LP4054
Standalone linear Li-ion battery charger with 800mA programmable charge current and safety features
Product Overview
Description
The LP4054 is a complete constant-current/constant-voltage linear charger for single-cell Li-ion and Li-Polymer batteries. It requires minimal external components - only a single external resistor is needed to set the charge current. The device can deliver up to 800mA charge current.
The charger operates from a 4.5V to 6.5V input and provides a regulated 4.2V charge voltage with ±1% accuracy. It automatically pre-conditions deeply discharged batteries with a trickle charge, then transitions to fast charge, and finally to constant-voltage mode. Charge termination occurs when charge current drops to 1/10 of the programmed value.
The LP4054 includes safety features such as thermal regulation, reverse current protection, and charge status indicator. When input power is removed, the device automatically enters low-power sleep mode with less than 2μA battery drain. Available in a compact SOT-23-5 package, it is ideal for portable electronics.
Product Series
LP
Primary Application
Portable media players
Key Features
- Complete standalone charger
- Up to 800mA programmable charge current
- ±1% charge voltage accuracy
- Automatic trickle, fast, and CV charging
- C/10 charge termination
- Thermal regulation protection
- Low <2μA sleep mode current
- Charge status indicator output
Specifications
| Input Voltage Range | 4.5V - 6.5V |
|---|---|
| Charge Voltage | 4.2V (±1% accuracy) |
| Charge Current | Up to 800mA (programmable) |
| Trickle Charge Current | 10% of fast charge |
| Charge Termination | C/10 threshold |
| Sleep Mode Current | <2μA |
| Thermal Regulation | 120°C junction temperature |
| Charge Status Output | Open-drain indicator |
| Operating Temperature | -40°C to +85°C |
| Package | SOT-23-5 |
Applications
Portable media players
Electronic system design
Bluetooth headsets
Electronic system design
GPS devices
Electronic system design
Digital cameras
Electronic system design
Handheld instruments
Electronic system design
FAE Expert Insights
"The LP4054 is a reliable and simple Li-ion charger that I've used in many portable product designs. The minimal external component count (just one resistor for current setting) makes it very cost-effective. The ±1% charge voltage accuracy ensures safe and complete charging without overcharging the battery. I particularly like the thermal regulation feature - it automatically reduces charge current if the die temperature exceeds 120°C, preventing thermal shutdown during high-temperature charging. The charge status pin is useful for driving an LED indicator. One implementation tip: the charge current programming resistor should be placed close to the IC, and the PROG pin should be bypassed with a small capacitor (100pF) for noise immunity. The 2μA sleep mode current is excellent - it won't drain the battery when USB power is disconnected. I've used this charger in everything from Bluetooth headsets to GPS devices with excellent reliability. Overall, a solid, no-frills Li-ion charger at a great price point."
Simple standalone Li-ion charger with minimal external components and reliable operation
— Zhang Wei, BeiLuo
Frequently Asked Questions
What is the maximum charge current of LP4054?
The LP4054 can deliver up to 800mA of charge current. The charge current is programmed using a single external resistor connected to the PROG pin. The resistor value is calculated as R_PROG = 1000V / I_CHG. For example, use 1kΩ for 1A (limited to 800mA max), or 2kΩ for 500mA.
Up to 800mA programmable charge current; set with external resistor R_PROG = 1000V / I_CHG.
What is the charge voltage accuracy of LP4054?
The LP4054 provides a regulated 4.2V charge voltage with ±1% accuracy. This high accuracy ensures safe charging without overcharging the battery, which is critical for battery safety and longevity. The tight voltage regulation prevents the battery voltage from exceeding safe limits.
±1% accuracy ensures safe charging; important for battery safety and cycle life.
How does LP4054 charge a deeply discharged battery?
LP4054 automatically implements a three-stage charging algorithm. For deeply discharged batteries (voltage below 2.9V), it starts with trickle charge at 10% of the programmed current. Once the battery voltage reaches 2.9V, it switches to fast charge (constant current). When the battery approaches 4.2V, it transitions to constant voltage mode until charge termination.
Automatic three-stage charging ensures safe recovery of deeply discharged batteries.
When does LP4054 terminate charging?
LP4054 terminates charging when the charge current drops to 1/10 (C/10) of the programmed fast charge current during constant voltage mode. This indicates the battery is fully charged. After termination, the charger monitors the battery voltage and automatically restarts charging if the voltage drops by approximately 100mV.
C/10 termination ensures full charge; automatic recharge maintains battery capacity.
What is the sleep mode current of LP4054?
When input power is removed, LP4054 automatically enters sleep mode with less than 2μA current drain from the battery. This ultra-low sleep current prevents battery drain when the device is stored or not connected to power, extending shelf life.
<2μA sleep mode current prevents battery drain during storage or when unplugged.
What external components are needed for LP4054?
LP4054 requires minimal external components: a programming resistor (typically 1-2kΩ) to set charge current, an input bypass capacitor (4.7μF or 10μF ceramic), and optionally a charge status LED with current limiting resistor. This minimal BOM reduces cost and board space.
Minimal external components; programming resistor, input capacitor, optional status LED.
Does LP4054 have thermal protection?
Yes, LP4054 includes thermal regulation that automatically reduces charge current if the die temperature exceeds 120°C. This feature prevents thermal shutdown and allows charging to continue at a reduced rate in high-temperature environments, improving reliability.
Thermal regulation prevents overheating; charging continues at reduced rate if needed.