Features
| • | Switching frequency from 50 kHz to 1 MHz |
| • | Switching frequency synchronize range 250 kHz to 1 MHz (LM2745 Only) |
| • | Startup with a pre-biased output load |
| • | Power stage input voltage from 1V to 14V |
| • | Control stage input voltage from 3V to 6V |
| • | Output voltage adjustable down to 0.6V |
| • | Power Good flag and shutdown |
| • | Output overvoltage and undervoltage detection |
| • | ±1.5% feedback voltage accuracy over temperature |
| • | Low-side adjustable current sensing |
| • | Adjustable soft-start |
| • | Tracking and sequencing with shutdown and soft start pins |
| • | TSSOP-14 package |
Description The LM2745/8 are high-speed synchronous buck regulator controllers with an accurate feedback voltage accuracy of ±1.5%. It
can provide simple down conversion to output voltages as low as 0.6V. Though the control sections of the IC are rated for
3 to 6V, the driver sections are designed to accept input supply rails as high as 14V. The use of adaptive non-overlapping
MOSFET gate drivers helps avoid potential shoot-through problems while maintaining high efficiency. The IC is designed for
the more cost-effective option of driving only N-channel MOSFETs in both the high-side and low-side positions. It senses the
low-side switch voltage drop for providing a simple, adjustable current limit.
The LM2745/8 features a fixed-frequency voltage-mode PWM control architecture which is adjustable from 50 kHz to 1 MHz with
one external resistor. In addition, the LM2745 also allows the switching frequency to be synchronized to an external clock
signal over the range of 250 kHz to 1 MHz. This wide range of switching frequency gives the power supply designer the flexibility
to make better tradeoffs between component size, cost and efficiency.
Features include the ability to startup with a pre-biased load on the output, soft-start, input undervoltage lockout (UVLO)
and Power Good (based on both undervoltage and overvoltage detection). In addition, the shutdown pin of the IC can be used
for providing startup delay, and the soft-start pin can be used for implementing precise tracking, for the purpose of sequencing
with respect to an external rail.
Applications
| • | Down Conversion from 3.3V |
| • | Cable Modem, DSL and ADSL |
| • | Laser Jet and Ink Jet Printers |
| • | Low Voltage Power Modules |
| • | DSP, ASIC, Core and I/O |
|
Also Recommended
| LM2743▲ | Synchronous Buck Controller With Tracking And Soft-Start |
| LM2745▲ | Frequency Synchronization |
| LM2747▲ | Frequency Synchronization, Starts Up Into Pre-biased Loads, +/-1% Accuracy |
| LM3743▲ | Low-Voltage Synchronous Buck Controller In MSOP-10 |
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LM2748
LM2743
