Bill of materials

The following tables contain components needed to assemble the NTP clock driver. To overcome the PCB manufacturing cost, and reduce the board size, we employ many surface-mounted components into this module.

Designator	Value	Package	Quantity	Notes
R1, R11, R13, R15, R17, R23	22KΩ	SMD 0805	6
R2	0Ω	SMD 0805	1
R3, R4, R5, R6, R7, R8, R9	220Ω	SMD 0805	7
R10	2.2KΩ	SMD 0805	1
R12, R14, R16, R18, R26, R27	1KΩ	SMD 0805	6
R19, R20	4.7KΩ	SMD 0805	2
R21, R22	470Ω	SMD 0805	2
R24, R25	10KΩ	SMD 0805	2
R28	2.7KΩ	SMD 0805	1
R29, R30, R31, R32	49.9Ω	SMD 0805	4	Tolerance: 1%
C1, C2	15pF	SMD 0805	2
C3, C4	22pF	SMD 0805	2
C5	10µF / 10V	SMD 3216	1	SMD Tantalum Capacitor
C6, C7	18pF	SMD 0805	2
C8, C9	0.01µF	SMD 0805	2
C10	220µF/ 16V	THT	1
C11	470µF / 25V	THT	1
C12, C20	0.1µF	THT	2
C13, C14, C15, C16, C17, C18, C19, C21, C22, C23	0.1µF	SMD 0805	10
D1	SS14	SMD SMA	1
L1	10µH	SMD 0805	1
L2	33µH	SMD	1	10.4mm × 10.4mm Shielded Power Inductor
Y1	16.000MHz Crystal	HC49	1
Y2	12.000MHz Crystal	HC49	1
Y3	25.000MHz Crystal	HC49	1
J1	2.54mm, 8-pin header	THT (Vertical)	1
J2	2.54mm, 4-pin header	THT (Vertical)	1
J3	2.54mm, 2-rows × 4-pin header	THT (Vertical)	1
J4	Mini USB - Type B, 5-pin connector	SMD	1
J5	HR911105A	THT	1
J6	2.54mm 2-rows × 3-pin header	THT (Vertical)	1
J7	3.5mm, 2-pin screw terminal	THT (Vertical)	1
SW1	6mm angled tactile switch	THT	1	C&K PTS645VK392LFS
BT1	CR1220 battery holder	SMD	1	Harwin S8411-45R
	7.2V, 2.3-inch, red color, common anode, 7-segment display	THT	4	FJS23101BH or SA23-11EWA

Semiconductor components

This section contains a list of semiconductor components used in the NTP clock driver.

Reference designator	Value	Quantity	Package	Datasheet
Q1, Q3, Q5, Q7	BC817	4	SOT-23	https://assets.nexperia.com/documents/data-sheet/BC817_SER.pdf
Q2, Q4, Q6, Q8	BC858	4	SOT-23	https://assets.nexperia.com/documents/data-sheet/BC856_BC857_BC858.pdf
U1	ATmega328P	1	TQFP-32	https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf
U2	ULN2803A	1	SOIC-18W	https://www.st.com/resource/en/datasheet/uln2804a.pdf
U3	DS3231M	1	SOIC-16W	https://datasheets.maximintegrated.com/en/ds/DS3231M.pdf
U4	PCF8574	1	SOIC-16W	https://www.nxp.com/docs/en/data-sheet/PCF8574_PCF8574A.pdf
U5	CH340G	1	SOIC-16	https://datasheet.lcsc.com/lcsc/2008191806_WCH-Jiangsu-Qin-Heng-CH340G_C14267.pdf
U6	ENC28J60-I/SS	1	SSOP-28	https://ww1.microchip.com/downloads/en/DeviceDoc/39662e.pdf
U7	L7808	1	TO-252-3	https://www.st.com/resource/en/datasheet/l78.pdf
U8	LM1117-3.3	1	SOT-223-3	https://www.onsemi.com/pdf/datasheet/lm1117-d.pdf
U9	LM2596S-5	1	TO-263-5	https://www.ti.com/lit/gpn/LM2596