www.fairchildsemi.com FAN7031 2W Stereo Power Amplifier with Four Selectable Gain Setting and Headphone Drive Features Description • 1.85WRMS and 2.45WRMS Power Per Each Channel Into 4Ω Load With Less Than 1% and 10% THD+N, Respectively • Selectable Gain Via Internal Gain Control Circuit Which Eliminates External Gain Setting Resistors : 6dB, 10.3dB, 15.6dB, 21.6dB(Select) • Low Quiescent Current : Typical 5.5mA@5V • Low Shutdown Current : Typical 0.04µA@5V • Fully Differential Input, Which Immunes the Common Mode Noise • Stereo Headphone Drive • Active Low Shutdown Logic • Guaranteed Stability Under No Load Condition • Thermally Enhanced Surface-Mount 20TSSOP-EP Package The FAN7031 is a dual fully differential power amplifier in a 20-pin TSSOP-EP thermally enhanced package. When delivering 1.85W of continuous RMS power into 4Ω speaker at 5V supply, the FAN7031 has less than 1% of THD+N over the entire audible frequency range, 20Hz to 20kHz. To save power consumption in the portable applications, the FAN7031 provides shutdown function. Setting the shutdown pin to ground level, the FAN7031 falls into shutdown mode and consumes less than 4µA over all supply voltage range, 2.7V to 5.5V. Two gain setting pins(G0 and G1) control the gain of the FAN7031. The gain is selectable to 6dB, 10dB, 15.6dB and 21.6dB. The FAN7031 provides the singleended(SE) operation by setting SE/BTL pin to above VDD/2. Using SE/BTL pin and a mechanical switch which provides at the headphone jack, SE mode and BTL mode are automatically determined. Additional components such as resistors for gain setting and bootstrap capacitors are not needed, making the FAN7031 well suited for portable sound systems and other hand-held sound equipment. Target applications include notebook and desktop computers and portable audio equipment. 20-TSSOP-EP 1 Rev. 1.0.1 ©2003 Fairchild Semiconductor Corporation FAN7031 Internal Block Diagram RINROUT+ RIN+ ROUT- CONTROL Gain Control SE/BTL SD SE/BTL Control On/Off Control G0 G1 BIAS TSD VDD/2 BYPASS Current Source LINLOUT+ LIN+ LOUT- 2 FAN7031 Pin Assignments GND 1 20 GND G0 SD G1 ROUT+ LOUT+ LIN- RINVDD PVDD1 ROUT- Heat Sink PVDD2 RIN+ LOUTLIN+ NC SE/BTL BYPASS 10 11 GND Pin Description Pin No Symbol I/O 1* GND - Ground Decription 2 G0 I Gain Selection Input(MSB) 3 G1 I Gain Selection Input(LSB) 4 LOUT+ O Left Channel (+) Output 5 LIN- I Left Channel (-) Input 6** PVDD2 I Left Channel Power Supply Voltage 7 RIN+ I Right Channel (+) Input 8 LOUT- O Left Channel (-) Output 9 LIN+ I Left Channel (+) Input 10 BYPASS O Bypass Capacitor Connect 11* GND - Ground 12 SE/BTL I Single-Ended & BTL Selection: GND ≤ SE/BTL ≤ VDD/2:BTL Mode VDD/2 < SE/BTL ≤ VDD: SE Mode 13 NC - No Connection 14 ROUT- O Right Channel (-) Output 15** PVDD1 I Right Channel Power Supply Voltage 16** VDD I Power Supply Voltage 17 RIN- I Right Channel (-) Input 18 ROUT+ O Right Channel (+) Output 19 SD I Shutdown Logic Low SD=VDD: Chip Enable SD=GND: Chip Shutdown 20* GND - Ground * All GND is internally tied together. ** For the best performance, VDD, PVDD1 and PVDD2 must be the same voltage level(strongly recommend). 3 FAN7031 Absolute Maximum Ratings Parameter Symbol Maximum Supply Voltage VDDmax 6.0V V PD Internally Limited W Power Dissipation Value Unit Operating Temperature TOPG -40 ~ +85 °C Storage Temperature TSTG -65 ~ +150 °C Junction Temperature TJ 150 °C Thermal Resistance (Junction to Ambient) Rthja ESD Rating (Human Body Model) 30.4 °C/W 112.5 2000 Remark See Derating Curve Multi Layer Board Single Layer Board V Note1 : Rthja was derived using a JEDEC multi layer and single layer. Operating Ratings Parameter Power Supply Voltage 4 Symbol Min Typ Max Unit VDD 2.7 - 5.5 V FAN7031 Electrical Characteristics (VDD = 5.0V, Ta = 25°C, unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit -25 - 25 mV - 5.5 10 mA - 0.04 4 µA - 1.85 - W - 2.45 - W - 6 - dB SE/BTL=GND, G0=GND, G1=VDD, Vin=2.44Vpp, No Load - 10.3 - dB SE/BTL=GND, G0=VDD, G1=GND, Vin=1.34Vpp, No Load - 15.6 - dB SE/BTL=GND, G0=VDD, G1=VDD, Vin=0.66Vpp, No Load - 21.3 - dB SE/BTL=VDD, Vin=2.44Vpp, No Load - 4.3 - dB - 0.2 0.75 % 40 70 - dB Min. Typ. Max. Unit Offset Voltage VOFF Supply Current IDD No Input, No Load Shutdown Current ISD SD = GND THD+N =1%, RL = 4Ω, f = 1kHz THD+N =10%, RL = 4Ω, f = 1kHz SE/BTL=GND, G0=GND, G1=GND, Vin=4Vpp, No Load Output Power PO BTL Mode Gain Av SE Mode Gain RL=4Ω, Av=6dB Total Harmonic Distortion + Noise THD+N PO = 1W, RL=4Ω, f = 20kHz Power Supply Rejection Ratio PSRR Cbyp = 0.47µF, RL=4Ω, BTL Mode, ∆VDD=500mVpp, f = 1kHz Electrical Characteristics (Continued) (VDD = 3.3 V, Ta = 25°C, unless otherwise specified) Parameter Symbol Conditions Offset Voltage VOFF -25 - 25 mV Supply Current IDD RL=4Ω, Av=6dB No Input, No Load - 4.3 8 mA Shutdown Current ISD SD = GND - 0.08 4 µA Output Power PO THD+N =10%, RL = 4Ω, f=1kHz - 1.02 - W Total Harmonic Distortion + Noise THD+N PO = 0.5W, RL = 4Ω, f = 20kHz - 0.2 0.75 % Power Supply Rejection Ratio PSRR Cbyp = 0.47µF, RL=4Ω, BTL Mode, ∆VDD=330mVpp, f = 1kHz 40 70 - dB Min. Typ. Max. Unit Electrical Characteristics (Continued) (VDD = 2.7 V, Ta = 25°C, unless otherwise specified) Parameter Symbol Conditions Offset Voltage VOFF -25 - 25 mV Supply Current IDD RL=4Ω, Av=6dB No Input, No Load - 4.1 7 mA Shutdown Current ISD SD = GND - 0.04 4 µA Output Power PO THD+N =10%, RL = 4Ω, f=1kHz - 0.54 - W Total Harmonic Distortion + Noise THD+N PO = 0.25W, RL = 4Ω, f = 20kHz - 0.2 0.75 % Power Supply Rejection Ratio PSRR Cbyp = 0.47µF, RL=4Ω, BTL Mode, ∆VDD=270mVpp, f = 1kHz - 65 - dB 5 FAN7031 Performance Characteristics 10 10 5 5 2 2 1 1 20kHz 0.5 BTL mode VDD=5V RL=8ohm Av=6dB 0.5 THD [%] THD [%] 20kHz 0.2 1kHz 0.1 20Hz 0.02 0.005 0.002 0.001 10m 0.1 1kHz 0.05 0.05 0.01 0.2 0.02 20m 20Hz 0.01 BTL mode VDD=5V RL=4ohm Av=6dB 0.005 0.002 50m 100m 200m 500m 1 2 0.001 10m 3 20m 50m 100m Output Power [W] Figure 1. THD+N vs. Output Power 10 5 5 2 2 1 1 20kHz THD [%] THD [%] 1kHz 0.05 20kHz 0.2 0.1 1kHz 0.002 20m 50m 100m 200m 500m 1 20Hz 0.01 BTL mode VDD=3.3V RL=4ohm Av=6dB 0.005 0.005 0.002 0.001 10m 2 20m 50m Output Power [W] 10 5 5 2 2 1 1 20kHz 500m 1 BTL mode VDD=2.7V RL=8ohm Av=6dB 0.5 1kHz THD [%] THD[%] 0.2 200m Figure 4. THD+N vs. Output Power 10 0.5 100m Output Power [W] Figure 3. THD+N vs. Output Power 0.1 0.05 20kHz 0.2 0.1 1kHz 0.05 0.02 0.02 20Hz 0.01 0.002 20m 50m 100m 200m Output Power [W] Figure 5. THD+N vs. Output Power 500m 20Hz 0.01 BTL mode VDD=2.7V RL=4ohm Av=6dB 0.005 6 3 0.02 20Hz 0.01 0.001 10m 2 0.05 0.02 0.001 10m 1 BTL mode VDD=3.3V RL=8ohm Av=6dB 0.5 0.2 0.1 500m Figure 2. THD+N vs. Output Power 10 0.5 200m Output Power [W] 0.005 0.002 1 0.001 10m 20m 50m 100m 200m Output Power [W] Figure 6. THD+N vs. Output Power 500m 1 FAN7031 Performance Characteristics(Continued) 10 10 Single-ended mode VDD=5V RL=32ohm Av=4.3dB 5 15.6dB 1 1 0.5 0.5 0.2 20kHz 0.1 1m 2m 5m 10m 20m 1kHz 6dB 10.3dB 20Hz 0.02 500u 0.02 50m 0.01 10m 100m 200m 20m 50m 21.6dB 5 15.6dB 10.3dB 20kHz 15.6dB 1 1 0.5 0.5 0.2 0.1 3 10.3dB 6dB 0.2 1kHz 0.05 6dB 10.3dB 20m 50m 15.6dB 100m BTL mode VDD=3.3V RL=4ohm 21.6dB 200m 500m 1 1kHz 6dB 10.3dB 0.02 0.01 10m 2 20m 50m Output Power [W] 15.6dB 100m 21.6dB BTL mode VDD=2.7V RL=4ohm 200m 500m 1 Output Power [W] Figure 9. THD+N vs. Gain Figure 10. THD+N vs. Gain 10 10 5 VDD=5V Output power =1W RL=4ohm 2 0.5 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.002 50 100 VDD=3.3V Output power = 500mW RL=4ohm 1 0.5 THD [%] THD [%] 2 0.1 0.02 0.001 20 1 21.6dB 2 6dB THD [%] THD [%] 2 1 500m 10 20kHz 5 2 200m Figure 8. THD+N vs. Gain 10 5 21.6dB Output Power [W] Figure 7. THD+N vs. Output Power 0.01 10m 15.6dB 100m Output Power [W] 0.05 6dB 0.2 0.05 200u 10.3dB 0.1 1kHz 0.05 0.01 100u BTL mode VDD=5V RL=4ohm 21.6dB 2 THD [%] THD [%] 2 20kHz 5 200 500 1k 2k Frequency [Hz] Figure 11. THD+N vs. Frequency 5k 10k 20k 0.001 20 50 100 200 500 1k 2k 5k 10k 20k Frequency [Hz] Figure 12. THD+N vs. Frequency 7 FAN7031 Performance Characteristics(Continued) 10 5 2 10 VDD=2.7V Output power = 250mW RL=4ohm 5 2 1 0.2 0.5 THD [%] THD [%] 1 0.5 0.1 0.05 Single-ended mode VDD=5V Output power = 50mW RL=32ohm 0.2 0.02 0.1 0.01 0.05 0.005 0.02 0.002 0.001 20 50 100 200 500 1k 2k 5k 10k 0.01 20 20k 50 100 200 500 Frequency [Hz] +0 -10 -20 -30 -30 -40 -40 -50 -50 -60 -70 -80 -110 50 100 200 500 1k 2k 5k 10k -120 20 20k 50 100 200 500 1k 2k 20k +0 Single-ended mode VDD=5V Output power = 50mW RL=32ohm -10 -20 -40 -50 -50 -60 -70 -80 -60 -70 -80 Right-to-Left -90 -90 -100 -100 Left-to-Right -110 50 100 200 VDD=5V+/-5% RL=4ohm -30 -40 PSRR [dB] Crosstalk [dB] 10k Left-to-Right Figure 16. Crosstalk vs. Frequency +0 500 -110 1k 2k 5k Frequency [Hz] Figure 17. Crosstalk vs. Frequency 8 20k Right-to-Left Frequency [Hz] Figure 15. Crosstalk vs. Frequency -120 20 10k -70 Frequency [Hz] -30 5k -60 -100 -110 -20 20k VDD=5V Output power = 1W RL=8ohm -90 Right-to-Left -100 -10 10k -80 Left-to-Right -90 -120 20 5k +0 VDD=5V Output power = 1W RL=4ohm Crosstalk [dB] Crosstalk [dB] -20 2k Figure 14. THD+N vs. Frequency Figure 13. THD+N vs. Frequency -10 1k Frequency [Hz] 10k 20k -120 20 50 100 200 500 1k 2k Frequency [Hz] Figure 18. PSRR vs. Frequency 5k FAN7031 Performance Characteristics(Continued) +0 -10 -20 -30 -30 -40 -40 PSRR [dB] PSRR [dB] -20 +0 -10 VDD=3.3V+/-5% RL=4ohm -50 -60 -50 -60 -70 -70 -80 -80 -90 -90 -100 -100 -110 -110 -120 20 50 100 200 500 1k 2k 5k 10k -120 20 20k VDD=2.7V+/-5% RL=4ohm 50 100 200 500 Frequency [Hz] +0 +0 -10 -10 -20 -20 -30 -30 -40 -40 -50 -60 -70 -90 -100 20 50 100 200 -80 -90 500 1k 2k 5k 10k -100 20 20k 5k 10k 20k 10k 20k Single-ended mode VDD=3.3V+/-5% RL=32ohm Cbyp=0.47uF 50 100 200 +0 -10 -20 -20 -30 -30 -40 -40 -50 -60 -70 0.1µF -80 -90 500 1k 2k Frequency [Hz] Figure 23. PSRR vs. Frequency 5k 10k 20k 0.47µF 1µF 4.7µF 10µF -70 Single-ended mode VDD=2.7V+/-5% RL=32ohm Cbyp=0.47uF 200 2k -50 -60 100 1k Figure 22. PSRR vs. Frequency +0 50 500 Frequency [Hz] PSRR [dB] PSRR [dB] 20k -70 Single-ended mode VDD=5V+/-5% RL=32ohm Cbyp=0.47uF -10 -100 20 10k -60 Figure 21. PSRR vs. Frequency -90 5k -50 Frequency [Hz] -80 2k Figure 20. PSRR vs. Frequency PSRR [dB] PSRR [dB] Figure 19. PSRR vs. Frequency -80 1k Frequency [Hz] -100 20 Single-ended mode VDD=5V+/-5% RL=32ohm 50 100 200 500 1k 2k 5k Frequency [Hz] Figure 24. PSRR vs. Bybass Capacitor 9 FAN7031 Performance Characteristics(Continued) G0=VDD, G1=VDD +20 +20 +15 G0=VDD, G1=VDD +15 G0=VDD, G1=GND Gain [dB] Gain [dB] G0=VDD, G1=GND +10 G0=GND, G1=VDD +5 +10 G0=GND, G1=VDD +5 G0=GND, G1=GND VDD=5V No load Cin=0.47uF +0 20 50 +0 100 200 500 1k 2k 5k 10k 20k G0=GND, G1=GND VDD=3.3V No load Cin=0.47uF 20 50 100 200 500 Frequency [Hz] 1k 2k 5k 10k Frequency [Hz] Figure 25. BTL Mode Gain vs. Frequency Figure 26. BTL Mode Gain vs. Frequency 6.0m +20 G0=VDD, G1=VDD 5.0m +15 4.0m IDD Current [A] Gain [dB] G0=VDD, G1=GND +10 G0=GND, G1=VDD 3.0m 2.0m +5 +0 20 50 1.0m G0=GND, G1=GND VDD=2.7V No load Cin=0.47uF 0.0 100 200 500 1k 2k 5k 10k 20k 0 1 2 3 4 5 Supply Voltage [V] Frequency [Hz] Figure 27. BTL Mode Gain vs. Frequency Figure 28. IDD vs. Supply Voltage 25.0n 8.0m 20.0n VDD=5V Current [A] Shutdown Current [A] 6.0m 15.0n 10.0n VDD=2.7V 2.0m 5.0n 0.0 0.0 -1 0 1 2 3 4 5 6 7 Supply Voltage [V] Figure 29. Shutdown Current vs. Supply Voltage 10 VDD=3.3V 4.0m 8 0 1 2 3 4 Shutdown Pin Voltage [V] Figure 30. IDD vs. Shutdown Pin Voltage 5 20k FAN7031 Performance Characteristics(Continued) 5.5m 4.5m 5.0m BTL mode 4.0m IDD Current [A] IDD Current [A] BTL mode 4.5m Single-Ended mode 4.0m 3.5m Single-Ended mode 3.0m 3.5m VDD=3.3V VDD=5V 3.0m 2.5m 0 1 2 3 4 5 -0.5 0.0 0.5 1.0 SE/BTL Pin Voltage [V] 1.5 2.0 2.5 3.0 3.5 SE/BTL Pin Voltage [V] Figure 31. IDD vs. SE/BTL Pin Voltage Figure 32. IDD vs. SE/BTL Pin Voltage 0.7 4.5m 0.6 4.0m VDD=5V 0.5 Power Dissipation [W] IDD Current [A] BTL mode 3.5m Single-Ended mode 3.0m 0.4 0.3 VDD=3.3V 0.2 VDD=2.7V VDD=2.7V 2.5m THD less than 1% RL=8ohm f=1kHz 0.1 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 SE/BTL Pin Voltage [V] 1.0 1.5 Output Power [W] Figure 33. IDD vs. SE/BTL Pin Voltage Figure 34. Power Dissipation vs. Output Power 3.0 1.4 VDD=5V BTL mode f=1kHz RL=4ohm 2.5 1.0 2.0 Output Power [W] Power Dissipation [W] 1.2 0.8 0.6 VDD=3.3V 0.4 VDD=2.7V THD less than 1% RL=4ohm f=1kHz 0.2 10% THD+N 1.5 1% THD+N 1.0 0.5 0.0 0.0 0.0 0.5 1.0 1.5 Output Power [W] Figure 35. Power Dissipation vs. Output Power 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Supply Voltage [V] Figure 36. Output Power vs. Supply Voltage 11 FAN7031 Performance Characteristics(Continued) 2.0 2.5 BTL mode f=1kHz RL=8ohm 1.5 2.0 Output Power [W] 10% THD+N Output Power [W] BTL mode VDD=5V f=1kHz 1.0 1% THD+N 1.5 10% THD+N 1.0 1% THD+N 0.5 0.5 0.0 0.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0 8 16 24 Supply Voltage [V] 32 40 48 56 64 RL-Load Resistance [Ω] Figure 37. Output Power vs. Supply Voltage Figure 38. Output Power vs. Load Resistance 0.7 1.2 BTL mode VDD=3.3V f=1kHz 1.0 BTL mode VDD=2.7V f=1kHz 0.6 0.5 Output Power [W] Output Power [W] 0.8 0.6 0.4 10% THD+N 0.4 10% THD+N 0.3 0.2 1% THD+N 1% THD+N 0.2 0.1 0.0 0 8 16 24 32 40 48 56 0.0 64 0 8 16 24 32 40 48 56 64 RL-Load Resistance [Ω] RL-Load Resistance [Ω] Figure 39. Output Power vs. Load Resistance Figure 40. Output Power vs. Load Resistance 800.0m 0.30 Single-Ended mode VDD=5V f=1kHz 700.0m Single-Ended mode VDD=3.3V f=1kHz 0.25 600.0m 0.20 400.0m Output Power [W] Output Power [W] 500.0m 10% THD+N 300.0m 200.0m 0.15 10% THD+N 0.10 1% THD+N 1% THD+N 0.05 100.0m 0.00 0.0 0 8 16 24 32 40 48 56 RL-Load Resistance [Ω] Figure 41. Output Power vs. Load Resistance 12 64 0 8 16 24 32 40 48 56 RL-Load Resistance [Ω] Figure 42. Output Power vs. Load Resistance 64 FAN7031 Performance Characteristics(Continued) 0.20 4.5 Single-Ended mode VDD=2.7V f=1kHz 4.0 Power Dissipation [W] Output Power [W] 0.10 10% THD+N 0.05 M u lti L a ye r 3.5 0.15 3.0 2.5 2.0 1.5 S in g le L a ye r 1.0 1% THD+N 0.5 0.0 0.00 0 8 16 24 32 40 48 56 RL-Load Resistance [Ω] Figure 43. Output Power vs. Load Resistance 64 0 25 50 75 100 125 150 A m bient Tem perature [°C] Figure 44. Power Derating Curve 13 FAN7031 Typical Application Circuits Single-Ended Inputs VDD 104 10µF VDD 6,15,16 0.47µF Right channel Single ended Input RIN- 17 18 RIN+ 7 ROUT+ 0.47µF Right Output (BTL) 330µF 14 ROUT- VDD VDD 10kΩ 19 2 3 10kΩ 10kΩ 0.47µF Left channel Single ended Input BIAS & CONTROL 10 BYPASS 100kΩ 12 LIN+ 9 4 LIN- 5 Stereo Output 1µF VREF G0 G1 GAIN SELECT SD SE/BTL LOUT+ 1kΩ 330µF 0.47µF Left Output (BTL) 8 LOUT- 1,11,20 GND 14 1kΩ 100kΩ FAN7031 Typical Application Circuits(Continued) Differential Inputs VDD 104 10µF VDD 6,15,16 0.47µF Right channel Differential Input RIN- 17 18 RIN+ 7 ROUT+ 0.47µF Right Output (BTL) 330µF 14 ROUT- VDD VDD 10kΩ 10kΩ 10kΩ 0.47µF Left channel Differential Input BIAS & CONTROL 100kΩ 10 BYPASS 12 LIN+ 9 4 LIN- 5 Stereo Output 1µF VREF G0 G1 19 2 3 GAIN SELECT SD 1kΩ 100kΩ SE/BTL LOUT+ 1kΩ 330µF 0.47µF Left Output (BTL) 8 LOUT- 1,11,20 GND 15 FAN7031 Functional Description The FAN7031 is a stereo 2W amplifier capable of delivering 1.85W continuous RMS power into a 4-ohm load. This device has less than 0.75% THD+N across the entire frequency range at an output power of 1W. A thermally enhanced TSSOP package is used to allow for maximum dissipation of package heat. Gain selection is achieved by driving G0 and G1 inputs according to the table below. G0 G1 SE/BTL AV Zin 0 0 0 6dB 90kΩ 0 1 0 10.3dB 55kΩ 1 0 0 15.6dB 30kΩ 1 1 0 21.6dB 15kΩ X X 1 4.3dB 55kΩ Gain select pins are activated only when SE/BTL pin is set to low level. If SE/BTL pin is high, the amplifier configuration is changed as SE(single-ended) mode and the gain of SE amplifier is fixed to 4.3dB (about 1.64). Gain is varied by changing the taps on input resistors, and such change in gain will cause variation in the input impedance. Input impedance (Zin) is described in the above table. The impedance variation determines amplifier lowest bandwidth. Thus, input DC decoupling capacitors must be carefully selected. Applications Information PCB Layout and Supply Regulation Metal trace resistance between the BTL output and the parasitic resistance of the power supply line both heavily affect the output power. In order to obtain the maximum power depicted in the performance characteristics figures, outputs, power and ground lines need wide metal trace. The parasitic resistance of the power line increases ripple noise and degrades the THD and PSRR performance. To reduce such unwanted effect, large capacitor must be connected between VDD pin and GND pin as close as possible. To improve power supply regulation performance, use a low ESR capacitor. Power Supply Bypassing Selection of proper power supply bypassing capacitor is critical to obtaining lower noise as well as higher power supply rejection. Larger capacitors may help to increase immunity to the supply noise. However, considering economical design, attaching 10µF electrolytic capacitor or tantalum capacitor with 0.1µF ceramic capacitor as close as possible to the VDD pins are enough to get a good supply noise rejection. Selection of Input Capacitor Input capacitor blocks DC signal also low frequency input signal. Thus, this capacitor acts as a high pass filter. The -3dB frequency of this filter is determined by input capacitor and input impedance of the amplifier. The frequency is 1 f – 3dB = ----------------------------2π ⋅ Zin ⋅ C As shown previously, the input impedance is changed by selecting gain. Considering smallest Zin (=15kW), the capacitance which meets f-3dB frequency of 20Hz is 0.53uF. Thus, selecting the capacitance higher than 0.53uF, the lowest frequency of audio signal can be amplified without gain loss. 16 FAN7031 BLT Mode of Operation vs. Single Ended Mode of Operation The FAN7031 offers both BTL (Bridge-Tied Load) and SE (Single Ended) operation. When SE/BTL pin is low, BTL operation is selected. In BTL operation, maximum output power is increased 4 times comparing with SE operation at the same load, output swing and supply condition because output swing is doubled. Thus, BTL mode is useful to drive a speaker load. On the other hand, when SE/BTL pin is high, one amplifier configured BTL driver is turned off and only single amplifier is activated. In this mode, maximum output power is reduced and the quiescent power consumption is saved about half. Thus, SE mode is adequate for head-phone load. The output power of BTL and SE are expressed as follows respectively: 2 Vp P BTL = --------------- , 2 ⋅ RL 2 Vp P SE = --------------- . 8 ⋅ RL To use the amplifier in SE mode, the output DC voltage must be blocked not to increase power consumption. Thus, the load is tied to output via output DC blocking capacitor. The capacitor size can be chosen using above f-3dB equation. For example, assuming the load impedance is 32W, 249uF capacitor guarantees 20Hz signal transmission to the load without gain reduction. Shutdown Mode The device moves to a shutdown mode when the shutdown pin is at 0V. For normal operation the shutdown pin should be at VDD. This pin should never be left unconnected. 17 FAN7031 Mechanical Dimensions Package Dimensions in millimeters 20TSSOP-EP 18 FAN7031 Ordering Information Device Package Operating Temperature FAN7031MTF 20TSSOP-EP -40°C ~ +85°C 19 FAN7031 DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 8/11/03 0.0m 001 Stock#DSxxxxxxxx 2003 Fairchild Semiconductor Corporation