MD0105 features ? up to 130v input voltage protection ? low on resistance - 15 typical ? fast switching speed ? four electrically isolated channels ? no external supplies needed applications ? medical ultrasound imaging ? ndt applications ? fast resettable fuses ? high side switches ? data acquisition general description the supertex MD0105 is a high voltage current limiting protection device. it is designed to protect a low noise receiver from the high voltage transmit pulses in ultrasound applications and is commonly referred to as a t/r (transmit and receive) switch. the MD0105 can be considered as a normally closed switch with a typical switch resistance of 15 , allowing small signals to pass. once the voltage drop across the two terminals exceeds a nominal value of 2.0v, the device will start to turn off. in the off state, the MD0105 can withstand up to 130v across its terminals. a small amount of current, typically 200a, is allowed to fow through. the MD0105 is not limited to just ultrasound applications. it can also be used for resettable fuses to protect power lines, output short circuit protection, and data acquisition. the MD0105 is available in an 18-lead 5x5mm dfn package as a four-channel device. typical application circuit four-channel high voltage protection t/r switch tr ansmitter piezo tr ansducers b a receiver tx rx high voltage switches +130v -130v t/r switch MD0105 logic control and signal processing supertex inc. supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com
2 MD0105 absolute maximum ratings 1 -g indicates package is rohs compliant (green) ordering information device package option 18-lead dfn 5.00x5.00mm body 1.00mm height (max) 0.50mm pitch MD0105 MD0105k6-g pin confgurations product marking 18-lead dfn (k6) (top view) (pads are at bottom of device) package may or may not include the following marks: si or 18-lead dfn (k6) parameter value v a - v b liihuhwldorowdjhgurs 0 to 140v maximum junction temperature +125c storage temperature range -65c to 150c 3rhuglvvlsdwlr/hdg)1 2 1.6w notes: 1. absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditions is not implied. continuous operation of the device at the absolute rating level may affect device reliability. all voltages are referenced to device ground. 2. mounted on fr4 board, 25mm x 25mm x 1.57mm 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 nc b1 nc b2 nc b3 nc b4 nc nc a1 nc a2 nc a3 nc a4 nc MD0105 llllll yyww aaaccc l = lot number yy = last digit of year sealed ww = code for week sealed a = assembler id c = country of origin = ?green? packaging electrical characteristics (t j = 25oc, unless otherwise specifed) sym parameter min typ max units conditions bv a-b breakdown voltage from a to b or b to a 130 - - v i a-b = 1.0ma r sw switch on resistance from a to b or b to a - 15 - i a-b = 5.0ma v trip v a-b trip point to turn off - 1.0 2.0 v --- v off switch turn off voltage - 2.0 - v i a-b = 1.0ma i a-b(off) switch off current - 200 300 v a-b = 130v i peak peak switching current - 60 - ma --- t off turn off time - - 20 ns --- t on turn on time - - 20 ns --- c sw(on) switch on capacitance from a to b or b to a - 21 - pf sw = on c sw(off) switch off capacitance from a to b or b to a - 15 - pf v sw = 25v bw small signal bandwidth - 100 - mhz r load t j operating junction temperature -40 - +125 c --- esd sensitive devic e e supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com
3 MD0105 block diagram switch control com a b typical i-v characteristics i a-b -v off -v trip +130v i a-b = -200a -130v i a-b = +200a v a-b r sw = 15 +i peak -i peak +v trip +v off +1.0ma +1.0ma functional description the supertex MD0105 can be considered as a normally closed switch controlled by a switch control (please refer to the block diagram). the switch control monitors the voltage drop across terminals a and b. if the voltage difference is greater than 2.0v, the t/r switch will start to open. once in the open state, there is a small amount of current fowing through the t/r switch, 200a, to detect if the high voltage is still present or not. the t/r switch will not close until the voltage across termi - nal a and b drops below 2.0v. a pair of back-to-back di - odes from the receive side of the switch to ground is needed to complete the circuit and to allow the initial peak current (about 60ma) to fow through the switch so it can drop 2.0v. if the diodes are not present, then there is no current path and the voltage drop across terminal a and b will be less than 2.0v, so the switch will remain in the closed position. the MD0105 does not require any power supply. there are only two active pins; one connects to the transmitter side, one connects to the receiver side. on resistance when the voltage across terminals a and b are below 2.0v, the switch is in the receive mode and the r on is typically 15. once the voltage across the terminals a and b is greater than 2.0v, the switch is in the transmit mode and blocking the high voltage pulses from passing through to the receiver and damaging it. supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com
4 MD0105 switch capacitance the typical switch on capacitance (c sw(on) ) is 21pf. this is measured from a to b when the switch is on. the switch off capacitance is a function of the voltage across the t/r switch. the c sw(off) is about 12 to 19 pf for 10v to 130v of the transmit voltage. t on and t off time the t on and t off of the MD0105 are less than 20ns, which provide a fast switch between the transmit mode and the re - ceive mode. the t on and t off are input rise/fall time depen - dent. the t/r switch turns on and off faster when the rise and fall times of the transmit pulse are faster. on the other hand, the switch turns on and off slower if the rise and fall times of the transmit pulse are slower. pad name description 1 nc no internal connection 2 a1 switch terminal a1 3 nc no internal connection 4 a2 switch terminal a2 5 nc no internal connection 6 a3 switch terminal a3 7 nc no internal connection 8 a4 switch terminal a4 9 nc no internal connection pad name description 10 nc no internal connection 11 b4 switch terminal b4 12 nc no internal connection 13 b3 switch terminal b3 14 nc no internal connection 15 b2 switch terminal b2 16 nc no internal connection 17 b1 switch terminal b1 18 nc no internal connection center tab --- connect to ground pin description supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com
5 MD0105 (the package drawing(s) in this data sheet may not refect the most current specifcations. for the latest package outline information go to http://www.supertex.com/packaging.html .) doc.# dsfp-MD0105 b080211 18-lead dfn package outline (k6) 5.00x5.00mm body, 1.00mm height (max), 0.50mm pitch symbol a a1 a3 b d d2 e e2 e l l1 dimension (mm) min 0.80 0.00 0.20 ref 0.18 4.85* 4.20 ? 4.85* 3.50 ? 0.50 bsc 0.30 ? 0.00* 0 o nom 0.90 0.02 0.25 5.00 4.35 ? 5.00 3.65 ? 0.40 ? - - max 1.00 0.05 0.30 5.15* 4.45 ? 5.15* 3.75 ? 0.50 ? 0.15 14 o jedec registration mo-229, variation vjjd-2, issue c, aug. 2003. * this dimension is not specifed in the jedec drawing. ? this dimension differs from the jedec drawing. drawings not to scale. supertex doc. #: dspd-18dfnk65x5p050, version a013111. notes: 1. a pin 1 identifer must be located in the index area indicated. the pin 1 identifer can be: a molded mark/identifer; an embedded metal marker; or a printed indicator. 2. depending on the method of manufacturing, a maximum of 0.15mm pullback (l1) may be present. 3. the inner tip of the lead may be either rounded or square. seating plane t op vi ew side v iew bottom v iew a a1 d e d2 e b e2 a3 l l1 v iew b vi ew b 1 note 3 note 2 note 1 (index area d/2 x e/2) note 1 (index area d/2 x e/2) 1 supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such appl ications unless it receives an adequate ?product liability indemnification insurance agreement.? supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. no responsibility is assumed for possible omissions and inaccuracies. circuitry and specifications are subject to change without notice. for the latest product specifications refer to the supertex inc. (website: http//www .supertex.com) ?201 1 supertex inc. a ll rights reserved. unauthorized use or reproduction is prohibited. supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com
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