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us90a / US91A 24v hall ic fan driver 390109026302 page 1 of 12 data sheet rev 002 apr/07 features and benefits low cost high sensitivity hall sensor locked rotor protection and auto-restart power-efficient cmos and power mosfets built-in output protection clamping diode integrated tachometer (us90a) or alarm (US91A) sig nal output 2-coil fan driver with fg/rd output in 4-pin vk / va and 8-pin narrow soic packages (all rohs compliant) application examples 12v/24v fans peak current up to 500ma ordering information part no. temperature code package code us90a e (-40c to 85c) vk (4-pin to-92) us90a e (-40c to 85c) dc (8-pin narrow soic) us90a e (-40c to 85c) va (4-pin to-92 flat) US91A e (-40c to 85c) vk (4-pin to-92) US91A e (-40c to 85c) dc (8-pin narrow soic) US91A e (-40c to 85c) va (4-pin to-92 flat) 1 functional diagram 2 general description the us90a/91a is a one-chip solution for driving two-coil brushless dc cooling fans. based on the advanced melexis cmos process, the ic contains a hall-effect sensor, dynamic offset correction and low side output drivers. frequency generator or rotation detection is available. the open-drain output makes the connectivity with any external interface such as hardware monitoring or super i/o ic easier. these features are combined with the melexis patented no-v dd design to fit the ic in small 4-pin vk and va package. the device is also delivered in dc package for automatic assembly.
us90a / US91A 24v hall ic fan driver 390109026302 page 2 of 12 data sheet rev 002 apr/07 table of contents 1 functional diagram ............................... ................................................... ...................... 1 2 general description.............................. ................................................... ....................... 1 3 glossary of terms ................................ ................................................... ....................... 3 4 absolute maximum ratings ......................... ................................................... ............... 3 5 pin definitions and descriptions................. ................................................... ............... 3 6 general electrical specifications ................ ................................................... ............... 4 7 magnetic specifications .......................... ................................................... .................... 4 8 driver output vs magnetic pole................... ................................................... ............... 4 9 detailed general description ..................... ................................................... ................. 5 10 unique features................................. ................................................... ........................ 5 11 performance graphs .............................. ................................................... ................... 6 11.1 r dson vs t j ................................................... ................................................... ................................................... ............. 6 11.2 r dson vs v dd ................................................... ................................................... ................................................... ......... 6 11.3 magnetic parameters vs t j ................................................... ................................................... ............................ 6 11.4 magnetic parameters vs v dd ................................................... ................................................... ......................... 6 11.5 i dd vs t j ................................................... ................................................... ................................................... .................... 6 11.6 i dd vs v dd ................................................... ................................................... ................................................... ................ 6 11.7 v ol vs t j ................................................... ................................................... ................................................... .................. 7 11.8 power dissipation vs. t a ................................................... ................................................... ................................. 7 12 application information......................... ................................................... .................... 7 12.1 typical application with pull-up resistor ................................................... .................. 7 12.2 configuration for reverse voltage / ground hot-swi tch protection and enhanced esd module protection ................................................... ................................................... ....... 7 13 application comments ............................ ................................................... .................. 7 14 standard information regarding manufacturability of melexis products with different soldering processes...................... ................................................... .................. 8 15 esd precautions ................................. ................................................... ....................... 8 16 package information............................. ................................................... ..................... 9 16.1 vk package information (4-pin to92) ................................................... ................................................... ... 9 16.2 dc package information (8-pin narrow soic) ................................................... .................................. 10 16.3 va package information (4-pin to92 flat) ................................................... ........................................... 11 17 disclaimer...................................... ................................................... ........................... 12
us90a / US91A 24v hall ic fan driver 390109026302 page 3 of 12 data sheet rev 002 apr/07 3 glossary of terms two-coil fan a fan with two-coil windings where cur rent alternates from 1 coil to the other depending on the direction of the magnetic field. millitesla (mt), gauss units of magnetic flux densi ty : 1mt = 10 gauss v dd voltage on the coils common node. i dd current supplying the chip which flows through the coil connected to the switched off output driver. peak output current the current flowing in the coil at start-up, only limited by the coil resistance r coil and the output driver resistance r dson. continuous output current the current flowing in th e coil when the fan is spinning normally. locked rotor the state when the fan stopped spinnin g due to mechanical blockage. fg frequency generator or tachometer output rd rotation detection or alarm output lfpm linear feet per minute ? unit of airflow veloc ity 4 absolute maximum ratings parameter symbol value units fan supply voltage v dd 30 v peak output current i outp 500 ma continuous output current i outc 250 ma fg / rd output current i fg (rd) 20 ma operating temperature range t a - 40 to 85 c junction temperature t j 125 c storage temperature range t s - 55 to 150 c magnetic flux density b unlimited mt table 1: absolute maximum ratings exceeding the absolute maximum ratings may cause pe rmanent damage. exposure to absolute-maximum- rated conditions for extended periods may affect de vice reliability. 5 pin definitions and descriptions pin name pin number (vk) pin number (dc) pin number (va) function fg (rd) 1 1 1 fg (rd) open drain output signal out1 2 2 2 open drain coil driver 1 out2 3 4 4 open drain coil driver 2 gnd 4 3 3 ground pin - - 5, 6, 7, 8 - not connected table 2: pin definitions and descriptions us90a (us 91a)
us90a / US91A 24v hall ic fan driver 390109026302 page 4 of 12 data sheet rev 002 apr/07 6 general electrical specifications dc operating parameters t a = 25 o c, v dd = 24v (unless otherwise specified) parameter symbol test conditions min typ max units fan supply voltage v dd operating, r coil = 50 4.7 (1) 30 v supply current i dd 2 4 ma output saturation voltage v dson 1,2 i out = 150ma 375 mv output saturation voltage v dson 1,2 i out = 250ma 625 mv output clamp voltage v out 1,2 60 v fg / rd output low voltage v ol i ol = 10ma 250 500 mv fg / rd output clamp voltage v clamp 28 v fg / rd output leakage current i leak v fg (v rd ) = 18v 10 :a dc thermal resistance r thja one-sided pcb, zero lfpm 150 c/watt vk thermal resistance r thja one-sided pcb, zero lfpm 200 c/watt va thermal resistance r thja one-sided pcb, zero lfpm 170 c/watt locked rotor period t on 0.25 s locked rotor period t off 1.5 s output switching delay t delay dead time when both drivers are off 200 us table 3: general electrical specifications note 1: the minimal value of vdd should be determined using the following equation: v dd = 4.5v + r coil * i dd 7 magnetic specifications dc operating parameters t a = 25 o c, v dd = 24v (unless otherwise specified) parameter symbol test conditions min typ max units operate point b op 3 6 mt release point b rp -6 -3 mt hysteresis b hyst 2 6 mt table 4: magnetic specifications 8 driver output vs magnetic pole parameter test conditions out1 out2 north pole b < brp C all packages high low south pole b > bop - all packages low high table 5: driver output vs. magnetic pole note 3: the magnetic pole is applied facing the branded sid e of the package
us90a / US91A 24v hall ic fan driver 390109026302 page 5 of 12 data sheet rev 002 apr/07 9 detailed general description the us90a/91a is a one-chip solution for driving tw o-coil brushless dc fans. based on advanced melexis cmos process, the ic contains a hall-effect sensor, dynamic offset correction and low side output driv ers. the output drivers out1 and out2 are fully protecte d against switching transients. so there is no need for an external zener diode to cut the high voltage spi kes induced by the fan coils. the us90a has an open-drain integrated tachometer f g output that follows the hall signal. in the US91A, the open-drain rotation detection out put rd is active low during normal spinning of the motor. it goes high when the flux switching frequency beco mes too low, which means the motor is blocked. 10 unique features the absence of a v dd pin enables the two low side output drivers and fg /rd signal output to fit in a four-pin vk package. the lack of a v dd pin decreases also the probability to damage the c hip due to reverse voltage connection, using the coil resistance to limit the reverse current. in this condition, the total rever se current is twice the peak current value of the fan used. the built-in locked-rotor protection will automatic ally shut off the coil current when the rotor is me chanically blocked, or the rotational speed drops below 60 rpm (4-pole rotor magnet). the fan will try to restart every 1.5 seconds until the obstruction is clear. the on / off cycling reduces the average stall current to 1/7 normal; this is enough to prevent overheating or damage to most fans. both the us90a and US91A have this featu re.
us90a / US91A 24v hall ic fan driver 390109026302 page 6 of 12 data sheet rev 002 apr/07 11 performance graphs 11.1 r dson vs t j 0 1 2 3 4 5 -40 -20 0 20 40 60 80 100 120 tj (c) ron (ohms) vdd = 5v vdd = 24v 11.2 r dson vs v dd 0 1 2 3 4 5 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 vdd (volts) ron (ohms) tj = -40c tj = 25c tj = 125c 11.3 magnetic parameters vs t j -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 -40 -20 0 20 40 60 80 100 120 tj (c) magnetic field (mt) bop, vdd=5v bop, vdd=24v brp, vdd=5v brp, vdd=24v 11.4 magnetic parameters vs v dd -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 vdd (volts) magnetic field (mt) bop, tj=25c bop, tj=125c brp, tj=25c brp, tj=125c bop, tj=-40c brp, tj=-40c 11.5 i dd vs t j 0 0.5 1 1.5 2 2.5 3 3.5 4 -40 -20 0 20 40 60 80 100 120 tj (c) idd (ma) vdd = 5v vdd = 24v 11.6 i dd vs v dd 0 0.5 1 1.5 2 2.5 3 3.5 4 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 vdd (volts) idd (ma) tj = -40c tj = 25c tj = 125c
us90a / US91A 24v hall ic fan driver 390109026302 page 7 of 12 data sheet rev 002 apr/07 11.7 v ol vs t j 0 0.1 0.2 0.3 0.4 0.5 -40 -20 0 20 40 60 80 100 120 tj (c) fg/rd output saturation voltage (volts) vdd=5v ; iol=10ma vdd=24v ; iol=10ma 11.8 power dissipation vs. t a 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 -40 -20 0 20 40 60 80 100 120 140 ta (c) allowable power dissipation (w) vk - r th = 200c/w - pd max = 500mw t a = 25c t a max = 85c t j max = 125c va - r th = 170c/w - pd max = 588mw dc - r th = 150c/w - pd max = 666mw 12 application information 12.1 typical application with pull-up resistor 12.2 configuration for reverse voltage / ground hot-switch protection and enhanced esd module protection 13 application comments figure 12.2 shows the application including several external protections. the diode d revprot best protects the chip and fan coils for reverse vo ltage condition. the capacitor c bypass is recommended if the supply ground may be disconn ected while running even though the positive supply point is still connected. this capacitor provides a path to ground for the remaini ng energy in the coil which has to be evacuated. without it, the energy can flow from out1/out2 to the fg/rd dri ver, without any limitation and may cause eos damage. its value has to be tuned depending on the coils ch aracteristics. bigger inductance requires bigger ca pacitor. the no-v dd design enables esd protection at fan module level to be easily improved. the fan coils prevent and filter fast current stress on out1 and out2, re sulting in better esd protection. adding the option al capacitor c out enhances the esd protection of the logic output. h ence, the fan module is able to withstand esd stress at relatively high value without damage.
us90a / US91A 24v hall ic fan driver 390109026302 page 8 of 12 data sheet rev 002 apr/07 14 standard information regarding manufacturability of melexis products with different soldering processes our products are classified and qualified regarding soldering technology, solderability and moisture s ensitivity level according to following test methods: reflow soldering smd?s (s urface m ount d evices) ? ipc/jedec j-std-020 moisture/reflow sensitivity classification for nonh ermetic solid state surface mount devices (classification reflow profiles according to table 5-2) ? eia/jedec jesd22-a113 preconditioning of nonhermetic surface mount device s prior to reliability testing (reflow profiles according to table 2) ? melexis working instruction 341901308 wave soldering smd?s (s urface m ount d evices) and thd?s (t hrough h ole d evices) ? en60749-20 resistance of plastic- encapsulated smd?s to combin ed effect of moisture and soldering heat ? eia/jedec jesd22-b106 and en60749-15 resistance to soldering temperature for through-hol e mounted devices ? melexis working instruction 341901309 iron soldering thd?s (t hrough h ole d evices) ? en60749-15 resistance to soldering temperature for through-hol e mounted devices ? melexis working instruction 341901309 solderability smd?s (s urface m ount d evices) and thd?s (t hrough h ole d evices) ? eia/jedec jesd22-b102 and en60749-21 solderability ? melexis working instruction 3304312 for all soldering technologies deviating from above mentioned standard conditions (regarding peak temperature, temperature gradient, temperature prof ile etc) additional classification and qualificatio n tests have to be agreed upon with melexis. the application of wave soldering for smd?s is allo wed only after consulting melexis regarding assuran ce of adhesive strength between device and board. for more information on the lead free topic please see quality page at our website: http://www.melexis.com/quality.aspx 15 esd precautions electronic semiconductor products are sensitive to electro static discharge (esd). always observe electro static discharge control pro cedures whenever handling semiconductor products.
us90a / US91A 24v hall ic fan driver 390109026302 page 9 of 12 data sheet rev 002 apr/07 16 package information 16.1 vk package information (4-pin to92) 5.22 +/-0.10 4.20 +/-0.10 3.65 +/-0.10 1.42 +/-0.10 0.46 +0.02 - 0.03 0.38 +/-0.03 1.27 +/-0.03 3.81 +/-0.03 0.00 0.20 10.50 +/-0.30 1.55 +/-0.10 0.73 +/-0.10 3 +2 (2x) 5 (2x) +2 -1 0.38 +/-0.03 e.d.m process surface ro1.6~2.4um 0.30 +/-0.10 (2x) 3 +2 (2x) 5 (2x) +2 -1 notes: 1. all dimensions are in millimeters 2. package dimension exclude molding flash. mold flash shall not exceed 0.127mm. 3. to preserve reliability, it is recommended to have total lead length equal to 2.5mm minimum, measured from the package line. 4. vk package is a pin through-hole package, hence adapted for wave soldering process. a reflow soldering process is not recommended with vk package as it may seriously affect device reliability. marking: 1 st line : us90a (US91A) - name of the device 2 nd line : xxxx - assembly lot number (4 last digits) 2.5 min see note 3 hall plate location notes: 1. all dimensions are in millimeters 2. typical values 0.52 2.25 1.05
us90a / US91A 24v hall ic fan driver 390109026302 page 10 of 12 data sheet rev 002 apr/07 16.2 dc package information (8-pin narrow soic) 5.80 6.20 3.81 3.99 1.37 1.57 1.52 1.72 1.95
us90a / US91A 24v hall ic fan driver 390109026302 page 11 of 12 data sheet rev 002 apr/07 16.3 va package information (4-pin to92 flat) 0.30 +/-0.05 5.38 +/-0.05 5.16 +/-0.08 0.40 +/-0.05 1.27 +/-0.05 3.81 +/-0.05 5 5(2x) 0.25 5(2x) 5(2x) notes: 1. all dimensions are in millimeters 2. package dimension exclude end flash marking: top side: 1 st line : us90a (US91A) - name of the device 2 nd line : xxxxxx - assembly lot number (last 6 digits) bottom side: yyww : yy = year ww = week hall plate location 2.69 notes: 1. all dimensions are in millimeters 2. typical values 0.33 4.30 +/-0.20 1 max 0.40 0.60 1x45(ref) +0.06 - 0.07 1.10 1.20 45(typ) 0.24 0.29 0.61 0.66 45(2x)
us90a / US91A 24v hall ic fan driver 390109026302 page 12 of 12 data sheet rev 002 apr/07 17 disclaimer devices sold by melexis are covered by the warranty and patent indemnification provisions appearing in its term of sale. melexis makes no warranty, express, s tatutory, implied, or by description regarding the information set forth herein or regarding the freed om of the described devices from patent infringemen t. melexis reserves the right to change specifications and prices at any time and without notice. therefo re, prior to designing this product into a system, it is nece ssary to check with melexis for current information . this product is intended for use in normal commercial ap plications. applications requiring extended tempera ture range, unusual environmental requirements, or high reliability applications, such as military, medical life- support or life-sustaining equipment are specifical ly not recommended without additional processing by melexis for each application. the information furnished by melexis is believed to be correct and accurate. however, melexis shall no t be liable to recipient or any third party for any dama ges, including but not limited to personal injury, property damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or consequ ential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the t echnical data herein. no obligation or liability to recipien t or any third party shall arise or flow out of mel exis? rendering of technical or other services. ? 2002 melexis nv. all rights reserved. for the latest version of this document, go to our website at www.melexis.com or for additional information contact melexis direc t: europe and japan: all other locations: phone: +32 1367 0495 phone: +1 603 223 2362 e-mail: sales_europe@melexis.com e-mail: sales_usa@mel exis.com iso/ts 16949 and iso14001 certified

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