Datasheet
I
CIN(RMS)
= 12A
0.5 x 0.5 = 6A
D =
V
OUT
V
IN
I
CIN(RMS)
= I
OUT
D(1 - D)
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Bill of Materials
5 Bill of Materials
The Bill of Materials is shown below, including the manufacturer and part number.
Table 2. Bill of Materials
ID DESCRIPTION VENDOR PART NUMBER QUANTITY
AC INJ Header, TH, 100mil, 2x1, Gold Samtec Inc. TSW-102-07-G-S 1
plated, 230 mil above insulator
C1 CAP, CERM, 1 uF, 10V, +/-10%, MuRata GRM188R71A105KA61D 1
X7R, 0603
C3, C4, C5, C6, CAP, CERM, 100 uF, 6.3V, +/- MuRata GRM31CR60J107ME39L 6
C7, C8 20%, X5R, 1206
C9 CAP, CERM, 0.1 uF, 50V, +/- TDK C1608X7R1H104K 1
10%, X7R, 0603
C
C1
CAP, CERM, 2700 pF, 50V, +/- MuRata GRM1885C1H272JA01D 1
5%, C0G/NP0, 0603
C
C2
CAP, CERM, 82 pF, 50V, +/-5%, MuRata GRM1885C1H820JA01D 1
C0G/NP0, 0603
C
C3
CAP, CERM, 820 pF, 50V, +/-5%, MuRata GRM1885C1H821JA01D 1
C0G/NP0, 0603
C
SS
CAP, CERM, 0.033 uF, 16V, +/- MuRata GRM188R71C333KA01D 1
10%, X7R, 0603
GND_FI, GND_FO, Standard Banana Jack, Johnson 108-0740-001 4
VIN_F, VOUT_F Uninsulated, 15A Components
L1 Inductor, Shielded Drum Core, Vishay-Dale IHLP4040DZERR56M01 1
Powdered Iron, 560nH, 27.5A,
0.0018 ohm, SMD
R1 RES, 1.0 ohm, 5%, 0.1W, 0603 Vishay-Dale CRCW06031R00JNEA 1
R
AC
RES, 49.9 ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060349R9FKEA 1
R
C1
RES, 7.32 kohm, 1%, 0.1W, 0603 Vishay-Dale CRCW06037K32FKEA 1
R
C2
RES, 165 ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW0603165RFKEA 1
R
FB1
, R
FB2
, R
PG
RES, 10 kohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060310K0JKEA 3
SH-J1 Shunt, 100mil, Gold plated, Black Samtec Inc. SNT-100-BK-G 1
U1 12A Buck DC/DC Converter Texas LM21212-1 1
Instruments
6 Component Selection
This section provides a walk-through of the design process of the LM21212-1 evaluation board. Unless
otherwise indicated all equations assume units of amps (A) for current, farads (F) for capacitance, henries
(H) for inductance, and volts (V) for voltages.
6.1 Input Capacitors: C1, C2, C3
The required RMS current rating of the input capacitor for a buck regulator can be estimated by the
following equation:
(1)
The variable D refers to the duty cycle, and can be approximated by:
(2)
From this equation, it follows that the maximum I
CIN(RMS)
requirement will occur at a full 12A load current
with the system operating at 50% duty cycle. Under this condition, the maximum I
CIN(RMS)
is given by:
(3)
7
SNVA467B–February 2011–Revised May 2013 AN-2107 LM21212-1 Evaluation Board
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