound Medical Imaging, PZT HF Probes

The MAX481E, MAX483E, MAX485E, MAX487E- MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environments. Each driver output and receiver input is protected against ±15kV electro-static discharge (ESD) shocks, without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw as little as 120µA supply current when unloaded or when fully loaded with disabled drivers (see Selector Guide). Additionally, the MAX481E, MAX483E, and MAX487E have a low-current shutdown mode in which they consume only 0.5µA. All parts operate from a single +5V supply.Drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.The MAX487E and MAX1487E feature quarter-unit-load receiver input impedance, allowing up to 128 transceivers on the bus. The MAX488E-MAX491E are designed for full-duplex communications, while the MAX481E, MAX483E, MAX485E, MAX487E, and MAX1487E are designed for half-duplex applications. For applications that are not ESD sensitive see the pinand function-compatible MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487.ApplicationsIndustrial-Control Local Area NetworksLevel TranslatorsLow-Power RS-422 TransceiversLow-Power RS-485 TransceiversTransceivers for EMI-Sensitive Applications

The MAX4810/MAX4811/MAX4812 integrated circuits generate high-voltage, high-frequency, unipolar or bipolar pulses from low-voltage logic inputs. These dual pulsers feature independent logic inputs, independent high-voltage pulser outputs with active clamps and independent high-voltage supply inputs.The MAX4810/MAX4811/MAX4812 feature a 9Ω output impedance for the high-voltage outputs, and a 27Ω impedance for the active clamp. The high-voltage outputs are guaranteed to provide 1.3A output current.All devices use three logic inputs per channel to control the positive and negative pulses and active clamp. Also included are two independent enable inputs. Disabling EN ensures the output MOSFETs are not accidentally turned on during fast power-supply ramping. This allows for faster ramp times and smaller delays between pulsing modes. A low-power shutdown mode reduces power consumption to less than 1µA. All digital inputs are CMOS compatible.The MAX4810 includes clamp output overvoltage protection, while the MAX4811 features both pulser output and clamp output overvoltage protection. The MAX4812 does not provide overvoltage protection. See theOrdering Information/Selector Guidein the full data sheet.The MAX4810/MAX4811/MAX4812 are available in a 56-pin (7mm x 7mm), TQFN exposed-pad package and are specified over the 0°C to +70°C commercial temperature range.ApplicationsCleaning EquipmentFlaw DetectionPiezoelectric DriversTest InstrumentsUltrasound Medical Imaging