KA9270 AUDIO FILTER INTRODUCTION 20-DIP-300A The KA9270 is a monolithic integrated circuit designed for audio filter. It is used in compact disc player, digital audio tape recorder, etc. FEATURES 20-SOP-375 • Functions: * Buffer for impedence matching * Low pass filter * De - emphasis control * Mute control * Reference voltage circuit ( 1/2 VCC AMP ) • Gain adjustable of audio output • Minimum number of external parts required • Recommand operation supply voltage range : 5.0 ~ 12.0V Device Package KA9270 20-DlP-300A KA9270D 20-SOP- 375 Operating Temperature 20°C ~ +75°C BLOCK DIAGRAM 20 LPF OUTPUT2 LPF2B 19 18 VREF RIPPLE 17 16 DE-EMPHA DE-EMPHA DE-EMPHA CTL OUT2 IN3 15 14 13 BUFFER OUT2 INPUT2 12 11 Vcc LPF2 - - DE-AMP2 + - - + + + 1/2Vcc-AMP BUFFER2 BUFFER1 MUTE SW + - DE-EM SW + 1 2 LPF OUTPUT1 - DE-AMP1 LPF1 GND + - 3 LPF1B 4 MUTE CONTROL INPUT 5 6 7 8 9 DE-EMPHA DE-EMPHA DE-EMPHA DE-EMPHA BUFFER CONTROL CTL OUT1 IN1 OUT1 INPUT Fig. 1 10 INPUT1 KA9270 AUDIO FILTER ABSOLUTE MAXIMUM RATINGS (Ta = 25°C) Characteristic Supply Voltage Power Dissipation Operating Temperature Storage Temperature Symbol Value Unit VCC PD T OPR T STG 16 550 -20 ~ + 75 -45 ~ + 150 V µW °C °C ELECTRICAL CHARACTERISTICS (Ta = 25°C, VCC = 8V, f = 1KHz, RL = 10KΩ, De-emphasis; off, Mute; off, S1 & S2; off, unless otherwise specified) Characteristic Symbol Test Conditions Quiescent Circuit Current ICC VI = 0 Maximum Output Voltage VOM THD = 1% Total Harmonic Distortion THD VO = 0dBm Min Typ Max 1 4 6 1.8 2.1 Frequency Characteristics Cross Talk Signal to Noise Ratio fv CT S/N VO = 6dBm VO = 0dBm 0.01 0.05 f = 1KHz 0.01 0.05 f = 10KHz 0.05 0.1 f = 16KHz 0.1 0.2 0.1 0.2 f = 100Hz -0.1 0 0.1 f = 1KHz 0 0 0 f = 10KHz -0.5 0 0.5 f = 16KHz -1.0 0 1.0 f = 20KHz -1.5 0 1.5 f = 100Hz 70 80 f = 1KHz 65 75 f = 10KHz 60 65 73 80 VO = 0dBm, RG = 600Ω 20KHz LPF mA Vrms f = 100Hz f = 20KHz Unit % dB dB dB Channel Balance CB VO = 0dBm -1.0 0 1.0 dB Open Loop Gain GVO VI = 900mVrms -2.6 -0.6 1.0 dB Gain Adjusting Range GVR VI = 900mV, S1, S2; ON 4.5 6 Mute Attenuation Ratio ATTMUTE VI = 900mV, Mute SW; ON 40 50 -0.87 -0.37 f = 1KHz De-emphasis DEEMPH De-emphasis: ON Note: De-emphasis input conditions: VO = 0dBm De-emphasis off position dB dB 0.13 f = 5KHz -6.03 -4.53 -3.03 f = 16KHz -10.53 -9.03 -7.53 dB KA9270 AUDIO FILTER TEST CIRCUIT CH2 OUTPUT (Vo) 3.3§Þ + 1/2 Vcc 0.0015§Þ 10K 47§Þ 0.01§Þ 1M 5.6K 0.0012§Þ Vcc + 330pF 12K 4.7§Þ 27K CH2-INPUT (from SIGNAL GENERATOR OUTPUT) 27K 5K + 5.6K 5.6K + 4.7§Þ 20 19 18 17 16 15 14 13 + 12 - 11 VI Vcc 1/2 Vcc LPF2 - - DE-AMP2 + - - + + + BUFFER2 BUFFER1 MUTE SW + - DE-EM SW + 2 - DE-AMP1 LPF1 1 + - 3 4 5 6 7 8 9 5.6K + 330pF CH1 OUTPUT (Vo) 5.6K 27K 5.6K + 3.3§Þ 0.0015§Þ 10K CH1-INPUT (from SIGNAL GENERATOR OUTPUT) 10 27K 4.7§Þ 5K MUTE CONTROL SIGNAL (MUTE) DE-EMPHASIS CONTROL SIGNAL (DE-EM) 0.0012§Þ 1M Fig. 2 12K + VI - KA9270 AUDIO FILTER APPLICATION INFORMATION 1. BUFFER INPUT + (from D/A Converter Output) to De-emphasis input - Fig. 3 It is used for impedance matching, between D/A converter output and de-emphasis input. 2. DE-EMPHASIS a) De-emphasis operation condition Control Input De-emphasis Operation High ON Low OFF b) De-emphasis characteristic at the de-emphasis ON C1 R5 R4 R6 Vi + Vo Fig. 4 Equevalent Circuit of De-emphasis ON Mode Av R4 / R6 T1 = C1 (R4 + R5) T2 = C1 X R5 The de-emphasis charcteristics is dependent on the external parts value. KA9270 AUDIO FILTER 3. MUTE R QON R6 Where: RQON = internal TR ON resistance - Vi Vo + Fig. 5 Equivalent Circuit of Mute Switch ON Mode Mute attenuation [M (att)] ratio is as follow; M (att) = 20 log VO VI = 20 log RQON (dB) R6 4. LOW PASS FILTER R1 R3 R2 Vi C4 - C3 + Fig. 6 Equivalent Circuit of LPF Cut off frequency (FC) is as follow: fC = 1 2π√R2 R1 C3 C4 (Hz) KA9270 AUDIO FILTER APPLICATION CIRCUIT 3.3§Þ + CH2 OUTPUT RL 10K 1/2 Vcc C9 R12 1M 5.6K 120uP Vcc 4.7¥ì + C10 R11 19 C8 + 5.6K 330p 20 12K R9 CH2-INPUT (from DAC OUTPUT) 1500p 27K 27K 5.6K R8 R7 R10 10¥ì 18 C7 17 16 15 4.7¥ì C8 + 13 14 12 11 Vcc LPF2 - - DE-AMP2 + - - + + + BUFFER2 BUFFER1 MUTE SW + - DE-EM SW + 2 - DE-AMP1 LPF1 1 + - 3 4 5 6 7 8 9 5.6K CH1 OUTPUT (Vo) + R1 330p C5 3.3¥ì R2 RL 10K C3 + 1500p + C4 10 10u R3 5.6K R4 27K DE-EMPHASIS CONTROL SIGNAL (DE-EM) 1200p 1M Fig. 7 C7 4.7¥ì 27K C2 MUTE CONTROL SIGNAL (MUTE) R6 12K CH1-INPUT (from DAC OUTPUT) KA9270 AUDIO FILTER (PCB PATTERN)