The NS4816 is a filter-free Class G audio power amplifier with automatic gain control (AGC) and a built-in high-efficiency charge pump boost power supply. The chip continuously detects the output power and adjusts the internal gain accordingly to avoid prolonged overloading of the speaker.
    The NS4816's integrated charge pump generates a 5.9V supply voltage to the output stage of the power amplifier. Under the condition of 8Ω load and lithium battery power supply, it can continuously output 1W constant power (THD+N=1%). The NS4816 has a maximum efficiency of 81%, which greatly extends battery life when playing music.
    The NS4816's AGC technology with multiple levels of constant output power helps designers choose the right power to match different speakers.
    The NS4816 comes in a WLCSP package (1.63mm*1.63mm).

Full differential amplification

Charge pump boost converter
    The NS4816 has a 1.5x charge pump converter. This converter can boost the supply voltage VDD to output a higher voltage PVDD to supply the power output stage. Usually above 5.9V, the overvoltage protection circuit is activated to protect the PVDD from exceeding the maximum allowable operating voltage.

One-line pulse control
    The NS4816 uses a one-line pulse control operating mode, which can be selected by the user by entering a pulse signal on the SHDN pin

Mode switching timing
    To avoid entering the wrong state, power on the NS4816 before entering the control signal. When it is necessary to switch the working mode, the SHDN should be pulled down for more than 1ms before entering a new control signal

Automatic gain control
    The AGC function ensures automatic gain regulation of the amplifier through an internal PGA, and the chip continuously detects the output and adjusts the gain on the amplifier signal path. This function can sense the volume information to avoid overloading the speaker volume. The gain varies with the audio signal in a voltage gradient of 0.5dB (power gradient of 1dB), and when the signal amplitude is stable, the gain does not change. Under long-term high-power working condition, AGC function effectively extends the life of the speaker.

Power supply decoupling capacitor
    The NS4816 is a high-performance Class G audio power amplifier, so the power supply needs to be decoupled to improve efficiency and reduce THD. For high-frequency transient signals, burrs and interference signals such as digital jitter, it is necessary to place a low ESR 4.7µF ceramic capacitor as close to the VDD pin as possible to ensure the best results, because the parasitic inductance and resistance of any connection between the capacitor and the chip will reduce efficiency. At the same time, in order to filter out the high-frequency noise signal, it is necessary to place a 0.1µF capacitor.

Charge pump charging capacitor
    Charge pump charge capacitor is used to transfer energy between the power supply and charge pump load, and its value directly affects the load adjustment rate and output capacity of the charge pump. Too small charge capacitor will affect the load adjustment rate and output capacity of the charge pump, thus affecting the output power of the power amplifier. The larger the charge capacitance of the charge pump, the stronger the load adjustment rate and driving capacity. It is recommended to use 2.2uF/10V, low ESR X7R, X5R ceramic capacitors.

Charge pump holds capacitance C PVDD
    Keeping the ESR value of the capacitor C PVDD significantly affects the ripple of the PVDD, increasing this capacitance decreases the ripple and decreasing the capacitance increases the ripple. A 4.7µF/10V capacitor is recommended.

Magnetic bead filter
    When the circuit sensitive frequency exceeds 1MHz, no LC filter causes the system to fail the EMI test, a magnetic bead filter can be used. The filter can pass FCC and CE tests, as both only test for radioactive interference above 30MHz. A magnetic bead with high impedance at high frequencies and low impedance at low frequencies can be selected, and has sufficient current capacity to drive the load. If the EMI sensitive circuit below 1MHz or the horn to the chip has a long wire, you can choose the LC filter. Make sure the bead is as close to the VOP and VON pins as possible when using.

TVS tube
    In order to improve the performance of ESD system, a pair of symmetrical TVS tubes are needed to ensure good sound quality performance, pay attention to the tube should be close to the horn.

PCB layout Recommendations
    In order to give full play to the performance of the NS4816 chip, the PCB design must be carefully considered and try to follow the following principles:
    1. The length to width ratio of the power cable should be as small as possible, it must be routed separately, the wiring should be short and thick, and the width should be greater than 0.75mm. The decoupling capacitor must be closest to the IC power pin.
    2. The booster capacitors C1 and C2 should be as close to the IC as possible, and the cables should be short and thick. If there are holes, ensure the current strength of the holes. The PVDD capacitor is as close as possible to the PVDD pin of the chip.
    3. The signal input capacitor resistor is close to the positive and negative input ends of the chip, and should be wired in parallel.
    4. The magnetic bead at the power output end is as close as possible to the positive and negative output end of the IC, the magnetic bead should be closely connected to the grounded capacitor, and the capacitor must be fully grounded. The output line is wider than 0.5mm.

Built-in AGC function, 3-stage constant output power control:
1.2W, 1W, 0.8W(8Ω)
Built-in charge pump power system
High productivity: 81%
Maximum output power Po=2.2W
    (RL=8Ω, VDD=4.2V, THD+N=10%)
Low THD+N=0.015%
    (f=1kHz, RL=8Ω, Po=0.5W, VDD=3.8V)
Built-in thermal protection and overvoltage protection
Built-in Pop and Click noise suppression
High resistance to RF interference
One-line pulse control
NS4816 in WLCSP package (1.63mm*1.63mm)

Mobile phones and tablets
Portable media player