LM4961LQBD/NOPB National Semiconductor, LM4961LQBD/NOPB Datasheet - Page 9

• Manufacturer Part Number: LM4961LQBD/NOPB
• Manufacturer: National Semiconductor

Specifications of LM4961LQBD/NOPB

• Lead Free Status / Rohs Status: Compliant

(V
in ringer mode. This enables the boost converter and sets the
externally configurable closed loop gain selection to BW1. If
the Band-SW pin has a logic low (GND) applied to its terminal
then the device is in receiver mode. In this mode the boost
converter is disabled and the gain selection is switched to
BW2. This allows the amplifier to be powered directly from the
battery minus the voltage drop across the Schottky diode.
PROPER SELECTION OF EXTERNAL COMPONENTS
Proper selection of external components in applications using
integrated power amplifiers, and switching DC-DC convert-
ers, is critical for optimizing device and system performance.
Consideration to component values must be used to maxi-
mize overall system quality.
The best capacitors for use with the switching converter por-
tion of the LM4961 are multi-layer ceramic capacitors. They
have the lowest ESR (equivalent series resistance) and high-
DD
) is applied to the Band-SW pin (pin 19) the amplifier is
FIGURE 2. Transient Current Spike Reduction Configuration
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REDUCING TRANSIENT CURRENT SPIKE
Due to the quick turn-on time of the Boost Converter, a tran-
sient supply current spike is observed on shutdown release.
To reduce the rise time of the output voltage (V
ducing the value of the supply current spike, please refer to
application circuit in Figure 2. Using this configuration will al-
low the user to reduce the transient supply current spike
without the Boost Converter experiencing any stability issues.
est resonance frequency, which makes them optimum for
high frequency switching converters.
When selecting a ceramic capacitor, only X5R and X7R di-
electric types should be used. Other types such as Z5U and
Y5F have such severe loss of capacitance due to effects of
temperature variation and applied voltage, they may provide
as little as 20% of rated capacitance in many typical applica-
tions. Always consult capacitor manufacturer’s data curves
before selecting a capacitor. High-quality ceramic capacitors
can be obtained from Taiyo-Yuden.
200940a3
www.national.com
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), thus re-