View MAX9814ETD-T_8219417.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

general description the max9814 is a low-cost, high-quality microphone amplifier with automatic gain control (agc) and low- noise microphone bias. the device features a low-noise preamplifier, variable gain amplifier (vga), output amplifier, microphone-bias-voltage generator and agc control circuitry. the low-noise preamplifier has a fixed 12db gain, while the vga gain automatically adjusts from 20db to 0db, depending on the output voltage and the agc thresh- old. the output amplifier offers selectable gains of 8db, 18db, and 28db. with no compression, the cascade of the amplifiers results in an overall gain of 40db, 50db, or 60db. a trilevel digital input programs the output amplifier gain. an external resistive divider controls the agc threshold and a single capacitor programs the attack/release times. a trilevel digital input programs the ratio of attack-to-release time. the hold time of the agc is fixed at 30ms. the low-noise microphone-bias- voltage generator can bias most electret microphones. the max9814 is available in the space-saving, 14-pin tdfn package. this device is specified over the -40? to +85? extended temperature range. applications features ? automatic gain control (agc) ? three gain settings (40db, 50db, 60db) ? programmable attack time ? programmable attack and release ratio ? 2.7v to 5.5v supply voltage range ? low input-referred noise density of 30nv/ hz ? low thd: 0.04% (typ) ? low-power shutdown mode ? internal low-noise microphone bias, 2v ? available in the space-saving, 14-pin tdfn (3mm x 3mm) package ? -40? to +85? extended temperature range microphone amplifier with agc and low-noise microphone bias ordering information simplified block diagram low-noise reference agc 2.7v to 5.5v lna +12db vga +20db/0db gain +8/+18/ +28db micbias r micbias micin micout c out gnd c in v dd shdn max9814 part temp range pin-package max9814etd+t -40? to +85? 14 tdfn-ep* + denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. * ep = exposed pad. pin configurations appear at end of data sheet. digital still cameras digital video cameras pdas bluetooth headsets entertainment systems (e.g., karaoke) two-way communicators high-quality portable recorders ip phones/telephone conferencing 19-0764; rev 2; 6/09 functional diagrams pin configurations appear at end of data sheet. functional diagrams continued at end of data sheet. ucsp is a trademark of maxim integrated products, inc. available evaluation kit available 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. max9814
microphone amplifier with agc and low-noise microphone bias absolute maximum ratings electrical characteristics (v dd = 3.3v, shdn = v dd , c ct = 470nf, c cg = 2?, gain = v dd , t a = t min to t max , unless otherwise specified. typical values are at t a = +25?.) (note 1) stresses beyond those listed under ?bsolute 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. v dd to gnd ..............................................................-0.3v to +6v all other pins to gnd.................................-0.3v to (v dd + 0.3v) output short-circuit duration.....................................continuous continuous current (micout, micbias).......................?00ma all other pins ....................................................................?0ma continuous power dissipation (t a = +70?) 14-pin tdfn-ep (derate 16.7mw/? above +70?) ........................1481.5mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? lead temperature (soldering, 10s) .................................+300? bump temperature (soldering) reflow............................+235? parameter symbol conditions min typ max units general operating voltage v dd guaranteed by psrr test 2.7 5.5 v supply current i dd 3.1 6 ma shutdown supply current i shdn 0.01 1 a input-referred noise density e n bw = 20khz, all gain settings 30 nv/ hz output noise bw = 20khz 430 ? rms bw = 22hz to 22khz (500mv rms output signal) 61 signal-to-noise ratio snr a-weighted 64 db dynamic range dr (note 2) 60 db f in = 1khz, bw = 20hz to 20khz, r l = 10k , v t h = 1v ( thr eshol d = 2v p - p ) , v i n = 0.5m v r m s , v c t = 0v 0.04 total harmonic distortion plus noise thd+n f in = 1khz, bw = 20hz to 20khz, r l = 10k, v th = 0.1v (threshold = 200mv p-p ), v in = 30mv rms , v ct = 2v 0.2 % amplifier input bias v in 1.14 1.23 1.32 v maximum input voltage v in_max 1% thd 100 mv p-p input impedance z in 100 k gain = v dd 39.5 40 40.5 gain = gnd 49.5 50 50.6 maximum gain a gain = unconnected 59.5 60 60.5 db gain = v dd 18.7 20 20.5 gain = gnd 29.0 30 30.8 minimum gain gain = unconnected 38.7 40 40.5 db maximum output level v out_rms 1% thd+n, v th = micbias 0.707 v rms regulated output level agc enabled, v th = 0.7v 1.26 1.40 1.54 v p-p agc attack time t attack c ct = 470nf (note 3) 1.1 ms a/r = gnd 1:500 a/r = v dd 1:2000 attack/release ratio a/r a/r = unconnected 1:4000 ms/ms max9814 2 maxim integrated
microphone amplifier with agc and low-noise microphone bias note 1: devices are production tested at t a = +25?. limits over temperature are guaranteed by design. note 2: dynamic range is calculated using the eiaj method. the input is applied at -60dbfs (0.707? rms ), f in = 1khz. note 3: attack time measured as time from agc trigger to gain reaching 90% of its final value. note 4: cg is connected to an external dc voltage source, and adjusted until v micout = 1.23v. note 5: cg connected to gnd with 2.2?. parameter symbol conditions min typ max units micout high output voltage v oh i out sourcing 1ma 2.45 v micout low output voltage v ol i out sinking 1ma 3 mv micout bias micout unconnected 1.14 1.23 1.32 v output impedance z out 50 minimum resistive load r load_min 5k maximum capacitive drive c load_max 200 pf maximum output current i out_max 1% thd, r l = 500 12ma output short-circuit current i sc 38 ma agc mode; v dd = 2.7v to 5.5v (note 4) 35 50 f = 217hz, v ripple = 100mv p-p (note 5) 55 f = 1khz, v ripple = 100mv p-p (note 5) 52.5 power-supply rejection ratio psrr f = 10khz, v ripple = 100mv p-p (note 5) 43 db microphone bias microphone bias voltage v micbias i micbias = 0.5ma 1.84 2.0 2.18 v output resistance r micbias i micbias = 1ma 1 output noise voltage v micbias_noise i micbias = 0.5ma, bw = 22hz to 22khz 5.5 ? rms dc, v dd = 2.7v to 5.5v 70 80 power-supply rejection ratio psrr i micbias = 0.5ma, v ripple = 100mv p-p , f in = 1khz 71 db trilevel inputs (a/r, gain) a/r or gain = v dd 0.5v dd / 180k 0.5v dd / 100k 0.5v dd / 50k tri-level input leakage current a/r or gain = gnd 0.5v dd / 180k 0.5v dd / 100k 0.5v dd / 50k ma input high voltage v ih v dd x 0.7 v input low voltage v il v dd x 0.3 v shutdown enable time t on 60 ms shutdown disable time t off 40 ms digital input ( shdn) shdn input leakage current -1 +1 ? input high voltage v ih 1.3 v input low voltage v il 0.5 v agc threshold input (th) th input leakage current -1 +1 ? electrical characteristics (continued) (v dd = 3.3v, shdn = v dd , c ct = 470nf, c cg = 2?, gain = v dd , t a = t min to t max , unless otherwise specified. typical values are at t a = +25?.) (note 1) max9814 maxim integrated 3
microphone amplifier with agc and low-noise microphone bias typical operating characteristics (v dd = 5v, c ct = 470nf, c cg = 2.2?, v th = v micbias x 0.4, gain = v dd (40db), agc disabled, no load, r l = 10k, c out = 1?, t a = +25?, unless otherwise noted.) gain vs. frequency max9814 toc01 frequency (hz) gain (db) 10k 1k 100 10 20 30 40 50 60 70 80 0 10 100k gain = unconnected gain = 0 gain = 1 power-supply rejection ratio vs. frequency max9814 toc02 frequency (hz) psrr (db) 10k 1k 100 -70 -60 -50 -40 -30 -20 -10 0 -80 10 100k v ripple = 200mv p-p micbias power-supply rejection ratio vs. frequency max9814 toc03 frequency (hz) psrr (db) 10k 1k 100 -100 -90 -80 -70 -60 -50 -40 -30 -110 10 100k v ripple = 200mv p-p supply current vs. supply voltage max9814 toc04 supply voltage (v) supply current (ma) 5.5 5.0 4.0 4.5 3.5 3.0 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 2.5 2.5 6.0 shutdown current vs. supply voltage max9814 toc05 supply voltage (v) shutdown current (na) 5.5 5.0 4.5 4.0 3.5 3.0 0.1 0.2 0.3 0.4 0.5 0 2.5 6.0 microphone bias voltage vs. microphone bias source current max9814 toc06 i micbias (ma) v micbias voltage (v) 25 20 15 10 5 0.5 1.0 1.5 2.0 2.5 0 030 total harmonic distortion plus noise vs. frequency max9814 toc07 frequency (hz) thd+n (%) 10k 1k 100 0.1 1 10 0.01 10 100k v out = 800mv rms total harmonic distortion plus noise vs. output voltage max9814 toc08 output voltage (v rms ) thd+n (%) 1.0 0.5 0.1 1 10 0.01 0 1.5 f in = 300hz, 1khz, and 3khz f in = 10khz input-referred noise vs. frequency max9814 toc09 frequency (khz) input-referred noise (v rms /hz) 10 1 0.1 100 10 0.01 100 1000 1 micin ac-coupled to gnd max9814 4 maxim integrated
microphone amplifier with agc and low-noise microphone bias micbias noise vs. frequency max9814 toc10 frequency (hz) micbias noise (nv rms /hz) 10k 1k 100 100 1000 10,000 10 10 100k small-signal pulse response max9814 toc11 200s/div v micin 10mv/div 0v v micout 500mv/div 0v c l = 10pf turn-on response max9814 toc12 20ms/div v shdn 5v/div 0v v micbias 2v/div 0v v micout 1v/div 0v v out vs. v in max9814 toc13 v in (mv rms ) v out (v rms ) 100 50 0.25 0.50 0.75 1.00 0 0 150 v th = 1v v th = 0.75v v th = 0.5v agc enabled gain = 1 v out vs. v in max9814 toc14 v in (mv rms ) v out (v rms ) 30 20 10 0.25 0.50 0.75 1.00 0 040 v th = 1v v th = 0.75v v th = 0.5v agc enabled gain = 0 v out vs. v in max9814 toc15 v in (mv rms ) v out (v rms ) 10 5 0.25 0.50 0.75 1.00 0 015 v th = 1v v th = 0.75v v th = 0.5v agc enabled gain = unconnected attack time max9814 toc16 200s/div v micout 500mv/div c ct = 47nf 0v attack time max9814 toc17 200s/div v micout 500mv/div c ct = 100nf 0v hold and release time max9814 toc18 20ms/div v micout 500mv/div c ct = 47nf a/r = gnd 0v typical operating characteristics (continued) (v dd = 5v, c ct = 470nf, c cg = 2.2?, v th = v micbias x 0.4, gain = v dd (40db), agc disabled, no load, r l = 10k, c out = 1?, t a = +25?, unless otherwise noted.) max9814 maxim integrated 5
microphone amplifier with agc and low-noise microphone bias hold and release time max9814 toc19 40ms/div v micout 500mv/div c ct = 47nf a/r = v dd 0v hold and release time max9814 toc20 100ms/div v micout 500mv/div c ct = 47nf a/r = unconnected 0v pin description pin tdfn name function 1c t timing capacitor connection. connect a capacitor to ct to control the attack and release times of the agc. 2 shdn active-low shutdown control 3 cg amplifier dc offset adjust. connect a 2.2? capacitor to gnd to ensure zero offset at the output. 4, 11 n.c. no connection. connect to gnd. 5v dd power supply. bypass to gnd with a 1? capacitor. 6 micout amplifier output 7 gnd ground 8 micin microphone noninverting input 9a / r tri-level attack and release ratio select. controls the ratio of attack time to release time for the agc circuit. a/r = gnd: attack/release ratio is 1:500 a/r = v dd : attack/release ratio is 1:2000 a/r = unconnected: attack/release ratio is 1:4000 10 gain tri-level amplifier gain control. gain = v dd , gain set to 40db. gain = gnd, gain set to 50db. gain = unconnected, uncompressed gain set to 60db. 12 bias amplifier bias. bypass to gnd with a 0.47? capacitor. 13 micbias microphone bias output 14 th agc threshold control. th voltage sets gain control threshold. connect th to micbias to disable the agc. ep exposed pad. connect the tdfn ep to gnd. typical operating characteristics (continued) (v dd = 5v, c ct = 470nf, c cg = 2.2?, v th = v micbias x 0.4, gain = v dd (40db), agc disabled, no load, r l = 10k, c out = 1?, t a = +25?, unless otherwise noted.) max9814 6 maxim integrated
microphone amplifier with agc and low-noise microphone bias max9814 agc disabled 400s/div v micin 100mv/div v micout (ac-coupled) 1v/div max9814 fig01a max9814 agc enabled 400s/div v micin 100mv/div v micout (ac-coupled) 1v/div max9814 fig01b 0v 0v 0v 0v detailed description the max9814 is a low-cost, high-quality microphone amplifier with automatic gain control (agc) and a low- noise microphone bias. the max9814 consists of sever- al distinct circuits: a low-noise preamplifier, a variable gain amplifier (vga), an output amplifier, a microphone- bias-voltage generator, and agc control circuitry. an internal microphone bias voltage generator pro- vides a 2v bias that is suitable for most electret con- denser microphones. the max9814 amplifies the input in three distinct stages. in the first stage, the input is buffered and amplified through the low-noise preampli- fier with a gain of 12db. the second stage consists of the vga controlled by the agc. the vga/agc combi- nation is capable of varying the gain from 20db to 0db. the output amplifier is the final stage in which a fixed gain of 8db, 18db, 20db is programmed through a sin- gle tri-level logic input. with no compression from the agc, the max9814 is capable of providing 40db, 50db, or 60db gain. automatic gain control (agc) a device without agc experiences clipping at the output when too much gain is applied to the input. agc pre- vents clipping at the output when too much gain is applied to the input, eliminating output clipping. figure 1 shows a comparison of an over-gained microphone input with and without agc. the max9814? agc controls the gain by first detect- ing that the output voltage has exceeded a preset limit. the microphone amplifier gain is then reduced with a selectable time constant to correct for the excessive output-voltage amplitude. this process is known as the attack time. when the output signal subsequently low- ers in amplitude, the gain is held at the reduced state for a short period before slowly increasing to the nor- mal value. this process is known as the hold and release time. the speed at which the amplifiers adjust to changing input signals is set by the external timing capacitor c ct and the voltage applied to a/r. the agc threshold can be set by adjusting v th . gain reduction is a function of input signal amplitude with a maximum agc attenuation of 20db. figure 2 shows the effect of an input burst exceeding the preset limit, out- put attack, hold and release times. if the attack and release times are configured to respond too fast, audible artifacts often described as ?umping?or ?reathing?can occur as the gain is rapidly adjusted to follow the dynamics of the signal. for best results, adjust the time constant of the agc to accommodate the source material. for applications in which music cds are the main audio source, a 160? attack time with an 80ms release time is recommend- ed. music applications typically require a shorter release time than voice or movie content. figure 1. microphone input with and without agc max9814 maxim integrated 7
attack time the attack time is the time it takes for the agc to reduce the gain after the input signal has exceeded the threshold level. the gain attenuation during the attack time is exponential, and defined as one-time constant. the time constant of the attack is given by 2400 x c ct seconds (where c ct is the external timing capacitor): use a short attack time for the agc to react quickly to transient signals, such as snare drum beats (music) or gun shots (dvd). use a longer attack time to allow the agc to ignore short-duration peaks and only reduce the gain when a noticeable increase in loudness occurs. short- duration peaks are not reduced, but louder pas- sages are. this allows the louder passages to be reduced in volume, thereby maximizing output dynamic range. hold time hold time is the delay after the signal falls below the threshold level before the release phase is initiated. hold time is internally set to 30ms and nonadjustable. the hold time is cancelled by any signal exceeding the set threshold level, and the attack time is reinitiated. release time the release time is how long it takes for the gain to return to its normal level after the output signal has fall- en below the threshold level and 30ms hold time has expired. release time is defined as release from a 20db gain compression to 10% of the nominal gain set- ting after the input signal has fallen below the th threshold and the 30ms hold time has expired. release time is adjustable and has a minimum of 25ms. the release time is set by picking an attack time using c ct and setting the attack-to-release time ratio by configur- ing a/r as shown in table 1: use a small ratio to maximize the speed of the agc. use a large ratio to maximize the sound quality and prevent repeated excursions above the threshold from being independently adjusted by the agc. agc output threshold the output threshold that activates agc is adjustable through the use of an external resistive divider. once the divider is set, agc reduces the gain to match the output voltage to the voltage set at the th input. microphone bias the max9814 features an internal low-noise micro- phone bias voltage capable of driving most electret condenser microphones. the microphone bias is regu- lated at 2v to provide that the input signal to the low- noise preamplifier does not clip to ground. applications information programming attack and release times attack and release times are set by selecting the capacitance value between ct and gnd, and by set- ting the logic state of a/r (table 1). a/r is a tri-level logic input that sets the attack-to-release time ratio. the attack and release times can be selected by utiliz- ing the corresponding capacitances listed in table 2. microphone amplifier with agc and low-noise microphone bias 10ms/div v ct 500mv/div v micout (ac-coupled) 1v/div attack release hold 0v 0v a/r attack/release ratio gnd 1:500 v dd 1:2000 unconnected 1:4000 figure 2. input burst exceeding agc limit table 1. attack-and-release ratios t release (ms) c ct t attack (ms) a/r = gnd a/r = v dd a/r = unconnected 22nf 0.05 25 100 200 47nf 0.11 55 220 440 68nf 0.16 80 320 640 100nf 0.24 120 480 960 220nf 0.53 265 1060 2120 470nf 1.1 550 2200 4400 680nf 1.63 815 3260 6520 1? 2.4 1200 4800 9600 table 2. attack-and-release time max9814 8 maxim integrated
setting the agc threshold to set the output-voltage threshold at which the micro- phone output is clamped, an external resistor-divider must be connected from micbias to ground with the out- put of the resistor-divider applied to th. the voltage v th determines the peak output-voltage threshold at which the output becomes clamped. the maximum signal swing at the output is then limited to two times v th and remains at that level until the amplitude of the input signal is reduced. to disable agc, connect th to micbias. microphone bias resistor micbias is capable of sourcing 20ma. select a value for r micbias that provides the desired bias current for the electret microphone. a value of 2.2k is usually sufficient for a microphone of typical sensitivity. consult the micro- phone data sheet for the recommended bias resistor. bias capacitor the bias output of the max9814 is internally buffered and provides a low-noise bias. bypass bias with a 470nf capacitor to ground. input capacitor the input ac-coupling capacitor (c in ) and the input resistance (r in ) to the microphone amplifier form a highpass filter that removes any dc bias from an input signal (see the typical application circuit/functional diagram ). c in prevents any dc components from the input-signal source from appearing at the amplifier out- puts. the -3db point of the highpass filter, assuming zero source impedance due to the input signal source, is given by: choose c in such that f -3db_in is well below the lowest frequency of interest. setting f -3db_in too high affects the amplifier? low-frequency response. use capacitors with low-voltage coefficient dielectrics. aluminum electrolytic, tantalum, or film dielectric capacitors are good choices for ac-coupling capacitors. capacitors with high-voltage coefficients, such as ceramics (non-c0g dielectrics), can result in increased distortion at low frequencies. output capacitor the output of the max9814 is biased at 1.23v. to elimi- nate the dc offset, an ac-coupling capacitor (c out ) must be used. depending on the input resistance (r l ) of the following stage, c out and r l effectively form a highpass filter. the -3db point of the highpass filter, assuming zero output impedance, is given by: shutdown the max9814 features a low-power shutdown mode. when shdn goes low, the supply current drops to 0.01?, the output enters a high-impedance state, and the bias current to the microphone is switched off. driving shdn high enables the amplifier. do not leave shdn unconnected. power-supply bypassing and pcb layout bypass the power supply with a 0.1? capacitor to ground. reduce stray capacitance by minimizing trace lengths and place external components as close to the device as possible. surface-mount components are recommended. in systems where analog and digital grounds are available, connect the max9814 to analog ground. f 1 2rc 3db_out l out ? = f 1 2r c 3db_in in in ? = microphone amplifier with agc and low-noise microphone bias max9814 maxim integrated 9
microphone amplifier with agc and low-noise microphone bias typical application circuit/functional diagram agc micbias bias r micbias 2.21k r 1 150k r 2 100k micin c out gnd v dd c in 0.1f a/r micbias gain th micout v dd v dd shdn c bypass 1f c bias 0.47f cg c cg 2.2f ct c ct 470nf ref lna vga r out *the device has been configured with an attack time of 1.1ms, 40db gain, and an attack-and-release ratio of 1:500. max9814 max9814 10 maxim integrated
microphone amplifier with agc and low-noise microphone bias chip information process: bicmos pin configuration max9814 tdfn top view 245 13 11 10 micbias n.c. gain shdn n.c. v dd 1 14 + th ct 3 12 bias cg 6 9 a/r micout 7 8 micin gnd *ep max9814 maxim integrated 11
microphone amplifier with agc and low-noise microphone bias package type package code document no. 14 tdfn-ep t1433-2 21-0137 package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . max9814 12 maxim integrated
microphone amplifier with agc and low-noise microphone bias common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l0.20 0.40 pkg. code n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.05 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.10 mo229 / weed-3 0.40 bsc - - - - 0.200.05 2.40 ref t1433-2 14 2.300.10 1.700.10 t633-2 6 1.500.10 2.300.10 0.95 bsc mo229 / weea 0.400.05 1.90 ref t833-2 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref t833-3 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref 2.300.10 mo229 / weed-3 2.00 ref 0.250.05 0.50 bsc 1.500.10 10 t1033-2 0.250.05 2.00 ref 10 0.50 bsc mo229 / weed-3 2.300.10 1.500.10 t1033mk-1 0.40 bsc - - - - 0.200.05 2.40 ref t1433-3f 14 2.300.10 1.700.10 package information (continued) for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . max9814 maxim integrated 13
microphone amplifier with agc and low-noise microphone bias revision history revision number revision date description pages changed 0 3/07 initial release 1 2/09 updated ordering information , absolute maximum ratings , pin description , and pin configuration sections to include ep for tdfn package 1, 2, 6, 11 2 6/09 removed ucsp package 1, 2, 6, 11, 12 max9814 14 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.

▲Up To Search▲

Price & Availability of MAX9814ETD-T

	To Download MAX9814ETD-T Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .