Current consumption from V CC1 and V EE1 (per channel), MAX4805 V CC1 = -V EE1 = +2V, V CC2 = -V EE2 = +5V. Current consumption from MAX4805A

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1 /A General Description The /A 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 /A 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 is optimized for PZT applications, and the A is optimized for CMUT applications. The /A feature eight operational amplifiers configured in a noninverting configuration. The small-signal output impedance of these operational amplifiers is 65I (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 /A 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 P V. The high-voltage (HV) protection is automatically activated as soon as the TX voltage is greater than Q2.7V (typ); no dedicated TX/RX signal is required. The and the A differ in terms of input-current noise, input impedance, and voltage gain. Depending on the equivalent transducer source impedance, either the or the A can be used to optimize a better noise figure. The /A are available in the 32-pin TQFN package. All devices are specified for the commercial NC to +7NC temperature range. Features S High Density/8 Channels Per Package S I/O Protection for TX Burst Up to ±V S Very Fast Recovery Time After TX Burst 1.5µs (typ) S OVP for Signals Greater Than ±2.7V (typ) S Extremely Low Power Dissipation 8mW/ch (typ) S 65I (typ) Low-Signal Output Impedance S 44MHz -3dB Bandwidth (typ) S Voltage Gain 6dB () (typ), 9dB (A) (typ) S Low Voltage Noise 2.2nV/ Hz (typ) () S Low Voltage Noise 2.2nV/ Hz (typ) (A) S Low Current Noise 2.pA/ Hz (typ) () S Low Current Noise 1.7pA/ Hz (typ) (A) S Ultra-Small (5mm x 5mm), 32-Pin TQFN Package Applications Ultrasound Medical Imaging, CMUT Probes Ultrasound Medical Imaging, PZT HF Probes Ultrasound Imaging, PZT NDT Probes Ordering Information/Selector Guide PART VOLTAGE NOISE (nv/ Hz) CURRENT NOISE (pa/ Hz) VOLTAGE GAIN (db) APPLICATIONS PIN-PACKAGE CTJ PZT 32 TQFN-EP* ACTJ PZT, CMUT 32 TQFN-EP* Note: All devices are specified over the C to +7 C operating temperature range. *EP = Exposed pad. +Denotes a lead(pb)-free/rohs-compliant package. For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at ; Rev ; 4/1

2 /A ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) V, V... (V -.3V) to +V V - V...-.5V to +.5V V IN_...-.5V to +.5V,...-.3V to +6V,...-6V to +.3V...-V to +.3V EN...-.3V to +6V Continuous Power Dissipation (T A = +7NC) 32-Pin TQFN (derate 34.5mW/NC above +7NC) mW Junction-to-Ambient Thermal Resistance B JA (Note 1)...29NC/W Junction-to-Case Thermal Resistance B JC (Note 1)...2NC/W Operating Temperature Range... NC to +7NC Storage Temperature Range NC to +15NC Junction Temperature NC Lead Temperature (soldering, 1s)...+3NC Soldering Temperature (reflow)...+26nc Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS ( = - = +2V Q2.5%, T A = NC to +7NC, unless otherwise noted. Typical values are at = - = +2V, = - = +5V, T A = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage 1 = V Supply Voltage 2 = V Supply Current from and I CC1 A Current consumption from and (per channel), = - = +2V, = - = +5V Current consumption from and (per channel), = - = +2V, = - = +5V ma Supply Current from and I CC2 = - = +2V, = - = +5V (per channel) (in reception) 25 5 FA Substrate Supply Current I = - = +2V, V = -V, V = square pulses with Q6V amplitude, f = 5MHz, duty cycle = 2%, PRF = 2kHz, C EXT = pf (per channel) (in transmission) 1 FA Power Dissipation in Reception PD1 A = - = +2V, = - = +5V (per channel) (in reception) (no signal applied) = - = +2V, = - = +5V (per channel) (in reception) (no signal applied) mw 2 Maxim Integrated

3 DC ELECTRICAL CHARACTERISTICS (continued) ( = - = +2V Q2.5%, T A = NC to +7NC, unless otherwise noted. Typical values are at = - = +2V, = - = +5V, T A = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Power Dissipation in Transmission PD2 = - = +2V, V = -V, V = square pulses with Q6V amplitude, f = 5MHz, duty cycle = 2%, PRF = 2kHz, C EXT1 (between and IN_) = pf, C EXT2 (between and GND) = pf (per channel) (in transmission) 2 mw Total Supply Current in Low-Power Mode I OFF EN = GND.1 1 FA and IN_ DC Output Bias V OFF unconnected A mv Small-Signal Output Resistance R OUT V = 5mV TA = +25NC T A = T MIN to T MAX I DC Output V OUT RL = I (T A = +25NC) (Note 3) 4 mv P-P R L = I, THD < 5% (peak to peak), Maximum Output Range V P-P f = 5MHz 5 mv P-P R L = 1kI () db Voltage Gain A V R L = 1kI (A) db Transmission Diode On-Resistance R ON I = 1A 1.5 I Transmission Drop TX DROP I = 1mA mv Positive OVP Thresholds V OVP+ T A = +25NC Output Impedance R 1kI, T = - = +5V A = T MIN to T MAX V Negative OVP Threshold V OVP- Output Impedance R 1kI, = - = +5V /A T A = +25NC T A = T MIN to T MAX IN_ input () ki Input Resistance R IN IN_ input (A) ki LOGIC INPUT (EN).25 x Low-Level Input Voltage V IL V.75 x High-Level Input Voltage V IH V Logic-Input Leakage I LEAK FA V Maxim Integrated 3

4 /A AC ELECTRICAL CHARACTERISTICS ( = - = +2V Q2.5%, T A = NC to +7NC, unless otherwise noted. Typical values are at = - = +2V, = - = +5V, T A = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Total Harmonic Distortion THD f = 5MHz, R L = 1kI, V IN = 2mV P-P -5 db Bandwidth BW -3dB bandwidth, R L = 75I, C L = 2pF, V IN = 2mV P-P 44 MHz f = 5MHz () 2.2 Input-Voltage Noise on IN_ E NOISE f = 12.5MHz (A) 2.2 nv/ Hz f = 5MHz () 2. Input-Current Noise on IN_ I NOISE f = 12.5MHz (A) 1.7 pa/ Hz Output Impedance Z OUT f = 5MHz 7 I Input Impedance Z IN f = 5MHz 3.8 A 9.1 ki Equivalent Input Capacitance C IN 3.5 pf Channel Crosstalk CT f = 5MHz, V OUT =.5V P-P (adjacent channels), R IN = 1kW -4 db Slew Rate Power-Supply Rejection Ratio SR V IN_ = Q2mV square wave, V = QmV, R L = 1kI () V IN_ = Q15mV square wave, V = QmV, R L = 1kI (A) Enable Time t EN EN signal high to normal operation 5 Fs Disable Time t DIS EN signal low to low-power mode 1.5 Fs Note 2: All specifications are % tested at T A = +25NC, unless otherwise noted. Limits over temperature are guaranteed by design. Note 3: Guaranteed by design. Not production tested. P 2 P 25 PSRR- f = 5MHz, 1mV P-P -43 PSRR- f = 5MHz, 1mV P-P -45 PSRR- f = 5MHz, 1mV P-P -43 Signal-to-Noise Ratio SNR C EXT = pf (see Figure 1) 17 dbv Recovery Time After a Transmitted Pulse t R = - = +5V, Q5V P RTZ Pulse P Q6V (see Figure 2) V/Fs db 1.5 Fs 4 Maxim Integrated

5 /A Test Circuits +5V -5V +2V -2V /A (SINGLE OPERATIONAL AMPLIFIER) C EXT IN_ GND +5V EN -V Figure 1. SNR Test Circuit V PULSE - V DIODE V t R V DIODE V IN_ A V 1kΩ V PULSE Figure 2. Recovery Time Test Circuit Maxim Integrated 5

6 /A Typical Operating Characteristics ( = - = +2V, = - = +5V, T A = +25NC, unless otherwise noted.) BANDWIDTH (db) BANDWIDTH vs. FREQUENCY () R L = 5Ω 3mV P-P 4mV P-P /5A toc1 BANDWIDTH (db) BANDWIDTH vs. FREQUENCY (A) R L = 5Ω 3mV P-P 4mV P-P /5A toc2 INPUT IMPEDANCE MAGNITUDE (kω) INPUT IMPEDANCE MAGNITUDE vs. FREQUENCY A /5A toc OUTPUT IMPEDANCE MAGNITUDE (Ω) OUTPUT IMPEDANCE MAGNITUDE vs. FREQUENCY /5A toc4 THD (db) R L = 1kΩ THD vs. FREQUENCY /5A toc5 NOISE FIGURE (db) NOISE FIGURE vs. FREQUENCY R S = 5Ω A /5A toc EQUIVALENT VOLTAGE INPUT NOISE (nv/ Hz) EQUIVALENT VOLTAGE INPUT NOISE vs. FREQUENCY A 1 /5A toc7 EQUIVALENT CURRENT INPUT NOISE (pa/ Hz) EQUIVALENT CURRENT INPUT NOISE vs. FREQUENCY A 1 /5A toc8 CURRENT CONSUMPTION (ma) CURRENT CONSUMPTION vs. TEMPERATURE I CC2 I EE1 I CC1 I EE TEMPERATURE ( C) /5A toc9 6 Maxim Integrated

7 /A Typical Operating Characteristics (continued) ( = - = +2V, = - = +5V, T A = +25NC, unless otherwise noted.) CURRENT CONSUMPTION (ma) A CURRENT CONSUMPTION vs. TEMPERATURE I CC2 I EE1 I CC1 I EE TEMPERATURE ( C) /5A toc1 PSRR+ AND PSRR- (db) PSRR+ AND PSRR- vs. FREQUENCY EE1 1 1 /5A toc11 PSRR+ AND PSRR- (db) PSRR+ AND PSRR- vs. FREQUENCY A 1 1 /5A toc12 TRANSIENT RESPONSE WITH PULSE AT ±2mV /5A toc13 4ns/div 2mV/div 2mV/div TRANSIENT RESPONSE WITH PULSE AT ±15mV /5A toc14 A TRANSIENT RESPONSE WITH PULSE AT ±6V /5A toc15 2mV/div 5V/div 2mV/div 5mV/div 4ns/div ns/div Maxim Integrated 7

8 /A Pin Configuration TOP VIEW OUT7 TX7 IN7 EN IN8 TX8 OUT8 IN OUT TX IN A IN EP 1 TX OUT IN1 TX6 TX1 OUT1 OUT6 GND GND VCC1 VEE1 OUT5 TX5 OUT2 TX2 IN2 IN5 TQFN (5mm 5mm) CONNECT EXPOSED PAD (EP) TO. Pin Description PIN NAME FUNCTION 1 IN1 Channel 1 LV Buffer Input. Connect a HV capacitor between TX1 and IN1 (see the Applications 2 TX1 Channel 1 HV Buffer Input. Connect TX1 to the transducer side. 3 OUT1 Channel 1 Buffer Output. Connect OUT1 to the cable side. 4, 21 GND Ground 5 Negative Op Amp Voltage Supply (-2V (typ)). Bypass to GND with a nf ceramic capacitor. 6 OUT2 Channel 2 Buffer Output. Connect OUT2 to the cable side. 7 TX2 Channel 2 HV Buffer Input. Connect TX2 to the transducer side. 8 IN2 Channel 2 LV Buffer Input. Connect a HV capacitor between TX2 and IN2 (see the Applications 9 OUT3 Channel 3 Buffer Output. Connect OUT3 to the cable side. 1 TX3 Channel 3 HV Buffer Input. Connect TX3 to the transducer side. 11 IN3 Channel 3 LV Buffer Input. Connect a HV capacitor between TX3 and IN3 (see the Applications 12 Negative T/R Switch Voltage Supply (-5V (typ)). Bypass to GND with a nf ceramic capacitor. 13 Positive T/R Switch Voltage Supply (+5V (typ)). Bypass to GND with a nf ceramic capacitor. 14 IN4 Channel 4 LV Buffer Input. Connect a HV capacitor between TX4 and IN4 (see the Applications 15 TX4 Channel 4 HV Buffer Input. Connect TX4 to the transducer side. 16 OUT4 Channel 4 Buffer Output. Connect OUT4 to the cable side. 8 Maxim Integrated

9 PIN NAME FUNCTION 17 IN5 Pin Description (continued) Channel 5 LV Buffer Input. Connect a HV capacitor between TX5 and IN5 (see the Applications 18 TX5 Channel 5 HV Buffer Input. Connect TX5 to the transducer side. 19 OUT5 Channel 5 Buffer Output. Connect OUT5 to the cable side. 2 Positive Op Amp Voltage Supply (+2V (typ)). Bypass to GND with a nf ceramic capacitor. 22 OUT6 Channel 6 Buffer Output. Connect OUT6 to the cable side. 23 TX6 Channel 6 HV Buffer Input. Connect TX6 to the transducer side. 24 IN6 Channel 6 LV Buffer Input. Connect a HV capacitor between TX6 and IN6 (see the Applications 25 OUT7 Channel 7 Buffer Output. Connect OUT7 to the cable side. 26 TX7 Channel 7 HV Buffer Input. Connect TX7 to the transducer side. 27 IN7 /A Channel 7 LV Buffer Input. Connect a HV capacitor between TX7 and IN7 (see the Applications 28 EN Enable Input. CMOS-Level Input. Drive EN low to turn off op amp and three-state I/O. Drive EN high for normal operation. 29 Substrate (lowest voltage in the system) (-V). Bypass with a high-voltage, nf ceramic capacitor to GND. 3 IN8 Channel 8 LV Buffer Input. Connect a HV capacitor between TX8 and IN8 (see the Applications 31 TX8 Channel 8 HV Buffer Input. Connect TX8 to the transducer side. 32 OUT8 Channel 8 Buffer Output. Connect OUT8 to the cable side. EP Exposed Pad. Connect EP to. Functional Diagram /A (SINGLE OPERATIONAL AMPLIFIER) IN_ GND EN Maxim Integrated 9

10 /A Detailed Description The /A 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 SNR for transducers featuring high-output impedance. This results in greater penetration depth and sensitivity. The /A can be adopted in ultrasound probes without any change in the system (scanner machine). Typical applications include high-impedance PZT and CMUT in-probe buffering and amplification. The is optimized for PZT applications, and the A is optimized for CMUT applications. The /A feature eight operational amplifiers configured in a noninverting configuration. The small-signal output impedance of these operational amplifiers is 65I (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 /A provide HV protection for inputs and outputs of the operational amplifiers. The operational amplifier inputs are protected by an external HV capacitor. An integrated automatic HV 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 bursts up to QV. The HV protection is automatically activated as soon as the TX voltage is greater than Q2.7V (typ); no dedicated TX/RX signal is required. The and the A differ in terms of input current noise, input impedance, and voltage gain. Depending on the equivalent transducer source impedance, either the or the A can be used to optimize a better noise figure. Operational Amplifier The features eight low-noise amplifiers (LNA) in a noninverting configuration with a 5.7dB (typ) gain. The A features 8 LNAs in a noninverting configuration with a 9dB (typ) gain. These LNAs are enabled/ disabled by the EN input. Enable (EN) Drive EN high to enable and connect all the operational amplifiers to the outputs. Drive EN low to disable all the operational amplifiers and disconnect from the outputs. When EN is low, the transmission is still possible and the power consumption is zero. This is useful in Continuous Wave Doppler (CWD) mode when typically half of the transducer array is used for transmit and half for receive (see Table 1). Transmit/Receive (T/R) Switch The output of the LNA is protected by an automatic T/R switch. When voltage at exceeds the Q2.7V (typ) thresholds, the switch is automatically opened (highimpedance). The switch is automatically closed (equivalent impedance 65I (typ)) when is between the Q2.7V (typ) thresholds. A dedicated control signal is not required to open or close the switch in typical ultrasound systems. In addition, the switch can be controlled by the EN input. To use the device only in transmit mode (with zero power consumption), drive EN low. This is useful in CWD mode when typically half of the transducer array is used for transmit and half for receive (see Table 1). Table 1. Truth Table EN LNA STATUS T/R SWITCH STATUS Low X Shutdown Open High < V TH- On Open High V TH- < V < V TH+ On Closed (In Receive Mode) High > V TH+ On Open X = Don t care. V TH+ = +2.7V (typ). V TH- = -2.7V (typ). 1 Maxim Integrated

11 /A /A (SINGLE OPERATIONAL AMPLIFIER) V CC C COUP IN_ V CC V EE V EE V PP GND EN PULSER V NN HEAD PROBE MAIN FRAME Figure 3. Ultrasound Probe Application Circuit Applications Information The use of /A can result in transmit signal attenuation. During transmission, the excitation burst reaching the transducer is typically attenuated because of the nonidealities of the automatic T/R switch and because of the capacitor connected between and IN_ that results in an extra load for the transmitter. This attenuation depends on the burst frequency and on-transmitter source impedance. It can typically be compensated by increasing the burst amplitude from the system. The capacitor connected between and IN_ can be chosen in the 47pF to 15pF range depending on the equivalent output impedance of the transducer. A higher capacitance value guarantees a lower attenuation of the received echo signal at expenses of a greater attenuation of the transmit signal. Figure 3 shows a typical ultrasound probe application. An accurate bypass of the voltage supply is required. In particular, it is recommended to have bypass capacitors on VCC1, VEE1, VCC2, VEE2, and pins as close as possible to the device. For noisy power supplies, a capacitor-inductor-capacitor (CLC) filter on each voltage supply is recommended. Power-On/Power-Off Sequences The /A do not require special poweron/off sequencing of the VCC1, VEE1, VCC2, and VEE2 supply voltage. Note: Turn on first. Turning off last is recommended. Supply Bypassing Bypass VCC1, VEE1, VCC2, VEE2, and with nf capacitor as close as possible to the device. PROCESS: BiCMOS Chip Information Package Information For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 32 TQFN-EP T Maxim Integrated 11

12 /A REVISION NUMBER REVISION DATE DESCRIPTION Revision History PAGES CHANGED 4/1 Initial release Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 12 Maxim Integrated 16 Rio Robles, San Jose, CA USA Maxim Integrated The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.