Solution

Solar Night Light LSNL001

Indoor solar night light solution based on LS6821 low-light energy harvesting IC. Charges during the day using indoor light, automatically turns on via PIR motion sensing at night, and delays turning off after the person leaves. Minimal external circuitry, ultra-low power, permanently maintenance-free.

Indoor light charging PIR motion sensing Programmable delay off <500nA storage power

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Solution Overview

The Lingsi solar night light solution charges during the day using indoor light, automatically lights up when someone passes by at night via motion sensing, and delays turning off after the person leaves the sensing area.

Key Features

• Indoor light charging, no external power needed
• Programmable light-off delay
• Programmable light/dark threshold
• Programmable storage/shipping mode
• Minimal external circuit, only 8 BOM components

Solution Framework

PV Cell → LS6821 Energy Management → PIR motion detection → LED Lighting

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PV Cell

Indoor/sunlight converted to electricity by PV cell, input to LS6821 VSI pin

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LS6821 Energy Management

Charge/discharge management, storage mode detection, system power control, integrated PIR sensor signal processing

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PIR Sensor

Detects human motion, triggers light. Standby only 12.19µA, ultra-low power

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LED Lighting

2 warm-white LEDs (3000K), controlled by LS6821 for on/off and delay

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Li Battery Storage

Charges via indoor light during the day, discharges to drive PIR and LED at night, energy self-sufficient

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LDO Regulator

LR8103A-T33 fixed 3.3V output, providing stable power for PIR sensor

State Machine

4 operating states, smart switching, optimized power consumption

SM0 Storage/Shipping Mode <500 nA

After assembly and first power-on, enters this mode during extended darkness (e.g. in packaging). Only entered once.

Power source: LS6821 self-consumption

SM1 Charging Mode 2-5 µA

After exiting SM0, enters this mode immediately when charging conditions are met (light available, battery chargeable).

Power source: LS6821 self-consumption

SM2 Sensing Mode 13.56 µA

When light is insufficient and sensing conditions are met, the system starts detecting human motion.

Power source: LS6821 + LDO + PIR (PIR 12.19µA)

SM3 Lighting Mode 1.43 mA

When human motion is detected, LED lighting turns on immediately. Delays turning off after the person leaves.

Power source: LS6821 + LDO + PIR + LED

State transition conditions

→ SM0 → SM1: Light detected after first power-on
→ SM1 → SM2: No PV light + sensing conditions met
→ SM2 → SM3: Human motion detected
→ SM3 → SM2: No motion for 10 seconds
→ SM1/SM2 → SM0: PV CELL no light for extended time
→ SM2 → SM1: PV CELL has light

Performance Data

Charge condition - battery voltage4.1 V

Charge condition - charge current30 µA

Load current1.4 mA (3.3V)

Light duration10 min

Light energy consumed821.3 µWh

Recharge time neededApprox. 6.68 hours

Energy Balance Analysis

Under 3.3V load 1.4mA, light 10 min usage scenario, battery consumption approx. 821.3 µWh. If using indoor light at 30 µA to recharge, approximately 6.68 hours, meaning approximately 7 hours of daytime indoor light can replenish 10 minutes of nighttime lighting energy, achieving energy self-sufficiency.

BOM Component List

Minimal external circuit, only 8 components, extremely low total BOM cost

Component	Qty	Description
LS6821-C	1	Lingsi charge/discharge management + sensor signal processing
LR8103A-T33	1	Langrui LDO, fixed 3.3V output
XYC-PIR223W-S0	1	Xinyongcheng pyroelectric PIR sensor
XL-4008WWC	2	Chengxingguang LED, 3000K (warm white)
10µF (0805)	3	Capacitor
1µF (0603)	2	Capacitor
680KΩ (0603)	1	Resistor
1KΩ (0603)	2	Resistor

Solution: LSNL001 | Document version: R01 | Updated: 2025-11-24