BA7795LS

Video ICs VCR standard audio signal processor BA7795LS / BA7795FS The BA7795LS and BA7795FS are standard audio signal processor ICs. They contain a playback preamplifier, line amplifier, recoeding amplifier, ALC circuit, EQ switch circuit and high-voltage head switch, and provide all of the functions required for normal-audio signal processing on a single IC with a minimum number of external components required. •Applications recorders and tape decks Video cassette •Features in compact SZIP and SSOP-A24-pin pack1) Available 2) 3) 4) 5) ages. High-with standing-voltage head switch (AC with standing voltage: Min. 80VP-P (f = 70kHz) ). Simple, three-mode EQ switch built-in (BA7795LS). Built-in LINE / TUNER selector switch. High-performance low-noise playback amplifier. Input conversion noise figure – 122dBV (Typ. Rg = 680, DIN AUDIO). 6) ALC level can be varied. 7) ALC loop external mute eliminates audible noise at power on, and ALC attack noise. 8) Signal processing circuit can be constructed with the addition of just a few external components. •Block diagram EP LP + HEAD EQ 1 REC 2 PB IN REC HSW 3 REC 4 GND RIPPLE FILTER 5 6 PB PB NFB VCC 7 8 SP EQ CTRL 9 PB EQ 10 PB / TU / EE CTRL 11 PB 12 PB OUT PB LINE IN ALC LEVEL 13 14 BIAS + 20dB LINE – 8dB LINE ALC FILTER BIAS 15 ALC 16 LINE IN MUTE CTRL 17 – 8dB TUNER 18 TUNER IN REC NFB 19 20 REC OUT 21 REC BF 22 GND LINE OUT EP REC EQ 23 – 20dB MUTE 24 REC / EE CTRL BA7795LS ∗ The BA7795FS has a different pin layout to the BA7795LS. 1 Video ICs BA7795LS / BA7795FS •Absolute maximum ratings (Ta = 25°C) Parameter Applied voltage Power dissipation BA7795LS BA7795FS Symbol VCC Pd Topr Tstg Limits 13 400∗1 800∗2 – 10 ~ + 65 – 55 ~ + 125 Unit V mW °C °C Operating temperature Storage temperature ∗1 Reduced by 4.0mW for each increase in Ta of 1°C over 25°C. ∗2 Reduced by 8.0mW for each increase in Ta of 1°C over 25°C. •Recommended operating conditions (Ta = 25°C) Parameter Power supply voltage Symbol VCC Limits 7.5 ~ 12.5 Unit V •Pin descriptions BA7795LS Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 BA7795FS Pin No. 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 Pin name HEAD EQ PB IN REC HSW GND RIPPLE FILTER PB NFB VCC PB EQ EQ CTRL PB OUT PB / TU / EE CTRL PB LINE IN ALC LEVEL ALC FILTER BIAS LINE IN MUTE CTRL TUNER IN REC NFB GND REC OUT BF OUT REC EQ REC / EE CTRL Function Head resonance capacitor switch Playback amplifier input / playback head switch High-withstanding voltage recording head switch GND (playback amplifier) Ripple filter Playback amplifier feedback Power supply Playback EQ switch EQ control Playback amplifier output PB / TU / EE control (PB / EE control) Playback line amplifier ALC level setting ALC filter time constant Bias Line input MUTE control Tuner input (REC / EE control) Recording amplifier feedback GND Recording amplifier output Line amplifier output Recording EQ switch (recording EQ switch 2) REC / EE control (recording EQ switch 1) 2 Video ICs BA7795LS / BA7795FS CC •Electrical characteristics (unless otherwise noted, Ta = 25°C, V Parameter Quiescent current EE Quiescent current PB Quiescent current REC 〈Line amplifier〉 Power supply gain (PB input) Power supply gain (LINE1, LINE2, TU inputs) Distortion Maximum output level Output residual noise ALC level ALC distortion Mute attenuation ratio 〈Recording amplifier〉 Voltage gain Distortion Maximum output level Open loop gain 〈Playback preamplifier〉 Open loop gain Input conversion noise Total gain 〈Head switch〉 PB head switch impedance REC head switch impedance REC head switch AC withstanding voltage RPH RRH BVRHAC — — 80 GVOP VNINP GVCP-L 62 — 56 GVCR THDR VOmR GVOR 19.0 — 5.5 65 GVCP GVCL THDL VOmL VNOL VOA THDA MT 27.0 19.0 — 5.0 — – 7.0 — — Symbol IqEE IqPB IqREC Min. 6.3 6.3 4.9 = 9V, and f = 1kHz) Max. 10.8 10.8 8.4 Unit mA mA mA Conditions When no signal When no signal When no signal Typ. 8.3 8.3 6.4 28.0 20.0 0.1 7.2 – 81.5 – 6.0 0.18 – 82.5 29.0 21.0 0.3 — – 75 – 5.0 0.5 – 72 dB dB % dBV dBV dBV % dB VO = – 8dBV VO = – 8dBV VO = – 8dBV, RL = 4.7kΩ∗1 THD = 1%, RL = 4.7kΩ∗1 Rg = 4.7kΩ, DIN AUDIO VIN = – 23dBV R1 / R2 = 8.2 / 39kΩ VIN = – 23dBV, RL = 4.7kΩ∗1 Vo = 0dBV, DIN AUDIO LINE, TUNER input→REC OUT VO = – 8dBV VO = – 8dBV, RL = 4.7kΩ∗1 THD = 1%, RL = 4.7kΩ∗1 20.0 0.03 7.4 77 21.0 0.3 — — dB % dBV dB 68 – 122.5 57.5 — – 114 59 dB dBV dB Ω Ω VP-P f = 70kHz Rg = 680Ω, DIN AUDIO PB IN →BF OUT 11 11 100 20 20 — ∗1 Measured at BW = 400Hz to 30kHz. 3 Video ICs BA7795LS / BA7795FS •Input / output circuits 10kΩ EQ CTRL 56kΩ PB / TU / EE CTRL REC / EE CTRL 56kΩ MUTE CTRL 56kΩ REC PB HSW Fig. 1 4 Video ICs BA7795LS / BA7795FS •Measurement circuit BA7795LS REC 1 1k 3.3µ 680 EP LP + + 2 3 REC 4 330 22µ 0.01µ 4.7k PB 0.1µ 2.2M + PB IN 68k ON: GVOPB AC BIAS IN 22µ 5 6 7 + + 33µ VCC 8 8.2k SP EQ CTRL 9 10 PB / TU / EE CTRL 11 12 4.7k 12k 14 ALC – 8dB LINE + 28dB + R2 13 R1 47µ 15 BIAS 330k PB ON: ALC OFF 0.1µ 16 4.7k LINE IN LINE MUTE CTRL ON: GVEREC + 17 1.5k – 8dB TUNER 18 0.1µ 4.7k TUNER IN 19 15k 100µ 20 21 REC BF 22 + REC OUT 4.7k RL 10µ + MUTE 4.7k EP 23 – 20dB LINE OUT 10µ 24 REC / EE CTRL Units: R [Ω] C [F] ∗ Fig. 2 The BA7795FS has a different pin layout to the BA7795LS. 5 Video ICs BA7795LS / BA7795FS •Circuit operation (1) EE oparation The input switch is used to select the audio signal input source (LINE or TUER). This signal is amplified by the line amplifier (voltage gain: 20dB at 1kHz). The ALC circuit controls the line amplifier output level. The ALC level is set externally. If mute mode is set in this state, the switch that connects the output buffer will go off, but the ALC loop will not be cut. (2) Recoeding In recording mode, the recording amplifier directly connected to the line amplifier operates. The PB HEAD switch in the playback equalizer amplifier block switches on, and the signal is not input to the playback equalizer amplifier. The line amplifier output is attenuated by 20dB before it is input to the recording amplifier, so if the feedback components are chosen to given a gain of 20dB, the same REC OUT output level as the line amplifier can be obtained. It is also possible to switch the REC equalizer characteristic to suit the tape speed by switchig the control signal to EQ CTRL. The recording amplifier gain and equalizer characteristics are set externally. Signal flow for EE and recording operation EP LP + 1 REC 3.3µ 2 22µ 4 330 3 22µ 5 6 PB REC VCC 33µ 7 8 EQ CTRL 9 10 PB / TU / EE CTRL 39k 13 8.2k BIAS 8.2k 4.7k 4.7k 11 PB 12 47µ 14 15 ALC – 8dB MUTE CTRL 1.5k LINE 17 + 28dB 16 + 19 15k – 8dB 18 20 21 REC BF + 22 MUTE 23 EP – 20dB 24 BIAS OSC REC + B BA7795LS Fig. 3 Signal flow for EE / recording ∗ The BA7795FS has a different pin layout to the BA7795LS. 6 + 0.1µ + + + + 330k 0.01µ 12k 2.2M LINE IN TUNER IN RL LINE OUT 10µ REC / EE CTRL Units: R [Ω ] C [F] Video ICs (3) Playback operation The signal applied to PB IN is amplified by playback equalizer amplifier. At this time, the REC HEAD switch is switched on by a control signal to REC / EE, and the potential on one side of the head is fixed at GND . The playback equalizer amplifier gain and equalizer characteristics are set externally. The playback level is set by the resistor divider between PB OUT and the playback line input, The signal to the playback line input passes though the input switch, is amplified by 20dB in the line amplifier, and is output to the output buffer (the voltage BA7795LS / BA7795FS gain is different to that for the LINE input and TUNER input). It is possible to switch between the input block head equalizer resonance point and playback equalizer characteristic using the EQ CTRL control signal. The line output can be stopped by setting muting mode on using the MUTE CTRL signal. The ALC circuit and recording amplifier are stopped in playback mode. Signal flow for playback operation 1 EP LP + REC + 2 22µ 4 3.3µ 3 REC 330k 22µ 33µ 5 + + + PB 6 7 330k 8 SP VCC 0.01µ EQ CTRL 9 8.2k 10 12k PB / TU / EE CTRL 39k 11 PB 4.7k 0.1µ 12 4.7k 13 8.2k BIAS + 14 47µ 15 ALC + 28dB – 8dB 2.2M 16 0.1µ – 8dB MUTE CTRL 1.5k 17 LINE LINE IN 18 0.1µ 20 TUNER IN 19 15k + 10µ 21 REC BF 4.7k 22 + 10µ LINE OUT EP 23 – 20dB MUTE 24 BIAS OSC REC + B REC / EE CTRL BA7795LS Units: R [Ω] C [F] Fig. 4 Signal flow for playback ∗ The BA7795FS has a different pin layout to the BA7795LS. 7 Video ICs BA7795LS / BA7795FS •Control/ mode tablePB / TU / EE CTRL (1) REC EE CTRL, Control pins REC / EE L L L H H H PB / TU / EE L M H L M H Mode LINE Mode TUNER PB LINE REC TUNER REC inhibit PB HSW OFF OFF OFF ON ON — Function REC HSW ON ON ON OFF OFF — LINE SW LINE TUNER PB LINE TUNER — REC AMP OFF OFF OFF ON ON — If REC / EE CTRL is set to "M", the REC pause state is possible (REC head switch: open, REC amplifier: off). (2) MUTE CTRL Control pins MUTE H L Mode MUTE MUTE Function LINE SW OPEN CLOSE (3) EQ CTRL Control pins EQ L M H 2 MODE SP — EP Mode 3 MODE SP LP EP HEAD EQ SW OFF ON ON Function PB EQ SW CLOSE OPEN OPEN REC EQ SW OFF OFF ON The L, M and H thresholds are: L to M: 1.7V, L to H: 2.5V, and M to H: 3.3V. 8 Video ICs BA7795LS / BA7795FS •Application example (BA7795LS) REC EP 1 3.3µ LP + 2 330 4 22µ + 3 22µ 33µ + 5 6 PB 7 330k 8 SP VCC REC EQ CTRL 9 8.2k 10 PB / TU / EE CTRL R1 11 PB 12 13 R2 BIAS 15 ALC – 8dB LINE + 28dB MUTE CTRL 1.5k 19 15k 21 REC BF 22 + + 14 2.2M 0.1µ 16 0.1µ 18 TUNER IN LINE IN 17 LINE – 8dB TUNER 20 RL LINE OUT MUTE EP 23 – 20dB 10µ 24 REC / EE CTRL BIAS OSC REC + B Units: R [Ω] C [F] ∗ The BA7795FS has a different pin layout to the BA7795LS. Fig. 5 + + + 0.01µ 12k 4.7k 4.7k 0.1µ 47µ 9 Video ICs BA7795LS / BA7795FS •Operation notes (1) ALC level Set the ALC level in the range – 8dBV to 0dBV by selecting the values of resistors R1 and R2 connected between BIAS, ALC LEVEL and GND. The formula for approximating the value of this resistor is as follows: (2) Mute signal Apply the mute signal shown below at power on and off. If the muting time is short, a pop sound will be audible, particularly when the power is switched on. VCC 1 VOA = 2 1 = 2 R1 VCC – 0.7 • • R1 + R2 2 R1 • VBIAS • R1 + R2 (H) (H) MUTE CTRL 2sec or more LINE OUT Fig. 7 If the ALC level setting is too low, level variation will increase compared to that of the standerd level (VOA = – 6dBV), and conversely, if the level is too high, the level variation will decrease, but distortion will increase.There is almost no temperature characteristic, but the ALC level does vary with supply voltage (VCC) as shown in the formula above. Use care when setting it. Also, be certain to apply the mute signal when switching between PB / LINE / TU. In the case of LINE / TU switching, it is possible to suppress switching noise by applying a time constant to the signal, in which case it is not necessary to apply the mute signal. (3) Recording control Do not switch the PB and REC modes on togther. This will cause faulty operation. (4) Line output The line output can drive a load resistance of up to 2kΩ. Depending on the type of load, it can cause local oscillation (eg. large capacitive loads that draw large current), so caution is required. In particular, when there is a possibility that the line output will be connected to a shielded cable, or line cable, connect a resistor of about 1k Ω in series with the output so that the capacitive load is not directly coupled to the IC output terminal. VBIAS = VCC – 0.7 2 BIAS ALC LEVEL R1 VBIAS R1 + R2 Fig. 6 10 Video ICs BA7795LS / BA7795FS •Electrical characteristic curves 40 VCC = 9V ALC; OFF OUTPUT LEVEL: VOA (dBV) 10 MAXIMUM OUTPUT LEVEL: VOmL (dBV) VCC = 9V f = 1kHz 0 13 15 20 30 GAIN: GVCLT (dB) R1 = 12kΩ R1 = 18kΩ R1 = 39kΩ 10 R1 5.6kΩ – 10 20 0 VCC = 9V (ALC; OFF) f = 1kHz THD = 1% (0.4 ~ 30kHz) 10 – 10 – 20 0 – 20 + 200 500 1k 2k 10µ RL 5k 10k LINE 100 100 1k 10k 100k 1M – 30 – 40 – 30 – 20 – 10 0 10 FREQUENCY: f (Hz) INPUT LEVEL: VIN (dBV) OUTPUT IMPEDANCE RL (Ω) Fig. 8 Gain vs. frequency (PB amplifier) Fig. 9 Line amplifier ALC input / output characteristics Fig. 10 Line amplifier load drive characteristics 100 PB 10 OUTPUT NOISE LEVEL: VON (dBV) SW 8 10 6 8.2k 330k 12k 0.01µ 22µ – 70 LINE VCC = 9V ALC; OFF DIN AUDIO 0 – 10 OUTPUT LEVEL: VO (dBV) – 20 – 30 – 40 – 50 – 60 – 70 – 80 – 90 TU→LINE PB→LINE MUTE 80 GAIN: GVOP – GVC (dB) GVO 2 – 80 60 EP (SW: OFF) 330 + ∗ BA7795LS – 90 40 SP (SW: ON) 20 – 100 DIN AUDIO VCC = 9V CIN = 4.7µF 100 200 500 1k 2k 5k 10k – 100 0 100 1k 10k 100k 1M 10M – 110 10 100 1k 10k 100k FREQUENCY: f (Hz) FREQUENCY: f (Hz) INPUT IMPEDANCE: Rg (Ω) Fig. 11 Playback amplifier frequency characteristics Fig. 12 Line amplifier crosstalk Fig. 13 Playback amplifier output noise characteristics 11 Video ICs BA7795LS / BA7795FS •External dimensions (Units: mm) BA7795LS BA7795FS 21.8 ± 0.2 2.8 ± 0.2 9.9 ± 0.5 10.0 ± 0.2 24 7.8 ± 0.3 5.4 ± 0.2 13 5.8 ± 0.2 2.0Min. 2.54 ± 0.25 1 23 1.8 ± 0.1 0.889 0.5 ± 0.1 0.1 0.3 + 0.05 – 1 12 0.11 0.8 0.36 ± 0.1 0.3Min. 0.15 2 24 SZIP24 SSOP-A24 12 0.15 ± 0.1