Last Updated on March 16, 2024
USB Rechargeable LED circuit designed for longer glowing time. This circuit has USB C Receptacle hence we can charge this circuit battery easily. LiPo (Lithium polymer) 3.7V, 500mAH battery used in this prototype circuit, you can use lower current rating Li-Po battery also. We can directly remove and connect LiPo battery with this circuit through JST connector.
This USB Rechargeable LED circuit has three white LEDs, due to the low power LEDs consumption this circuit gives longer duration glowing time. Hence it can be used as Rechargeable LED mini emergency light circuit.
Circuit Diagram
Components Required (BOM)
| 1 | C1, C2, C3 | 4.7µF | C_0805_2012Metric | 3 | ||
| 2 | C4 | 2.2µF | C_0805_2012Metric | 1 | ||
| 3 | R4, R5 | 5.1KΩ | R_0805_2012Metric | 2 | ||
| 4 | R1 | 2KΩ | R_0805_2012Metric | 1 | ||
| 5 | R2 | 470Ω | R_0805_2012Metric | 1 | ||
| 6 | R3 | 1.5KΩ | R_0805_2012Metric | 1 | ||
| 7 | L1 | 6.8µH | L_6.3×6.3_H3 | 1 | ||
| 8 | D8 | 1N4007 | D_1206_3216Metric | 1 | ||
| 9 | D3 | ZHCS400TA | D_SOD-323 | 1 | ||
| 10 | D2 | LED-G | LED_0805_2012Metric | 1 | ||
| 11 | D4, D5, D6 | LED | LED_1206_3216Metric_Castellated | 3 | ||
| 12 | U1 | MCP73831-2-OT | SOT-23-5 | 1 | ||
| 13 | U2 | LT1932 | SOT-23-6 | 1 | ||
| 14 | BT1 | 3.7v 500mah li-po | JST_EH_B02B-EH-A_1x02_P2.50mm_Vertical | 1 | ||
| 15 | S1 | JS102011SAQN | SW_JS102011SAQN | 1 | ||
| 16 | J1 | 105450-0101 | MOLEX_105450-0101 | 1 |
Construction & Working
This circuit has Regulator & charger section, then battery and then LED driver section. Power supply is taken from the USB C connector VBus and GND terminals and then IC MCP73831/2 miniature single cell fully integrated li-Ion, li-Polymer charge management controller Regulates the power supply and gives output voltage as 4V and output current as 500mA, you can program this IC to give different range of output current by changing Resistor value at PROG pin, refer data sheet for more details.
A slide switch S1 (SPDT SMD) connects battery with LED driver circuit section. Through this switch power supply flows to the LED driver IC LT1932, it is a constant current DC / DC LED driver in thin SOT package. It drives the output white LED devices. If you need high luminance then choose high power white LEDs, don’t forget to change the footprint in PCB files and bill of materials.
Printed Circuit Board (PCB)
USB Rechargeable LED Circuit PCB Gerber files.
Interactive Board Viewer
