Video ICs 4-channel video-signal PRE / REC amplifier BA7274S The BA7274S PRE / REC amplifier has been designed for use in video cassette recorders. It is compatible with fourhead decks, and has four head amplifiers, a chroma output amplifier, and FM output amplifier (with AGC circuit), an envelope detector, a fixed-current drive recording amplifier, a channel switch circuit, and record / playback switch integrated only one monolithic IC. Applications *VCRs *1)Features Suitable for 4-head decks. 2) Integration of the head-section signal processing circuits (REC and head amplifiers, AGC, and envelope detector) only one IC allows compact deck designs. 3) The head amplifier has low input capacitance and low noise (VNIN = 0.4Vrms), and both the playback and recording systems have a wide frequency range. 4) The REX amplifier employs a fixed-output current system to minimize change in the recording current due to load fluctuation. The maximum recording current output is a large 30mAP-P. Built-in channel and record / playback switches (switched to PB VCC and REC VCC). Peaking amplifier pin provided for external setting of peak value. Compact SDIP 32 pin package. Auto-tracking compatible. 5) 6) 7) 8) *Absolute maximum ratings (Ta = 25C) Parameter Symbol Limits Unit Power supply voltage VCC Power dissipation Pd 1370 mW Operating temperature Topr - 20 ~ + 70 C Storage temperature Tstg - 55 ~ + 150 C 7 (PRE) 13 (PRE) V Reduced by 11.0mW for each increase in Ta of 1C over 25C. *Recommended operating conditions (Ta = 25C) Parameter Symbol Min. Typ. Max. Unit Conditions Operating power supply voltage (playback) VCC (P) 4.5 5.0 5.5 V 25pin Operating power supply voltage (recording) VCC (R) 11.5 12 12.5 V 21pin The PRE and REC VCC are used for mode switching. If the PRE and REC VCC voltages are applied together, the amplifier systems and head switch will go on simultaneously causing a large current to flow. This must be avoided, so do not make pins 21 and 25 "H" (0.5V or more) together. 1 31 32 2 28 29 HSW PRE 2 PRE 3 23 PRE 1 H SW CTRL HA SW HSW ENVE DET PRE 4 HA SW CTRL +- 19 PRE GND 30 PRE VCC REC GND EQ SW 18 EQ CTRL 27 ENVE DET 22 PEAKING 26 COMP 20 AGC AMP 25 PRE VCC 24 ENVE. 21 AGC DET Video ICs BA7274S *Block diagram 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Video ICs BA7274S *Electrical characteristics (unless otherwise noted, Ta = 25C) Parameter Symbol Min. Typ. Max. Unit Supply current ICC-P 23 34 44 mA Voltage gain (CH1 to CH4) GVP 49 57 62 dB Maximum chroma output level VOMC 1.3 1.5 -- VP-P AGC output amplitude level VAGC 130 180 220 mVP-P Conditions Playback system VCC = 5V -- VIN = 0.3mV P-P, 100kHz AGC control sensitivity VAGC - 1.0 1.0 3.0 dB VIN = 0.15 ~ 0.6mVP-P, 4MHz AGC freguency char. (CH1 to CH4) Gf1 ~ 4 - 2.0 2.0 4.0 dB VIN = 0.3mVP-P, 10MHz / 1MHz dB 4MHz Crosstalk CT -- - 40 - 33 VN1 ~ 4 -- 0.4 1.2 V rms Head switching threshold voltage VTH3 2.0 2.5 3.0 V High: CH1, 4 Head amplifier switching threshold voltage VTH4 2.0 2.5 3.0 V High: CH3 or 4 High: CH1 or 2 > CH3 or 4 Low: CH3 or 4 > CH1 or 2 Input conversion noise (CH1 to CH4) ENVELOPE comparison output amplitude Low: CH2, 3 Low: 1 or 2 V24 4.3 -- -- V COMP (ENVE) switch threshold VTHP2 0.3 1.3 1.8 V High: STOP Low: ENVE OUT ENVE detector output level SP VENV-S1 1.3 1.6 2.1 V CHROMA OUT = 0.0VP-P ENVE detector output level SP VENV-S2 2.6 2.9 3.3 V CHROMA OUT = 0.5VP-P, 4MHz ENVE detector output level EP VENV-E1 1.3 1.6 1.9 V CHROMA OUT = 0.0VP-P ENVE detector output level EP VENV-E2 3.4 3.7 4.1 V CHROMA OUT = 0.5VP-P, 4MHz PRE switch on resistance R16, 18 -- 5 10 ICC-R 30 47 65 mA IL 30 -- -- mAP-P Recording current secondary distortion DL -- - 35 - 31 dB Recording current load characteristics IL -- 1 3 mA IL = 30mA, 4MHz, 8.2 ~ 15H Recording current freguency char. Gf -5 -3 1.5 dB IL = 10mA, 8MHz / 100kHz High: EP Low: SP Recording system VCC = 12V Supply current Maximum output current EP / SP switching threshold voltage REC switch ON resistance VTHR 2 0.8 1.3 1.8 V R5, 7, 10, 12 -- 10 15 IL = 30mAP-P , 4MHz 3 Video ICs BA7274S *Measurement circuit REC CURRENT SENSE 10 0.1 10 0.1 10 0.1 10 0.1 17 16 100 EQ SW 510 18 REC GND 510 0.1 15 0.0047 19 14 HA SW CTRL 20 50 ENVE DET 21 0.01 22 13 + 30 AGC OUT 31 AGC OUT 32 PRE 3 PRE 2 Fig. 1 4 PRE IN ch3 8 + 1 560 + 0.1 560 7 10 6 PRE 1 PRE GND 1 HSW CTRL 33 AGC DET 29 5.1k 10 1 9 0.1 28 30p EQ CTRL 0.01 1.5k 10 PRE IN ch2 HSW 27 PEAKING CHROMA OUT AGC AMP 50k ENVE DET 26 ENVE. 25 ENVE OUT HA SW COMP PRE VCC 24 10 11 0.1 23 PRE VCC 5V + 0.1 12 0.01 COMP. OUT 560 PRE IN ch4 HSW REC VCC 12V REC VCC 0.01 HEAD AMP SW CTRL 1 PRE 4 200 REC IN 5 10 PRE IN ch1 1 4 + 560 3 HEAD SW CTRL 2 EQ CTRL 1 Units: R [] C [F] L [L] REC Y.IN 28 32 HSW PRE 2 HA SW PRE 3 23 PRE 1 H SW CTRL ENVE DET HSW ENVE DET PRE 4 HA SW CTRL 19 H SW 31 +- REC GND EQ SW 17 H AMP SW 29 PRE GND 30 PRE VCC 18 EQ CTRL 27 PEAKING 26 COMP 22 AGC AMP 25 PRE VCC 24 ENVE. 21 AGC DET 20 EP ``H'' PRE Y.OUT PRE VCC 5V PRE C.OUT ENVE (DET) OUT ENVE (COMP) OUT REC VCC 12V REC C.IN EP B EP A SP B SP A HEAD Video ICs BA7274S *Application example 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Fig. 2 5 Video ICs BA7274S pin logic *(1)Control Playback head switching H. AMP SW 14pin HEAD SW 3pin Selected head H CH1 (PRE AMP pin 5 input) L CH2 (PRE AMP pin 7 input) L CH3 (PRE AMP pin 10 input) H CH4 (PRE AMP pin 12 input) L H (2) EP / SP switching envelope comparator ON / OFF switch (pin 2) REC VCC 21pin PRE VCC 25pin H (REC) L L H (PB) EP / SP 2pin Mode H EP (REC AMP pin 16 output) L SP (REC AMP pin 17 output) H ENVE. detector output pin 26 EP mode ENVE. comparator output pin 24 stopped "H" L ENVE. detector output pin 26 SP mode ENVE. comparator output pin 24 operating, see (3) (3) Envelope comparator output (pin 24) COMP. OUT 24pin Conditions H CH1 or CH2 output > CH3 or CH4 output L CH1 or CH2 output < CH3 or CH4 output Note: The correspondence between channels and amplifiers is as follows: CH CH1 CH2 CH3 CH4 PRE AMP PRE AMP 1 PRE AMP 2 PRE AMP 3 PRE AMP 4 6 Video ICs BA7274S *Electrical characteristic curve ENVELOPE DETECTOR OUTPUT VOLTAGE: (VDC) 5 4 EP 3 SP 2 1 0 0 100 200 300 400 500 600 700 800 9001000 OUTPUT VOLTAGE 28pin (mVP-P) Fig. 1 Playback signal envelope detector characteristics *External dimensions (Units: mm) 28.0 0.3 17 0.51Min. 3.2 0.2 4.7 0.3 8.4 0.3 32 1 16 10.16 0.3 0.1 1.778 0.5 0.1 0 ~ 15 SDIP32 7