LTC4121/LTC4121-4.2 - 40V 400mA Synchronous Step-Down Battery Charger
The LTC®4121 is a 400mA constant-current/constantvoltage (CC/CV) synchronous step-down battery charger. In addition to CC/CV operation, the LTC4121 regulates its input voltage to a programmable percentage of the input open-circuit voltage. This technique maintains maximum power transfer with high impedance input sources such as solar panels.
An external resistor programs the charge current up to 400mA. The LTC4121-4.2 is suitable for charging Li-Ion/ Polymer batteries, while the programmable float voltage of the LTC4121 is suitable for several battery chemistries.
The LTC4121 and LTC4121-4.2 include an accurate RUN pin threshold, low voltage battery preconditioning and bad battery fault detection, timer termination, auto-recharge, and NTC temperature qualified charging. The FAULT pin provides an indication of bad battery or temperature faults.
Once charging is terminated, the LTC4121 signals end-ofcharge via the CHRG pin, and enters a low current SLEEP mode. An auto-restart feature starts a new charging cycle if the battery voltage drops by 2.2%.
Features
Typical Application  | Applications
Packaging  |
Order Information
| Part Number | Package | Temp | Price(1-99) | Price (1k)* |
|---|---|---|---|---|
| LTC4121EUD-4.2#PBF | 3x3 QFN-16 | E | $3.71 | $2.60 |
| LTC4121EUD-4.2#TRPBF | 3x3 QFN-16 | E | $2.66 | |
| LTC4121EUD#PBF | 3x3 QFN-16 | E | $3.71 | $2.60 |
| LTC4121EUD#TRPBF | 3x3 QFN-16 | E | $2.66 | |
| LTC4121IUD-4.2#PBF | 3x3 QFN-16 | I | $4.29 | $3.00 |
| LTC4121IUD-4.2#TRPBF | 3x3 QFN-16 | I | $3.06 | |
| LTC4121IUD#PBF | 3x3 QFN-16 | I | $4.29 | $3.00 |
| LTC4121IUD#TRPBF | 3x3 QFN-16 | I | $3.06 |
Demo Boards
| Part Number | Description | Price |
|---|---|---|
| DC1977A-A | LTC4121EUD-4.2 Demo Board | VIN = 4.4V to 40V, 400mA Sync Buck Li Ion Battery Charger | $125.00 |
| DC1977A-B | LTC4121EUD Demo Board | 400mA Synchronous Buck Battery Charger, VIN = 4.4V to 40V, VBAT = Adjustable | $125.00 |
