Features

Direct path #8482;

- Eliminate the pop -up/click sound

- Eliminate the output DC blocking capacitor

3.0V to 3.7V power supply voltage

low noise and THD

-Sto signal ratio gt; 109db

- Typical VN LT; 7 μVRMS 20 --20kHz

-10kΩ THD+N LT; 0.002%

Enter the output voltage of 5kΩ load

–3.3V power supply voltage is 2VRMS

stereo direct access path #8482; headphones:

- 32Ω40mW at 3.3V power supply voltage

--16 ]

Differential input

Power induction UV protection

short circuit and heat protection

± 8KV IEC ESD Protection

compatible with

DRV602

and DRV603 123] LCD and PDP TV

Blu -ray CD #8482;, DVD player

mini/miniature combination system

] sound card

Instructions

DRV604

is a 2VRMS non -pop -up stereo line drive with a three -dimensional sound headset output. To reduce the number and cost of components. This device is very suitable for single -power electronic products with key design parameters.

The DirectPath design #8482; technically, the DRV604 can drive 2 VRM to 5kΩ load. The headset output can generate a clean 40MW to 32Ω load from the 3.3V power supply. Essence The device has a differential input and uses an external gain setting resistance. The resistance supports the gain range of -1V/V to -10V/V. The headset and line output have ± 8KV IEC ESD protection, which can achieve simple ESD protection circuits. DRV604 has built -in enable control, which can achieve no pop -up switch control. DRV604 can use its built -inThe comparator monitor the external power supply voltage so that it can be turned off in the state of power, and then the upstream audio DAC will produce clicks and pop -up sounds.

Compared with the traditional method of generating headphones and 2VRMS output, using DRV604 in audio products can greatly reduce the number of components. DRV604 does not require a power supply greater than 3.3V to generate 5.6VPP output, nor does it need to be powered by meso. DRV604 integrates its own charge pump to generate a negative power rail and provide a clean, non -pop -up ground bias 2VRMS output.

DRV604 provides 28 -pin HTSSOP. For a stereo line drive without HP amplifier, see DRV603.

System box diagram

Order information

( 1) For the latest software packages and ordering information, see the software package option appendix at the end of this document.

Typical features, line drives

Typical features, headphones

] Application information

Line driver amplifier

Single -power headset and line driver amplifier usually requires DC capacitors. The above figure in FIG. 13 illustrates the connection between the traditional line drive amplifier and the load and output signal.

The DC blocking capacitor of the headset amplifier is usually very large. During the power -powered period, a quiet circuit is required to minimize the clicks and bangs of the headset and line drive. Output capacitors and mute circuits consume PCB area, increase assembly costs, and reduce the preservation of audio output signals.

Direct path #8482; The amplifier structure runs from a single power supply, but provides a negative voltage track with internal charge pump.

Combined with the positive track provided by the user and the negative IC, the equipment runs in an effective division mode.

The output voltage is now zero -centered and can be swinged to the positive or negative, which is combined with the built -in click to reduce the circuit DirectPath #8482; the amplifier does not require the output DC blocking capacitors.

The bottom block diagram and waveform of FIG. 13 illustrates the structure of the ground reference headset and line drive. This is the architecture of DRV604.

Component selection

Charging pump

The charge pump flying capacitor is used to transfer charge during the production of the negative power supply voltage. PVSS capacitors must be at least equal to the charge pump capacitor to allow maximum charge transfer. Low ESR capacitor is an ideal choiceChoose, the typical value is 1 μF. For high -voltage parts, the capacitance value of less than 1 μF cannot be recommended, because this will limit the negative voltage swing in the low impedance load.

Remove the capacitor

DRV604 is a direct path #8482; requires sufficient power to be coupled to ensure the lower amplifier with a lower noise and total harmonic distortion (THD). A good low -equal series resistor (ESR) ceramic capacitor is usually 1 μF, where the effect is the best. Putting this off -coupled container near DRV604 is important for the performance of the amplifier. For filtering low -frequency noise signals, a 10 μF or larger capacitor will be helpful to place near the audio power amplifier, but it does not need it in most applications because the PSRR of the device is very high.

Increase setting resistance range

Must choose the gain setting resistor RIN and RFB to keep the noise, stability, and input capacitor size of the DRV604 within the acceptable range. The voltage gain is defined as RFB divided by Rin. Choosing too low value requires a large input AC coupling capacitor, CIN. Choosing a high value will increase the noise of the amplifier. Table 1 lists the recommended resistance value of different gain settings.

External and under voltage detection

DRV604 contains an internal precision band gap reference voltage and 2 comparators, one for monitoring the power supply voltage , PVDD-U-LD and PVDD-UHP, the other is an optional voltage for external users on monitoring pin 25. The internal PVDD monitor is set to 2.8 V, lagging behind 200 MV.

External pressure detection can be used to turn off DRV604 before the input device emits a pop -up signal. The shutdown threshold at the EX_VP pin is 1.25 V. Use the resistor separator to obtain the shutdown threshold and lag of the application.

The selected threshold can be determined as follows:

under the conditions of R13 gt; gt; r11 | r12 123]

For example, to get VUVP 4.5 V and 400 MV stagnation, please use R11 10 kΩ, R12 3 kΩ and R13 22kΩ.

In order to filter the peak and noise, a capacitor can be added to R12.

Input the lock -lock capacitor

DC input blocking capacitor needs to be connected to the input pin of DRV604 with the audio signal. These capacitors block the DC parts of the audio source and allow DRV604 to input appropriate bias to provide maximum performance. Input blocking capacitors also limits DC gain to 1, To limit the DC offset voltage at the output end.

These capacitors and input resistance RIN form high -pass filter. The deadline is calculated with Formula 1. For this calculation, the capacitance used is input blocking capacitors, and the resistance is the input resistance selected from the Table 1. When the two of the two values u200bu200bare given, the frequency and/or capacitance can be determined.

Use DRV604 as a second -order filter

Some audio DACs currently used need a external low -pass filter to eliminate external noise. This is a possible DRV604 because it can be used like a standard operation amplifier. Several filter topology can achieve single -end and differential. In the figure below, multiple feedback (MFB) with differential input and single -end input shows.

The figure shows an AC coupling capacitor to remove the DC component from the source. It is used to prevent any DC component in the source and reduce the DC gain to 1, which helps the output DC bias Move to minimize.

The resistance value should have a low value of low noise, but it should also have sufficient high value to obtain small -sized communication coupling caps. C2 can be divided into two, and the middle point is grounded, which can increase the common modulus attenuation.

Popular free power supply

By maintaining low EN_LD and EN_HP and/or EX_UVPs that maintain low during the rise and decrease of power, ensure that there is no pop -up power supply. The pin should be kept at a lower level until the input AC coupling convergence container is fully charged, and then the EN_XX pin is high, so that the AC coupling can be properly charged, thereby achieving non -pop -up power power. Figure 16 illustrates the priority.

Double -dimensional sound line driver

DRV604 headset stereo amplifier can also be used as a line drive. When the driver 5KΩ load impedance, it has the same line as the line amplifier. High output voltage capacity. This makes DRV604 very suitable for dual Scart output applications on LCD TVs, or multi -line outputs such as DVD or Blu -ray player. Among them, 2X DRV604 can provide a very space -saving solution for 8CH line output.

Capacity load

DRV604 can directly drive up to 220pf high -capacitor load, adding a 47Ω or larger output series resistor by output the line drive, which can accept higher capacitive loads Essence

The gain setting the resistor RIN and RFB must be close to the input pin to minimize the capacitance load on these input pins and ensure the maximum stability of the DRV604.

The ground trajectory is recommended as a star-ground wiring to minimize the buzz interference.

PVDD, PVSS down coupling capacitors and charge pumpsThe capacitor should be connected in a short -term.

Compatible with DRV603

DRV604 stereo line driver part is compatible with DRV603 pins.Therefore, a single PCB layout can be used for different output configurations together with the filling option.

Application circuit Single -end input and output, the line part of the line is 3.3 times, the gain part of the headset is 3 to 3 to 3Note.AC coupling input, Qualcomm is extremely 1.6Hz, 50kHz is a second -order low -pass filter at 50kHz.