demoboard stv5722 stv5726 AN630/0693 summary page i introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ii stv5722 application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 iii stv5722 fm audio application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 iv stv5726 : 4 video heads amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 v pcb layout pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 vi silkscreen printing pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 i - introduction one pcb, three applications, many options. to take advantage of the pin to pin compatibility of the 2 heads video amplifier stv5722 with the 4 heads video amplifier stv5726 is the guideline of this demoboard. with one pcb three main applications can be realized : - stv5722 in a 2 video heads playback/record solution - stv5722 in a 2 fm audio playback/record solu- tion - stv5726 in a 4 video heads playback/record solution. additionnaly the pcb layout of the board offers the user several application options as desired. ii - stv5722 application the demoboard is mounted according to the typical application diagram (figure 1). a single 5v supply line is necessary for both play- back and record mode. application options allowed by the pcb lay- out figure 2 gives an example of an electrical diagram using the pcb options. - r7, c14 low pass filter can be added on the playback envelop signal (triv : tracking infor- mation video) - r6, d2 is an optional circuit that can be used to encrease the record circuit when recording on a premagnetized tape (owr : overwritting) - r9 is also an optional component which allows to change the recording current from head to head. this may be used when the recording efficiency is a little bit different from one head to the other (low cost scanners). iii - stv5722 fm audio applica tion the stv5722 can be used as a fm audio head amplifier. to do so, a external buffer circuit can be implemented on the board. with this confoguration the playback gain is in- creased from 60db (ty p.) to 68.6db (typ.) (such a high gain is normally requested for fm audio head amplification). figure 3 gives an example in which the board has been configurated for fm audio amplification. 1/7
v cc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 c11 10nf r5 12k w r3 8.2k w c12 22nf r4 2.2k w c13 22nf rec c rec y owr triv (env) h sync sw-h v cc gnd sw-rec yc pb r12 100 w d3 1n4148 l1 47 m h c15 22 m f c16 22nf c6 22nf c4 22nf c3 22nf c5 22nf r1 1k w c1 22nf j1 heads connector j2 connector to main board stv5722 AN630-01-01.eps figure 1 : stv5722 typical application (2 video heads) v cc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 c11 10nf r5 12k w r3 8.2k w c12 22nf r4 2.2k w c13 22nf rec c rec y owr triv (env) h sync sw-h v cc gnd sw-rec yc pb r12 100 w d3 1n4148 l1 47 m h c15 22 m f c16 22nf c6 22nf c4 22nf c3 22nf c5 22nf r1 1k w c1 22nf j1 heads connector j2 connector to main board stv5722 r6 33k w jp2 r7 10k w r9 220k w c14 10nf d2 1n4148 AN630-02.eps figure 2 : stv5722 application example using the pcb layout options stv5722 - stv5726 demoboard 2/7
v cc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 c11 10nf r5 12k w r4 2.2k w c13 22nf fm in owr triv (env) h sync sw-h v cc gnd sw-rec fm pb d3 1n4148 l1 47 m h c15 22 m f c16 22nf c6 22nf c4 22nf c3 22nf c5 22nf j1 heads connector j2 connector to main board stv5722 q2 bc558 q1 bc550 r17 1k w r15 2.7k w r13 8.2k w r14 2.7k w r16 1k w c18 22nf AN630-03.eps figure 3 : stv5722 fm audio application stv5722 - stv5726 demoboard 3/7
iv - stv5726 : 4 video heads amplifica tion the demoboard is mounted according to the typical application diagram (figure 4). a single 5v supply line is necessary for both playback and record mode. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 stv5726 r3 8.2k w r4 2.2k w c12 22nf c13 22nf r5 12k w rec c rec y sw-s owr triv (env) h sync sw-m sw-h env c v cc gnd sw-rec yc pb r10 8.2k w r11 22k w d1 1n4148 d3 1n4148 c16 22nf c15 22 m f l1 47 m h r12 100 w c11 10nf c7 22nf c9 22nf c10 22nf c8 22nf r1 1k w c1 22nf c2 22nf r2 1k w j1 heads connector j2 connector to main board AN630-04.eps figure 4 : stv5726 typical application stv5722 - stv5726 demoboard 4/7
application options allowed by the pcb lay- out figure 5 gives an example of an electrical diagram using the pcb options. - r7, c14 low pass filter can be added on the playback envelop signal (triv : tracking infor- mation video) - r6, d2 is an optional circuit that can be used to encrease the record circuit when recor ding on a premagnetized tape (owr : overwritting) - r8 allows to change the record gain from sp to lp mode - r9 jp2 allows to change the record current from head to head (only for low cost scanner where small gain difference may appear from head to head). jp2 is connected to sw-h input if g c (h2lp) < g c ( h1lp) jp2 is connected to env-c output if g 2 (h2lp) < g c (h1lp) g c is the required current gain for the amplifier to compensate the gain difference in the scanner - c17 may be used to filter env c output. * jp1 : when possible this jumper can be used to simplfy the record damping filters r1 c1 and r2 c2. example are given in figure 6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 stv5726 r3 8.2k w r4 2.2k w c12 22nf c13 22nf r5 12k w rec c rec y sw-s owr triv (env) h sync sw-m sw-h env c v cc gnd sw-rec yc pb r10 8.2k w r11 22k w d1 1n4148 d3 1n4148 c16 22nf c15 22 m f l1 47 m h r12 100 w c11 10nf c7 22nf c9 22nf c10 22nf c8 22nf r1 1k w c1 22nf c2 22nf r2 1k w j1 head connector j2 connector to main board jp1 r6 33k w r7 33k w d1 1n4148 r9 220k w r8 220k w jp2 c17 1nf c14 10nf AN630-05.eps figure 5 : stv5726 application example using the pcb layout options stv5722 - stv5726 demoboard 5/7
1 2 3 9 10 11 jp1 r1 c st rec am p lp rec am p ms ms jp1 not used ? typical application * * jp1 used - c2 removed * jp1 used - c1, c2 removed, r2 replaced by a capacitor c the muting switch ms of the unused record amplifier limits the record crosstalk (ex : sp active / lp off). the muting switch ms of the unused record amplifier is used as ground for the damping filter (could be used only if the record crosstalk is acceptable). 1 2 3 9 10 11 jp1 r1 r2 c1 sp rec amp lp rec amp ms ms AN630-06.eps figure 6 : how to use jp1 to simplify the record damping filter stv5722 - stv5726 demoboard 6/7
r AN630-07.eps figure 7 r c13 c12 s2 d2 r7 r9 d1 r4 r3 c2 r2 s1 c1 c7 c4 c3 r1 j1 c8 c5 c9 c6 c10 c17 c16 r15 r13 q1 q2 r17 r10 r11 r6 r8 r5 c14 c15 l1 c18 d3 r12 r14 j2 r16 c11 stv5722/stv5726 demoboard v1.0 AN630-08.eps figure 8 v - pcb layout pattern (copper side) vi - silkscreen printing pattern (components side) stv5722 - stv5726 demoboard 7/7
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