Milpitas, Calif.—The LTC4076 and LTC4077 are Linear Technology’s second and third standalone linear lithium-ion battery charger chips with dual-input USB and AC adapter ports and offer designers various options to the company's earlier released LTC4075/X. The new chips, for single-cell batteries, automatically select the charging source, either an AC wall adapter or a USB port. Using a constant-current/constant-voltage algorithm, the chargers can deliver up to 950 mA from the wall adapter, or up to 650 mA of charge current from a USB supply. Applications include PDAs, MP3 players, lightweight portable medical and test equipment and large color screen cell phones.
The main differences between the LTC4075/X and the second and third offerings are in available current from the USB port and the devices' charge termination capabilities. The LTC4076 provides a choice of fixed C or C/5 USB charge current for low-power USB operation, and programmable C/x wall adapter and USB charge current termination.
The LTC4077 provides programmable C or C/x USB charge current for low-power USB operation and fixed C/10 wall adapter and USB C/10 or C/2 charge current termination. In contrast, the user sets the LTC4075's USB charge current with a resistor, and that device offers programmable C/x wall adapter and USB charge current termination. Unlike the LTC4075, the LTC4076/77 offer no USB power status output pin.
Access the LTC4076 datasheet by clicking here, and here for the LTC4077. The LTC4076/77 are offered in a low profile (0.75 mm) 10-lead 3-by-3 DFN package. The total solution footprint is less than 25 mm2 since no external MOSFET, sense resistor or blocking diode are required. To preserve battery energy, the LTC4076/77 draws less than 6 microamps from the battery terminal in standby and less than 2 microamps in shutdown mode. The LTC4076 and LTC4077 are rated for operation from -40C to +85°C.
Linear Technology, 1-800-4LINEAR, www.linear.com