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Precision clock
Alan-JH/precision-clockECE 362 Final Project
- Size
- 500 × 34 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 150
- Nets
- 169
- Pads
- 714
- Tracks, vias
- 2,606, 318
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 6 Nov 2025
- Updated
- 3 Dec 2025
Overview
Precision clock is an open-source printed circuit board by Alan-JH, from the Alan-JH/precision-clock repository on GitHub. It is a 4-layer board of 500 × 34 mm with 150 parts on 169 nets, routed with 2,606 tracks and 318 vias.
It is built around the SN74ABT244ADW, W25Q128JVSIQ and CD74HCT238M96, with the DS3232MZ+, USBLC6-2P6 and SC10-21SURKWA among its other parts. Its parts include 56 resistors, 33 capacitors, 16 transistors, 10 ICs and 5 diodes. It belongs with the lEDs and displays boards and the RP2350 boards of this library.
Main components
11
SN74ABT244ADW
SOIC-20-300mil-40℃~+85℃ 2 250uA 32mA 4 4.5V~5.5V 4.6ns@5V,50pF 64mA ABT Output enable Tri-State Unidirectional SOIC-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSTexas InstrumentsBuffer/Driver/Transceiver
W25Q128JVSIQ
SOIC-8-208mil-40℃~+85℃ 100,000 cycles 120ms@(32KB) 128Mbit 133MHz 1uA 2.7V~3.6V 20 Years 3ms Power-on reset、Hardware write protection、Software write protection、Write enable latch、Absolute write protection SPI SOIC-8-208mil NOR FLASH ROHSWinbondNOR FLASH
CD74HCT238M96
SOP-16-55℃~+125℃ 160uA 3/8 4.5V~5.5V 4mA 4mA 53ns@4.5V,50pF 74HCT Decoder Single Supply SOP-16 Signal Switches, Multiplexers, Decoders ROHSTexas InstrumentsSignal Switches, Multiplexers, Decoders
DS3232MZ+
SO-8-40℃~+85℃ 100nA 125uA 2.3V~4.5V Built-in I2C Temperature compensation、Backup power management and battery charging、InsideSRAM/NVRAM、Alarm function、Periodic interrupt output Yes SO-8 Real Time Clocks ROHSMaxim Integrated (Analog Devices)Real Time Clocks
USBLC6-2P6
SOT-666-6-40℃~+125℃ 150nA 17V 2 3.5pF 5.25V 5A@8/20us 6V ESD IEC 61000-4-2 Unidirectional SOT-666-6 ESD and Surge Protection (TVS/ESD) ROHSSTMicroelectronicsESD And Surge Protection (TVS/ESD)
SC10-21SURKWA
DIP-101 1 34mmx24mmx10.5mm 7 Segment 75mW Common Cathode Red DIP-10 LED Segment Displays ROHSKingbrightLED Segment Displays
BSS138
SOT-23-55℃~+150℃ 1 N-channel 1.1Ω@10V、1.2Ω@4.5V 1.2V 1.7nC@10V 17.5pF 340mA 350mW 50V 6.5pF N-Channel SOT-23 MOSFETs ROHShongjiachengMOSFETs
SFH 320-Z
LCC-2-40℃~+100℃ 15mA 165mW 35V 50nA 980nm LCC-2 Phototransistors ROHSOSRAM Opto SemiconPhototransistors
ABM8-272-T3
SMD3225-4P-40℃~+85℃ 10pF 12MHz 50Ω SMD crystal oscillator ±30ppm ±30ppm SMD3225-4P Crystals ROHSAbraconCrystalsBSS83P
SOT-23MOSFETsTECH PUBLIC
CR1220-2
--40~80℃ Battery base CR1220 Phosphor bronze - Battery holder base ROHSQ&JButton And Strip Battery Connector
README
README.mdprecision-clock
ECE 362 Final Project
Parts
150| Qty | Value | Footprint | References |
|---|---|---|---|
| 22 | 100nF | Capacitor_SMD:C_0402_1005Metric | C3, C10, C11, C12, C13, C14, C15, C16, C22, C23, C24, C25, C26, C28, C30, C31 +6 |
| 19 | SC10-21SURKWA | Display_Custom:SC10-21SURKWA | DS1, DS2, DS3, DS4, DS5, DS6, DS10, DS11, DS12, DS13, DS14, DS15, DS16, DS17, DS18, DS19 +3 |
| 16 | 47R | Resistor_SMD:R_0402_1005Metric | R32, R33, R41, R42, R43, R44, R45, R46, R47, R48, R49, R50, R51, R52, R53, R54 |
| 14 | 100K | Resistor_SMD:R_0402_1005Metric | R23, R26, R27, R28, R29, R30, R31, R34, R35, R36, R37, R38, R39, R40 |
| 13 | BSS138 | Package_TO_SOT_SMD:SOT-23 | Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, Q16 |
| 9 | 1K | Resistor_SMD:R_0402_1005Metric | R6, R11, R12, R13, R14, R15, R16, R17, R21 |
| 4 | 100R | Resistor_SMD:R_0402_1005Metric | R7, R8, R9, R10 |
| 4 | REDDOT | LED_THT:LED_D3.0mm | D2, D3, D4, D5 |
| 3 | 10uF | Capacitor_SMD:C_0805_2012Metric | C1, C2, C6 |
| 2 | 10K | Resistor_SMD:R_0402_1005Metric | R19, R20 |
| 2 | 120R | Resistor_SMD:R_0402_1005Metric | R55, R56 |
| 2 | 15pF | Capacitor_SMD:C_0402_1005Metric | C20, C21 |
| 2 | 1uF | Capacitor_SMD:C_0603_1608Metric | C27, C29 |
| 2 | 27 | Resistor_SMD:R_0402_1005Metric | R4, R5 |
| 2 | 4.7K | Resistor_SMD:R_0402_1005Metric | R24, R25 |
| 2 | 4.7uF | Capacitor_SMD:C_0402_1005Metric | C4, C17 |
| 2 | 4.7uF | RP2350_80QFN_minimal:C_0402_1005Metric_small_pads | C18, C19 |
| 2 | 5.1K | Resistor_SMD:R_0402_1005Metric | R1, R2 |
| 2 | BUTTON | Button_Switch_SMD:SW_SPST_PTS647_Sx38 | SW3, SW4 |
| 2 | CD74HCT238M96 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U7, U10 |
| 2 | SFH320 | LED_SMD:LED_PLCC-2_3.4x3.0mm_KA | Q1, Q2 |
| 2 | SN74ABT244ADW | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U8, U9 |
| 1 | 0R | Resistor_SMD:R_0402_1005Metric | R18 |
| 1 | 1M | Resistor_SMD:R_0402_1005Metric | R22 |
| 1 | 3.3uH | RP2350_80QFN_minimal:L_pol_2016 | L1 |
| 1 | 33 | Resistor_SMD:R_0402_1005Metric | R3 |
| 1 | ABM8-272-T3 | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | ANT | Connector_Coaxial:MMCX_Molex_73415-1471_Vertical | J3 |
| 1 | BOOTSEL | Button_Switch_SMD:SW_SPST_PTS647_Sx38 | SW1 |
| 1 | BSS83P | Package_TO_SOT_SMD:SOT-23 | Q3 |
| 1 | CR1220 | Battery_Custom:BAT_2895 | BT1 |
| 1 | DS3232M | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U6 |
| 1 | LED | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | NCP1117-3.3_SOT223 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U1 |
| 1 | PA1616S | PA1616S:PA1616S | U5 |
| 1 | RESET | Button_Switch_SMD:SW_SPST_PTS647_Sx38 | SW2 |
| 1 | RP2350_80QFN | RP2350_80QFN_minimal:RP2350-QFN-80-1EP_10x10_P0.4mm_EP3.4x3.4mm_ThermalVias | U4 |
| 1 | TC2050 | Connector:Tag-Connect_TC2050-IDC-FP_2x05_P1.27mm_Vertical | J2 |
| 1 | TestPoint | TestPoint:TestPoint_Pad_2.0x2.0mm | TP1 |
| 1 | USBLC6-2P6 | Package_TO_SOT_SMD:SOT-666 | U2 |
| 1 | USB_C_Receptacle_USB2.0_14P | Connector_USB:USB_C_Receptacle_G-Switch_GT-USB-7010ASV | J1 |
| 1 | W25Q128JVS | Package_SO:SOIC-8_5.3x5.3mm_P1.27mm | U3 |
Questions
How big is the Precision clock PCB?
It measures 500 × 34 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Precision clock use?
150 parts, built around the SN74ABT244ADW, W25Q128JVSIQ, CD74HCT238M96 and DS3232MZ+. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Precision clock KiCad files?
From the Alan-JH/precision-clock repository on GitHub, at the commit this page was made from: the board is precision-clock-pcb/precision-clock.kicad_pcb and its schematic precision-clock-pcb/display.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Precision clock design in my own project?
Its repository states no licence, so its author keeps all rights: ask Alan-JH before reusing the design.
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