Datasheet

PVIN
AVIN
EN
AGND PGND
FB
SW
LM2854MHX-1000
VIN
VOUT
SS
Cin2
Lf
Co2
Rfb1
Rc
Cc
Rfb2
Css
Cf
Rf
U1
Cin
Ren
GND
GND
+
Co
+
1.2V, 4A
2.95V ± 5.5V
12,13
16
15
14
1,2,3,
4,8,9
10
11
5,6,7
LM2854 Demo Board Details www.ti.com
2 LM2854 Demo Board Details
This application solution relates to the bill of materials shown in Section 6 and references the schematic
diagram in Figure 2. The board contains the LM2854MHX-1000 buck regulator IC with nominal switching
frequency, f
SW
, of 1MHz.
Figure 2. LM2854 Demo Board Schematic Diagram
3 Quick Step Procedure
Step 1: Set the power supply current limit to 3A. Turn off the power supply. Connect the power supply to
the VIN and GND terminals.
Step 2: Connect the load with a 4A capability to the VOUT and GND terminals.
Step 3: The EN terminal can be left open for normal operation as there is an on-board pull-up resistor.
Step 4: Set V
IN
to 3.0V with no load applied. V
OUT
should be in regulation with a nominal 1.2V output.
Step 5: Slowly increase the load while monitoring the output voltage. V
OUT
should remain in regulation with
a nominal 1.2V output as the load is increased up to 4A.
Step 6: Slowly sweep the input voltage from 2.95V to 5.5V. V
OUT
should remain in regulation with a
nominal 1.2V output.
Step 7: Temporarily short the EN terminal to GND to check the shutdown function.
Step 8: Increase the load beyond the normal range to check current limit. The output current should limit
at approximately 5.6A. Short the VOUT and GND terminals to verify short circuit protection.
2
AN-1880 LM2854 1MHz Buck Regulator Demo Board SNVA358B–August 2008–Revised May 2013
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