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for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim?s website at www.maxim integrated .com. octal high-voltage-protected, low-power, low-noise operational amplifiers 19-5242; rev 0; 4/10 ordering information/selector guide general description the max4805/max4805a are octal high-voltage-protect- ed operational amplifiers. these devices are a fully inte- grated, 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 featuri ng high-output impedance. this results in greater penetra- tion depth and sensitivity. the max4805/max4805a can be adopted in ultrasound probes without any change in the system (scanner machine). typical applica- tions include high-impedance piezoelectric transducers (pzt) and capacitive micromachined ultrasonic trans- ducers (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 65 i (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 exter- nal 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 100v. the high-voltage (hv) protection is automatically activated as soon as the tx voltage is greater than q 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 imped- ance, 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 com- mercial 0 n c to +70 n c temperature range. features s high density/8 channels per package s i/o protection for tx burst up to 100v s very fast recovery time after tx burst 1.5s (typ) s ovp for signals greater than 2.7v (typ) s extremely low power dissipation 8mw/ch (typ) s 65 i (typ) low-signal output impedance s 44mhz -3db bandwidth (typ) s voltage gain 6db (max4805) (typ), 9db (max4805a) (typ) s low voltage noise 2.2nv/ hz (typ) (max4805) s low voltage noise 2.2nv/ hz (typ) (max4805a) s low current noise 2.0pa/ hz (typ) (max4805) s low current noise 1.7pa/ hz (typ) (max4805a) 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 note: all devices are specified over the 0c to +70c operating temperature range. * ep = exposed pad. + denotes a lead(pb)-free/rohs-compliant package. part voltage noise (nv/ hz ) current noise (pa/ hz ) voltage gain (db) applications pin-package max4805 ctj+ 2.2 2.0 5.7 pzt 32 tqfn-ep* max4805a ctj+ 2.2 1.7 8.7 pzt, cmut 32 tqfn-ep* max4805/max4805a downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers stresses beyond those listed under ?absolute maximu m ratings? may cause permanent damage to the device . these are stress ratings only, and functional operation of the device at these or any other condi tions beyond those indicated in the operational sec tions of the specifications is not implied. exposur e to absolute maximum rating conditions for extended periods may affect device reliability. (all voltages referenced to gnd.) v tx_ , v out_ ......................................... (v gsub - 0.3v) to +100v v tx_ - v out_ ........................................................-0.5v to +0.5v v in_ .......................................................................-0.5v to +0.5v v cc1 , v cc2 .............................................................-0.3v to +6v v ee1 , v ee2 ...............................................................-6v to +0.3v gsub ..................................................................-100v to +0.3v en ............................................................................-0.3v to +6v continuous power dissipation (t a = +70 n c) 32-pin tqfn (derate 34.5mw/ n c above +70 n c) ....2758.6mw junction-to-ambient thermal resistance b ja (note 1) .................................................................29 n c/w junction-to-case thermal resistance b jc (note 1) ...................................................................2 n c/w operating temperature range ............................. 0 n c to +70 n c storage temperature range ............................ -65 n c to +150 n c junction temperature ................................................... +150 n c lead temperature (soldering, 10s) ................................+300 n c soldering temperature (reflow) ......................................+260 n c dc electrical characteristics (v cc1 = -v ee1 = +2v q 2.5%, t a = 0 n c to +70 n c, unless otherwise noted. typical values are at v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v, t a = +25 n c.) (note 2) absolute maximum ratings note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four- layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . parameter symbol conditions min typ max units supply voltage 1 v cc1 v cc1 = -v ee1 1.95 2 5 v supply voltage 2 v cc2 v cc2 = -v ee2 4.9 5 5.1 v supply current from v cc1 and v ee1 i cc1 max4805 current consumption from v cc1 and v ee1 (per channel), v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v 2.1 3.2 ma max4805a current consumption from v cc1 and v ee1 (per channel), v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v 1.9 3.0 supply current from v cc2 and v ee2 i cc2 v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v (per channel) (in reception) 25 50 f a substrate supply current i gsub v cc1 = -v ee1 = +2v, v gsub = -100v, v out_ = square pulses with q 60v ampli- tude, f = 5mhz, duty cycle = 2%, prf = 20khz, c ext = 100pf (per channel) (in transmission) 10 f a power dissipation in reception pd1 max4805 v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v (per channel) (in reception) (no signal applied) 8.4 13.2 mw max4805a v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v (per channel) (in reception) (no signal applied) 12.2 max4805/max4805a 2 maxim integrated downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers dc electrical characteristics (continued) (v cc1 = -v ee1 = +2v q 2.5%, t a = 0 n c to +70 n c, unless otherwise noted. typical values are at v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v, t a = +25 n c.) (note 2) parameter symbol conditions min typ max units power dissipation in transmission pd2 v cc1 = -v ee1 = +2v, v gsub = -100v, v out_ = square pulses with q 60v ampli- tude, f = 5mhz, duty cycle = 2%, prf = 20khz, c ext1 (between tx_ and in_) = 100pf, c ext2 (between tx_ and gnd) = 100pf (per channel) (in transmis- sion) 20 mw total supply current in low-power mode i off en = gnd 0.1 1 f a dc output bias v off tx_ and in_ unconnected max4805 -20 -3 +20 mv max4805a -50 -10 +50 small-signal output resistance r out v out_ = 50mv t a = +25 n c 48 65 101 i t a = t min to t max 35 140 dc output v out r l = 100 i (t a = +25 n c) (note 3) 400 mv p-p maximum output range v out_p-p r l = 100 i , thd < 5% (peak to peak), f = 5mhz 500 mv p-p voltage gain a v r l = 10k i (max4805) 5.1 5.7 6.1 db r l = 10k i (max4805a) 7.8 8.7 9.2 db transmission diode on-resistance r on i = 1a 1.5 i transmission drop tx drop i = 1ma 400 600 750 mv positive ovp thresholds v ovp+ output impedance r 1k i , v cc2 = -v ee2 = +5v t a = +25 n c 1.5 2.7 3.8 v t a = t min to t max 1.0 4.0 negative ovp threshold v ovp- output impedance r 1k i , v cc2 = -v ee2 = +5v t a = +25 n c -4.1 -2.9 -1.5 v t a = t min to t max -4.5 -1.0 input resistance r in in_ input (max4805) 2.7 4 5.4 k i in_ input (max4805a) 15.5 24 33.0 k i logic input (en) low-level input voltage v il 0.25 x v cc1 v high-level input voltage v ih 0.75 x v cc1 v logic-input leakage i leak -1 +1 f a max4805/max4805a maxim integrated 3 downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers ac electrical characteristics (v cc1 = -v ee1 = +2v q 2.5%, t a = 0 n c to +70 n c, unless otherwise noted. typical values are at v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v, t a = +25 n c.) (note 2) note 2: all specifications are 100% tested at t a = +25 n c, unless otherwise noted. limits over temperature are guaranteed by design. note 3: guaranteed by design. not production tested. parameter symbol conditions min typ max units total harmonic distortion thd f = 5mhz, r l = 1k i , v in = 20mv p-p -50 db bandwidth bw -3db bandwidth, r l = 75 i , c l = 20pf, v in = 20mv p-p 44 mhz input-voltage noise on in_ e noise f = 5mhz (max4805) 2.2 nv/ hz f = 12.5mhz (max4805a) 2.2 input-current noise on in_ i noise f = 5mhz (max4805) 2.0 pa/ hz f = 12.5mhz (max4805a) 1.7 output impedance z out f = 5mhz 70 i input impedance z in f = 5mhz max4805 3.8 k i max4805a 9.1 equivalent input capacitance c in 3.5 pf channel crosstalk ct f = 5mhz, v out = 0.5v p-p (adjacent channels), r in = 1k ? -40 db slew rate sr v in_ = q 200mv square wave, v out_ = q 100mv, r l = 1k i (max4805) p 20 v/ f s v in_ = q 150mv square wave, v out_ = q 100mv, r l = 1k i (max4805a) p 25 power-supply rejection ratio psrr- v cc1 f = 5mhz, 1mv p-p -43 db psrr- v ee1 f = 5mhz, 1mv p-p -45 psrr- gsub f = 5mhz, 1mv p-p -43 signal-to-noise ratio snr c ext = 100pf (see figure 1) 170 dbv recovery time after a transmitted pulse t r v cc2 = -v ee2 = +5v, q 5v p rtz pulse p q 60v (see figure 2) 1.5 f s enable time t en en signal high to normal operation 5 f s disable time t dis en signal low to low-power mode 1.5 f s max4805/max4805a 4 maxim integrated downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers test circuits figure 1. snr test circuit figure 2. recovery time test circuit max4805/max4805a (single operational amplifier) c ext v cc2 +2v -2v -100v v cc1 v ee1 gsub +5v en gnd +5v -5v v cc2 v ee2 v cc1 v ee2 v ee1 out_ tx_ in_ 1k ? v cc2 v out_ v pulse max4805 max4805a tx_ v diode v pulse - v diode v out_ 0v t r in_ out_ max4805/max4805a maxim integrated 5 downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers typical operating characteristics (v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v, t a = +25 n c, unless otherwise noted.) current consumption vs. temperature max4805/5a toc09 temperature (c) current consumption (ma) 60 50 40 30 20 10 5 10 15 20 0 0 70 max4805 i ee1 i ee2 i cc1 i cc2 equivalent current input noise vs. frequency max4805/5a toc08 frequency (mhz) equivalent current input noise (pa/ hz) 10 1 10 0.1 100 1 max4805 max4805a equivalent voltage input noise vs. frequency max4805/5a toc07 frequency (mhz) equivalent voltage input noise (nv/ hz) 10 10 1 100 1 max4805 max4805a noise figure vs. frequency max4805/5a toc06 frequency (mhz) noise figure (db) 10 1 2 3 4 5 6 70 1 100 r s = 500 ? max4805 max4805a thd vs. frequency max4805/5a toc05 frequency (mhz) thd (db) 10 -60 -40 -20 0 -80 1 100 r l = 1k ? output impedance magnitude vs. frequency max4805/5a toc04 frequency (mhz) output impedance magnitude ( ? ) 10 20 40 60 80 100 120 0 1 100 input impedance magnitude vs. frequency max4805/5a toc03 frequency (mhz) input impedance magnitude (k ? ) 10 5 10 15 20 25 0 1 100 max4805 max4805a bandwidth vs. frequency (max4805a) max4805/5a toc02 frequency (mhz) bandwidth (db) 10 -25 -20 -15 -10 -5 0 5 -30 1 100 r l = 50 ? 30mv p-p 400mv p-p bandwidth vs. frequency (max4805) max4805/5a toc01 frequency (mhz) bandwidth (db) 10 -25 -20 -15 -10 -5 0 -30 1 100 r l = 50 ? 30mv p-p 400mv p-p max4805/max4805a 6 maxim integrated downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers typical operating characteristics (continued)(v cc1 = -v ee1 = +2v, v cc2 = -v ee2 = +5v, t a = +25 n c, unless otherwise noted.) transient response with pulse at 60v max4805/5a toc15 100ns/div out_50v/div tx_ 50mv/div transient response with pulse at 150mv max4805/5a toc14 40ns/div tx_200mv/div out_ 200mv/div max4805a transient response with pulse at 200mv max4805/5a toc13 40ns/div tx_200mv/div out_ 200mv/div max4805 psrr+ and psrr- vs. frequency max4805/5a toc12 frequency (mhz) psrr+ and psrr- (db) 10 -50 -40 -30 -20 -10 0 -60 1 100 max4805a gsub v cc2 v cc1 v ee2 v ee1 psrr+ and psrr- vs. frequency max4805/5a toc11 frequency (mhz) psrr+ and psrr- (db) 10 -50 -40 -30 -20 -10 0 -60 1 100 max4805 gsub v cc1 v cc2 v cc1 v ee1 v ee2 current consumption vs. temperature max4805/5a toc10 temperature (c) current consumption (ma) 60 50 40 30 20 10 5 10 15 20 0 0 70 max4805a i ee1 i ee2 i cc1 i cc2 max4805/max4805a maxim integrated 7 downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers pin configuration pin description tqfn (5mm 5mm) top view 2930 28 27 1211 13 tx1 gnd v ee1 out2 tx2 14 in1 tx6gnd v cc1 in6out5 tx5 1 2 en 4 5 6 7 23 24 22 20 19 18 gsub in8 in4v cc2 v ee2 in3 out1 out6 3 21 31 10 tx8 tx3 32 9 out8 ep connect exposed pad (ep) to gsub. + out3 in7 26 15 tx4 tx7 25 16 out4 in2 in5 8 17 out7 max4805 max4805a pin name function 1 in1 channel 1?lv buffer input. connect a hv capacitor between tx1 and in1 (see the applications information section). 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 v ee1 negative op amp voltage supply (-2v (typ)). bypass v ee1 to gnd with a 100nf 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 information section). 9 out3 channel 3?buffer output. connect out3 to the cable side. 10 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 information section). 12 v ee2 negative t/r switch voltage supply (-5v (typ)). bypass v ee2 to gnd with a 100nf ceramic capacitor. 13 v cc2 positive t/r switch voltage supply (+5v (typ)). bypass v cc2 to gnd with a 100nf ceramic capacitor. 14 in4 channel 4?lv buffer input. connect a hv capacitor between tx4 and in4 (see the applications information section). 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. max4805/max4805a 8 maxim integrated downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers pin description (continued) functional diagram max4805/max4805a (single operational amplifier) v cc2 v cc1 v ee1 gsub en gnd v cc2 v ee2 v cc1 v ee2 v ee1 out_ tx_ in_ pin name function 17 in5 channel 5?lv buffer input. connect a hv capacitor between tx5 and in5 (see the applications information section). 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. 20 v cc1 positive op amp voltage supply (+2v (typ)). bypass v cc1 to gnd with a 100nf 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 information section). 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 channel 7?lv buffer input. connect a hv capacitor between tx7 and in7 (see the applications information section). 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 gsub substrate (lowest voltage in the system) (-100v). bypass gsub with a high-voltage, 100nf ceramic capacitor to gnd. 30 in8 channel 8?lv buffer input. connect a hv capacitor between tx8 and in8 (see the applications information section). 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 gsub. max4805/max4805a maxim integrated 9 downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers detailed description the max4805/max4805a are octal high-voltage-pro- tected operational amplifiers. these devices are a fully integrated, very compact solution for in-probe amplifi- cation 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 max4805/max4805a 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 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 65 i (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 max4805/max4805a provide hv protection for inputs and outputs of the operational amplifiers. the operational amplifier inputs are protected by an exter- nal 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 q 100v. the hv protec- tion is automatically activated as soon as the tx voltage is greater than q 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 imped- ance, either the max4805 or the max4805a can be used to optimize a better noise figure. operational amplifier the max4805 features eight low-noise amplifiers (lna) in a noninverting configuration with a 5.7db (typ) gain. the max4805a features 8 lnas in a noninverting config- uration 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 out_ outputs. drive en low to disable all the operational amplifiers and disconnect from the out_ 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 out_ exceeds the q 2.7v (typ) thresholds, the switch is automatically opened (high- impedance). the switch is automatically closed (equiva- lent impedance 65 i (typ)) when out_ is between the q 2.7v (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 x = don?t care. v th+ = +2.7v (typ). v th- = -2.7v (typ). en out_ lna status t/r switch status low x shutdown open high < v th- on open high v th- < v out_ < v th+ on closed (in receive mode) high > v th+ on open max4805/max4805a 10 maxim integrated downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers applications information the use of max4805/max4805a 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 tx_ 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 tx_ and in_ can be chosen in the 47pf to 150pf 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 attenua- tion of the transmit signal. figure 3 shows a typical ultra- sound probe application. an accurate bypass of the voltage supply is required. in particular, it is recommended to have bypass capacitors on v cc1 , v ee1 , v cc2 , v ee2 , and gsub 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 max4805/max4805a do not require special power- on/off sequencing of the v cc1 , v ee1 , v cc2 , and v ee2 supply voltage. note: turn on gsub first. turning off gsub last is rec- ommended. supply bypassing bypass v cc1 , v ee1 , v cc2 , v ee2 , and gsub with 100nf capacitor as close as possible to the device. chip information process: bicmos package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . 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. figure 3. ultrasound probe application circuit max4805/max4805a (single operational amplifier) v cc2 v cc pulser main frame head probe v cc1 v ee1 gsub en gnd v cc2 v ee2 v cc1 v ee2 v ee v ee1 v cc v ee v pp v nn out_ tx_ in_ c coup package type package code document no. 32 tqfn-ep t3255-4 21-0140 max4805/max4805a maxim integrated 11 downloaded from: http:///
octal high-voltage-protected, low-power, low-noise operational amplifiers revision history revision number revision date description pages changed 0 4/10 initial release ? max4805/max4805a downloaded from: http:/// maxim integrated 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 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. ? maxim integrated the maxim logo and maxim integrated are trademarks of maxim integrated products, inc.

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