UNISONIC TECHNOLOGIES CO., LTD PA3632 Preliminary CMOS IC DIRECT 2-VRMS AUDIO LINE DRIVER WITH ADJUSTABLE GAIN DESCRIPTION The UTC PA3632 is a pop-free stereo line driver with the integrated charge pump generating the negative supply rail which allows the removal of the output DC-blocking capacitors. The UTC PA3632 provides a clean, pop-free ground-biased audio signal. The UTC PA3632 is capable of driving 2VRMS into a 10kΩ load with 3.3V supply voltage. The device has differential inputs and uses external resistors for flexible gain setting. Gain can be configured individually for each channel. The UTC PA3632 has built-in active-mute control for pop-free audio on/off control. The UTC PA3632 has an external under-voltage detector that mutes the output when monitored voltage drop below set value. The device has differential inputs and uses external gain-setting resistors to support a gain range of ±1V/V to ±10V/V, and gain can be configured individually for each channel. Line outputs have ±8-Kv (HBM) IEC ESD protection, requiring just a simple resistor-capacitor ESD protection circuit. Using the UTC PA3632 in audio products can reduce component count considerably compared to traditional headphone amplifiers. FEATURES * Low THD+N<0.01% at 2Vrms Into 10kΩ * Stereo Direct Audio Line driver 2Vrms Into 10KΩ With 3.3V Supply * Integrated Charge Pump Generates Negative Supply Rail * High SNR, >90dB * Ground-Referenced Outputs Eliminate DC-Blocking Capacitors * Differential Input and Single-Ended Output * Adjustable Gain by External Gain-Setting Resistors * Pop-Free Under-Voltage Protection * Short-Circuit Protection * Click- and Pop-Reduction Circuitry * Active Mute Control for Pop-Free Audio On/Off Control ORDERING INFORMATION Ordering Number PA3632G-P14-R www.unisonic.com.tw Copyright © 2016 Unisonic Technologies Co., Ltd Package TSSOP-14 Packing Tape Reel 1 of 9 QW-R107-071.b PA3632 Preliminary MARKING PIN CONFIGURATION CMOS IC +INR 1 14 +INL -INR 2 13 -INL OUTR 3 12 OUTL GND 4 11 UVP Mute 5 10 GND VSS 6 9 VDD CN 7 8 CP UVP Charge Pump PIN DESCRIPTION PIN NO. 1 2 3 4, 10 5 6 7 8 9 11 12 13 14 PIN NAME +INR -INR OUTR GND Mute VSS CN CP VDD UVP OUTL -INL +INL DESCRIPTION Right-channel OPAMP positive input Right-channel OPAMP negative input Right-channel OPAMP output Ground Mute, active-low Supply voltage Charge-pump flying capacitor negative connection Charge-pump flying capacitor positive connection Positive supply Under-voltage protection; internal pull-up, unconnected if UVP function is unused. Left-channel OPAMP output Left-channel OPAMP negative input Left-channel OPAMP positive input UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC BLOCK DIAGRAM +INL + + Headphone Driver -INL - - -INR OUTR OUTL UVP GND Mute +INR Headphone Driver BIAS, UVP, Click and Pop, SCP Circuitry GND VDD VSS Charge Pump CN UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw CP 3 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC ABSOLUTE MAXIMUM RATING (over operating free-air temperature range, unless otherwise noted) PARAMETER SYMBOL RATINGS UNIT Supply voltage, VDD to GND -0.3~4 V Input Voltage VI VSS-0.3 ~ VDD+0.3 V Minimum Load Impedance-Line Outputs-OUTL, OUTR RL 600 Ω Mute to GND, UVP to GND -0.3 ~ VDD+0.3 V Maximum Operating Junction Temperature Range TJ -40 ~ +150 °C Storage Temperature Range TSTG -40 ~ +150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. THERMAL INFORMATION PARAMETER SYMBOL θJA θJC Junction to Ambient Junction to Case RATINGS 130 49 UNIT °C/W °C/W RECOMMENDED OPERATING CONDITIONS PARAMETER Power Supply Load Impedance SYMBOL VDD RL TEST CONDITIONS DC supply voltage MIN 3 0.6 TYP 3.3 10 MAX 3.6 UNIT V kΩ Low-Level Input Voltage VIL Mute 40 %VDD High-Level Input Voltage VIH Mute 60 %VDD Ambient Temperature TA -40 25 85 °C ELECTRICAL CHARACTERISTICS (TA=25°C, Charge pump: CP=1µF, unless otherwise noted) PARAMETER Output Offset Voltage Power-Supply Rejection Ratio High-Level Output Voltage Low-Level Output Voltage External UVP Detect Voltage External UVP Detect Hysteresis Current Charge-Pump Switching Frequency SYMBOL |VOS| PSRR VOH VOL VUVP_EX TEST CONDITIONS VDD=3.3V MIN VDD=3.3V VDD=3.3V 3.1 MAX 1 1.25 UNIT mV dB V V V 5 µA -3.05 VUVP_EX_HYSTE RESIS 400 kHz High-Level Input Current, Mute |IIH| VDD=3.3V, VIH=VDD 1 µA Low-Level Input Current, Mute |IIL| VDD=3.3V, VIL=0V 1 µA IDD VDD=3.3V, no load, Mute =VDD, no load 25 mA Supply Current fCP TYP 0.5 80 200 VDD=3.3V, no load, Mute =GND, disabled UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 300 14 14 mA 4 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC OPERATING CHARACTERISTICS (VDD=3.3V, RDL=10kΩ, RFB=30kΩ, RIN=15kΩ, TA=25°C, Charge pump: CP=1µF, unless otherwise noted)) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX THD+N=1%, VDD=3.3V, f=1kHz, 2 2.4 Output Voltage, Outputs in Phase VO RL=10KΩ Total Harmonic Distortion Plus Noise THD+N VO=2 VRMS, f=1kHz 0.002 Signal-to-Noise Ratio (Note 1) SNR A-weighted 105 Dynamic Range DNR A-weighted 105 Noise Voltage VN A-weighted 11 Output Impedance When Muted ZO Input-to-Output Attenuation When Muted Crosstalk-L to R, R to L Current Limit ILIMIT Note: SNR is calculated relative to 2 VRMS output. Vrms % dB dB μV Mute =GND 110 mΩ Mute =GND 80 dB VO=1 VRMS PVDD=3.3V -110 25 dB mA UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw UNIT 5 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC APPLICATION INFORMATION LINE DRIVER AMPLIFIERS Single-supply line-driver amplifiers typically require dc-blocking capacitors. The top drawing in Figure 1 illustrates the conventional line-driver amplifier connection to the load and output signal. DC blocking capacitors are often large in value. The line load (typical resistive values of 600Ω~10kΩ) combines with the dc blocking capacitors to form a high-pass filter. Equation 1 shows the relationship between the load impedance (RL), the capacitor (CO), and the cutoff frequency (fC). fC 1 (1) 2R L C O CO can be determined using Equation 2, where the load impedance and the cutoff frequency are known. CO 1 (2) 2R L f C If fC is low, the capacitor must then have a large value because the load resistance is small. Large capacitance values require large package sizes. Large package sizes consume PCB area, stand high above the PCB, increase cost of assembly, and can reduce the fidelity of the audio output signal. The DirectPath amplifier architecture operates from a single supply but makes use of an internal charge pump to provide a negative voltage rail. Combining the user-provided positive rail and the negative rail generated by the IC, the device operates in what is effectively a split-supply mode. The output voltages are now centered at zero volts with the capability to swing to the positive rail or negative rail. Combining this with the built-in click and pop reduction circuit, the DirectPath amplifier requires no output dc blocking capacitors. The bottom block diagram and waveform of Figure 1 illustrate the ground-referenced line-driver architecture. This is the architecture of the UTC PA3632. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC APPLICATION INFORMATION (Cont.) GAIN-SETTING RESISTOR RANGES The gain-setting resistors, RIN and Rfb, must be chosen so that noise, stability, and input capacitor size of the UTC PA3632 are kept within acceptable limits. Voltage gain is defined as Rfb divided by RIN. Table 1. Recommended Resistor Values GAIN -1V/V -1.5V/V -2V/V -10V/V INPUT RESISTOR VALUE, RIN 10kΩ 8.2kΩ 15kΩ 4.7kΩ FEEDBACK RESISTOR VALUE, Rfb 10kΩ 12kΩ 30kΩ 47kΩ UTC PA3632 UVP OPERATION The shutdown threshold at the UVP pin is 1.25V. The customer must use a resistor divider to obtain the shutdown threshold and hysteresis desired for a particular application. The customer-selected thresholds can be determined as follows: EXTERNAL UNDERVOLTAGE DETECTION External undervoltage detection can be used to mute/shut down the UTC PA3632 before an input device can generate a pop. The shutdown threshold at the UVP pin is 1.25V. The user selects a resistor divider to obtain the shutdown threshold and hysteresis for the specific application. The thresholds can be determined as follows: VUVP=(1.25–6μA×R3)×(R1+R2)/R2 Hysteresis=5μA×R3×(R1+R2)/R2 For example, to obtain VUVP=3.8V and 1-V hysteresis, we can use R1=3kΩ, R2=1kΩ, and R3=50kΩ. INPUT-BLOCKING CAPACITORS DC input-blocking capacitors are required to be added in series with the audio signal into the input pins of the PA3632. These capacitors block the dc portion of the audio source and allow the UTC PA3632 inputs to be properly biased to provide maximum performance. These capacitors form a high-pass filter with the input resistor, RIN. The cutoff frequency is calculated using Equation 3. For this calculation, the capacitance used is the input-blocking capacitor, and the resistance is the input resistor chosen from Table 1; then the frequency and/or capacitance can be determined when one of the two values is given. It is recommended to use electrolytic capacitors or high-voltage-rated capacitors as input blocking capacitors to ensure minimal variation in capacitance with input voltages. Such variation in capacitance with input voltages is commonly seen in ceramic capacitors and can increase low-frequency audio distortion. f CIN 1 1 or C IN (3) 2R IN C IN 2f C INR IN UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC APPLICATION INFORMATION (Cont.) CHARGE-PUMP FLYING CAPACITOR AND PVSS CAPACITOR The charge-pump flying capacitor serves to transfer charge during the generation of the negative supply voltage. The PVSS capacitor must be at least equal to the charge-pump capacitor in order to allow maximum charge transfer. Low-ESR capacitors are an ideal selection, and a value of 1μF is typical. Capacitor values that are smaller than 1μF can be used, but the maximum output voltage may be reduced and the device may not operate to specifications. If the UTC PA3632 is used in highly noise-sensitive circuits, it is recommended to add a small LC filter on the VDD connection. DECOUPLING CAPACITORS The UTC PA3632 is a DirectPath line-driver amplifier that requires adequate power supply decoupling to ensure that the noise and total harmonic distortion (THD) are low. A good, low equivalent-series-resistance (ESR) ceramic capacitor, typically 1μF, placed as close as possible to the device VDD lead works best. Placing this decoupling capacitor close to the UTC PA3632 is important for the performance of the amplifier. For filtering lower-frequency noise signals, a 10-μF or greater capacitor placed near the audio power amplifier would also help, but it is not required in most applications because of the high PSRR of this device. USING THE UTC PA3632 AS A SECOND-ORDER FILTER Several audio DACs used today require an external low-pass filter to remove out-of-band noise. This is possible with the UTC PA3632, as it can be used like a standard operational amplifier. Several filter topologies can be implemented, both single-ended and differential. In Figure 2, multi-feedback (MFB) with differential input and single-ended input are shown. An ac-coupling capacitor to remove dc content from the source is shown; it serves to block any dc content from the source and lowers the dc gain to 1, helping to reduce the output dc offset to a minimum. The resistor values should have a low value for obtaining low noise, but should also have a high enough value to get a small-size ac-coupling capacitor. With the proposed values of R1=15kΩ, R2=30kΩ, and R3=43kΩ, a dynamic range (DYR) of 106dB can be achieved with a 1-μF input ac-coupling capacitor. GAIN-SETTING RESISTORS The gain-setting resistors, RIN and Rfb, respectively, to minimize capacitive loading on these input pins and to ensure maximum stability of the UTC PA3632. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 9 QW-R107-071.b PA3632 Preliminary CMOS IC TYPICAL APPLICATION CIRCUIT Right - Input + C3 R1 C3 C3 R1 R1 C1 +INR C1 Right Output -INR + + Line Driver Line Driver - - R3 R2 +INL -INL C1 OUTL Mute Bias and UVP Circuitry 0.1µF GND R11 VDD 3.3-V Supply VSS CN Left Output UVP GND 1µF C2 C1 UTC PA3632 OUTR 0.1µF R1 R3 R3 R2 C3 R2 R2 C2 R3 Left - Input + Charge Pump R12 1µF CP LDO 1µF System Supply 10µF R1=15kΩ, R2=30kΩ, R3=43kΩ, C1=47pF, C2=180pF Differential-input, single-ended output, second-order filter UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 9 of 9 QW-R107-071.b