DEMOTS472Q

TS472 Very low noise microphone preamplifier with 2.0 V bias output and active low standby mode Features Flip-chip - 12 bumps ■ Low noise: 10 nV/√Hz typ. equivalent input noise at F = 1 kHz ■ Fully-differential input/output ■ 2.2 to 5.5 V single supply operation ■ Low power consumption at 20 dB: 1.8 mA ■ Fast start up time at 0 dB: 5 ms typ. ■ Low distortion: 0.1% typ. ■ 40 kHz bandwidth regardless of the gain ■ Active low standby mode function (1 μA max) ■ Low noise 2.0 V microphone bias output ■ Available in flip-chip lead-free package and in QFN24 4 x 4 mm package ■ ESD protection (2 kV) Pin connections (top view) Applications QFN24 ■ Video and photo cameras with sound input ■ Sound acquisition and voice recognition ■ Video conference systems ■ Notebook computers and PDAs Pin connections (top view) Description The TS472 is a differential-input microphone preamplifier optimized for high-performance PDA and notebook audio systems. This device features an adjustable gain from 0 to 40 dB with excellent power-supply and commonmode rejection ratios. In addition, the TS472 has a very low noise microphone bias generator of 2 V. NC 24 23 GND STBY VCC 22 21 20 NC 19 NC 1 18 NC BYP 2 17 OUT+ NC 3 16 OUT- GND 4 15 C2 IN- 5 14 C1 NC 6 13 NC It also includes a complete shutdown function, with active low standby mode. August 2009 NC Doc ID 11015 Rev 6 7 8 9 10 11 12 NC IN+ GS BIAS NC NC 1/25 www.st.com 25 Contents TS472 Contents 1 Typical application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5 4.1 Differential configuration principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2 Higher cut-off frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.3 Lower cut-off frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.4 Low-noise microphone bias source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5 Gain settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.6 Wake-up time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.7 Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.8 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.9 Single-ended input configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.10 Demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.1 Flip-chip package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2 QFN24 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 6 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2/25 Doc ID 11015 Rev 6 TS472 Typical application schematic Figure 1 shows a typical application schematic for the TS472. Figure 1. Application schematic (flip-chip) Optional C1 VCC Cs 1uF Rpos TS472_FC Vcc Cin+ + Electret Mic C2 U1 C1 C3 1uF C2 Cout+ IN+ OUT+ IN- OUT- Positive Output Cout- G BIAS 2.0V Rout- GAIN SELECT BYPASS Cb 1uF STDBY Bias Rout+ Negative Output CinRneg GND 1 Typical application schematic Standby Control Table 1. Description of external components Components Functional description Cin+, Cin- Input coupling capacitors that block the DC voltage at the amplifier input terminal. Cout+, Cout- Output coupling capacitors that block the DC voltage coming from the amplifier output terminal (pins C2 and D2) and determine the lower cut-off frequency (see Section 4.3: Lower cut-off frequency). Rout+, Rout- Output load resistors used to charge the output coupling capacitors Cout. These output resistors can be represented by an input impedance of a following stage. Rpos, Rneg Polarizing resistors for biasing of a microphone. Cs Supply bypass capacitor that provides power supply filtering. Cb Bypass pin capacitor that provides half-supply filtering. C1, C2 C3 Low pass filter capacitors allowing to cut the high frequency. Bias output filtering capacitor. Doc ID 11015 Rev 6 3/25 Typical application schematic Table 2. 4/25 TS472 Pin descriptions Pin name Flip-chip designator QFN designator IN+ A1 8 Positive differential input IN- B1 5 Negative differential input BIAS A2 10 2 V bias output GND C1 4, 22 Ground STBY C3 21 Standby BYP D1 2 Bypass GS B2 9 Gain select OUT- D2 16 Negative differential output OUT+ C2 17 Positive differential output C1 A3 14 Low-pass filter capacitor C2 B3 15 Low-pass filter capacitor Vcc D3 20 Power supply NC --- 3, 6, 7, 11, 12, 13, 18, 19, 23, 24 Pin description Not connected, floating pins Doc ID 11015 Rev 6 TS472 2 Absolute maximum ratings Absolute maximum ratings Table 3. Absolute maximum ratings Symbol VCC Vi Parameter Supply voltage (1) Input voltage Value Unit 6 V -0.3 to VCC+0.3 V Toper Operating free air temperature range -40 to + 85 °C Tstg Storage temperature -65 to +150 °C Maximum junction temperature 150 °C Rthja Thermal resistance junction to ambient: Flip-chip QFN24 180 110 °C/W ESD Human body model 2 kV ESD Machine model 200 V Lead temperature (soldering, 10sec) 250 °C Tj 1. All voltage values are measured with respect to the ground pin. Table 4. Operating conditions Symbol VCC A VSTBY Parameter Supply voltage Typical differential gain (GS connected to 4.7 kΩ or bias) Standby voltage input: Device ON Device OFF Value Unit 2.2 to 5.5 V 20 dB 1.5 ≤VSTBY ≤VCC GND ≤VSTBY ≤0.4 V Top Operational free air temperature range -40 to +85 °C Rthja Thermal resistance junction to ambient: Flip-chip QFN24 150 60 °C/W Doc ID 11015 Rev 6 5/25 Electrical characteristics 3 Electrical characteristics Table 5. Electrical characteristics at VCC = 3 V with GND = 0 V, Tamb = 25° C (unless otherwise specified) Symbol Parameter Min. Typ. Max. Unit Equivalent input noise voltage density REQ = 100 Ω at 1 kHz 10 nV -----------Hz Total harmonic distortion + noise 20 Hz ≤F ≤ 20 kHz, gain = 20 dB, Vin = 50 mVRMS 0.1 % Vin Input voltage, gain = 20 dB 10 BW Bandwidth at -3 dB Bandwidth at -1 dB pin A3, B3 floating 40 20 en THD+N G Overall output voltage gain (Rgs variable): Minimum gain, Rgs infinite Maximum gain, Rgs = 0 Zin 70 mVRMS kHz -3 39.5 -1.5 41 0 42.5 dB Input impedance referred to GND 80 100 120 kΩ RLOAD Resistive load 10 CLOAD Capacitive load ICC Supply current, gain = 20 dB ISTBY Standby current PSRR Power supply rejection ratio, gain = 20 dB, F = 217 Hz, Vripple = 200 mVpp, inputs grounded Differential output Single-ended outputs, Table 6. kΩ 1.8 100 pF 2.4 mA 1 μA dB -70 -46 Bias output: VCC = 3 V, GND = 0 V, Tamb = 25° C (unless otherwise specified) Symbol Parameter Min. Typ. Max. Unit Vout No load condition 1.9 2 2.1 V Rout Output resistance 80 100 120 W Iout Output bias current PSRR 6/25 TS472 Power supply rejection ratio, F = 217 Hz, Vripple = 200 mVpp Doc ID 11015 Rev 6 70 2 mA 80 dB TS472 Electrical characteristics Table 7. Differential RMS noise voltage Input referred noise voltage (μVRMS) Gain (dB) Output noise voltage (μVRMS) Unweighted filter A-weighted filter Unweighted filter A-weighted filter 0 15 10 15 10 20 3.4 2.3 34 23 40 1.4 0.9 141 91 Table 8. Bias output RMS noise voltage C3(1) (μF) Unweighted filter (μVRMS) A-weighted filter (μVRMS) 1 5 4.4 10 2.2 1.2 1. Bias output filtering capacitor. Table 9. Gain (dB) SNR (signal to noise ratio), THD+N < 0.5% Unweighted filter 20 Hz - 20 kHz (dB) A-weighted filter (dB) VCC = 2.2 V VCC = 3 V VCC = 5.5 V VCC = 2.2 V VCC = 3 V VCC = 5.5 V 0 75 76 76 79 80 80 20 82 83 83 89 90 90 40 70 72 74 80 82 84 Doc ID 11015 Rev 6 7/25 Electrical characteristics 2.5 2.5 Current Consumption (mA) Current Consumption (mA) 3.0 Tamb=85°C 2.0 1.5 Tamb=25°C 1.0 Tamb=-40°C 0.5 No Loads GS floating 0 Figure 4. 1 2 3 4 Power Supply Voltage (V) 5 Current consumption vs. standby voltage Tamb=85°C 1.0 2.0 Vcc=5V 1.0 0.5 No Loads GS floating Tamb = 25°C 0 Figure 6. 1 2 3 Standby Voltage (V) 4 0 1 Current consumption vs. standby voltage Vcc=5V 0.5 30 0.8 20 PSRR (dB) 6 1.0 1.0 0.4 5 Vcc=3V No Loads GS grounded Tamb = 25°C 0 1 Figure 7. 0.6 2 3 4 Power Supply Voltage (V) 1.5 0.0 5 Standby threshold voltage vs. power supply voltage No Loads GS grounded Figure 5. 2.0 Vcc=3V Tamb=-40°C 0.5 2.5 1.5 Tamb=25°C 1.5 0.0 6 Current consumption vs. power supply voltage 2.0 2.5 0.0 Standby Treshold Voltage (V) Figure 3. 3.0 0.0 2 3 Standby Voltage (V) 4 5 Frequency response Cb=1μ F, T AMB =25° C, Gain=20dB, Rout=100k Ω 10 no C1,C2 C1,C2=100pF 0 Cin,Cout=100nF 0.2 0.0 8/25 Current consumption vs. power supply voltage Current Consumption (mA) Current Consumption (mA) Figure 2. TS472 C1,C2=220pF -10 Cin,Cout=10nF No Loads Tamb = 25°C 2.2 3 4 Power Supply Voltage (V) 5 5.5 -20 10 Doc ID 11015 Rev 6 100 1000 Frequency (Hz) 10000 100000 TS472 Electrical characteristics Figure 8. Bias output voltage vs. bias output Figure 9. current 2.2 2.2 Vcc=2.5-6V Tamb=25°C 2.0 Bias Output Voltage (V) Bias Output Voltage (V) Bias output voltage vs. power supply voltage Tamb=85°C 1.8 1.6 Tamb=-40°C Ibias=0mA 2.0 Ibias=2mA 1.8 Ibias=4mA 1.6 Tamb=25°C 1.4 0 1 2 3 Bias Output Current (mA) 1.4 4 Figure 10. Bias PSRR vs. frequency 4 Power Supply Voltage (V) 5 5.5 Figure 11. Bias PSRR vs. frequency 0 0 Vripple=200mVpp Vcc=3V Cb=1 μ F Tamb =25 ° C -40 Vripple=200mVpp Vcc=5V Cb=1 μ F Tamb=25 ° C -20 PSRR (dB) -20 PSRR (dB) 3 2.2 Bias floating or 1k Ω to GND -60 Bias = 1k Ω to GND -40 -60 -80 -80 -100 -100 Bias floating 50 100 1000 50 10000 20k 100 1000 Frequency (Hz) Frequency (Hz) Figure 12. Differential output PSRR vs. frequency Figure 13. Differential output PSRR vs. frequency 0 PSRR (dB) -20 -30 0 Vripple=200mVpp Inputs grounded Vcc=3V Cb=1 μ F Cin=100nF Tamb=25 ° C -10 -20 GS grounded -40 GS=bias GS floating -50 PSRR (dB) -10 -30 -70 -70 100 1000 Frequency (Hz) 10000 20k GS grounded -50 -60 50 Vripple=200mVpp Inputs grounded Vcc=5V Cb=1 μ F Cin=100nF Tamb=25 ° C -40 -60 -80 10000 20k -80 50 Doc ID 11015 Rev 6 GS=bias GS floating 100 1000 Frequency (Hz) 10000 20k 9/25 Electrical characteristics TS472 Figure 14. Differential output PSRR vs. frequency Figure 15. Differential output PSRR vs. frequency 0 0 V RIPPLE =200mV PP , Inputs grounded -40 Cb=1μ F No Cb V CC =3V, Gain=20dB, Cin=1 μ F, T AMB =25° C -20 PSRR (dB) -20 PSRR (dB) V RIPPLE =200mV PP, Inputs grounded V CC =3V, Minimum Gain, Cin=1 μ F, T AMB =25° C Cb=100nF -60 -40 Cb=1μ F No Cb -60 -80 -80 -100 50 -100 50 Cb=100nF 100 1k Frequency (Hz) 10k 20k Figure 16. Single-ended output PSRR vs. frequency 1k Frequency (Hz) 10k 20k Figure 17. Equivalent input noise voltage density 0 1000 -20 -30 Cin=100nF R EQ=100 Ω Vcc=3V T AMB =25 ° C en (nV/√ Hz) Vripple=200mVpp Inputs grounded Cb=1μ F Cin=100nF Tamb=25° C -10 PSRR (dB) 100 -40 -50 100 10 -60 -70 Vcc=2.2V -80 100 50 Vcc=5V 1000 Frequency (Hz) 1 10 10000 20k Figure 18. Δgain vs. power supply voltage 0.25 Maximum Gain 100k F=1kHz V IN =5mV 0.00 Δ Gain (dB) Δ Gain (dB) 10k 0.50 F=1kHz Vin=5mV Tamb=25°C 0.6 0.4 0.2 -0.25 Maximum Gain -0.50 0.0 Gain=20dB Minimum Gain -0.2 -0.75 Gain=20dB -0.4 2.2 10/25 1k Frequency (Hz) Figure 19. Δgain vs. ambient temperature 1.0 0.8 100 3 4 Power Supply Voltage (V) 5 5.5 -1.00 -40 Doc ID 11015 Rev 6 Minimum Gain -20 0 20 40 Ambient Temperature (°C) 60 80 TS472 Electrical characteristics Figure 20. Maximum input voltage vs. gain, THD+N