nju3555 NJU8752/52b -1- ver.2004-08-05 analog signal input class d amplifier for piezo speaker general description the NJU8752/NJU8752b is an analog signal input monaural class d amplifier for piezo speaker. the NJU8752/52b includes inversion operational amplifier input circuit, pwm modulator, an output-short protector and a low voltage detector. input part operates on 3.3v(typ) as power supply and output part operates up to 16.0v(max). therefore, it drives piezo speaker with louder sound and high efficiency. the NJU8752/52b incorporates btl amplifier, which eliminate ac coupling capacitors, capable of driving piezo speaker with simple external lc low-pass filters. class d operation achieves lower power operation for piezo speaker, thus the NJU8752/52b is suited for battery powered applications. features piezo speaker driving 1-channel analog signal input, 1-channel btl output standby(hi-z), mute control voltage gain 31db(NJU8752) 20db(NJU8752b) built-in low voltage detector built-in short protector operating voltage input: 2.7 ~ 3.6v (NJU8752) 3.1 ~ 3.6v (NJU8752b) output: 6.0 ~ 16.0v c-mos technology package outline ssop14 (NJU8752 / 52b) qfn20 / qfn28 (NJU8752b) pin configuration package outline NJU8752v / 52bv preliminary NJU8752bkm1 NJU8752bkp4 v dd in test 1 muteb v ss v ss com test 2 stbyb v ss 1 2 3 4 5 14 13 12 11 10 6 7 9 8 out p v ddo out n v ddo ssop14 (NJU8752v / 52bv) 20 1 nc nc nc v ss v dd com test 2 stbyb v ss out n v ddo v ddo v ddo v ddo nc out p v ss muteb test 1 in qfn20 ( NJU8752bkm1 ) qfn28 (NJU8752bkp4) 28 1 nc nc nc v ss v dd com test 2 stbyb out n v ddo v ddo v ddo v ddo nc out p v ss muteb test 1 in nc nc nc nc nc nc nc v ss nc
NJU8752/52b - 2 - ver.2004-08-05 block diagram pin description no. ssop14 qfn20 qfn28 symbol i/o function 1 19 26 v dd ? power supply: v dd =3.3v 2 1 1 in i signal input 3 2 2 test 1 i maker test 1 this pin must be connected to gnd. 4 3 3 muteb i mute control low : mute on high : mute off 5,10,14 4,12,17 5,17,24 v ss ? power gnd: v ss =0v 6 5 7 out p o positive output 7,8 6,7,9,10 8,9,13,14 v ddo ? output power supply : v ddo =16.0v max. 9 11 15 out n o negative output 11 13 18 stbyb i standby control low : standby on high : standby off 12 14 19 test 2 i maker test 2 this pin must be connected to gnd. 13 15 21 com ? analog common ? 8,16,18,20 4,6,10,11, 12,16,20,22, 23,25,27,28 nc ? non connection *v ss (ssop14:pin no.5,10,14, qfn20:pin no.4,12,17, qfn28:pin no.5,17,24) should be connected at a nearest point to the ic. *v ddo (ssop14:pin no.7,8, qfn20:pin no.6,7,9,10, qfn28:pin no.8,9,13,14) should be connected at a nearest point to the ic. *muteb(ssop14: pin no.4, qfn20, qfn28:pin no.3) and stbyb(ssop14:pin no.11, qfn20:pin no.13, qfn28:pin no.18) must be connected to v dd , when these pins are not used. pulse width modulator short protector v dd control logic low voltage detecto r soft start v ss + - + - in com muteb test 1 stbyb test 2 v ddo out p v ss v ddo out n v ss
nju3555 NJU8752/52b -3- ver.2004-08-05 functional description (1) signal output the out p and out n generate pwm output signals, which will be converted to analog signal via external 2nd-order or higher lc filter. a switching regulator with a high response against a voltage fluctuation is the best selection for the v ddo , which are the power supply for output drivers. to obtain better thd performance, the stabilization of the power is required. (2) standby by setting the stbyb pin to ?l?, the standby mode is enabled. in the standby mode, the entire functions of the NJU8752/52b enter a low-power state, and the output pins (out p and out n ) are high impedance. (3) mute by setting the muteb pin to ?l?, the mute function is enabled. in the mute mode, the output pins (out p and out n ) output square wave (duty: 50%). (4) low voltage detector when the power supply voltage drops down to below v dd (min), the internal oscillation is halted for prevention to generate unwanted frequency, and the output pins (out p and out n ) become in high impedance. (5) short circuit protection the short protector, which protects the NJU8752/52b against high short-circuit current, turns off the output driver. after about 5 seconds from the protection, the NJU8752/52b returns to normal operation. the short protector functions at the following accidents. ? short between out p and out n ? short between out p and v ss ? short between out n and v ss note 1) the detectable current and the period for the protection depend on the power supply voltage and ambient temperature. note 2) the short protector is not effective for a long term short-circuit but for an instantaneous accident. continuous high-current may cause permanent damage to the NJU8752/52b .
NJU8752/52b - 4 - ver.2004-08-05 absolute maximum ratings (ta=25 c) parameter symbol rating unit supply voltage v dd v ddo -0.3 ~ +4.0 -0.3 ~ +18.0 v v input voltage vin -0.3 ~ v dd +0.3 v operating temperature topr -40 ~ +85 c storage temperature tstg -40 ~ +125 c ssop14 450 qfn20 620 power dissipation qfn28 p d 640 mw * : mounted on two-layer board of based on the jedec. note 1) all voltage are relative to ?v ss =0v? reference. note 2) the lsi must be used inside of the ?absolute maximum ratings?. otherwise, a stress may cause permanent damage to the lsi. note 3) de-coupling capacitors for v dd -v ss and v ddo -v ss should be connected for stable operation. electrical characteristics -NJU8752- (ta=25 c, v dd =3.3v, v ddo =12.0v, v ss =0v,input signal=1khz, input signal level=200mvrms, frequency band=20hz~20khz, load impedance=0.8 f, 2nd-order 34khz lc filter(q=0.75)) parameter symbol conditions min typ max unit note v dd supply voltage v dd 2.7 3.3 3.6 v v ddo supply voltage v ddo 6.0 12.0 16.0 v input impedance z in in pin - 20 - k ? voltage gain a v - 31 - db output thd thd input signal level =200mvrms - 0.05 0.08 % 4 maximum output vo output thd=10% 7 10 - vrms s/n sn a weight - 80 - db 4 dynamic range drange a weight - 83 - db 4 maximum mute attenuation mat 90 - - db operating current(stanby) i st - - 1 a operating current (no signal input) i dd no-load operating no signal input - 3.5 10 ma v ih muteb, stbyb pins 0.7v dd - v dd v input voltage v il muteb, stbyb pins 0 - 0.3v dd v input leakage current i lk muteb, stbyb pins - - 1.0 a
nju3555 NJU8752/52b -5- ver.2004-08-05 -NJU8752b- (ta=25 c, v dd =3.3v, v ddo =12.0v, v ss =0v,input signal=1khz, input signal level=700mvrms, frequency band=20hz~20khz, load impedance=0.8 f, 2nd-order 34khz lc filter(q=0.75)) parameter symbol conditions min typ max unit note v dd supply voltage v dd 3.1 3.3 3.6 v v ddo supply voltage v ddo 6.0 12.0 16.0 v input impedance z in in pin - 20 - k ? voltage gain a v - 20 - db output thd thd input signal level =700mvrms - 0.05 0.08 % 4 maximum output vo output thd=10% 7 10 - vrms s/n sn a weight - 80 - db 4 dynamic range drange a weight - 83 - db 4 maximum mute attenuation mat - 90 - db operating current(stanby) i st - - 1 a operating current (no signal input) i dd no-load operating no signal input - 3.5 10 ma v ih muteb, stbyb pins 0.7v dd - v dd v input voltage v il muteb, stbyb pins 0 - 0.3v dd v input leakage current i lk muteb, stbyb pins - - 1.0 a note 4) test system of the output thd, s/n and dynamic range the output thd, s/n and dynamic range are tested in the system shown in figure 1, where a 2nd-order lc lpf and another filter incorporated in an audio analyzer are used. 2nd-order lpf : refer to ?typical application circuit?. filters : 22hz hpf + 20khz lpf(aes17) (with the a-weight filter for s/n and dynamic-range tests) input signal thd measuring apparatus filte r 20khz (aes17) 2nd-order lc lpf NJU8752/52b test board audio analyzer figure 1. output thd, s/n and dynamic range test system NJU8752/52b
NJU8752/52b - 6 - ver.2004-08-05 typical application circuit figure 2.1 application circuit example (ssop14) NJU8752/52b v dd (1) v ss (14) out p (6) out n (9) 33~47 f v ddo 0.1 f v ddo test1(3) test2 ( 12 ) 33~47 ? 5~10 ? 0.5~2 ? 0.01 ? llb2520 is manufactured by toko, inc. for detail information, please refer its technical papers. llb2520 llb2520 NJU8752/52b v dd (19) v ss (17) out p (5) out n (11) 33~47 f v ddo 0.1 f v ddo test1(2) test2 ( 14 ) 33~47 ? 5~10 ? 3.3k ? 0.01 llb2520 llb2520 piezo speaker 0.5~2
nju3555 NJU8752/52b -7- ver.2004-08-05 note 5) de-coupling capacitors must be connected between each power supply pin and gnd. the capacity value should be adjusted on the application circuit and the operation temperature. it may malfunction if capacity value is small. note 6) the power supply for v ddo require fast driving response performance such as a switching regulator for better thd. thd performance becomes worse by ripple if the capacity of de-coupling capacitors is small. note 7) the above circuit shows only application example and does not guarantee the any electrical characteristics. therefore, please test the circuit carefully to fit your application. the cutoff frequency of the lc filter influences the quality of sound. the q factor of the lc filter must be less than ?1?. otherwise, the operating current increase when the frequency of input signal is closed to the cutoff frequency. note 8) the transition time for muteb and stbyb signals must be less than 100 s. otherwise, a malfunction may be occurred. note 9) (1)-(26) indicates pin number. [caution] the specifications on this databook are only given for information , without any guarantee as regards either mistakes or omissions. the application circuits in this databook are described only to show representative usages of the product and not intended for the guarantee or permission of any right including the industrial rights. piezo speaker 0.5~2 f v ddo 0.1 f v ddo test1(2) test2 ( 19 ) 33~47 ? 5~10 ? 3.3k ? 0.01 llb2520 llb2520 ? llb2520 is manufactured by toko, inc. for detail information, please refer its technical papers. figure 2.3 application circuit example (qfn28)
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