LM4804LQX/NOPB National Semiconductor, LM4804LQX/NOPB Datasheet - Page 10

• Manufacturer Part Number: LM4804LQX/NOPB
• Description: IC AMP AUDIO PWR 1.9W MONO 28LLP
• Manufacturer: National Semiconductor
• Series: Boomer®r
• Type: Class ABr

Specifications of LM4804LQX/NOPB

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 1.9W x 1 @ 8 Ohm
• Voltage - Supply: 2.7 V ~ 6.1 V
• Features: Depop, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 28-LLP
• Operational Class: Class-AB
• Audio Amplifier Output Configuration: 1-Channel Mono
• Output Power (typ): 1.9x1@8OhmW
• Audio Amplifier Function: Speaker
• Total Harmonic Distortion: 0.13@8Ohm@1.5W%
• Single Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (typ): 3/5V
• Power Supply Requirement: Dual
• Power Dissipation: 1.8W
• Rail/rail I/o Type: No
• Power Supply Rejection Ratio: 72dB
• Single Supply Voltage (min): Not RequiredV
• Single Supply Voltage (max): Not RequiredV
• Dual Supply Voltage (min): 2.7/3V
• Dual Supply Voltage (max): 5/6.1V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 28
• Package Type: LLP EP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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Application Information
GATED OSCILLATOR CONTROL SCHEME
The on/off regulation mode of the LM4804, along with its
ultra-low quiescent current, results in good efficiency over a
very wide load range. The internal oscillator frequency can
be programmed using an external resistor to be constant or
vary with the battery voltage. Adding a capacitor to program
the frequency allows the designer to adjust the duty cycle
FIGURE 2. Functional Diagram of the LM4804’s Regulator
FIGURE 3. Typical Step-Up Regulator Waveforms
(Continued)
10
and optimize it for the application. Adding a resistor in addi-
tion to the capacitor allows the duty cycle to dynamically
compensate for changes to the input/output voltage ratio.
We call this a Ratio Adaptive Gated Oscillator circuit. Using
the correct RC components to adjust the oscillator allows the
part to run with low ripple and high efficiency over a wide
range of loads and input/output voltages.
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