LM3205TLEV National Semiconductor, LM3205TLEV Datasheet - Page 11

• Manufacturer Part Number: LM3205TLEV
• Description: BOARD EVALUATION LM3205TL
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3205TLEV

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 0.8 ~ 3.6V
• Current - Output: 650mA
• Voltage - Input: 2.7 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 2MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM3205
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -

Block Diagram
Operation Description
The LM3205 is a simple, step-down DC-DC converter opti-
mized for powering RF power amplifiers (PAs) in mobile
phones, portable communicators, and similar battery pow-
ered RF devices. It is designed to allow the RF PA to operate
at maximum efficiency over a wide range of power levels from
a single Li-Ion battery cell. It is based on a current-mode buck
architecture, with synchronous rectification for high efficiency.
It is designed for a maximum load capability of 650mA in PWM
mode.
Maximum load range may vary from this depending on input
voltage, output voltage and the inductor chosen.
Efficiency is typically around 96% for a 400mA load with 3.4V
output, 4.2V input. The output voltage is dynamically pro-
grammable from 0.8V (typ.) to 3.6V (typ.) by adjusting the
voltage on the control pin without the need for external feed-
back resistors. This ensures longer battery life by being able
to change the PA supply voltage dynamically depending on
its transmitting power.
FIGURE 2. Functional Block Diagram
11
Additional features include current overload protection and
thermal overload shutdown.
The LM3205 is constructed using a chip-scale 8-pin microS-
MD or 10-pin LLP package. These packages offers the small-
est possible size, for space-critical applications such as cell
phones, where board area is an important design considera-
tion. Use of a high switching frequency (2MHz) reduces the
size of external components. As shown in Figure 1, only three
external power components are required for implementation.
Use of a microSMD package requires special design consid-
erations for implementation. (See microSMD Package As-
sembly and use in the Applications Information section.) Its
fine bump-pitch requires careful board design and precision
assembly equipment. Use of this package is best suited for
opaque-case applications, where its edges are not subject to
high-intensity ambient red or infrared light. Also, the system
controller should set EN low during power-up and other low
supply voltage conditions. (See Shutdown Mode in the Device
Information section.)
20158035
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