Texas Instruments LM22672 1A SIMPLE SWITCHER Regulator LM22672EVAL/NOPB LM22672EVAL/NOPB Datenbogen
Produktcode
LM22672EVAL/NOPB
LM22672-ADJ
+
GND
+
VIN
EN
SW
BOOT
FB
GND
RT/SYNC
VIN 4.5V to 42V
C2
22
P
F
C1
2.2
2.2
P
F
EN
SYNC
R3*
C3
10 nF
10 nF
L1
22
P
H
C4
120
P
F
C5*
GND
R2
1.54 k
1.54 k
:
R1
976
:
D1
60V, 1A
VOUT 3.3V
*component not populated on LM22672EVAL evaluation board
C6
1
1
P
F
SS
Evaluation Board Setup
Figure 1. Evaluation Board Schematic
2
Evaluation Board Setup
Before applying power to the LM22672 evaluation board, all external connections should be verified. The
external power supply must be turned off and connected with proper polarity to the VIN and GND posts. A
load resistor or electronic load should be connected between the VOUT and GND posts as desired. Both
the VIN and VOUT connections should use the closest GND posts respective to VIN or VOUT. The output
voltage can be monitored with a multi-meter or oscilloscope at the VOUT post.
external power supply must be turned off and connected with proper polarity to the VIN and GND posts. A
load resistor or electronic load should be connected between the VOUT and GND posts as desired. Both
the VIN and VOUT connections should use the closest GND posts respective to VIN or VOUT. The output
voltage can be monitored with a multi-meter or oscilloscope at the VOUT post.
Once all connections to the evaluation board have been verified, input power can be applied. A load
resistor or electronic load does not require connection during startup. If the EN test point is left floating,
the output voltage will ramp up when an input voltage is applied. Make sure that the external power supply
(input voltage power source) is capable of providing enough current so that the adjusted output voltage
can be obtained. Keep in mind that the startup current will be greater than the steady state current.
resistor or electronic load does not require connection during startup. If the EN test point is left floating,
the output voltage will ramp up when an input voltage is applied. Make sure that the external power supply
(input voltage power source) is capable of providing enough current so that the adjusted output voltage
can be obtained. Keep in mind that the startup current will be greater than the steady state current.
3
Synchronization and Adjustable Frequency
A SYNC test point is provided to allow synchronization of the LM22672 to an external clock signal. Space
for a frequency adjust resistor, R3, is also provided. Refer to the LM22672 datasheet (
for a frequency adjust resistor, R3, is also provided. Refer to the LM22672 datasheet (
) for more
details about the synchronizing and adjustable frequency features.
4
Precision Enable
The EN test point provided on the LM22672 evaluation board can be used to shut down the LM22672
when connecting this test point to ground.
when connecting this test point to ground.
5
Soft-Start
The capacitor C6 sets the amount of soft-start. A 1 µF soft-start capacitor is used for slow start-up. See
the LM22672 datasheet (
the LM22672 datasheet (
) for details about the soft-start function.
2
AN-1896 LM22672 Evaluation Board
SNVA369D – September 2008 – Revised April 2013
Copyright © 2008–2013, Texas Instruments Incorporated