Datasheet

Evaluation Board Bill of Materials (BOM)

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4 Evaluation Board Bill of Materials (BOM)

Table 1. Board Bill of Materials (BOM)

Component Description Manufacturer Manufacturer Part Number Package

C1 CERAMIC 100 pF 25V NPO AVX 06033A101KAT2A 0603

C2,C7 CERAMIC 0.1 µF 16V X7R TDK C1608X7R1C104M 0603

C3,C4 CERAMIC 1.0 µF 25V X7R TDK C1608X7R1E105M 0603

C5 N/A N/A N/A N/A

C6 CERAMIC 4.7 nF 50V X7R TDK C1608X7R1H472J 0603

C8 CERAMIC 1.0 µF 25V X7R TDK C3216X7R1E105K 1206

C9, C10 CERAMIC 10 µF 25V X5R TDK C3225X5R1E106K 1210

C11, C12 CERAMIC 47 µF 10V X5R TDK C3225X5R1A476M 1210

C13 TANT 47 µF 25V Kemet T495X476K025ATE150 CASE D

C14, C15 N/A N/A N/A N/A

D1 N/A N/A N/A N/A

L1 3.3 µH 9.0A SMD Wurth Electronics 744314330 SMD

LD1 LED GREEN CML CMDA5CG7D1Z 0805

R3, R6 10 kΩ 0603 1% Yageo RC0603FR-710KL 0603

R2 249Ω 0603 1% Yageo RC0603FR-07249RL 0603

R1, R4 100 kΩ 0603 1% Yageo RC0603FR-07100KL 0603

R5 45.3 kΩ 0603 1% Yageo RC0603FR-0745K3L 0603

R7 7.15 kΩ 0603 1% Yageo RC0603FR-077K15RL 0603

R8 1Ω 0603 1% Yageo RC0603FR-071RL 0603

U1 LM21305 Buck Regulator Texas Instruments LM21305 WQFN-28

U2 IC BUFF NON-INV Fairchild NC7SZ125M5X SOT23-5

5 Connection Descriptions

Terminal

Description

Silkscreen

PVIN Connect the power supply between this terminal and the GND terminal beside it. The device is rated

between 3V to 18V. The absolute maximum voltage rating is 20V.

GND The GND terminals are meant to provide a close return path to the power and signal terminal beside them.

They are all connected together on the board.

SW The SW terminal is connected to the switch node of the power stage. It can be used to monitor the switch

node waveform using an oscilloscope.

VOUT The VOUT terminal is connected to the output capacitor on the board and should be connected to the load.

AVIN_EXT The LM21305 evaluation board facilitates using a separate supply voltage to AVIN via JP1 selection and

connection to the AVIN_EXT terminal. An AVIN voltage of 5V will result in optimal efficiency in most cases.

EN This terminal connects to the EN pin of the device. The EN is pulled up to AVIN via a 10 kΩ resistor on the

board. It also can be externally controlled through this terminal. If driven externally, a voltage typically

greater than 1.2V will enable the device.

PGOOD This terminal connects to the Power Good output of the device. There is a 100 kΩ pull-up resistor from this

pin to the 2V5 bias rail.

AN-2042 LM21305 Evaluation Board SNVA432C–March 2010–Revised May 2013

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