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PDF LM4901 Data sheet ( Hoja de datos )
| Número de pieza | LM4901 | |
| Descripción | 1.6 Watt Audio Power Amplifier | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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December 2002
LM4901
1.6 Watt Audio Power Amplifier with Selectable
Shutdown Logic Level
General Description
The LM4901 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 1 watt of continuous average power to an 8Ω BTL
load and 1.6 watts of continuous avearge power to a 4Ω BTL
load with less than 1% distortion (THD+N) from a 5VDC
power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4901 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption is a primary re-
quirement.
The LM4901 features a low-power consumption shutdown
mode. To facilitate this, Shutdown may be enabled by either
logic high or low depending on mode selection. Driving the
shutdown mode pin either high or low enables the shutdown
pin to be driven in a likewise manner to enable shutdown.
The LM4901 contains advanced pop & click circuitry which
eliminates noise which would otherwise occur during turn-on
and turn-off transitions.
The LM4901 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
j Improved PSRR at 217Hz & 1KHz
j Power Output at 5.0V, 1% THD, 4Ω
j Power Output at 5.0V, 1% THD, 8Ω
j Power Output at 3.0V, 1% THD, 4Ω
j Power Output at 3.0V, 1% THD, 8Ω
j Shutdown Current
62dB
1.6W (typ)
1.07W (typ)
525mW (typ)
390mW (typ)
0.1µA (typ)
Features
n Available in space-saving packages: LLP, micro SMD,
and MSOP
n Ultra low current shutdown mode
n BTL output can drive capacitive loads
n Improved pop & click circuitry eliminates noise during
turn-on and turn-off transitions
n 2.0 - 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
n Unity-gain stable
n External gain configuration capability
n User selectable shutdown High or Low logic Level
Applications
n Mobile Phones
n PDAs
n Portable electronic devices
Typical Application
20019801
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200198
www.national.com
http://www.Datasheet4U.com
1 page  
Electrical Characteristics VDD = 2.6V (Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for TA =
25˚C. (Continued)
Note 12: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The LM4901IBL demo board (views featured
in the Application Information section) has two inner layers, one for VDD and one for GND. The planes each measure 611mils x 661mils (15.52mm x 16.79mm)
and aid in spreading heat due to power dissipation within the IC.
Note 13: Maximum power dissipation in the device (PDMAX) occurs at an output power level significantly below full output power. PDMAX can be calculated using
Equation 1 shown in the Application Information section. It may also be obtained from the power dissipation graphs.
Note 14: The Exposed-DAP of the LDA10B package should be electrically connected to GND or an electrically isolated copper area. the LM4901LD demo board
(views featured in the Application Information section) has the Exposed-DAP connected to GND with a PCB area of 86.7mils x 585mils (2.02mm x 14.86mm) on
the copper top layer and 550mils x 710mils (13.97mm x 18.03mm) on the copper bottom layer.
Note 15: The thermal performance of the LLP package (LM4901LD) when used with the exposed-DAP connected to a thermal plane is sufficient for driving 4Ω
loads. The LM4901LD demo board (views featured in the Application Information section) can drive 4Ω loads at the maximum power dissipation point (1.267W)
without thermal shutdown circuitry being activated. The other available packages (MSOP & micro SMD) do not have the thermal performance necessary for driving
4Ω loads with a 5V supply and are not recommended for this application.
External Components Description
(Figure 1)
Components
1. Ri
2. Ci
3. Rf
4. CS
5. CB
Functional Description
Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a
high pass filter with Ci at fC= 1/(2π RiCi).
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
highpass filter with Ri at fc = 1/(2π RiCi). Refer to the section, Proper Selection of External Components,
for an explanation of how to determine the value of Ci.
Feedback resistance which sets the closed-loop gain in conjunction with Ri.
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
section for information concerning proper placement and selection of the supply bypass capacitor.
Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External
Components, for information concerning proper placement and selection of CB.
Typical Performance Characteristics
THD+N vs Frequency
at VDD = 5V, 8Ω RL, and PWR = 500mW
THD+N vs Frequency
at VDD = 3V, 8Ω RL, and PWR = 250mW
20019830
5
20019831
www.national.com
5 Page 
Typical Performance Characteristics (Continued)
Shutdown Hysteresis Voltage
3V, SD Mode = VDD (High)
Shutdown Hysteresis Voltage
3V, SD Mode = GND (Low)
200198A2
Shutdown Hysteresis Voltage
2.6V, SD Mode = VDD (High)
200198A3
Shutdown Hysteresis Voltage
2.6V, SD Mode = GND (Low)
200198A4
200198A5
11 www.national.com
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| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LM4901.PDF ] | |
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