LM4701T National Semiconductor, LM4701T Datasheet - Page 11

• Manufacturer Part Number: LM4701T
• Description: LM4701 Overture Audio Power Amplifier Series 30W Audio Power Amplifier with Mute and Standby Modes
• Manufacturer: National Semiconductor

Typical Performance Characteristics
Pulse Power Limit
Standby Current (I
Standby Pin Voltage
Application Information
MUTE MODE
By placing a logic-high voltage on the mute pin, the signal
going into the amplifiers will be muted. If the mute pin is left
floating or connected to a logic-low level, the amplifier will be
in a non-muted state. Refer to the Typical Performance
Characteristics section for curves concerning Mute Attenu-
ation vs Mute Pin Voltage.
STANDBY MODE
The standby mode of the LM4701 allows the user to drasti-
cally reduce power consumption when the amplifier is idle.
By placing a logic-high voltage on the standby pin, the ampli-
fier will go into Standby Mode. In this mode, the current
drawn from the V
for both amplifiers. The current drawn from the V
typically 2.1 mA. Clearly, there is a significant reduction in
idle power consumption when using the standby mode. Re-
fer to the Typical Performance Characteristics section for
curves showing Supply Current vs Standby Pin Voltage for
both supplies.
UNDER-VOLTAGE PROTECTION
Upon system power-up, the under-voltage protection cir-
cuitry allows the power supplies and their corresponding ca-
pacitors to come up close to their full values before turning
on the LM4701 such that no DC output spikes occur. Upon
CC
CC
supply is typically less than 10 µA total
) vs
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Pulse Power Limit
Supply Current (I
Standby Pin Voltage
EE
supply is
(Continued)
EE
11
) vs
turn-off, the output of the LM4701 is brought to ground be-
fore the power supplies such that no transients occur at
power-down.
OVER-VOLTAGE PROTECTION
The LM4701 contains over-voltage protection circuitry that
limits the output current to approximately 3.5 Apk while also
providing voltage clamping, though not through internal
clamping diodes. The clamping effect is quite the same,
however, the output transistors are designed to work alter-
nately by sinking large current spikes.
SPiKe PROTECTION
The
peak-temperature stressing of the power transistor array.
The Safe Operating Area graph in the Typical Performance
Characteristics section shows the area of device operation
where SPiKe Protection Circuitry is not enabled. The wave-
form to the right of the SOA graph exemplifies how the dy-
namic protection will cause waveform distortion when en-
abled.
THERMAL PROTECTION
The LM4701 has a sophisticated thermal protection scheme
to prevent long-term thermal stress of the device. When the
temperature on the die reaches 165˚C, the LM4701 shuts
down. It starts operating again when the die temperature
drops to about 155˚C, but if the temperature again begins to
rise, shutdown will occur again at 165˚C. Therefore, the de-
vice is allowed to heat up to a relatively high temperature if
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LM4701
is
Supply Current vs
Case Temperature
Input Bias Current vs
Case Temperature
protected
from
instantaneous
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