8002

8002

8002

8002

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additional changes must be made. These changes can include reduced supply voltage, higher load impedance, or

reduced ambient temperature. Internal power dissipation is a function of output power. Refer to the Typical

Performance Characteristics curves for power dissipation information for different output powers and output loading.

POWER SUPPLY BYPASSING

As with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection.

The capacitor location on both the bypass and power supply pins should be as close to the device as possible. Typical

applications employ a 5V regulator with 10µF tantalum or electrolytic capacitor and a ceramic bypass capacitor which

aid in supply stability. This does not eliminate the need for bypassing the supply nodes of the 8002. The selection of a

bypass capacitor, especially CB, is dependent upon PSRR requirements, click and pop performance (as explained in the

section, Proper Selection of External Components), system cost, and size constraints.

SHUTDOWN FUNCTION

In order to reduce power consumption while not in use, the 8002 contains shutdown circuitry that is used to turn off the

amplifier’s bias circuitry. In addition, the 8002 contains a Shutdown Mode pin (LD and MH packages only), allowing

the designer to designate whether the part will be driven into shutdown with a high level logic signal or a low level

logic signal. This allows the designer maximum flexibility in device use, as the Shutdown Mode pin may simply be tied

permanently to either VDD or GND to set the 8002 as either a "shutdown-high" device or a "shutdown-low" device,

respectively. The device may then be placed into shutdown mode by toggling the Shutdown pin to the same state as the

Shutdown Mode pin. For simplicity’s sake, this is called "shutdown same", as the 8002 enters shutdown mode

whenever the two pins are in the same logic state. The MM package lacks this Shutdown Mode feature, and is

permanently fixed as a ‘shutdown-low’ device. The trigger point for either shutdown high or shutdown low is shown as

a typical value in the Supply Current vs Shutdown Voltage graphs in the Typical Performance Characteristics section.

It is best to switch between ground and supply for maximum performance. While the device may be disabled with

shutdown voltages in between ground and supply, the idle current may be greater than the typical value of 0.1µA. In

either case, the shutdown pin should be tied to a definite voltage to avoid unwanted state changes.

In many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry, which

provides a quick, smooth transition to shutdown. Another solution is to use a single-throw switch in conjunction with

an external pull-up resistor (or pull-down, depending on shutdown high or low application). This scheme guarantees

that the shutdown pin will not float, thus preventing unwanted state changes.

PROPER SELECTION OF EXTERNAL COMPONENTS

Proper selection of external components in applications using integrated power amplifiers is critical to optimize device

and system performance. While the 8002 is tolerant of external component combinations, consideration to component

values must be used to maximize overall system quality. The 8002 is unity-gain stable which gives the designer

maximum system flexibility. The 8002 should be used in low gain configurations to minimize THD+N+N values, and

maximize the signal to noise ratio. Low gain configurations require large input signals to obtain a given output power.

Input signals equal to or greater than 1Vrms are available from sources such as audio codecs. Please refer to the section,

Audio