voice our achievement of 16-speed dvd recording required pushing our circuit technologies to the limit to get the utmost performance from sony s process technolo- gies. the two of us on this devel- opment team had to come up with a lot of mutual support and en- couragement during this design effort. we are probably not the only ones who are hoping that this achievement marks the end of the competition for ever higher speeds. optical pickup chipset with photodetector ics supports high-speed writing to cd and dvd cxa2702ga/CXA2716GA/cxa2701ga although it has only been a year since sony released the cxa2676ga and cxa2677ga * for dvd 8-speed recording, dvd recording speed has already reached 16. sony s newly-developed cxa2701ga and cxa2702ga/ CXA2716GA optical pickup photodetector ics (pdics) support this 16 record speed. * : see cx-news, volume 32, for details on the cxa2676ga and cxa2677ga. cxa2702ga/CXA2716GA rf/servo pdics supports high-speed cd/dvd write operations (cd-r: 52-speed, dvd-r: 16-speed) wpp1 (b+c) and wpp2 (a+d) outputs, which are optimal for dvd address pit detection variable limiter function cxa2702ga: eight-division photodiode CXA2716GA: twelve-division photodiode 18-pin lga cob small package cxa2701ga laser front monitor pdic differential output two-channel structure (vin1, vin2) 12-pin lga cob small package cxa2702ga/CXA2716GA the cxa2702ga is a photodetector ic (pdic) that was developed as the photo- detector for optical pickups used in dvd r/rw recording drives. like the earlier 8-speed cxa2677ga, it provides the wpp1 and wpp2 signals that are optimal for address pit signal detection. in increasing the recording speed to 16, sony added a 3 gain switching function to wpp1 and wpp2. the new ic thus has an additional 2 bits of control compared to the earlier gain switching system. the cxa2702ga also now provides an input pin that can control the output limiter volt- age externally so that applications can set the limiter voltage to provide optimal pickup performance. note that although the cxa2702ga includes a built-in 8-division photodiode that supports the same differential push-pull method as the earlier product (cxa2677ga), sony has also added to the product lineup the CXA2716GA, which includes a built-in 12-division photodiode that supports the differential astigmatism method. both the cxa2702ga and CXA2716GA feature the extremely fast main output settling time (for a 1 v amplitude) of 6 ns. cxa2701ga like the earlier 8-speed cxa2676ga, the cxa2701ga adopts a two-channel structure to allow the cd laser and the dvd laser power levels to be set individu- ally. however, the output was changed to the differential type in this new product. this was because the output at the read power became even smaller due to low- ering the gain of the first stage i-v ampli- fier (transimpedance amplifier) to 1/ 2 to support 16-speed laser diodes. switch- ing to a differential amplifier improves the signal-to-noise ratio by 2 and also allows the common mode noise in the transmis- sion system to be cancelled. support for lead-free mounting since the chip on board (cob) package adopted for these ics has excellent resis- tance to heat, these ics support mounting with lead-free solder. they allow two-pass reflow mounting with a peak temperature of 250 c. note: since the thermal resistance is strongly influenced by the usage environment, verify the details of the specifications in advance, or contact your sony representative for consultation.
figure 1 cxa2701ga block diagram figure 2 cxa2702ga block diagram (items in parentheses apply to the CXA2716GA.) figure 3 cxa2701ga pin configuration figure 4 cxa2702ga pin configuration (items in parentheses apply to the CXA2716GA.) figure 7 CXA2716GA acceptance pattern dimensions figure 5 cxa2701ga acceptance pattern dimensions figure 6 cxa2702ga acceptance pattern dimensions figure 8 recommended reflow soldering temperature profile (lead-free soldering) vout+ vcc vc gnd low 740 ? 1 k ? 1 k ? 200 ? 200 ? 50 k ? 50 k ? high high photodiode sw vin1 vin2 ivout vr2 vr1 4 11 vc_moni 12 1 9 6 10 5 8 gnd 2 1.8 1 vout 7 low + + + 1 10 5 4 14 17 12 7 vcc vc gnd vlimit rf+ a vc b c d rf wpp1 wpp2 3 2 swa swb 6 3 a a vc a' + + + + + + + + + + + + 8 b 3 b vc b' 13 c 3 c vc c' 11 d 3 d vc d' 9 e (ef2) 3 e (e2+f2) vc 18 f (ef1) 3 f (e1+f1) vc 16 g (ef3) 3 g (e3+f3) vc 15 h (ef4) 3 h (e4+f4) vc a b c d b' vc vcc vc c' a' vc d' 9 10 11 12 ivout vout sw vout+ vin2 vin1 vc vc_moni gnd gnd nc vcc 1 2 3 5 6 7 8 4 14 15 16 17 18 rf+ d a wpp1 wpp2 c b h (ef4) g (ef3) rf f (ef1) vcc swb swa vlimit gnd 1 2 3 4 6 7 8 e (ef2) 9 11 vc 10 12 13 5 0.7 mm photosensitive area position: at the package center 180 c 150 c 2 to 4 c/s (3 to 6 c/s) 2 to 6 c/s peak: 250 c max. 230 c or more pre heating zone 90 30 s 30 10 s soldering zone heating time temperature 250 200 150 100 50 [ c] note: the temperatures shown are package surface temperatures. 120 120 150 120 d 120 35 35 c a b e4 e3 e1 e2 f4 f3 f1 f2 unit: m h 120 g f 120 e 150 120 d 120 35 35 c a b unit: m
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