LINEAR Universal Li-ION Battery Charger - USB & 6V to 36V Input in 2cm² Efficiency - Design Note 395 Liu Yang Operation Instructions User Manual
Summary
The LTC4089 is a highly compact, universal power management solution designed for advanced handheld electronics. It seamlessly integrates Li-Ion charging and robust system power delivery, allowing devices like GPS units and digital cameras to charge batteries via USB or high-voltage inputs while simultaneously powering the load—all in under 2cm. This manual provides detailed schematics and technical analysis, demonstrating superior efficiency and reliability compared to traditional dual-input chargers. Ideal for engineers designing next-generation portable equipment requiring consistent power from varied sources.
Page 1 Text Content
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Universal Li-Ion Battery Charger Operates from USB and 6V to 36V Input in Just 2cm2 – Design Note 395 Liu Yang Introduction 3mm × 6mm DFN package. The LTC4089’s buck regula-
There are a number of advantages to offering USB and tor output voltage tracks the battery voltage to within high input voltage power and battery-charging capabil- 300m V. This Bat-Track TM feature minimizes overall power ity in handheld devices such as GPS navigators, PDAs, dissipation. The LTC4089-5 has a fi xed 5V at OUT when digital still cameras, photoviewers and MP3 players. For power is applied at HVIN. When power is supplied from instance, charging and operation from USB offers the the USB port, the power manager maximizes the available obvious convenience of not requiring a travel adapter. High power to the system load; up to the full USB available voltage sources, such as Firewire and 12V to 24V adapters power of 2.5W. It automatically adjusts the Li-Ion battery are even better, since they provide faster charging than charge current with respect to the system load current USB and allow charging in more places, such as in the car. to maintain the total input current compliance within the Nevertheless, there is an important design consideration USB limits. The total solution size is less than 2cm2 with with high voltage power sources: the voltage difference all components on one side of the PCB.
between the high voltage source and the battery in the
Adaptive High Voltage Buck Minimizes Total Power
handheld is very large. Since a linear charger cannot handle
the power dissipation, a switching charger is required.
The LTC4089’s buck converter output voltage VOUT tracks
The LTC®4089 and LTC4089-5 (see Figure 1) conve- the battery voltage VBAT. It is always 0.3V higher than niently integrate a high voltage and wide input range VBAT, so that the battery can be charged quickly while (6V to 36V with 40V absolute maximum) monolithic
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
1.2A buck switching regulator and a USB power man-
Bat-Track is a trademark of Linear Technology Corporation. ager/charger into a compact thermally enhanced All other trademarks are the property of their respective owners.
BOOST SW C3
HVIN HVOUT
6V TO 36V C1
HVEN HVOUT
HVPR Q1
U1 R6 LTC4089EDJC 10k
(TO SYSTEM LOAD)
IN OUT OUT
4.35V TO 5.5V C5 C6
4.7µF HPWR GATE Q2 4.7µF 6.3V 6.3V C4
0.15µF SUSP BAT Li-ION+
(OPTIONAL)
TIMER CHRG
R3 2.1k VNTC
CLPROG R5
PROG NTC VC GND GND
RNTC 10k
DN395 F01
Figure 1. The LTC4089 Schematic Illustrates Multiple Input Voltage Capability
Page Summary Contents For LINEAR Universal Li-ION Battery Charger - USB & 6V to 36V Input in 2cm² Efficiency - Design Note 395 Liu Yang Operation Instructions User Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 98.73 KB |
| Published | June 02, 2026 |
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Frequently Asked Questions
What are the possible input voltage sources for this charger?
It accepts USB power and a wide range of high voltages from 6V to 36V (40V absolute maximum).
What is the main benefit of using the LTC4089 power manager?
It enables simultaneous charging and system operation by adapting power sources, ensuring fast recharge and stable voltage supply.
Is physical space a concern for this product?
No, it minimizes size, with the total solution being less than 2cm (11.3mm x 17.5mm).
How is charging performance impacted when using USB power?
It maximizes available current, delivering up to the full 2.5W USB power to the system load.