Texas Instruments 1.5A High Efficiency Synchronous Switching Regulator LM2653-ADJEVAL LM2653-ADJEVAL Datenbogen
Produktcode
LM2653-ADJEVAL
User's Guide
SNVA012B – May 1999 – Revised April 2013
AN–1133 LM2653EVAL 1.5A Synchronous Switching
Regulator Evaluation Board
1
Introduction
The LM2653 switching regulator provides high efficiency power conversion over a 100:1 load range (1.5A
to 15 mA). This feature makes the LM2653 an ideal fit in battery-powered applications.
to 15 mA). This feature makes the LM2653 an ideal fit in battery-powered applications.
Synchronous rectification and 75 m
Ω
internal switches provide up to 97% efficiency. At light loads, the
LM2653 enters a low power hysteretic or “sleep” mode to keep the efficiency high. In many applications,
the efficiency still exceeds 80% at 15 mA load. A shutdown pin is available to disable the LM2653 and
reduce the supply current to 7 µA.
the efficiency still exceeds 80% at 15 mA load. A shutdown pin is available to disable the LM2653 and
reduce the supply current to 7 µA.
The IC contains patented current sensing circuitry for current mode control. This feature eliminates the
external current sensing required by other current-mode DC-DC converters.
external current sensing required by other current-mode DC-DC converters.
The IC has a 300kHz fixed frequency internal oscillator. The high oscillator frequency allows the use of
extremely small, low profile components.
extremely small, low profile components.
The evaluation board can be obtained by ordering part number LM2653EVAL from your local Texas
Instruments sales office, or TI's website at
Instruments sales office, or TI's website at
2
Evaluation Board Design
The evaluation board is designed to supply 2.5 V at up to 1.5A. The input voltage range is 4 V to 14 V.
Components were selected based on the design procedure in the LM2653 1.5A High Efficiency
Synchronous Switching Regulator Data Sheet (
Components were selected based on the design procedure in the LM2653 1.5A High Efficiency
Synchronous Switching Regulator Data Sheet (
). The feedback resistors can be adjusted to
achieve a different output voltage:
V
OUT
= 1.238 V x [1+ (R
1
/R
2
)]
(1)
Choose 1% resistors between 10 k
Ω
to 100 k
Ω
for R1 and R2.
PCB layout is critical to reduce noises and ensure specified performance. For layout guidelines, see the
LM2653 1.5A High Efficiency Synchronous Switching Regulator Data Sheet (
LM2653 1.5A High Efficiency Synchronous Switching Regulator Data Sheet (
). The artwork for
the evaluation board is shown at the end of this application report.
The schematic for the evaluation board is shown in
, and the parts list is given in
When the undervoltage protection occurs, the output voltage can be pulled below ground as the inductor
current is reversed through the synchronous FET. For applications that need to be protected from a
negative voltage, a clamping diode D2 is recommended.
current is reversed through the synchronous FET. For applications that need to be protected from a
negative voltage, a clamping diode D2 is recommended.
The PGOOD flag goes low whenever the overvoltage or undervoltage latch protection is enabled. The
overvoltage protection will be enabled immediately when the output voltage exceeds 110% of its nominal.
While the undervoltage latch protection will wait for a period of time set by the LDELAY capacitor. If the
output voltage is still below 80% of its nominal after this waiting period, the latch protection will be
enabled.
overvoltage protection will be enabled immediately when the output voltage exceeds 110% of its nominal.
While the undervoltage latch protection will wait for a period of time set by the LDELAY capacitor. If the
output voltage is still below 80% of its nominal after this waiting period, the latch protection will be
enabled.
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1
SNVA012B – May 1999 – Revised April 2013
AN–1133 LM2653EVAL 1.5A Synchronous Switching Regulator Evaluation
Board
Copyright © 1999–2013, Texas Instruments Incorporated