SGM4056
Complete CC/CV linear charger for single-cell Li-ion batteries with programmable charge current up to 1A.
Product Overview
Description
The SGM4056 is a complete constant-current/constant-voltage linear charger for single-cell lithium-ion batteries.
The device requires minimal external components and includes an internal power MOSFET for compact designs.
Charge current is programmable up to 1A using an external resistor.
Product Series
SGM
Primary Application
Portable media players
Key Features
- Complete single-cell Li-ion charger
- Programmable charge current up to 1A
- No external MOSFET or blocking diode needed
- Thermal regulation for safe operation
- Charge status output indicator
Specifications
| Input Voltage | 4.3V - 6.5V |
|---|---|
| Charge Current | Programmable up to 1A |
| Battery Voltage | 4.2V (4.35V option) |
| Charge Efficiency | 90%+ |
| Protection Features | OVP, thermal, reverse current |
| Package | SOT-23-5, DFN-2x2-8 |
Applications
Portable media players
Electronic system design
Bluetooth headsets
Electronic system design
Portable medical devices
Medical electronics
Power banks
Electronic system design
Handheld instruments
Electronic system design
FAE Expert Insights
"The SGM4056 is a reliable and cost-effective solution for single-cell Li-ion charging. The integrated thermal regulation is particularly valuable - it automatically reduces charge current if die temperature exceeds safe limits, preventing thermal shutdown during charging. I have used this charger in numerous consumer electronics designs with excellent results. The minimal external component count (just two resistors and two capacitors) makes it ideal for space-constrained applications. For best performance, ensure the input capacitor is placed close to the IC and use appropriate trace widths for charge current paths."
Simple and reliable single-cell Li-ion charging solution
— Steven Wu, BeiLuo
Frequently Asked Questions
How do I program the charge current for the SGM4056?
The charge current is programmed using a resistor connected between the PROG pin and ground. The formula is: Icharge = 1000V / Rprog. For example, a 1k resistor programs 1A charge current, while a 2k resistor programs 500mA. The resistor should be 1% tolerance for accurate current programming. The PROG pin can also be used to monitor charge current during charging by measuring the voltage (1V = 1A). For thermal management, ensure the programmed current does not cause excessive heating at maximum ambient temperature.
Calculate Rprog based on desired charge current. Consider thermal constraints when selecting current level.
What is the charge cycle behavior of the SGM4056?
The SGM4056 follows a standard Li-ion charging profile: 1) Trickle charge - if battery voltage is below 2.9V, charges at 10% of programmed current until battery recovers; 2) Constant current (CC) - charges at full programmed current until battery reaches 4.2V; 3) Constant voltage (CV) - maintains 4.2V while charge current gradually decreases; 4) Charge termination - when current drops to 10% of programmed value, charging stops; 5) Automatic recharge - if battery voltage drops below 4.05V, charging restarts. The STAT pin indicates charging status (low = charging, high = complete).
The automatic charge cycle requires no microcontroller intervention. Monitor STAT pin for charge status indication.
Can the SGM4056 charge batteries with different chemistries?
The SGM4056 is specifically designed for lithium-ion and lithium-polymer batteries with 4.2V charge voltage. It should not be used for other battery chemistries such as NiMH, NiCd, or lead-acid batteries which have different charge profiles and voltage requirements. For LiFePO4 batteries (3.6V charge voltage), use chargers specifically designed for that chemistry. SGMICRO offers different variants with alternative charge voltages - contact us for options if you require 4.35V or other charge voltages.
Use SGM4056 only for standard Li-ion/Li-poly batteries (4.2V). Contact us for other battery chemistry solutions.
What thermal management is required for the SGM4056?
The SGM4056 includes internal thermal regulation that reduces charge current if die temperature exceeds approximately 120C. However, proper thermal design is still important: 1) Ensure adequate copper area on PCB for heat dissipation; 2) Place thermal vias under the IC package; 3) Avoid placing heat-sensitive components near the charger; 4) Consider ambient temperature and airflow in the enclosure; 5) For high-current charging, use larger copper pours or external heatsinking. The thermal regulation feature provides safety margin but should not be relied upon for normal operation.
Design adequate thermal management for your charge current and ambient conditions. The IC will protect itself if limits are exceeded.
How can I implement charging status indication with the SGM4056?
The SGM4056 provides charge status through the STAT pin: 1) During charging - STAT pin is pulled low (can sink up to 10mA); 2) Charge complete - STAT pin becomes high impedance; 3) Fault condition - STAT pin blinks at 1Hz (if battery fault detected). To implement LED indication: connect an LED with current-limiting resistor between VCC and STAT for charging indication, or between STAT and ground for charge-complete indication. For microcontroller monitoring, connect STAT to a GPIO with pull-up resistor - low indicates charging, high indicates complete or standby.
Connect LED and resistor to STAT pin for visual indication. Use pull-up resistor for microcontroller interface.