u4476b preliminary information rev. a3, 08-mar-01 1 (7) if amplifier / converter for dvb (cable) description the u4476b is a bipolar circuit for the processing of dvb-cable if signals ( d igital v ideo b roadcasting). the amplifier/ converter is suitable for qam modulated if signals (1st if) and provides the gain controlled 2nd if. with 5 v supply voltage the ic allows application in rf/if front ends for dvb-cable receivers (set top boxes). features gain controlled amplifier for the 1st if (36 mhz) if converter for the 2nd if (7 mhz); vco circuit is controlled by external pll bandwidth of the output signal: 10 mhz (1 db) internal agc with average detection for the qam modulated dvb signal, reference level is adjustable 5 v supply voltage; low-power consumption package: 28-pin small outline plastic package (so28) block diagram tuner agc band gap control agc: qam vco pll i 2 c if 2 tuner v s 2nd if input select 12703 5 6 9 10 ref (dvb) 7 12 11 24 3821 23 22 20 18 13 15 28 if 1 figure 1. block diagram
u4476b rev. a3, 08-mar-01 preliminary information 2 (7) ordering information extended type number package remarks U4476B-MFLG3 so28 taped and reeled, 2000 pcs pin description 1 2 3 4 5 6 7 8 10 9 27 22 21 20 18 19 17 12 11 28 25 26 23 24 v in1 c agc gnd v in2 v in2 rtop nc v in1 itun c ref nc nc v vco v vco gnd lo out nc v tun nc v s nc nc nc agc ref 16 15 14 13 14529 v out nc nc v sw figure 2. pinning pin symbol function 1, 2 nc not connected 3 c ref capacitor for internal band gap reference voltage 4 nc not connected 5, 6 v in1 if input 1 (symmetrical) 7 c agc dvb agc (time constant) 8 gnd ground 9, 10 v in2 if input 2 (symmetrical) 11 rtop take-over point, tuner agc 12 itun tuner agc output current 13 v out output signal (2nd if) 14 nc not connected 15 v sw if input selector switch 16 nc not connected 17 nc not connected 18 v tun input for the external vco tuning voltage 19 nc not connected 20 lo out local oscillator output (reference signal) 21 gnd ground 22, 23 v vco vco circuit (symmetrical) 24 v s supply voltage 25 nc not connected 26 nc not connected 27 nc not connected 28 agc ref external reference voltage (comparator dvb agc) absolute maximum ratings parameters symbol value unit supply voltage v s 5.5 v supply current i s 100 ma power dissipation, v s = + 5.5 v p tot 550 mw output currents i out 5 ma junction temperature t j 125 c storage temperature t stg 25 to +125 c electrostatic handling *) v esd tbd v *) equivalent to discharging a 200-pf capacitor through a 0- resistor
u4476b preliminary information rev. a3, 08-mar-01 3 (7) operating range parameters symbol value unit supply voltage range v s 4.5 to 5.5 v ambient temperature t amb 0 to +85 c thermal resistance parameters symbol value unit junction ambient when soldered to pcb r thja 75 k/w electrical characteristics v s = 5 v, t amb = 25 c parameters test conditions / pins symbol min. typ. max. unit dc supply supply voltage v s 4.5 5.0 5.5 v supply current i s 80 100 ma if inputs input sensitivity, rms value v in 80 120 m v rms input impedance see note 1 r in 1.2 k input capacitance see note 1 c in 2 pf dvb agc (qam modulation) if gain control range if2 output voltage pin 13 = 1.8 v pp g v 60 65 db vco oscillator frequency f vco 43 60 mhz tuning range f vco = 43 mhz c vco = 8.2 pf f tun 1.5 mhz local oscillator output signal f vco = 43 mhz c vco = 8.2 pf loout 100 mv local oscillator control signal f vco = 43 mhz c vco = 8.2 pf vtun 0.5 2.7 4.5 v 2nd if output output current source output current sink i out 2 5 4 ma output resistance see note 1 r out 100 output amplitude peak-to-peak value v o,vid 1.6 1.8 2.0 v dc output voltage 2.2 v bandwidth of 2nd if (1 db) r l 1 k , c l 50 pf b 10 mhz frequency response over agc range b 2.0 db if input switch control voltage input 1 is active input 2 is active see also note 2, `high' (if1 active, pin 56) `low' (if2 active, pin 910) v sw v sw 2.5 3.5 1.5 v v switching current (pin 15 to ground) i sw 30 a
u4476b rev. a3, 08-mar-01 preliminary information 4 (7) electrical characteristics v s = 5 v, t amb = +25 c parameters test conditions / pins symbol min. typ. max. unit tuner agc available tuner agc current i tun 1 2 4 ma allowable output voltage v out 0.3 13.5 v if slip tuner agc current i tun : 10% to 90% g if 8 10 db if input signal for minimum take over point v in 4 mv if input signal for maximum take over point v in 40 mv variation of the take over point by temperature (pin 28 open) t amb = 55 c if agc: g v = 46 db v in 2 3 db notes: 1. this parameter is given as an application information and not tested during production. 2. without external control voltage (pin not connected) the input 1 is automatically selected. basic application circuit 28 1234 u4476b 567 8 910 11 12 13 14 27 26 25 24 23 22 21 20 19 18 17 16 15 8.2 pf 10 nf 22 f 50 k 10 nf dvb ref vco frequency 10 k 2.2 f if 1 if 2 agc tuner agc take over point tuner agc 2 nd if 1 u4744b 2 3 4 8 7 6 5 50 10 nf 10 nf if 10 nf 2.2 f +12 v 13900 v s vco tuning input switch saw 1 saw 2 2.2 f *) *) u4744b: saw driver, device phased out, not for new development current figure 3.
u4476b preliminary information rev. a3, 08-mar-01 5 (7) im3 measurements and application recommendations im3 measurement for correct measurement of im3 with the 2-carrier method, it is necessary to control the internal if amplifier via an external voltage at pin 7. the criteria for a correct value of the external control voltage is the output amplitude of 1.8 v pp (or lower). please note that each change of the input level requests a correction of the external gain control voltage at pin 7 in order to achieve the 1.8-v pp output level again. in this case, im3 is nearly 43 db, independent from the input level. with an output voltage of 1.5 v pp only, the im3 is about 50 db. anyway, if the output amplitude is more than 1.8 v pp (specified), the im3 will decrease rapidly. in the graphic below, im3 is shown for two different conditions: 30 32 34 36 38 40 42 44 46 48 50 40 50 60 70 80 90 100 im3 ( db ) input voltage (each carrier) ( db v ) 14778 v out = 1.5 v pp v out = 1.8 v pp figure 4. im3 vs. if input voltage and if2out voltage test conditions: input: f 1 = 38 mhz, f 2 = 39 mhz, lo = 43 mhz circuitry for external gain control if the gain control of the ic is carried out by an external dsp, the internal charge pumps of the agc (pin 7) have to be overlapped by an external voltage source. the internal agc currents are 20 m a. therefore, the minimum current capacity of the external voltage source should be 30 m a or more. the circuitry shown in figure 5 takes some more current. 14581 s852t 10 k w 100 nf to pin 7 +5 v from dsp figure 5. external lo application if the internal vco is not used, the lo can be fed unbalanced or balanced to the vco pins 22 and 23. the application shown below is generating an unbalanced lo signal by using a 36-mhz third-overtone quartz reference. the application circuit is taken from iqd limited crystal product data book. the lo signal is fed unbalanced with 1 nf coupling capacity to pin 22. pin 23 has to be blocked to ground with an 1-nf capacitor. the typical lo amplitude is 100 db m v. the variation of the lo input amplitude should not exceed 5 db (better: 3 db). 560 w 100 pf 490 nh 4.7 k w 47 pf 68 pf 560 w 1 nf s852t to pin 22 +5 v 10 k w 14582 figure 6. note: with external lo operation, pin 18 (vco tuning voltage) should be connected to the supply voltage, and pin 20 (lo output) should not be connected to the pcb.
u4476b rev. a3, 08-mar-01 preliminary information 6 (7) package information 13033 technical drawings according to din specifications 0.25 0.10 package so28 dimensions in mm 0.4 1.27 16.51 18.05 17.80 2.35 7.5 7.3 9.15 8.65 10.50 10.20 0.25 28 15 114
u4476b preliminary information rev. a3, 08-mar-01 7 (7) ozone depleting substances policy statement it is the policy of atmel germany gmbh to 1. meet all present and future national and international statutory requirements. 2. regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. it is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances (odss). the montreal protocol ( 1987) and its london amendments ( 1990) intend to severely restrict the use of odss and forbid their use within the next ten years. various national and international initiatives are pressing for an earlier ban on these substances. atmel germany gmbh has been able to use its policy of continuous improvements to eliminate the use of odss listed in the following documents. 1. annex a, b and list of transitional substances of the montreal protocol and the london amendments respectively 2. class i and ii ozone depleting substances in the clean air act amendments of 1990 by the environmental protection agency (epa) in the usa 3. council decision 88/540/eec and 91/690/eec annex a, b and c (transitional substances) respectively. atmel germany gmbh can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances. we reserve the right to make changes to improve technical design and may do so without further notice . parameters can vary in different applications. all operating parameters must be validated for each customer application by the customer. should the buyer use atmel wireless & microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify atmel wireless & microcontrollers against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. data sheets can also be retrieved from the internet: http://www.atmelwm.com atmel germany gmbh, p.o.b. 3535, d-74025 heilbronn, germany telephone: 49 (0)7131 67 2594, fax number: 49 (0)7131 67 2423
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