G1427 Global Mixed-mode Technology Inc. 2W Stereo Audio Amplifier 6dB\10dB\15.6dB\21.6dB Selectable Gain Settings Features General Description G1427 is a stereo audio power amplifier in 24pin TSSOP thermal pad package. It can drive 2.0W continuous RMS power into 4Ω load per channel in Bridge-Tied Load (BTL) mode at 5V supply voltage. Its THD is smaller than 1% under the above operation condition. To simplify the audio system design in the notebook application, G1427 supports the Bridge-Tied Load (BTL) mode for driving the speakers, Single-End (SE) mode for driving the headphone. For the low current consumption applications, the SHDN mode is supported to disable G1427 when it is idle. The current consumption can be reduced to 160µA (typically). Internal Gain Control, Which Eliminates External Gain-Setting Resistors Depop Circuitry Integrated Output Power at 1% THD+N, VDD=5V --2.0W/CH (typical) into a 4Ω Load --1.2W/CH (typical) into a 8Ω Load Bridge-Tied Load (BTL), Single-Ended (SE) Stereo Input MUX PC-Beep Input Fully differential Input Shutdown Control Available Surface-Mount Power Package 24-Pin TSSOP-P Amplifier gain is internally configured and controlled by two terminals (GAIN0, GAIN1). BTL gain settings of 6dB, 10dB, 15.6dB, 21.6dB are provided, while SE gain is always configured as 4.1dB (inverting) for headphone driving. G1427 also supports two input paths, that means two different amplitude AC signals can be applied and chosen by setting HP/ LINE pin. It enhances the hardware designing flexibility. Applications Stereo Power Amplifiers for Notebooks or Desktop Computers Multimedia Monitors Stereo Power Amplifiers for Portable Audio Systems Ordering Information ORDER NUMBER ORDER NUMBER (Pb free) TEMP. RANGE PACKAGE G1427F31U G1427F31Uf -40°C to +85°C TSSOP-24 (FD) Note: U:Tape & Reel (FD): Thermal Pad Pin Configuration G1427 GND/HS GND/HS 1 24 GAIN0 2 23 RLINEIN GAIN1 3 22 SHUTDOWN LOUT+ 4 21 ROUT+ LLINEIN 20 RHPIN LPHIN 5 6 19 VDD PVDD 7 18 PVDD HP/LINE RIN 8 17 LOUT- 9 16 ROUT- LIN BYPASS 10 11 15 14 SE/BTL PC-BEEP GND/HS 12 13 GND/HS Thermal Pad Top View TSSOP-24 Bottom View TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 1 G1427 Global Mixed-mode Technology Inc. Absolute Maximum Ratings Power Dissipation (1) TA ≤ 25°C ………...….…………………………..2.7W TA ≤ 70°C ………...….…………………………..1.7W Electrostatic Discharge, VESD Human body mode..…………………….…………3000(2) Supply Voltage, VCC…………………..…..…….….…...6V Operating Ambient Temperature Range TA…….…………………………….……….-40°C to +85°C Maximum Junction Temperature, TJ…..……….….150°C Storage Temperature Range, TSTG….…-65°C to+150°C Reflow Temperature (soldering, 10sec)……..……260°C Note: (1) : Recommended PCB Layout (2) : Human body model : C = 100pF, R = 1500Ω, 3 positive pulses plus 3 negative pulses Electrical Characteristics DC Electrical Characteristics, TA=+25°C PARAMETER SYMBOL CONDITION MIN TYP MAX UNIT 4.5 5 5.5 V 2 --- --- V SE/ BTL , HP/ LINE , SHUTDOWN , GAIN0, --- --- 0.8 V GAIN1 VDD = 5V,Gain = 2 --- mV Supply voltage VDD High-Level Input voltage, VIH VDD VIH SE/ BTL , HP/ LINE , SHUTDOWN , GAIN0, Low-Level Input voltage, VIL VIL GAIN1 DC Differential Output Voltage VO(DIFF) Supply Current in Mute Mode IDD VDD = 5V IDD in Shutdown ISD VDD = 5V Stereo BTL Stereo SE ----- 5 50 7.5 13 4 160 7 300 mA µA (AC Operation Characteristics, VDD = 5.0V, TA=+25°C, RL = 4Ω, unless otherwise noted) PARAMETER Output power (each channel) see Note SYMBOL P(OUT) Total harmonic distortion plus noise THD+N Maximum output power bandwidth BOM Power supply ripple rejection PSRR Channel-to-channel output separation Line/HP input separation BTL attenuation in SE mode Input impedance Signal-to-noise ratio Output noise voltage MIN TYP MAX THD = 1%, BTL, RL = 4Ω G=-2V/V CONDITION --- 2 --- THD = 1%, BTL, RL = 8Ω G=-2V/V --- 1.25 --- THD = 10%, BTL, RL = 4Ω G=-2V/V THD = 10%, BTL, RL = 8Ω G=-2V/V THD = 0.1%, SE, RL = 32Ω PO = 1.6W, BTL, RL = 4Ω G=-2V/V ------------- 2.5 1.6 85 100 60 80 ------------- PO = 1W, BTL, RL = 8Ω G=-2V/V PO = 75mW, SE, RL = 32Ω VI = 1V, RL = 10KΩ, SE THD = 5% F=1kHz, BTL mode G=-2V/V CBYP=1µF f = 1kHz Vn PO = 500mW, BTL, G=-2V/V BTL, G=-2V/V, A Weighted filter W mW m% --- 30 --- ----- >15 68 ----- kHz dB --- 80 --- dB ----- dB dB MΩ ----- dB µV (rms) ----ZI UNIT 80 85 See Table 2 --90 --45 Note :Output power is measured at the output terminals of the IC at 1kHz. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 2 G1427 Global Mixed-mode Technology Inc. Typical Characteristics Table of Graphs FIGURE vs Frequency vs Output Power 1,2,7,8,13,14,19,21 3,4,5,6,9,10,11,12,15,16,17,18,20 Output Noise Voltage vs Output Voltage vs Frequency 22 27 Vn Supply Ripple Rejection Ratio vs Frequency 23,24 PO PD Crosstalk Output Power Power Dissipation vs Frequency vs Load Resistance vs Output Power 25,26 28,29 30,31 THD +N Total Harmonic Distortion Plus Noise Total Harmonic Distortion Plus Noise vs Output Frequency Total Harmonic Distortion Plus Noise vs Output Frequency 10 5 2 1 10 VDD=5V RL=3Ω BTL Po=1.75W 5 Av=21.6dB 2 VDD=5V RL=3Ω BTL,Av=6dB 1 Av=15.6dB 0.5 Po=0.5W 0.5 % % 0.2 0.2 0.1 0.1 0.0 5 Po=1W 0.05 Av=10dB Av=6dB 0.0 2 0.02 0.0 1 20 0.01 20 50 100 200 50 0 1k 2k 5k 10k 2 0k Po=1.5W 50 100 20 0 5 00 Hz 2k 5k 10k Figure 1 Figure 2 Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 20 k 10 VDD=5V RL=3Ω BTL,Av=6dB 15kHz 5 2 VDD=5V RL=3Ω BTL,Av=10dB 15kHz 5 2 1 1 0.5 0.5 % 1kHz % 1kHz 0.2 0.2 0.1 0.1 0.05 0.0 5 20Hz 0.02 0.01 3m 1k Hz 20Hz 0.0 2 5m 10m 20m 50 m 100m 200 m 50 0m 1 2 0.0 1 3m 3 W 5m 10m 20m 50 m 100m 200m 500m 1 2 3 W Figure 3 Figure 4 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 3 G1427 Global Mixed-mode Technology Inc. Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 10 5 2 2 1 1 0.5 0.5 1kHz % 0.2 0.1 0.02 0.01 3m 1kHz % 0.2 0.05 15kHz 5 15kHz 0.1 VDD=5V RL=3Ω BTL,Av=15.6dB 5m 10m 20m 20Hz 0.05 0.02 50 m 100m 200 m 50 0m 1 2 0.01 3m 3 5m 1 50 m 200 m Figure 6 50 0m 1 2 3 Total Harmonic Distortion Plus Noise vs Frequency 10 5 Av=21.6dB 2 VDD=5V RL=4Ω BTL,Av=6dB 1 0.5 0.5 Av=15.6dB Po=0.25W % 0.2 0.2 Av=6dB 0.1 Po=1.5W 0.1 0.0 5 0.05 Av=10dB 0.0 1 20 50 0.02 100 200 50 0 1k 2k 5k 10k Po=1W 0.01 20 2 0k 50 100 20 0 5 00 Hz 1k 2k 5k 10k 20 k Hz Figure 7 Figure 8 Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 10 5 VDD=5V RL=4Ω BTL,Av=6dB 15kHz 2 5 VDD=5V RL=4Ω BTL,Av=10dB 15kHz 2 1 1 0.5 0.5 1kHz % 1kHz % 0.2 0.2 0.1 0.1 0.05 0.0 5 20Hz 20Hz 0.02 0.01 3m 100m Figure 5 VDD=5V RL=4Ω BTL Po=1.75W % 0.0 2 20m W 10 2 10m W Total Harmonic Distortion Plus Noise vs Frequency 5 20Hz VDD=5V RL=3Ω BTL,Av=21.6dB 0.0 2 5m 10m 20m 50 m 100m 200 m 50 0m 1 2 0.0 1 3m 3 W 5m 10m 20m 50 m 100m 200m 500m 1 2 3 W Figure 9 Figure 10 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 4 G1427 Global Mixed-mode Technology Inc. Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 10 15kHz 5 5 15kHz 2 2 1kHz 1 1 1kHz 0.5 0.5 % % 0.2 0.2 0.05 0.02 0.01 3m 20Hz 0.1 0.1 VDD=5V RL=4Ω BTL,Av=15.6dB 5m 10m 20m 0.05 20Hz 0.02 50 m 100m 200 m 50 0m 1 2 0.01 3m 3 VDD=5V RL=4Ω BTL,Av=21.6dB 5m 10m 20m 50 m 100m 2 1 Figure 12 Total Harmonic Distortion Plus Noise vs Frequency Total Harmonic Distortion Plus Noise vs Frequency 2 3 10 VDD=5V RL=8Ω BTL,Av=6dB 5 2 1 1 0.5 0.5 % Po=0.25W 0.2 0.1 50 0m Figure 11 10 5 200 m W W VDD=5V RL=8Ω BTL Po=1W Av=15.6dB % 0.2 Av=21.6dB 0.1 Po=1W 0.05 Av=6dB 0.0 5 Po=0.5W 0.02 0.01 20 50 100 20 0 5 00 1k Av=10dB 0.0 2 2k 5k 10k 0.0 1 20 20 k 50 100 200 50 0 1k 2k Hz Hz Figure 13 Figure 14 5k 10k 2 0k Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 10 VDD=5V RL=8Ω BTL,Av=6dB 5 15kHz 2 VDD=5V RL=8Ω BTL,Av=10dB 5 15kHz 2 1 1 0.5 0.5 % % 0.2 0.2 1kHz 1kHz 0.1 0.1 0.05 0.0 5 20Hz 0.02 0.01 3m 5m 10m 20Hz 0.0 2 20m 50 m 100m 200 m 50 0m 1 2 0.0 1 3m 3 5m 10m 20m 50 m 100m 200m W W Figure 15 Figure 16 500m 1 2 3 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 5 G1427 Global Mixed-mode Technology Inc. Total Harmonic Distortion Plus Noise vs Output Power Total Harmonic Distortion Plus Noise vs Output Power 10 10 5 VDD=5V RL=8Ω BTL,Av=15.6dB 15kHz 2 5 15kHz 2 1 1 0.5 0.5 1kHz % 1kHz % 0.2 0.2 0.1 0.1 20Hz 0.05 0.05 0.02 0.01 3m 0.02 5m 10m 20m 50 m 100m 200 m 50 0m 1 2 0.01 3m 3 5 VDD=5V RL=32Ω SE,Av=4.1dB 2 1 2 3 15kHz 0.2 Po=75mW 0.1 0.05 20Hz 0.05 50 10 0 200 1kHz 0.02 Po=25mW 50 0 1k 2k 5k 1 0k 0.01 1m 20k 2m 5m 10 m 2 0m Hz W Figure 19 Figure 20 50m 100m 20 0m Total Harmonic Distortion Plus Noise vs Output Voltage Total Harmonic Distortion Plus Noise vs Frequency 10 10 5 1 50 0m VDD=5V RL=32Ω SE,Av=4.1dB % Po=50mW 0.1 2 200 m 10 1 0.01 20 100m Total Harmonic Distortion Plus Noise vs Output Power 0.5 0.02 50 m Figure 18 0.5 0.2 20m Figure 17 1 % 10m W 10 2 5m 20Hz W Total Harmonic Distortion Plus Noise vs Frequency 5 VDD=5V RL=8Ω BTL,Av=21.6dB 5 VDD=5V RL=10kΩ SE,Av=4.1dB Cout=1000µF 2 1 0.5 VDD=5V RL=10kΩ SE,Av=4.1dB Cout=1000µF 0.5 % % 0.2 0.2 0.1 0.05 0.05 0.02 0.02 0.01 20 50 10 0 200 50 0 Hz 1k 15kHz 20Hz 0.1 Vo=1Vrms 2k 5k 1 0k 0.01 100m 20k Figure 21 1kHz 2 00m 300 m 400 m 50 0m 7 00m Vo-Outpu t Vol tage-Vrms 1 2 3 Figure 22 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 6 G1427 Global Mixed-mode Technology Inc. Supply Ripple Rejection Ratio vs Frequency +0 T T -10 T T T Supply Ripple Rejection Ratio vs Frequency +0 T T VDD=5V RL=8Ω Cb=1µF BTL -20 -30 -20 -30 -40 d B VDD=5V RL=8Ω Cb=1µF SE -10 -40 Av=21.6dB -50 d B -50 -60 -60 -70 -70 Av=6dB -80 -80 -90 -90 -100 20 -100 20 50 10 0 200 50 0 Hz 1k 2k 5k 1 0k 20k 50 100 200 5 00 Figure 23 -35 -40 -45 -50 T 20 k 5k 1 0k 20k -25 -30 VDD=5V Po=1W RL=8Ω BTL,Av=6dB -35 -40 -45 -50 -55 d B -60 VDD=5V Po=1W RL=8Ω SE,Av=4.1dB -60 -65 -65 L TO R -70 L TO R -70 -75 -75 -80 -80 -85 -85 -90 50 100 200 5 00 1k 2k 5k R TO L -90 R TO L -95 -100 20 10k Channel Separation -55 d B 5k -20 -25 -30 2k Figure 24 Channel Separation -20 1k Hz -95 10k -100 20 20 k 50 10 0 200 50 0 1k Hz Hz Figure 25 Figure 26 Output Noise vs Frequency 2k Output Power vs Load Resistance 2.5 5 00u 4 00u 2 00u VDD=5V RL=4Ω BTL,Av=6dB A-Weighted filter 1.5 1 00u V VDD=5V THD+N=1% BTL Each Channel 2 Output Power(W) 3 00u 70u 60u 50u 40u 1 30u 0.5 20u 10u 20 50 100 200 5 00 1k 2k 5k 10k 0 20 k 0 Hz Figure 27 10 20 Load Resistance(Ω) 30 40 Figure 28 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 7 G1427 Global Mixed-mode Technology Inc. Power Dissipation vs Output Power Output Power vs Load Resistance 1.8 0.7 1.6 VDD=5V THD+N=1% SE Each Channel 0.5 0.4 RL=3Ω 1.4 Power Dissipation Output Power(W) 0.6 0.3 0.2 1.2 RL=4Ω 1 VDD=5V BTL Each Channel 0.8 0.6 0.4 0.1 RL=8Ω 0.2 0 0 4 8 12 16 20 24 Load Resistance(Ω) 28 32 0 Figure 29 0.5 1 1.5 Po-Output Pow er(W) 2 2.5 Figure 30 Recommend PCB Footprint Power Dissipation vs Output Power 0.35 Power Dissipation(W) 0.3 RL=4Ω 0.25 0.2 0.15 0.1 RL=8Ω 0.05 VDD=5V SE Each Channel RL=32Ω 0 0 0.2 0.4 0.6 0.8 Po-Output Pow er(W) Figure 31 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 8 G1427 Global Mixed-mode Technology Inc. Pin Description PIN NAME 1,12,13,24 2 GND/HS GAIN0 I/O I Ground connection for circuitry, directly connected to thermal pad. Bit 0 of gain control FUNCTION 3 4 GAIN1 LOUT+ I O Bit 1 of gain control Left channel + output in BTL mode, + output in SE mode. 5 LLINEIN I Left channel line input, selected when HP/ LINE pin is held low. 6 LPHIN I Left channel headphone input, selected when HP/ LINE pin is held high. 7,18 8 9 10 11 14 PVDD RIN LOUTLIN BYPASS PC-BEEP I I O I 15 SE/ BTL I Power supply for output stages. Common right input for fully differential inputs. AC ground for single-ended inputs. Left channel - output in BTL mode, and high impedance in SE mode. Common left input for fully differential inputs. AC ground for single-ended inputs. Tap to voltage divider for internal mid-supply bias generator. The input for PC-BEEP mode. PC-BEEP is enabled when at least eight continuous > 1-VPP (peak to peak) square waves is input to PC-BEEP pin. Hold low for BTL mode, hold high for SE mode. 16 17 ROUTHP/ LINE O I 19 VDD Right channel - output in BTL mode, high impedance state in SE mode. MUX control input, hold high to select headphone inputs (6,20), hold low to select line inputs (5,23). Analog VDD input supply. This terminal needs to be isolated from PVDD to achieve highest performance. 20 RHPIN I Right channel headphone input, selected when HP/ LINE pin is held high. 21 22 ROUT+ SHUTDOWN O I Right channel + output in BTL mode, positive output in SE mode. Places entire IC in shutdown mode when held low, expect PC-BEEP remains active. 23 RLINEIN I Right channel line input, selected when HP/ LINE pin is held low. I TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 9 G1427 Global Mixed-mode Technology Inc. Block Diagram RLINEIN RHPIN Right MUX _ ROUT+ + RIN PC-Beep PC-Beep _ GAIN0 GAIN1 SE/BTL HP/LINE LLINEIN LHPIN ROUT- + BYPASS Depop Circuitry Gain/MUX Control PVDD Power Management VDD SHUTDOWN GND Left MUX LOUT+ _ + LIN LOUT- _ + TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 10 G1427 Global Mixed-mode Technology Inc. Application Circuit Right Linein Negative Differential Input 1µF 23 RLINEIN 20 RHPIN Right MUX 1µF Right Hpin Negative Differential Input _ 8 14 PC-Beep 11 BYPASS 2 3 15 GAIN0 GAIN1 17 HP/LINE 5 LLINEIN 6 LHPIN SE/BTL Depop Circuitry 220µF VDD PVDD Gain/MUX Control Power Management VDD SHUTDOWN Left MUX LOUT+ 7,18 VDD 22 1µF 10µF Note 100K 1K 4 _ + 10 1K 19 1,12,13,24 GND Left Hpin Negative 1µF Differential Input Left Hpin/Linein Positive Differential Input 16 PC-Beep _ 2.2µF Left Linein Negative Differential Input 1µF ROUT- RIN + 1µF PC-BEEP Input Signal 21 + Right Hpin/Linein Positive 1µF Differential Input ROUT+ 220µF LIN 1µF LOUT- 3 _ + 0.1µF Application Circuit Using Differential Inputs Note: 1µF ceramic capacitor should be placed as close as possible to the IC to filter the higher-frequency noise. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 11 G1427 Global Mixed-mode Technology Inc. Application Circuit (continued) Right Hpin Input 1µF 23 RLINEIN 20 RHPIN Right MUX 1µF _ Right Linein Input ROUT+ 21 ROUT- 16 + RIN 14 PC-Beep 11 BYPASS 2 3 15 GAIN0 GAIN1 17 HP/LINE 5 LLINEIN 6 LHPIN 2.2µF Left Hpin Input 1µF SE/BTL Depop Circuitry 220µF VDD PVDD Gain/MUX Control Power Management VDD SHUTDOWN Left MUX 1µF LOUT+ 7,18 VDD 22 1µF 10µF Note 100K 1K 4 + 10 1K 19 1,12,13,24 GND _ Left Linein Input PC-Beep _ 1µF PC-BEEP Input Signal 8 + 1µF 220µF LIN 1µF LOUT- 3 _ + 0.1µF Application Circuit Using Single-Ended Inputs Note: 1µF ceramic capacitor should be placed as close as possible to the IC to filter the higher-frequency noise. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 12 G1427 Global Mixed-mode Technology Inc. Application Information Table 2 Gain setting via GAIN0 and GAIN1 inputs The internal gain setting is determined by two input terminals, GAIN0 and GAIN1. The gains listed in Table 1 are realized by changing the taps on the input resistors inside the amplifier. This will cause the internal input impedance, ZI, to be dependent on the gain setting. Although the real input impedance will shift by 30% due to process variation from part-to-part, the actual gain settings are controlled by the ratios of the resistors and the actual gain distribution from part-topart is quite good. GAIN1 SE/ BTL AV (dB) 0 0 0 6 0 1 0 10 1 0 0 15.6 1 1 0 21.6 X X 1 4.1 Zi 45 15.6 70 10 90 6 The value of Ci is important to consider as it directly affects the bass performance of the application circuit. For example, if the input resistor is 15kΩ, the input capacitor is 1µF, the flat bass response will be down to 10.6Hz. Because the small leakage current of the input capacitors will cause the dc offset voltage at the input to the amplifier that reduces the operation headroom, especially at the high gain applications. The low-leakage tantalum or ceramic capacitors are suggested to be used as the input coupling capacitors. When using the polarized capacitors, it is important to let the positive side connecting to the higher dc level of the application. The typical input impedance at each gain setting is given in the Table 2. Each gain setting is achieved by varying the input resistance of the amplifier, which can be over 3 times from its minimum value to the maximum value. As a result, if a single capacitor is used in the input high pass filter, the -3dB or cut-off frequency will be also change over 3 times. To reduce the variation of the cut-off frequency, an additional resistor can be connected from the input pin of the amplifier to the ground, as shown in Figure 1. With the extra resistor, the cut-off frequency can be re-calculated using equation : f-3dB= 1/ 2πC(R||RI). Using small external R can reduce the variation of the cut-off frequency. But the side effect is small external R will also let (R||RI) become small, the cut-off frequency will be larger and degraded the bass-band performance. The other side effect is with extra power dissipation through the external resistor R to the ground. So using the external resistor R to flatting the variation of the cut-off frequency, the user must also consider the bass-band performance and the extra power dissipation to choose the accepted external resistor R value. C 21.6 In the typical application, an input capacitor Ci is required to allow the amplifier to bias the input signal to the proper dc level for optimum operation. In this case ,Ci and the input impedance of the amplifier, Zi, form a high-pass filter with the -3dB determined by the equation: f-3dB= 1/ (2πRI Ci) Input Resistance Input Signal AV (dB) 30 Input Capacitor Table 1 GAIN0 Zi (Kohm) Power Supply Decoupling The G1427 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to make sure the output total harmonic distortion (THD) as low as possible. The optimum decoupling is using two capacitors with different types that target different types of noise on the power supply leads. For high frequency transients, spikes, a good low ESR ceramic capacitor works best, typically 0.1µF/1µF used and placed as close as possible to the G1427 VDD lead. A larger aluminum electrolytic capacitor of 10µF or greater placed near the device power is recommended for filtering low-frequency noise. Optimizing DEPOP Operation Circuitry has been implemented in G1427 to minimize the amount of popping heard at power-up and when coming out of shutdown mode. Popping occurs whenever a voltage step is applied to the speaker and making the differential voltage generated at the two ends of the speaker. To avoid the popping heard, the bypass capacitor should be chosen promptly, 1/(CBx170kΩ) ≦ 1/(CI*(RI+RF)). Zf IN R Figure 1 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 13 G1427 Global Mixed-mode Technology Inc. Where 170kΩ is the output impedance of the mid-rail generator, CB is the mid-rail bypass capacitor, CI is the input coupling capacitor, RI is the input impedance, RF is the gain setting impedance which is on the feedback path. CB is the most important capacitor. Besides it is used to reduce the popping, CB can also determine the rate at which the amplifier starts up during startup or recovery from shutdown mode. Output coupling capacitor G1427 can drive clean, low distortion SE output power with gain –1V/V into headphone loads (generally 16Ω or 32Ω) as in Figure 3. Please refer to Electrical Characteristics to see the performances. A coupling capacitor is needed to block the dc-offset voltage, allowing pure ac signals into headphone loads. Choosing the coupling capacitor will also determine the -3dB point of the high-pass filter network, as Figure 4. fC=1/(2πRLCC) De-popping circuitry of G1427 is shown as below Figure 2. The PNP transistor limits the voltage drop across the 120kΩ by slewing the internal node slowly when power is applied. At start-up, the voltage at BYPASS capacitor is 0. The PNP is ON to pull the mid-point of the bias circuit down. So the capacitor sees a lower effective voltage, and thus the charging is slower. This appears as a linear ramp (while the PNP transistor is conducting), followed by the expected exponential ramp of an R-C circuit. For example, a 220µF capacitor with 32Ω headphone load would attenuate low frequency performance below 22.6Hz. So the coupling capacitor should be well chosen to achieve the excellent bass performance when in SE mode operation. VDD Vo(PP) For better performance, CB is recommended to be at least 1.5 times of input coupling capacitor CI. For example, if using 1µF input coupling capacitor, 2.2µF ceramic or tantalum low-ESR capacitors are recommended to achieve the better THD performance. CC RL Vo(PP) Figure 3 VDD 100 kΩ 120 kΩ Bypass -3 dB 100 kΩ fc Figure 4 Figure 2 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 14 G1427 Global Mixed-mode Technology Inc. Bridged-Tied Load Mode Operation G1427 has two linear amplifiers to drive both ends of the speaker load in Bridged-Tied Load (BTL) mode operation. Figure 5 shows the BTL configuration. The differential driving to the speaker load means that when one side is slewing up, the other side is slewing down, and vice versa. This configuration in effect will double the voltage swing on the load as compared to a ground reference load. In BTL mode, the peak-to-peak voltage VO(PP) on the load will be two times than a ground reference configuration. The voltage on the load is doubled, this will also yield 4 times output power on the load at the same power supply rail and loading. Another benefit of using differential driving configuration is that BTL operation cancels the dc offsets, which eliminates the dc coupling capacitor that is needed to cancelled dc offsets in the ground reference configuration. Low-frequency performance is then limited only by the input network and speaker responses. Cost and PCB space can be minimized by eliminating the dc coupling capacitors. Shutdown mode When the normal operation, the SHUTDOWN pin should be held high. Pulling SHUTDOWN low will mute the outputs and deactivate almost circuits except PC-BEEP monitoring block. At this moment, the current of this device will be reduced to about 160µA to save the battery energy. The SHUTDOWN pin should never be left unconnected during the normal applications. INPUT * HP/ LINE SE/ BTL SHUTDOWN X Low High Low High High High Low High High High High X Line Line headphone headphone Mute BTL SE BTL SE PC-BEEP Operation The PC-BEEP input allows a system beep to be sent directly from a computer through the amplifier to the speakers with a few external components. It is activated automatically by detecting the PC-BEEP input. The preferred input signal is a square wave or pulse train with an amplitude of 1-VPP or greater. To be accurately detected, the signal must be with at least 1-VPP amplitude, 8 continuous rising edges, rise and fall times less than 0.1µs. When the signal is no longer detected, the amplifier will return its previous operating mode and volume setting. VDD Vo(PP) RL X Low Low INPUT OUTPUT * Inputs should never be left unconnected X= do not care Input MUX And SE/ BTL Operation VDD AMPLIFIER STATE 2xVo(PP) -Vo(PP) When the PC-BEEP mode is activated, both the LINEIN and HPIN are deselected and the outputs will be driven in BTL mode with the signal from PC-BEEP. The gain setting will be also fixed at 0.3V/V, independent of the volume setting. If the device is in the SHUTDOWN mode, activating PC-BEEP will take the device out of shutdown mode and output the PC-BEEP input signal until the PC-BEEP signal no longer detected. And then the device will return the shutdown mode when no PC-BEEP signal is detected. Figure 5 The G1427 allows two different input sources applied to the audio amplifiers, which can be independent to the SE/ BTL setting. When HP/ LINE is held high, the headphone inputs are active. When the HP/ LINE is held low, the line inputs are selected. When SE/ BTL is held low, all four internal audio amplifiers are activated to drive the stereo speakers. When SE/ BTL is held high, two amplifiers are activated to drive the stereo headphones. The other two amplifiers are disable and keeping the outputs high impedance. The PC-BEEP input can be dc-coupled to save the coupling capacitor. This pin is set at mid-rail normally when no signal is present. If AC-coupling is desired, the value of the coupling capacitor should be chosen to satisfy the equation: CPCB≧ 1/( 2πfPCB*150KΩ) CPCB is the PC-BEEP AC-coupling capacitor. fPCB is the frequency of applied PC-BEEP input signal. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 15 G1427 Global Mixed-mode Technology Inc. Package Information C D 24 L 1.88 1.88 3.85 E1 E 2.8 0.71 1 Note 5 θ A2 A A1 e b NOTE: 1. Package body sizes exclude mold flash protrusions or gate burrs 2. Tolerance ±0.1mm unless otherwise specified 3. Coplanarity : 0.1mm 4. Controlling dimension is millimeter. Converted inch dimensions are not necessarily exact. 5. Die pad exposure size is according to lead frame design. 6. Follow JEDEC MO-153 SYMBOL A A1 A2 b C D E E1 e L y θ MIN. DIMENSION IN MM NOM. MAX. ----0.00 0.80 0.19 0.09 7.70 6.20 4.30 ----0.45 ----0º --------1.00 --------7.80 6.40 4.40 0.65 0.60 --------- 1.15 0.10 1.05 0.30 0.20 7.90 6.60 4.50 ----0.75 0.10 8º MIN. DIMENSION IN INCH NOM. MAX. ----0.000 0.031 0.007 0.004 0.303 0.244 0.169 ----0.018 ----0º --------0.039 --------0.307 0.252 0.173 0.026 0.024 --------- 0.045 0.004 0.041 0.012 0.008 0.311 2.260 0.177 ----0.030 0.004 8º Taping Specification PACKAGE Q’TY/REEL TSSOP-24 (FD) 2,500 ea F e e d D ir e c tio n T y p ic a l T S S O P P a c k a g e O r ie n ta tio n GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at any time without notice to change said circuitry and specifications. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Sep 23, 2005 16