LM4952

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SNAS230A – AUGUST 2004 – REVISED MAY 2013

(3)

For a typical application with a 12V power supply and an SE 4

Ω load, the maximum ambient temperature that

allows maximum stereo power dissipation without exceeding the maximum junction temperature is approximately

77°C for the TS package.

(4)

maximum junction temperature by reducing the power supply voltage or increasing the load resistance. Further

allowance should be made for increased ambient temperatures.

The above examples assume that a device is operating around the maximum power dissipation point. Since

internal power dissipation is a function of output power, higher ambient temperatures are allowed as output

power or duty cycle decreases.

If the result of Equation 1 is greater than that of Equation 2, then decrease the supply voltage, increase the load

impedance, or reduce the ambient temperature. Further, ensure that speakers rated at a nominal 4

Ω do not fall

below 3

created using additional copper area around the package, with connections to the ground pins, supply pin and

amplifier output pins. Refer to the Typical Performance Characteristics curves for power dissipation information at

lower output power levels.

POWER SUPPLY VOLTAGE LIMITS

Continuous proper operation is ensured by never exceeding the voltage applied to any pin, with respect to

ground, as listed in Absolute Maximum Ratings(1)(2)(3).

POWER SUPPLY BYPASSING

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

rejection. Applications that employ a voltage regulator typically use a 10µF in parallel with a 0.1µF filter

capacitors to stabilize the regulator's output, reduce noise on the supply line, and improve the supply's transient

response. However, their presence does not eliminate the need for a local 10µF tantalum bypass capacitance

connected between the LM4952's supply pins and ground. Do not substitute a ceramic capacitor for the

tantalum. Doing so may cause oscillation. Keep the length of leads and traces that connect capacitors between

the LM4952's power supply pin and ground as short as possible.

BYPASS PIN BYPASSING

voltage's stability and improves the amplifier's PSRR. The PSRR improvements increase as the bypass pin

capacitor value increases. Too large, however, increases turn-on time. The selection of bypass capacitor values,

SELECTING EXTERNAL COMPONENTS), system cost, and size constraints.

MICRO-POWER SHUTDOWN

The LM4952 features an active-low micro-power shutdown mode. When active, the LM4952's micro-power

shutdown feature turns off the amplifier's bias circuitry, reducing the supply current. The low 55µA typical

shutdown current is achieved by applying a voltage to the SHUTDOWN pin that is as near to GND as possible. A

voltage that is greater than GND may increase the shutdown current.

(1)

All voltages are measured with respect to the GND pin, unless otherwise specified.

(2)

Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for

which the device is functional, but do not specify specific performance limits. Electrical Characteristics state DC and AC electrical

specifications under particular test conditions which specify specific performance limits. This assumes that the device is within the

Operating Ratings. Specifications are not specified for parameters where no limit is given, however, the typical value is a good indication

of device performance.

(3)

If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and

specifications.

Copyright © 2004–2013, Texas Instruments Incorporated

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