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FAN7031
2W Stereo Power Amplifier with Four Selectable Gain Setting and Headphone Drive
Features
* 1.85WRMS and 2.45WRMS Power Per Each Channel Into 4 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 0.04A@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
Description
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 4 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 4A 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
(c)2003 Fairchild Semiconductor Corporation
FAN7031
Internal Block Diagram
RINROUT+ RIN+
ROUT-
CONTROL G0 G1 SE/BTL SD Gain Control SE/BTL Control On/Off Control
BIAS TSD VDD/2 Current Source BYPASS
LINLOUT+ LIN+
LOUT-
2
FAN7031
Pin Assignments
GND G0 G1 LOUT+ LINPVDD2 RIN+ LOUTLIN+ BYPASS
1
20
GND SD ROUT+ RINVDD PVDD1 ROUTNC SE/BTL
Heat Sink
10
11
GND
Pin Description
Pin No 1* 2 3 4 5 6** 7 8 9 10 11* 12 13 14 15** 16** 17 18 19 20* Symbol GND G0 G1 LOUT+ LINPVDD2 RIN+ LOUTLIN+ BYPASS GND SE/BTL NC ROUTPVDD1 VDD RINROUT+ SD GND I/O I I O I I I O I O I O I I I O I Ground Gain Selection Input(MSB) Gain Selection Input(LSB) Left Channel (+) Output Left Channel (-) Input Left Channel Power Supply Voltage Right Channel (+) Input Left Channel (-) Output Left Channel (+) Input Bypass Capacitor Connect Ground Single-Ended & BTL Selection: GND SE/BTL VDD/2:BTL Mode VDD/2 < SE/BTL VDD: SE Mode No Connection Right Channel (-) Output Right Channel Power Supply Voltage Power Supply Voltage Right Channel (-) Input Right Channel (+) Output Shutdown Logic Low SD=VDD: Chip Enable SD=GND: Chip Shutdown Ground Decription
* 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 Maximum Supply Voltage Power Dissipation Operating Temperature Storage Temperature Junction Temperature Thermal Resistance (Junction to Ambient) ESD Rating (Human Body Model) Symbol VDDmax PD TOPG TSTG TJ Rthja Value 6.0V Internally Limited -40 ~ +85 -65 ~ +150 150 30.4 112.5 2000 Unit V W C C C C/W V Multi Layer Board Single Layer Board See Derating Curve Remark
Note1 : Rthja was derived using a JEDEC multi layer and single layer.
Operating Ratings
Parameter Power Supply Voltage Symbol VDD Min 2.7 Typ Max 5.5 Unit V
4
FAN7031
Electrical Characteristics
(VDD = 5.0V, Ta = 25C, unless otherwise specified) Parameter Offset Voltage Supply Current Shutdown Current Output Power Symbol VOFF IDD ISD PO Conditions RL=4, Av=6dB No Input, No Load SD = GND THD+N =1%, RL = 4, f = 1kHz THD+N =10%, RL = 4, f = 1kHz SE/BTL=GND, G0=GND, G1=GND, Vin=4Vpp, No Load BTL Mode Gain Av SE/BTL=GND, G0=GND, G1=VDD, Vin=2.44Vpp, No Load SE/BTL=GND, G0=VDD, G1=GND, Vin=1.34Vpp, No Load SE/BTL=GND, G0=VDD, G1=VDD, Vin=0.66Vpp, No Load SE Mode Gain Total Harmonic Distortion + Noise Power Supply Rejection Ratio THD+N PSRR SE/BTL=VDD, Vin=2.44Vpp, No Load PO = 1W, RL=4, f = 20kHz Cbyp = 0.47F, RL=4, BTL Mode, VDD=500mVpp, f = 1kHz Min. -25 40 Typ. 5.5 0.04 1.85 2.45 6 10.3 15.6 21.3 4.3 0.2 70 Max. 25 10 4 0.75 Unit mV mA A W W dB dB dB dB dB % dB
Electrical Characteristics (Continued)
(VDD = 3.3 V, Ta = 25C, unless otherwise specified) Parameter Offset Voltage Supply Current Shutdown Current Output Power Total Harmonic Distortion + Noise Power Supply Rejection Ratio Symbol VOFF IDD ISD PO THD+N PSRR Conditions RL=4, Av=6dB No Input, No Load SD = GND THD+N =10%, RL = 4, f=1kHz PO = 0.5W, RL = 4, f = 20kHz Cbyp = 0.47F, RL=4, BTL Mode, VDD=330mVpp, f = 1kHz Min. -25 40 Typ. 4.3 0.08 1.02 0.2 70 Max. 25 8 4 0.75 Unit mV mA A W % dB
Electrical Characteristics (Continued)
(VDD = 2.7 V, Ta = 25C, unless otherwise specified) Parameter Offset Voltage Supply Current Shutdown Current Output Power Total Harmonic Distortion + Noise Power Supply Rejection Ratio Symbol VOFF IDD ISD PO THD+N PSRR Conditions RL=4, Av=6dB No Input, No Load SD = GND THD+N =10%, RL = 4, f=1kHz PO = 0.25W, RL = 4, f = 20kHz Cbyp = 0.47F, RL=4, BTL Mode, VDD=270mVpp, f = 1kHz Min. -25 Typ. 4.1 0.04 0.54 0.2 65 Max. 25 7 4 0.75 Unit mV mA A W % dB
5
FAN7031
Performance Characteristics
10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 10m 10 5 2 1
BTL mode VDD=5V RL=8ohm Av=6dB
20kHz
20kHz
THD [%]
0.5 0.2 0.1 0.05
THD [%]
1kHz
1kHz
20Hz BTL mode VDD=5V RL=4ohm Av=6dB
20m 50m 100m 200m Output Power [W] 500m 1 2 3
0.02 0.01 0.005 0.002 0.001 10m 20m
20Hz
50m
100m
200m
500m
1
2
3
Output Power [W]
Figure 1. THD+N vs. Output Power
Figure 2. THD+N vs. Output Power
10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 10m 20m 50m 100m 200m 500m
10 5 2 1
BTL mode VDD=3.3V RL=8ohm Av=6dB 20kHz 1kHz
20kHz 1kHz
THD [%]
0.5 0.2 0.1 0.05 0.02
THD [%]
20Hz
BTL mode VDD=3.3V RL=4ohm Av=6dB
1 2
0.01 0.005 0.002 0.001 10m 20m 50m
20Hz
100m Output Power [W]
200m
500m
1
Output Power [W]
Figure 3. THD+N vs. Output Power
Figure 4. THD+N vs. Output Power
10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 10m 20m 50m 100m Output Power [W] 200m
10 5 2 1
BTL mode VDD=2.7V RL=8ohm Av=6dB 20kHz 1kHz
20kHz
THD [%]
0.5 0.2 0.1 0.05 0.02
THD[%]
1kHz
20Hz
BTL mode VDD=2.7V RL=4ohm Av=6dB
500m 1
0.01 0.005 0.002 0.001 10m 20m 50m
20Hz
100m Output Power [W]
200m
500m
1
Figure 5. THD+N vs. Output Power
Figure 6. THD+N vs. Output Power
6
FAN7031
Performance Characteristics(Continued)
10 5 10
2 1 THD [%]
Single-ended mode VDD=5V RL=32ohm Av=4.3dB
5
20kHz
21.6dB 15.6dB 10.3dB
BTL mode VDD=5V RL=4ohm 6dB
2 1 THD [%] 0.5
0.5
0.2 0.1 0.05
20kHz 1kHz
0.2 0.1 0.05
1kHz
6dB 10.3dB 15.6dB
200m Output Power [W]
0.02 0.01 100u
20Hz
200u 500u 1m 2m 5m 10m 20m 50m 100m 200m
0.02 0.01 10m
21.6dB
500m 1 2 3
20m
50m
100m
Output Power [W]
Figure 7. THD+N vs. Output Power
Figure 8. THD+N vs. Gain
10 5
10
20kHz
21.6dB 15.6dB 10.3dB 6dB
5
20kHz
21.6dB 15.6dB 10.3dB 6dB
2 1
2 1 THD [%] 0.5
THD [%]
0.5
0.2 0.1 0.05
0.2 0.1
1kHz
6dB 10.3dB 15.6dB
200m
0.05
0.02 0.01 10m
21.6dB
500m
BTL mode VDD=3.3V RL=4ohm
1 2
1kHz
6dB 10.3dB 15.6dB
100m Output Power [W]
0.02 0.01 10m
21.6dB
200m
BTL mode VDD=2.7V RL=4ohm
500m 1
20m
50m
100m
20m
50m
Output Power [W]
Figure 9. THD+N vs. Gain
Figure 10. THD+N vs. Gain
10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 20 50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
10
VDD=5V Output power =1W RL=4ohm
5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 20
VDD=3.3V Output power = 500mW RL=4ohm
THD [%]
THD [%]
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
Figure 11. THD+N vs. Frequency
Figure 12. THD+N vs. Frequency
7
FAN7031
Performance Characteristics(Continued)
10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 20 50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k 0.02 0.01 20 10
VDD=2.7V Output power = 250mW RL=4ohm
5
2 1 THD [%] 0.5
Single-ended mode VDD=5V Output power = 50mW RL=32ohm
THD [%]
0.2 0.1 0.05
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
Figure 13. THD+N vs. Frequency
Figure 14. THD+N vs. Frequency
+0 -10 -20 -30 -40 Crosstalk [dB] Crosstalk [dB] -50 -60 -70 -80 -90 -100 -110 -120 20
+0
VDD=5V Output power = 1W RL=4ohm
-10 -20 -30 -40 -50 -60 -70 -80 -90
VDD=5V Output power = 1W RL=8ohm
Left-to-Right Right-to-Left
Right-to-Left Left-to-Right
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
-100 -110 -120 20
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
Figure 15. Crosstalk vs. Frequency
Figure 16. Crosstalk vs. Frequency
+0 -10 -20 -30 -40 Crosstalk [dB] -50 -60 -70 -80 -90 -100 -110 -120 20 PSRR [dB]
+0
Single-ended mode VDD=5V Output power = 50mW RL=32ohm
-10 -20 -30 -40 -50 -60 -70 -80 -90 -100
VDD=5V+/-5% RL=4ohm
Right-to-Left
Left-to-Right
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
-110 -120 20
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
Figure 17. Crosstalk vs. Frequency
Figure 18. PSRR vs. Frequency
8
FAN7031
Performance Characteristics(Continued)
+0 -10 -20 -30 -40 PSRR [dB] -50 -60 -70 -80 -90 -100 -110 -120 20 PSRR [dB] +0
VDD=3.3V+/-5% RL=4ohm
-10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 20
VDD=2.7V+/-5% RL=4ohm
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
50
100
200
500
1k Frequency [Hz]
2k
5k
10k
20k
Figure 19. PSRR vs. Frequency
Figure 20. PSRR vs. Frequency
+0 -10 -20 -30 -40 PSRR [dB] -50 -60 -70 -80 -90 -100 20 PSRR [dB]
+0 -10 -20 -30 -40 -50 -60 -70
Single-ended mode VDD=5V+/-5% RL=32ohm Cbyp=0.47uF
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
-80 -90 -100 20
Single-ended mode VDD=3.3V+/-5% RL=32ohm Cbyp=0.47uF
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
Figure 21. PSRR vs. Frequency
Figure 22. PSRR vs. Frequency
+0 -10 -20 -30 -40 PSRR [dB] -50 -60 -70 -80 -90 -100 20
+0 -10 -20 -30 -40 -50 -60 -70
0.1F
0.47F
1F
PSRR [dB]
4.7F
10F
Single-ended mode VDD=2.7V+/-5% RL=32ohm Cbyp=0.47uF
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
-80 -90 -100 20
Single-ended mode VDD=5V+/-5% RL=32ohm
50 100 200 500 1k Frequency [Hz] 2k 5k 10k 20k
Figure 23. PSRR vs. Frequency
Figure 24. PSRR vs. Bybass Capacitor
9
FAN7031
Performance Characteristics(Continued)
+20
G0=VDD, G1=VDD
+20
G0=VDD, G1=VDD
+15
+15
G0=VDD, G1=GND
Gain [dB] +10 Gain [dB] +10
G0=VDD, G1=GND
G0=GND, G1=VDD
+5
G0=GND, G1=VDD
+5
+0 20
VDD=5V No load Cin=0.47uF
50 100 200
G0=GND, G1=GND
+0 500 1k Frequency [Hz] 2k 5k 10k 20k 20
VDD=3.3V No load Cin=0.47uF
50 100 200
G0=GND, G1=GND
500
1k Frequency [Hz]
2k
5k
10k
20k
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
G0=VDD, G1=GND
IDD Current [A]
5k 10k 20k Gain [dB] +10
3.0m
G0=GND, G1=VDD
+5
2.0m
+0 20
VDD=2.7V No load Cin=0.47uF
50 100 200
G0=GND, G1=GND
1.0m
0.0
500 1k Frequency [Hz] 2k
0
1
2
3
4
5
Supply Voltage [V]
Figure 27. BTL Mode Gain vs. Frequency
Figure 28. IDD vs. Supply Voltage
25.0n
8.0m
20.0n
6.0m
VDD=5V VDD=3.3V VDD=2.7V
Shutdown Current [A]
15.0n
Current [A] 4.0m
10.0n
5.0n
2.0m
0.0
0.0
-1
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
Supply Voltage [V]
Shutdown Pin Voltage [V]
Figure 29. Shutdown Current vs. Supply Voltage
Figure 30. IDD vs. Shutdown Pin Voltage
10
FAN7031
Performance Characteristics(Continued)
5.5m
4.5m
5.0m
BTL mode
IDD Current [A] 4.5m IDD Current [A]
4.0m
BTL mode
3.5m
4.0m
Single-Ended mode
Single-Ended mode
3.0m
3.5m
VDD=5V
3.0m 0 1 2 3 4 5 SE/BTL Pin Voltage [V] 2.5m -0.5
VDD=3.3V
0.0 0.5 1.0 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
4.5m
0.7
0.6
4.0m
BTL mode
Power Dissipation [W]
0.5
VDD=5V
IDD Current [A]
3.5m
0.4
0.3
3.0m
Single-Ended mode
VDD=3.3V
0.2
VDD=2.7V
2.5m
VDD=2.7V
0.1
THD less than 1% RL=8ohm f=1kHz
1.0 1.5
0.0
0.0
0.5
1.0
1.5 SE/BTL Pin Voltage [V]
2.0
2.5
3.0
0.0
0.5 Output Power [W]
Figure 33. IDD vs. SE/BTL Pin Voltage
Figure 34. Power Dissipation vs. Output Power
3.0
1.4
1.2
VDD=5V
2.5
BTL mode f=1kHz RL=4ohm
Power Dissipation [W]
1.0
Output Power [W]
2.0
0.8
10% THD+N
1.5
0.6
VDD=3.3V VDD=2.7V
1% THD+N
1.0
0.4
0.2
THD less than 1% RL=4ohm f=1kHz
1.0 Output Power [W] 1.5 2.0
0.5
0.0 0.0 0.5
0.0 2.5 3.0 3.5 4.0 Supply Voltage [V] 4.5 5.0 5.5
Figure 35. Power Dissipation vs. Output Power
Figure 36. Output Power vs. Supply Voltage
11
FAN7031
Performance Characteristics(Continued)
2.0
2.5
1.5
BTL mode f=1kHz RL=8ohm 10% THD+N
2.0
BTL mode VDD=5V f=1kHz
Output Power [W]
1.0
Output Power [W]
1.5
10% THD+N
1.0
1% THD+N
0.5
1% THD+N
0.5
0.0 2.5 3.0 3.5 4.0 Supply Voltage [V] 4.5 5.0 5.5
0.0 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
Figure 37. Output Power vs. Supply Voltage
Figure 38. Output Power vs. Load Resistance
1.2
0.7
1.0
BTL mode VDD=3.3V f=1kHz
0.6
BTL mode VDD=2.7V f=1kHz
0.5
0.8 Output Power [W]
0.6
Output Power [W]
0.4
0.3
10% THD+N
0.4
10% THD+N 1% THD+N
0.2
0.2
1% THD+N
0.1
0.0 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
0.0 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
Figure 39. Output Power vs. Load Resistance
Figure 40. Output Power vs. Load Resistance
800.0m
0.30
700.0m
Single-Ended mode VDD=5V f=1kHz
0.25
Single-Ended mode VDD=3.3V f=1kHz
600.0m
0.20
500.0m Output Power [W]
Output Power [W]
400.0m
10% THD+N
0.15
10% THD+N
300.0m
0.10
200.0m
1% THD+N
100.0m
1% THD+N
0.05
0.0 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
0.00 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
Figure 41. Output Power vs. Load Resistance
Figure 42. Output Power vs. Load Resistance
12
FAN7031
Performance Characteristics(Continued)
0.20
4.5
Single-Ended mode VDD=2.7V f=1kHz
0.15
4.0 3.5 Power Dissipation [W] 3.0 2.5 2.0 1.5 1.0 0.5 0.0 M u lti L a ye r
Output Power [W]
0.10
10% THD+N
S in g le L a ye r
0.05
1% THD+N
0.00 0 8 16 24 32 40 48 56 64 RL-Load Resistance []
0
25
50
75
100
125
150
A m bient Tem perature [C]
Figure 43. Output Power vs. Load Resistance
Figure 44. Power Derating Curve
13
FAN7031
Typical Application Circuits
Single-Ended Inputs
VDD 10F VDD 6,15,16 Right channel Single ended Input 0.47F RIN- 17 RIN+ 7 0.47F Right Output (BTL) 14 ROUTVDD VDD SD G0 G1 10k 10k 0.47F Left channel Single ended Input 0.47F LIN+ 9 LIN- 5 10k 19 2 3
GAIN SELECT
104
18
ROUT+
330F 1k
100k BIAS & CONTROL 10 BYPASS 1F 100k 12 4 SE/BTL LOUT+ 330F Left Output (BTL) 8 LOUT1k Stereo Output
VREF
1,11,20 GND
14
FAN7031
Typical Application Circuits(Continued)
Differential Inputs
VDD 10F VDD 6,15,16 Right channel Differential Input 0.47F RIN- 17 RIN+ 7 0.47F Right Output (BTL) 14 ROUTVDD VDD SD G0 G1 10k 10k 10k LIN+ 9 LIN- 5 0.47F 19 2 3
GAIN SELECT
104
18
ROUT+
330F 1k
BIAS & CONTROL
100k 10 BYPASS 1F 100k SE/BTL LOUT+ 330F Left Output (BTL) 8 LOUT1k Stereo Output
VREF
12 4
0.47F Left channel Differential Input
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 1 1 X 0 1 0 1 X 0 0 0 0 1 6dB 10.3dB 15.6dB 21.6dB 4.3dB 90k 55k 30k 15k 55k
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 10F electrolytic capacitor or tantalum capacitor with 0.1F 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 = ---------------------------2 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 FAN7031MTF Package 20TSSOP-EP Operating Temperature -40C ~ +85C
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.
www.fairchildsemi.com 8/11/03 0.0m 001 Stock#DSxxxxxxxx 2003 Fairchild Semiconductor Corporation
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.

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