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_______________________________________________________________ maxim integrated products 1 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com. max16946/max16947 remote antenna, current-sense and ldo/switches 19-5575; rev 0; 9/10 general description the max16946/max16947 high-voltage, high-side, cur - rent-sense ldo/switches feature internal current limiting to prevent system damage due to fault conditions. the max16946 provides a fixed regulated 8.5v output volt - age or an adjustable 3.3v to 15v output voltage. the max16946 can also be configured as a switch, while the max16947 is only available as a switch. the input voltage range for both devices extends from 4.5v to 18v (45v tolerant), making the devices ideal for providing phantom power to remote radio-frequency low-noise amplifiers (lnas) in automotive applications. the devices monitor the load current and provide an analog output voltage proportional to the sensed load current. accurate internal current limit protects the input supply against both overload and short-circuit condi - tions. two open-drain fault indicator outputs indicate to the microprocessor when a short circuit, an open-load condition, or a short-to-battery condition exists. an over - temperature shutdown is also indicated by means of the current-sense amplifiers output voltage. a fault-blanking feature allows the devices to ignore momentary faults such as those caused by the charg - ing of capacitive loads during hot-swapping, preventing false alarms to the system. the devices feature short- to-battery protection to latch off the internal ldo/pass switch during a short-to-battery event. during a thermal overload, the devices reduce power dissipation by going into thermal shutdown. they include an active-low, high- voltage-compatible shutdown input to place them in low- power shutdown mode. the max16946 is available in thermally enhanced, 16-pin tqfn-ep and qsop-ep packages. the max16947 is avail - able in a 16-pin qsop package. both devices operate over the -40 n c to +105 n c temperature range. features s switch phantom power-on/off under c control s precision adjustable current limit 300ma (max), t a = +105 n c 500ma (max), t a = +85 n c (max16946 in sw mode only) s regulated output voltage (max16946)8.5v fixed or adjustable between 3.3v and 15v s current measurement analog voltage output s detect open-load and short-circuit conditions s provide open-drain fault signals ( sc and ol ) s overcurrent blanking during startup s thermal shutdown s aec-q100 qualified s -40 n c to +105 n c operating temperature range applications remote lna phantom power automotive safety and infotainment automotive remote module power note: all devices are specified over the -40c to +105c operating temperature range. /v denotes an automotive qualified part. + denotes a lead(pb)-free/rohs-compliant package. * ep = exposed pad. ** future productcontact factory for availability. ordering information functional diagram evaluation kit available high voltage sc comp sc ref short-to battery comp ol comp reverse- current comp charge pump and gate driver sens aout shdn in ref reg gnd () max16947 out fb (gnd) comp in current limit comp a v = 26v/v buffer buffer lim sc logic timer oscillator ol olt ref 5v regulator ulvo + refuv ovlo bandgap and thermal shutdown max16946 max16947 reverse current ref part pin-package output max16946 gee/v+** 16 qsop-ep* switch or ldo max16946gte/v+ 16 tqfn-ep* switch or ldo max16947 gee/v+** 16 qsop switch
2 ______________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches 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. sc , ol , reg to gnd ........................................... -0.3v to +6.0v olt, lim, fb, aout, ref, comp to gnd ..................................... -0.3v to (v reg + 0.3v) in, sens, shdn to gnd ...................................... -0.3v to +28v in, sens, shdn to gnd (< 1s) ............................ -0.3v to +45v out to gnd .......................................................... -0.3v to +20v in to sens ............................................................ -0.3v to +0.3v continuous power dissipation (t a = +70 n c) qsop (derate 9.5mw/ n c above +70 n c) ..................... 761mw qsop-ep (derate 22.7mw/ n c above +70 n c) ............ 1818mw tqfn-ep (derate 25mw/ n c above +70 n c) ..................... 2000mw junction-to-ambient thermal resistance ( b ja ) (note 1) qsop ......................................................................... 105 n c/w qsop-ep ...................................................................... 44 n c/w tqfn-ep ...................................................................... 40 n c/w junction-to-case thermal resistance ( b jc ) (note 1) qsop .......................................................................... 37 n c/w qsop-ep ........................................................................ 6 n c/w tqfn-ep ........................................................................ 6 n c/w operating temperature range ........................ -40 n c to +105 n c junction temperature ...................................... -40 n c to +150 n c storage temperature range ............................ -65 n c to +150 n c lead temperature (soldering, 10s) ................................ +300 n c soldering temperature (reflow) ...................................... +260 n c electrical characteristics (v in = 12v, v gnd = 0v, t a = -40 n c to +105 n c, unless otherwise noted. typical values are at t a = t j = +25 n c.) 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 power switch/ldo in operating supply range v in full performance 4.5 18 v output switched off (note 2) 28 v output switched off for < 1s (note 2) 45 v in supply current i cc v shdn > 2.4v, t a = +25 n c 2.1 2.6 ma in shutdown supply current i sd v shdn = v gnd , t a = +25 n c, v in = 12v 7 f a undervoltage lockout (rising) v uvlo falling v in 3.5 v rising v in 3.9 hysteresis 0.4 internal switch voltage drop v sw measured between sens and out while sourcing 100ma, fb grounded, sw oper - ation, t a = +25 n c, 4.5v < v in < 18v 0.20 v measured between sens and out while sourcing 100ma, fb grounded, sw operation, t a = +105 n c, 4.5v < v in < 18v (note 2) 0.2 0.25 v internal voltage regulator v reg i reg = 0ma, t a = +25 n c 5 v feedback voltage v fb max16946 only, ldo mode with fb connected to external resistive divider i out = 5ma to 150ma, 4.5v p v in p 18v 0.97 1 1.03 v i out = 2ma to 200ma, 4.5v < v in p 18v 0.95 1 1.05 v
_______________________________________________________________________________________ 3 max16946/max16947 remote antenna, current-sense and ldo/switches electrical characteristics (continued) (v in = 12v, v gnd = 0v, t a = -40 n c to +105 n c, unless otherwise noted. typical values are at t a = t j = +25 n c.) parameter symbol conditions min typ max units feedback input bias current i fb v fb = 1.0v, ldo mode, t a = +25 n c -0.5 +0.5 f a v fb = 1.0v, ldo mode, t a = +105 n c 0 fixed 8.5v to ldo mode feedback threshold v fb_th switching to ldo mode from fixed 8.5v 3.3 4.2 v adjustable output voltage range v out ldo mode with external resistive divider, v in > v out + v dropout (note 3) 3.3 15 v fb load regulation v in - v out r 2v, i out = 5ma to 100ma, ldo mode -2 % fb line regulation v in - v out r 2v, i out = 6ma, ldo mode 20 mv/v fixed 8.5v output voltage v out_8.5v i out = 5ma, ldo mode with internal resistive divider, 9v p v in p 18v 8.33 8.5 8.67 v power-supply rejection ratio psrr v in - v out r 2v, f = 100hz, ldo mode 50 db startup response time t st shdn rising to switch/ldo on, time need - ed to charge c comp = 0.1 f f 10 ms out pulldown resistor value r out_off v shdn = v gnd , t a = +25 n c 250 k i comp power-down resistor value r comp_off v shdn = v gnd , t a = +25 n c 120 k i current-sense amplifier aout gain a v v aout /(v in - v sens ), measured with v in - v sens = 20mv and 100mv, 4.5v < v in < 18v 25.35 26 26.65 v/v current-sense amplifier input voltage range v inr drop across the shunt resistor, normal operation 0 125 mv aout zero-current output voltage v aout_zs (v in - v sens ) = 0v, 4.5v < v in < 18v 0.368 0.4 0.432 v maximum aout voltage v aout_fs (v in - v sens ) = 125mv, if v lim = v ref then v aout(max) = 3v 3.65 v aout drive capability i aout (v in - v sens ) = 30mv 1.0 ma aout leakage current i aout_leak v shdn = v gnd , t a = +25 n c 2 f a sens leakage current i sens _leak v shdn = v gnd , t a = +25 n c 2 f a reference ref output voltage v ref 4.5v < v in < 18v 2.94 3 3.06 v ref undervoltage v ref_uv v ref falling 2.18 2.72 v ref output current i ref 100 f a ref leakage current i ref_leak v shdn = v gnd , t a = +25 n c 2 f a failure detection comparators open-load comparator input common-mode range v olt_cmr (note 2) 0.4 1.7 v open-load comparator offset voltage v olt_os v olt = 1.05v -40 0 +40 mv
4 ______________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches electrical characteristics (continued) (v in = 12v, v gnd = 0v, t a = -40 n c to +105 n c, unless otherwise noted. typical values are at t a = t j = +25 n c.) parameter symbol conditions min typ max units olt input bias current i olt v olt = 1.05v, t a = +25 n c -0.5 +0.5 f a v olt = 1.05v, t a = +105 n c 0 initial open-load blanking time t ol a switched open load is blanked for t ol 100 ms open-load glitch immunity t ol_glitch i out < i ol 10 100 f s current-limit comparator input common-mode range v lim_cmr if v lim is derived from ref then maximum voltage at lim is 3v (note 2) 1.7 3.65 v current-limit comparator input offset voltage v lim_os v lim = 2.675v -80 0 +80 mv lim input bias current i lim_bias v lim = 2.675v, t a = +25 n c -0.5 +0.5 f a v lim = 2.675v, t a = +105 n c 0 short-circuit aout voltage threshold v sc rising v aout at which the sc output asserts low, hysteresis of 40mv, 4.5v < v in < 18v 1.65 1.7 1.75 v short-circuit current blanking time t blank i out > i sc 100 ms delay time before retry after short-circuit current turn-off t retry i out > i sc 1100 ms in overvoltage lockout threshold v ovlo v in rising, hysteresis = 0.5v (typ) 19 21 23 v short-to-bat threshold in off-state v out_bat short to battery detected when v in - v out < v out_bat 0 250 500 mv reverse-current detection level v rev power switch on (sw or ldo mode), v rev = v in - v sens, v rev = -9.6mv produces v aout = 150mv, v rev = -5.7mv produc - es v aout = 250mv -9.6 -5.7 mv reverse-current shutdown time t sd_rev delay to shut down switch or ldo after v rev exceeds -7.7mv (typ), t a = +25 n c 5 f s feedback voltage out of range v fb_err ldo mode 1.12 1.28 v reverse-current blanking time for short-circuit events t rev_blank switching on and off into a temporary load (short-circuit events) 16 ms overtemperature protection thermal shutdown threshold t shdn +170 n c thermal shutdown hysteresis t hyst 15 n c logic sc , ol output-voltage low v ol sinking current = 1ma 0.4 v sc , ol open-drain leakage current i sc_leak , i ol_leak sc , ol not asserted, v sc = v ol = 5v, t a = +25 n c 1 f a
_______________________________________________________________________________________ 5 max16946/max16947 remote antenna, current-sense and ldo/switches note 2: guaranteed by design and not production tested. note 3: v dropout is voltage from v in to v out and includes drop across the sense resistor and internal power fet. additionally, v out + v dropout < v ovlo(min) = 19v. typical operating characteristics (v in = 14v, r sense = 0.5, t a = +25 c, unless otherwise noted.) electrical characteristics (continued) (v in = 12v, v gnd = 0v, t a = -40 n c to +105 n c, unless otherwise noted. typical values are at t a = t j = +25 n c.) shutdown supply current vs. supply voltage max16946 toc06 v in (v) i in (a) 16 14 12 10 8 6 1 2 3 4 5 6 7 0 4 18 fb = gnd shdn = 0 shutdown supply current vs. temperature max16946 toc05 temperature (c) iin (a) 100 75 50 25 0 -25 1 2 3 4 5 6 7 0 -50 125 fb = gnd shdn = 0 v in = 18v v in = 14v v in = 12v v in = 4.5v operating supply current vs. supply voltage (max16964/max16947 switch configuration) max16946 toc04 v in (v) i in (ma) 16 14 6 8 10 12 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 0 4 18 operating supply current vs. temperature (max16946/max16947 switch configuration) max16946 toc03 temperature (c) i in (ma) 100 75 50 25 0 -25 1 2 3 4 0 -50 125 operating supply current vs. temperature (max16946 8.5v ldo configuration) max16946 toc02 temperature (c) i in (ma) 100 75 50 25 0 -25 1 2 3 4 0 -50 125 fb = reg sense leakage current vs. temperature max16946 toc01 temperature (c) i sens (na) 100 75 -25 0 25 50 25 50 75 100 125 150 175 200 0 -50 125 fb = gnd shdn = 0 v in = 12v v in = 4.5v parameter symbol conditions min typ max units shdn input-voltage high v shdn_hi 2.7 v shdn input-voltage low v shdn_lo 0.8 v shdn input current i shdn v shdn > 6v 5 f a shdn off-time t shdn_off 150 256 420 f s
6 ______________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches typical operating characteristics (continued) (v in = 14v, r sense = 0.5, t a = +25 c, unless otherwise noted.) dropout voltage vs. load current (switched output) max16946 toc07 load current (ma) dropout voltage (mv) t a = -40c t a = +125 c t a = +25c 180 160 140 120 100 80 60 20 40 20 40 60 120 100 80 140 200 180 160 240 220 300 280 260 340 320 0 0 200 dropout voltage vs. load current (output = 5v) max16946 toc08 load current (ma) dropout voltage (mv) 180 160 120 140 40 60 80 100 20 20 40 60 80 100 120 140 160 180 200 240 220 280 260 300 320 340 0 0 200 t a = -40c t a = +105c t a = +25c dropout voltage vs. load current (output = 8.5v) max16946 toc09 load current (ma) dropout voltage (mv) 180 160 120 140 40 60 80 100 20 20 40 60 80 100 120 140 160 180 200 240 220 280 260 300 320 340 0 0 200 t a = -40c t a = +105c t a = +25c dropout voltage vs. supply voltage (switched output) max16946 toc10 supply voltage (v) dropout voltage (mv) 16 14 12 10 8 6 102 104 106 108 110 100 4 18 i out = 90ma output voltage vs. temperature max16946 toc11 temperature (c) v out (v) 100 75 50 25 0 -25 5.005 5.006 5.007 5.008 5.009 5.010 5.004 -50 125 v in = 10v v out = 5v i out = 90ma i out = 50ma output voltage vs. temperature (max16946 8.5v ldo configuration) max16946 toc12 temperature (c) v out (v) 100 75 50 25 0 -25 8.46 8.47 8.48 8.49 8.50 8.51 8.52 8.45 -50 125 v in = 12v fb = reg i out = 50ma i out = 90ma ref output voltage vs. temperature max16946 toc13 temperature (c) v ref (v) 100 75 25 50 0 -25 2.965 2.975 2.985 2.995 3.005 3.015 3.025 3.035 3.045 2.955 -50 125 i ref = 100a fb = reg power-supply rejection ratio vs. frequency max16946 toc14 frequency (hz) psrr (db) 10k 1k 100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 -100 10 100k i out = 5ma i out = 50ma v out = 3.3v power-supply rejection ratio vs. frequency max16946 toc15 frequency (hz) psrr (db) 10k 1k 100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 -100 10 100k i out = 5ma i out = 50ma v out = 8.5v
_______________________________________________________________________________________ 7 max16946/max16947 remote antenna, current-sense and ldo/switches typical operating characteristics (continued) (v in = 14v, r sense = 0.5, t a = +25 c, unless otherwise noted.) load transient response (5v ldo mode) max16946 toc16 i out 50ma/div v out (ac-coupled) 500mv/div 0a 100s/div line transient response (5v ldo mode) max16946 toc17 v in 5v/div v out (ac-coupled) 200mv/div 0v 4ms/div power-up waveforms (v out = 8.5v, i out = 90ma) max16946 toc18 i out 100ma/div v out 5v/div v in 5v/div 2ms/div power-up waveforms (sw mode , i out = 90ma) max16946 toc19 i out 100ma/div v out 5v/div v in 5v/div 2ms/div startup waveforms (v out = 8.5v , i out = 90ma) max16946 toc20 i out 100ma/div v out 5v/div 2ms/div v shdn 5v/div startup waveforms (sw mode, i out = 90ma) max16946 toc21 i out 100ma/div v out 5v/div 2ms/div v shdn 5v/div
8 ______________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches typical operating characteristics (continued) (v in = 14v, r sense = 0.5, t a = +25 c, unless otherwise noted.) high-voltage line transient response (max16947) max16946 toc22 v in 20v/div v out 10v/div i out 50ma/div v aout 1v/div 0v 0v 0a 45v 14v 100ms/div aout gain vs. temperature max16946 toc23 temperature (c) a v (v/v) 100 75 -25 0 25 50 25.25 25.50 25.75 26.00 26.25 26.50 26.75 27.00 25.00 -50 125 v in - v sens = 20mv and 100mv current-sense amplifier gain vs. temperature max16946 toc24 temperature (c) gain (v/v) 95 80 -25 -10 5 35 50 20 65 25.65 25.70 25.75 25.80 25.85 25.90 25.95 26.00 25.60 -40 110 overcurrent blanking time vs. temperature max16946 toc25 temperature (c) t blank (ms) 100 75 50 25 0 -25 150 200 250 300 350 400 100 -50 125 fb = gnd overcurrent blanking time vs. supply voltage max16946 toc26 v in (v) t blank (ms) 16 14 12 10 8 6 150 200 250 300 350 400 100 4 18 fb = gnd dropout voltage (v sens - v out ) vs. temperature (max16946 switch configuration) max16946 toc27 temperature (c) v sens - v out (mv) 100 75 -25 0 25 50 25 50 75 100 125 150 175 200 0 -50 125 i out = 100ma fb = gnd
_______________________________________________________________________________________ 9 max16946/max16947 remote antenna, current-sense and ldo/switches typical operating characteristics (continued) (v in = 14v, r sense = 0.5, t a = +25c, unless otherwise noted.) dropout voltage (v sens - v out ) vs. temperature (max16946 8.5v ldo configuration) max16946 toc28 temperature (c) v sens - v out (mv) 100 75 -25 0 25 50 25 50 75 100 125 150 175 200 0 -50 125 i out = 100ma fb = reg open-load fault (v out = 8.5v, i out = 50ma) max16946 toc29 i out 50ma/div v out 5v/div 100s/div v dl 5v/div clearing open-load fault (v out = 8.5v, i out = 50ma) max16946 toc30 i out 50ma/div v out 5v/div 100s/div v shdn 5v/div v dl 5v/div
10 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches pin configurations pin description 15 16 14 13 5 6 7 shdn gnd 8 in olt gnd ref 1 3 fb 4 12 10 9 gnd out aout ol sc comp sens lim 2 ep 11 reg tqfn top view + fb reg gnd 1 2 16 15 out gnd sens shdn in qsop top view 3 4 14 13 lim olt ol 5 12 ref comp sc 6 7 11 10 gnd aout 8 9 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 in out gnd gnd reg ref lim olt gnd top view qsop sens shdn sc gnd comp ol aout max16947 max16946 max16946 + ep + pin name function max16946 max16947 1 1 in input voltage. bypass in to gnd with a low-esr ceramic capacitor with a minimum value of 0.1 f f. 2 2 sens current-sense amplifier input. connect the sense resistor between sens and in. 3 3 shdn active-low shutdown input. drive shdn low for more than 360 f s to turn off the device. pulsing shdn low for less than t shdn_off clears the ol output. shdn is high-voltage compatible and is connected to in for normal operation. 4, 9, 15 4, 9, 14, 15 gnd ground 5 5 comp ldo compensation. connect a 0.1 f f ceramic capacitor between comp and gnd to compensate the ldo. 6 6 sc open-drain short-circuit indicator output. sc goes low when the load current is greater than the set short-circuit current threshold or when there is a short-to-battery fault. connect sc to a 10k i pullup resistor. see table 1. 7 7 ol open-drain open-load indicator output. ol goes low when the load current is lower than the set open-load current threshold or when there is a short-to-battery fault. connect ol to a 10k i pullup resistor. see table 1. 8 8 aout current monitor voltage output. aout can be used to measure the load current by means of an external adc. aout has a current drive capability of 1ma. bypass aout to gnd with a 15nf ceramic capacitor. see table 1. 10 10 olt open-load current threshold setting input. a resistive divider between ref, olt, and gnd sets the open-load current threshold. 11 11 lim current-limit setting input. connect a resistive divider from ref, lim, and gnd to set the current limit of the switch or ldo. alternatively, externally drive lim (not to exceed 3.65v) to set the current limit.
______________________________________________________________________________________ 11 max16946/max16947 remote antenna, current-sense and ldo/switches pin description (continued) detailed description the max16946/max16947 high-voltage, high-side, cur - rent-sense ldo/switches feature internal current limiting to prevent system damage due to fault conditions. the max16946 provides a regulated 8.5v output voltage fixed or adjustable from 3.3v to 15v. the max16946 can also be configured as a switch, while the max16947 is only available as a switch. the input voltage range for both devices extends from 4.5v to 18v (45v tolerant), making the devices ideal for providing phantom power to remote radio-frequency low-noise amplifiers (lnas) in automotive applications. the devices monitor the load current and provide an analog output voltage proportional to the sensed load current. accurate internal current-limit protects the input supply against both overload and short-circuit condi - tions. two open-drain fault indicator outputs indicate to the microprocessor when a short circuit, an open-load condition, or a short-to-battery condition exists. an over - temperature shutdown is also indicated by means of the current-sense amplifiers output voltage. a fault-blanking feature allows the devices to ignore momentary faults such as those caused by the charg - ing of capacitive loads during hot-swapping, prevent - ing false alarms to the system. the devices feature short-to-battery protection to latch off the internal ldo/ pass switch during a short-to-battery event and thermal overload. they include an active-low, high-voltage- compatible shutdown input to place them in low-power shutdown mode. current-sense amplifier the integrated current-sense amplifier employs a differ - ential amplifier that amplifies the voltage between in and sens. a sense resistor, r sense , is connected across in and sens. typical sense resistor values range between 0.25 i and 2 i . when the load current passes through the sense resistor, a voltage drop develops across it. the current-sense amplifier amplifies this voltage. the current-sense amplifier features an internally fixed gain of a v = 26v/v (typ). the following equations show the relationship between the current-sense amplifier output voltage (v aout ) and load current: ( ) ( ) ( ) ( ) ( ) ( ) ( ) in sens load sense aout v in sens v v v i a r v v a v v (v v ) v 0.4v ? = ? = ? + if lim is connected to ref, the maximum output voltage of aout is v aout_fs = 3v. if lim is externally driven to 3.65v, the maximum output voltage of aout extends to v aout_fs = 3.65v. the maximum aout voltage is always equal to v lim , the voltage at lim. aout is the output of an internal buffer with 1ma current drive capability. bypass aout to ground with a 15nf ceramic capacitor. pin name function max16946 max16947 12 12 ref +3v nominal reference output. ref has a current drive capability of 100 f a. 13 13 reg internal regulator +5v output. reg powers all internal blocks. do no use reg to supply power to external circuitry. bypass reg to gnd with a 1 f f capacitor. 14 fb feedback input (max16946 only). connect fb to gnd to configure the max16946 as a switch. connect fb to reg for an ldo with a fixed 8.5v output. connect to the center tap of an external resistive divider connected between out and gnd to adjust the output voltage of the ldo. 16 out switch or ldo output (max16946 only). out is either a switch or ldo output depending on the connection of fb. 16 out switch output ep exposed pad (max16946 only). connect ep to the ground plane for optimal heat dissipation. do not use ep as the only electrical ground connection.
12 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches load protection the devices monitor the load current through an external sense resistor and perform the following actions: u if the monitored current is lower than the set open- load current, the devices signal that there is an open- load (see the open load section). u if the monitored current is greater than the set short- circuit current (i sc ), the devices enter the short- circuit mode (see the short circuit and current limit section). the devices also perform a short-to-battery detection before the internal switch turns on. during normal opera - tion, reverse-current detection protects the devices from short-to-battery events (see the short-to-battery and reverse-current detection section). in addition, thermal shutdown protects the devices from overheating (see the thermal shutdown section). two open-drain fault indicator outputs ( ol and sc ) and the aout voltage indicate the devices status (table 1). open load if the load current drops below the open-load cur - rent threshold, the ol output latches low. an open- load condition does not turn off the internal switch. to unlatch the ol output, pulse shdn low for less than t shdn_off (150 f s min). keeping shdn low for longer than t shdn_off shuts down the device. the open-load current threshold is adjustable. connect a resistive divider between ref, the open-load current threshold adjustment input (olt), and gnd to set the open-load current threshold (see the open-load current threshold selection section). short circuit and current limit if the load current exceeds the set short-circuit cur - rent threshold (i sc ), the t blank timer begins counting. during this period, the load current is limited to the current limit set by the voltage at lim. if the overcurrent condition persists beyond t blank , sc asserts low and the internal switch turns off. the timer resets if the over - current condition disappears before the blanking time (t blank ) has elapsed. if the switch is turned off at the end of t blank , a retry timer (t retry ) starts immediately after the blanking time has elapsed, and during that time the switch stays off. at the end of t retry , the switch turns on again while sc stays low. if the fault still exists, the cycle repeats. if the fault has been removed, the switch stays on and sc goes high after the blanking time t blank . during retry when the switch is off, the current through the switch is zero. blanking time and retry time have fixed values of 100ms (min) and 1100ms (min), respectively. figures 1C4 show the response of the devices to the presence and removal of overcurrent conditions. the current-limit threshold is adjustable. connect a resistive divider between ref, the current-limit setting input (lim), and gnd to set the current-limit threshold. alternatively, externally drive lim (not to exceed 3.65v) to set the current-limit threshold (see the current-limit threshold selection section). the short-circuit current threshold depends on the value of the sense resistor and is calculated as follows: sc sense v 1.3v i r a = where a v is the gain of the internal current-sense ampli - fier and is equal to 26v/v and r sense is the sense resis - tor value.
______________________________________________________________________________________ 13 max16946/max16947 remote antenna, current-sense and ldo/switches figure 1. turn-on into temporary short circuit figure 2. turn-on into hard short circuit i lim i sc t blank t retry shdn sc load current t blank t i lim i sc shdn sc load current t blank t blank t retry t
14 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches figure 3. turn-on into temporary heavy load figure 4. turn-on into heavy load i lim i sc shdn sc load current t blank t retry t blank t shdn sc load current i lim i sc t blank t retry t blank t
______________________________________________________________________________________ 15 max16946/max16947 remote antenna, current-sense and ldo/switches short-to-battery and reverse-current detection it is possible for out to be shorted to the battery due to a fault in the system. the devices detect this failure by comparing the out voltage and the in voltage before the switch turns on. every time the switch turns on, such as at the end of the retry time, or once the thermal shut - down condition disappears, the short-to-battery detec - tion is performed. at this point, if the device detects the short-to-battery fault, the switch stays off and both sc and ol assert low (table 1). series inductance and the output capacitor can produce ringing during a short-circuit condition, resulting in an output voltage that temporarily exceeds the input volt - age. blanking is implemented during and immediately after a short-circuit event to prevent false triggering of the reverse-current detection. the reverse-current blank - ing time (t rev_blank ) is 16ms (typ). if the reverse cur - rent produces a v sense (v in - v sense ) less than -7.7mv (typ) for a duration greater than the blanking time, the device latches off the switch and both sc and ol assert low. thermal shutdown thermal-shutdown circuitry protects the devices from overheating. the switch turns off immediately when the junction temperature exceeds +170 n c (typ) (table 1). the switch turns on again after the device temperature drops by approximately +15 n c (typ). thermal shutdown is indicated by 0v on aout. undervoltage and overvoltage lockout the devices include undervoltage lockout circuitry (uvlo) to prevent erroneous switch operation when the input voltage goes below 3.5v (typ) during startup and brownout conditions. input voltages of less than 3.5v inhibit operation of the device by turning off the internal charge pump and the switch. these devices also feature an overvoltage lockout (ovlo) threshold of 21v (typ). when v in is greater than v ovlo , the device immediately turns off the switch and the internal charge pump. shutdown ( shdn ) the devices feature an active-low shutdown input ( shdn ) to place them into a low-power shutdown mode. the devices turn off and consume a 7 f a maximum (at v in = 12v) of shutdown current when shdn is driven low for greater than 360 f s. driving shdn high initiates a device turn-on with short-to-battery detection. pulsing shdn low for less than t shdn_off clears the ol output. internal reference (ref) the devices feature a 3v bandgap reference output, sta - ble over supply voltage and temperature. the reference has a current drive capability of 100 f a. use resistive dividers connected to ref to set the open-load current threshold and the current-limit threshold. do not use ref to drive external circuitry. internal +5v linear regulator (reg) the devices feature an internal regulator that regulates the input voltage to +5v to power all internal circuitry. bypass the regulator output (reg) to gnd with a 1 f f ceramic capacitor. do not use this regulator to power external circuitry. table 1. max16946/max16947 status truth table sc ol v aout (v) device status action taken 1 1 (i load o r sense ) o 26 + 0.4 normal operation none 0 1 (i load o r sense ) o 26 + 0.4 short circuit autoretry 1 0 (i load o r sense ) o 26 + 0.4 open load ol latched low 0 0 0.4 after switching off reverse current (on-state) switch/ldo latched off out short-to-battery (off-state), v out too high ( ldo mode) switch/ldo turned off as long as condition persists 1 1 0 thermal shutdown, v in overvoltage, v in undervoltage switch/ldo and aout turns off as long as condition persists ref undervoltage switch/ldo, aout, and ref turned off as long as condition persists
16 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches applications information choosing the sense resistor ideally, the maximum load current develops the full-scale sense voltage across the current-sense resistor. the current-sense amplifier output voltage is given by: v aout = a v x (v in - v sens ) + 0.4v where v aout is the output voltage of the current-sense amplifier, and a v is the gain of the current-sense ampli - fier of 26v/v (typ). calculate the maximum value for r sense , so that the amplified differential voltage across in and sens does not exceed the short-circuit aout voltage threshold of v sc = 1.7v (typ), which is defined in the electrical characteristics table: sc sense load(full_scale) v v 0.4v r i a ? = typical sense resistor values range between 0.25 i and 2 i . during normal operation, when the load current is less than the short-circuit current threshold, the maximum aout voltage is equal to v sc . when a short circuit to ground is present and the device goes into autoretry, the maximum aout voltage extends to v lim , the volt - age at lim. keep inductance low if i sense has a large high- frequency component. wire-wound resistors have the highest inductance, while metal film is somewhat better. low-inductance, metal-film resistors are also available. instead of being spiral wrapped around a core, as in metal-film or wire-wound resistors, they are a straight band of metal and are available in values under 1 i . because of the high current that flows through r sense , eliminate parasitic trace resistance from causing errors in the sense voltage. open-load current threshold selection a resistive divider between ref, olt, and gnd sets the open-load current threshold. see figure 5. use the following formula to set the desired open-load current threshold: 1 2 ref sense ol v r r v 1 r i a 0.4v ? = ? ? ? ? + ? ? where i ol is the desired open-load current threshold, a v is the current-sense amplifier gain (26v/v typical), and v ref is the reference voltage (3v typ). size r 1 and r 2 large enough so that the equivalent resistance of the resistive dividers used to set the open-load and current- limit thresholds does not exceed the ref output 100 f a drive capability. for example, to set the open-load current threshold at 10ma, using a 0.5 i sense resistor, use the following method to calculate the value of r 1 and r 2 : 1 2 r r 3v 1 0.5 0.01a 26v/v+0.4v ? = ? ? ? ? ? ? ? choose r 1 = 470k i and calculate r 2 as 100k i . figure 5. open-load current threshold selection figure 6. current-limit threshold selection max16946 max16947 ref olt r 1 r 2 max16946 max16947 ref lim r 1 r 2
______________________________________________________________________________________ 17 max16946/max16947 remote antenna, current-sense and ldo/switches current-limit threshold selection a resistive divider between ref, lim, and gnd sets the current-limit threshold. see figure 6. use the following formula to set the desired current-limit threshold: 1 2 ref sense cl v r r v 1 r i a 0.4v ? = ? ? ? ? + ? ? where i cl is the desired current-limit threshold, a v is the current-sense amplifier gain (26v/v typ), and v ref is the reference voltage (3v typ). size r 1 and r 2 large enough so that the equivalent resistance of the resistive dividers used to set the open-load and current-limit thresholds does not exceed the ref output 100 f a drive capability. for example, to set the current-limit threshold at 120ma, using a 0.5 i sense resistor, use the following method to calculate the value of r 1 and r 2 : 1 2 r r 3v 1 0.5 0.120a 26v/v+0.4v ? = ? ? ? ? ? ? ? choose r 1 = 83k i and calculate r 2 as 156k i . using an external reference use an external reference with resistive dividers as an alternative means of setting the current-limit and open- load current thresholds. the equations shown in the open-load current threshold selection and current- limit threshold selection sections are still applicable when using an external reference. in those equations, set v ref equal to the voltage of the external reference. when using the devices 3v reference, the maximum voltage at lim is v lim = 3v and is obtained by connect - ing lim to ref. when using an external reference, set the voltage at lim to no greater than v lim(max) = 3.65v. fixed/adjustable output voltage the max16946 is configurable to provide a fixed 8.5v output or as an adjustable ldo with an output between 3.3v and 15v. connect a resistive divider between out, fb, and gnd to set the output to the desired voltage, as shown in figure 7. connect fb to reg to configure the max16946 as an 8.5v ldo, as shown in figure 8. fb is regulated to 1.0v with q 3% accuracy for a load current between 5ma and 150ma. the accuracy falls to q 5% for a load current between 2ma and 200ma. select a value for r 1 and calculate r 2 as follows: 1 2 out fb r r v 1 v ? = ? ? ? ? ? ? select r 1 so that the maximum input bias current at fb is negligible compared to the total current going through r 1 . compensation capacitor compensate the ldo regulator by bypassing comp to gnd with a 0.1 f f ceramic capacitor. input capacitor connect a low-leakage ceramic capacitor from in to gnd to limit the input-voltage drop during momentary output short-circuit conditions and to protect the device against transients due to inductance in the in line. for example, use at least a 0.1 f f ceramic capacitor if the input inductance (including any stray inductance) is estimated to be 20 f h. larger capacitor values reduce the voltage undershoot and voltage overshoot in case of reverse current at the input. output capacitor in an analogous fashion to the input capacitor, an output capacitor protects the device against transients due to any series inductance in the output. under no conditions should the voltage on out go below -0.3v as specified in the absolute maximum ratings section. a schottky diode is required to clamp transients that go below ground. for example, with a 2.2mh series inductance, to avoid excessive ringing at the output, bypass out to gnd with not more than 0.1 f f capacitance. additionally, bypassing out to gnd with a 2.2 f f ceramic capacitor in series with a 10 i resistor reduces ringing caused by load current transients through a maximum 2.2mh series inductance. figure 7. adjustable output-voltage selection max16946 out fb r 1 r 2
18 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches layout and thermal dissipation to optimize the switch response time to output short- circuit condition, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. place input and output capacitors as close as possible to the device (no more than 5mm). in and out must be connected with wide short traces to the power bus. during normal operation in switch mode, the power dissipation is small and the package temperature change is minimal. in ldo mode, the power dissipation is given by: (v in - v out ) x i load + v in x i in if the output is continuously shorted to ground at the max - imum supply voltage, the devices are protected because the total power dissipated during the short is scaled down by the duty cycle imposed by the protection: vin(max) out(max) blank (max) retry blank v i t p t t = + figure 8. ldo with adjustable output voltage (3.3v to 15v) max16946 regulated phantom supply in sens error flags current- sense output on/off out fb comp ref lim olt gnd reg sc r 5 c out c in l out r 6 r 1 r 2 r 3 r 4 r pu ol aout shdn r sense battery input c supply
______________________________________________________________________________________ 19 max16946/max16947 remote antenna, current-sense and ldo/switches figure 9. ldo with fixed 8.5v output figure 10. input switched to output max16946 in sens error flags current- sense output on/off out fb comp ref lim olt gnd reg sc c out c in l out r 1 r 2 r 3 r 4 r pu ol aout shdn r sense battery input c supply regulated phantom supply max16946 max16947 in sens error flags current- sense output () max16947 out fb (gnd) comp ref lim olt gnd reg sc c out c in l out r 1 r 2 r 3 r 4 r pu ol aout shdn r sense battery input c supply regulated phantom supply
20 _____________________________________________________________________________________ max16946/max16947 remote antenna, current-sense and ldo/switches 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. chip information process: bicmos package type package code outline no. land pattern no. 16 qsop e16+5 21-0055 90-0167 16 qsop-ep e16e+10 21-0112 90-0239 16 tdfn-ep t1644+4 21-0139 90-0070
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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 21 ? 2010 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. max16946/max16947 remote antenna, current-sense and ldo/switches revision history revision number revision date description pages changed 0 9/10 initial release

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