DocumentationDatasheet
Reliability Data
Product Selector Card
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Features
- Seamless Transition Between Input Power Sources: Li-Ion/Polymer Battery, USB and 5V Wall Adapter
- 215mΩ Internal Ideal Diode Plus Optional External Ideal Diode Controller Provide Low Loss PowerPath™ When Wall Adapter/USB Input Not Present
- Load Dependent Charging Guarantees Accurate USB Input Current Compliance
- 3.95V Float Voltage Improves Battery Life Span and High Temperature Safety Margin
- Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate without Risk of Overheating*
- Selectable 100% or 20% Input Current Limit (e.g., 500mA/100mA)
- Battery Charge Current Independently Programmable Up to 1.2A
- Automatic Output Undervoltage Charge Current Reduction (LTC4085-3)
- Tiny (4mm × 3mm × 0.75mm) 14-Lead DFN Package
Typical Application
Description
The LTC®4085-3/LTC4085-4 is a USB power manager and Li-Ion/Polymer battery charger designed for portable battery-powered applications. The part controls the total current used by the USB peripheral for operation and battery charging. The total input current can be limited to 20% or 100% of a programmed value up to 1.5A (typically 100mA or 500mA). Battery charge current is automatically reduced such that the sum of the load current and charge current does not exceed the programmed input current limit.
The LTC4085-3/LTC4085-4 includes a complete constantcurrent/ constant-voltage linear charger for single cell Li-Ion batteries. These 3.95V versions of the standard LTC4085 are intended for applications which have extended battery lifetime requirements or those that require high temperature (approximately >60°C) operation or storage. Under these conditions, a reduced fl oat voltage will trade-off initial cell capacity for the benefi t of increased capacity retention over the life of the battery. A reduced fl oat voltage also minimizes swelling in prismatic and polymer cells, and avoids open CID (pressure fuse) in cylindrical cells.
The LTC4085-3/LTC4085-4 also includes a programmable termination timer, automatic recharging, an end-of-charge status output and an NTC thermistor.
| Float Voltage (V) | NTC Hot Threshold | Undervoltage Current Limit | |
|---|---|---|---|
| LTC4085 | 4.2V | 29% Vvntc | Yes |
| LTC4085-1 | 4.1V | 32.6% Vvntc | Yes |
| LTC4085-3 | 3.95V | 32.6% Vvntc | Yes |
| LTC4085-4 | 3.95V | 32.6% Vvntc | No |
4x3 DFN-14
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LTC4085EDE#PBF | DFN | 14 | E | $2.36 | $1.65 |
| LTC4085EDE#TRPBF | DFN | 14 | E | $1.71 | |
| LTC4085EDE-1#PBF | DFN | 14 | E | $2.36 | $1.65 |
| LTC4085EDE-1#TRPBF | DFN | 14 | E | $1.71 | |
| LTC4085EDE-3#PBF | DFN | 14 | E | $2.36 | $1.65 |
| LTC4085EDE-3#TRPBF | DFN | 14 | E | $1.71 | |
| LTC4085EDE-4#PBF | DFN | 14 | E | $2.36 | $1.65 |
| LTC4085EDE-4#TRPBF | DFN | 14 | E | $1.71 | |
| LTC4085EDE | DFN | 14 | E | $4.72 | $3.30 |
| LTC4085EDE#TR | DFN | 14 | E | $3.42 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.