general description the max2181 is a highly integrated fm variable-gain low-noise amplifier ideal for use in automotive fm and fm-diversity active antenna applications. the device features an fm signal path, providing 30db of gain range, controlled by an on-chip power detector. the fm signal path covers 76mhz to 162.5mhz. the device integrates a voltage regulator and pass tran - sistor, allowing operation using battery voltages in the +6v to +24v range. on-chip thermal protection automati - cally limits junction temperatures during extreme thermal conditions. the device is available in a small, 3mm x 3mm tqfn package and operates over the extended industrial tem - perature range (-40oc to +85oc). applications automotive active antenna features +6v to +24v supply voltage range integrated agc function eliminates external pin diodes high dynamic range low-noise, sub 3db noise figure low external bom integrated thermal protection small package (3mm x 3mm tqfn) integrated pass device and linear regulator integrated power detector integrated antenna sense 19-6558; rev 0; 12/12 ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maximintegrated.com/max2181.related . simplifed block diagram evaluation kit available fm v cc det v reg v ant fm output max2181 v cc max2181 fm automotive low-noise amplifier
maxim integrated 2 dc electrical characteristics (max2181 evaluation kit as shown, v batt = 8v to 15v, t a = -40oc to +85oc, unless otherwise noted. typical values are at v batt = 10v, t a = +25oc.) (note 2) 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.maximintegrated.com/thermal-tutorial . v batt .................................................................... -0.5v to +26v ldo ......................................................................... -0.5v to +6v fmout ................................................................. -0.5v to v ldo short-circuit protection fmout .................................. indefinite fmin ........................................................................ 130db vrf continuous power dissipation (t a = +70oc) (derate 20.8mw/oc above +70oc) .......................... 1666.7mw jc (junction to case) (note 1) ........................................ 7oc/w ja (junction to ambient) (note 1) .................................. 48oc/w operating temperature range ............................ -40oc to +85oc junction temperature ...................................................... +150oc storage temperature range ............................. -65oc to +165oc lead temperature (tqfn only, soldering, 10s) .............. +300oc soldering temperature (reflow) ....................................... +260oc absolute maximum ratings 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 ab solute maximum rating conditions for extended periods may affect device reliability. parameter conditions min typ max units supply voltage (v batt ) v batt operational range 8 10 15 v functional range (note 3) 15 24 voltage regulation v ldo (pin 12) 5.1 v supply current normal operation (v antsense = 0v or 6v < v antsense = 12v) 56 68 ma antenna fault, antsense open 15 25 gain control and agc control (fmdet, fmgain, antsense) antsense ground -50 a open 2.5 v ldo 50 a fmdet ground -65 a ldo 50 fmgain ground -50 a open 2.5 v ldo 50 a caution! esd sensitive device max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 3 ac electrical characteristics (max2181 evaluation kit, v batt = 8v to 15v, t a = -40 c to +85 c, unless otherwise noted. typical values are at v batt = 10v, load impedance = 50?, fmgain connected to ground, tuned for 87mhz to 108mhz, t a = +25 c.) (note 2) note 2: min and max values are production tested at t a = +25oc and +85oc. min and max limits at t a = -40oc are guaranteed by design and characterization. note 3: device automatically reduces current to limit die temperature within a safe range, but otherwise remains functional. note 4: guaranteed by design and characterization. note 5: tuned for 76mhz to 90mhz. parameter conditions min typ max units frequency range 76 162.5 mhz power gain maximum f in = 97mhz , fmgain connected to v ldo 6.0 8.3 10 db f in = 97mhz, fmgain open 5.0 7.2 9.0 f in = 97mhz, fmgain connected to ground 4.0 6.0 8.0 gain flatness 76mhz to 90mhz (notes 4, 5) 0.5 db 87mhz to 108mhz (note 4) 0.5 162.5mhz relative to 97mhz 3.2 noise figure f in = 97mhz, t a = +25oc 2.75 db input return loss 50? source 10 db output return loss 50? load 15 db gain control range f in = 97mhz 28 32 db imd3 v in = +120dbv/tone, +100dbv agc threshold, 99.5mhz and 100.5mhz tones 66 dbc agc threshold minimum output threshold 92 dbv maximum output threshold 106 agc threshold variation relative to 97mhz tone (76mhz to 108mhz) 1 db max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 4 typical operating characteristics (max2181 evaluation kit, v batt = 10v, tuned for 87mhz to 108mhz, fmgain connected to ground, t a = +25 c, unless otherwise noted.) gain vs. frequency max2181 toc04 frequency (mhz ) gain (db) 150 100 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 3.0 50 200 t a = +25c t a = -40c t a = +85c t a = +105c closed-loop output power and im 3 vs. input power max2181 toc0 7 input power per tone (dbv) output power and im3 (dbv) 115 105 95 85 20 40 60 80 100 120 0 75 125 closed-loop output power im3 input tones at 99mhz and 100mhz closed-loop output power and im 2 vs. input power max2181 toc0 8 input power per tone (dbv) output power and im2 (dbv) 115 105 95 85 20 40 60 80 100 120 0 75 125 input tones at 99mhz and 100mhz im2 (a-b) closed-loop output power v ldo vs. v bat t max2181 toc02 v batt (v) v ldo (v) 20 15 10 5.05 5.10 5.15 5.20 5.25 5.30 5.00 52 5 t a = +25c t a = -40c t a = +85c t a = +105c i batt vs. v bat t max2181 toc01 v batt (v) i batt (ma) 20 15 10 10 20 30 40 50 60 70 0 52 5 t a = +25c t a = -40c t a = +85c t a = +105c gain vs. frequenc y max2181 toc05 frequency (mhz ) gain (db) 150 100 3 4 5 6 7 8 9 10 11 12 2 50 200 v fmgain = 0v v fmgain = v ldo fmgain = high-z v ldo vs. v bat t max2181 toc03 v batt (v) v ldo (v) 10 8 4 6 2.5 3.0 3.5 4.0 5.0 4.5 5.5 6.0 2.0 21 2 t a = +25c t a = -40c t a = +85c t a = +105c noise figure vs. frequency max2181 toc06 frequency (mhz ) noise figure (db) 150 100 2.5 3.0 3.5 4.0 2.0 50 v fmgain = v ldo v fmgain = 0v max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 5 pin description pin confguration pin name function 1 rbias connect a 1% tolerance 20k? resistor to ground. 2 fmin fm input. ac couple to fm input bandpass flter. 3 antsense connect to antenna input connector center conductor through a 100k? resistor. 4 fmgain fm gain trim. connect to ground, leave open, or connect to v ldo for the desired fm gain. 5C7, 9, 14C16 n.c. no connection to die. suggested thermal path on layer 1 of pcb for packages exposed pad to thermal sink. 8 fmagc fm agc control line. connect a 1f capacitor to ground. 10 fmout fm vga output 11 fmdet fm attack point trim. connect the desired resistor to ground. 12 ldo dc regulator output. connect a bypass capacitor to ground. 13 v batt battery supply pin ep exposed pad. ground. 15 16 14 13 5 6 7 antsense fmgain 8 rbia s fmout n.c. ldo 13 n.c. 4 12 10 9 n.c. n.c. fmagc n.c. n.c. n.c. fmin fmdet 2 11 v batt tqfn max2181 top view + max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 6 detailed description setting signal path gain and agc attack point the max2181 allows independent variation of the gain and agc attack points on the fm signal path. gain and attack point are adjusted by changing the conditions on the fmgain and fmdet pins. fm signal path typical fm gain can be set using the fmgain pin as shown in table 1. the output attack point of the fm signal path is adjusted by changing the resistor rfmdet, con - nected to the fmdet pin. table 2 shows the attack point associated with several resistor values. antenna sensing in some applications, a bias voltage might be present on the car antenna or the car antenna might be dc shorted to ground in normal operation. in these situations, the device can sense an antenna fault condition and report this by setting the v batt current. connecting the antsense pin to the car antenna through a 100k? resistor enables this function. if a dc bias of 6v to 12v is present on the antenna, the device operates normally. if the antenna is dc shorted to ground, the device also operates normally. however, if the anten - na is a dc open circuit, the device v batt current drops to a value between 15ma to 25ma. this provides a method for the car audio system to detect an antenna fault. if this function is not required, the antsense pin should be connected to ground. layout recommendations for best performance, the device must be mounted on a pcb that is designed for a low thermal resistance. a thermal ground must be placed near the device. this can consist of a mounting screw to a large thermal mass, ideally placed no more than 5mm from the package. the backside ground of the max2181 must be connected to a thermal ground plane on the pcb using at least nine plated through holes. finally, a wide trace on the pcb top metal from the paddle area, connecting pins 5-7 and 14-16, and proceeding to the mounting hole further improves thermal performance. the max2181 is equipped with thermal-protection circuit - ry that maintains junction temperature at safe levels when the device is operated outside its specified operating range. for ambient temperatures up to +85oc and v batt up to +15v, the thermal protection does not engage. refer to www.maximintegrated.com for the max2181 evaluation kit schematic, gerber data, pads layout file, and bom information. table 1. fm signal path gain table 2. fm signal path attack point pin fmgain fm gain (db, typ) ground 6.0 open 7.2 v ldo 8.3 rfmdet (k?) fm output attack point (dbv, typ) 0 92 13 93.5 22 95 33 97 43 99 51 101.5 62 104 71 106 max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 7 typical application circuit 15 16 14 13 5 6 7 8 20k 62 43k fm output v ldo 105 l2: for 76mhz to 100mhz, l2 = 100nh for 87mhz to 108mhz, l2 = 82nh 27nh 33pf fmin antsense fmgain 13 n.c. 4 12 10 9 n.c. n.c. fmagc n.c. n.c. fmout fmdet v ldo 2 11 v batt max2181 + 10f 0.47f n.c. n.c. 10f v ldo 0.1f 1f 10f c2 100pf bas316 l1 470nh 47h rbia s max2181 fm automotive low-noise amplifer www.maximintegrated.com
maxim integrated 8 ordering information package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.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. +denotes a lead(pb)-free/rohs-compliant package. *ep = exposed pad. /v denotes an automotive qualified part. package type package code outline no. land pattern no. 16 tqfn t1633+2 21-0136 90-0030 part temp range pin-package max2181ete+ -40c to +85c 16 tqfn-ep* max2181ete/v+ -40c to +85c 16 tqfn-ep* max2181 fm automotive low-noise amplifer www.maximintegrated.com
? 2012 maxim integrated products, inc. 9 revision history revision number revision date description pages changed 0 12/12 initial release maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations 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 and the maxim integrated logo are trademarks of maxim integrated products, inc. max2181 fm automotive low-noise amplifer for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.
maxim integrated 10 max2181 fm automotive low-noise amplifer www.maximintegrated.com
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