Santa Clara, Calif. - Raising the functionality bar for power-management chips, National Semiconductor Corp. has seven highly integrated mixed-signal ASICs for portable systems to meet the expanding needs of wireless applications, particularly cell phones. At the same time, the company has unveiled a package called the Microfil that promises to extend the capability of the industry-standard MicroSMD package to significantly higher pinouts.
The five CMOS chips for general system management include the LP3935 and LP3938, which have a charger, seven linear regulators, USB transceiver, I2C interface and two LED/vibrator drivers. The family's most integrated package, the LP3941, includes 11 linear regulators and a host of extensive monitoring and control features.
The series also includes two basic chargers for lithium ion and nickel metal hydride batteries, the programmable LP3945 (charger, integrated pass transistor, I2C interface, LED drivers for charging status) and LP3946 (charger with integrated pass transistor, preprogrammed at the factory).
Two other chips, the LP3933 and the LP3936, are designed for the display-backlighting needs of cell phones. They include six LED drivers and one or two red-green-blue LED "fun lights" that can be programmed to flash and change color with the application.
The LP3935 is housed in a 48-pin leadless lead frame package (LLP-48). The LP3-938 is an upgraded version of the LP3935 with an improved charger and an additional regulator. Two of its eight regulators have an idle mode.
The most highly integrated of the system-management chips, the LP3941 for state-of-the-art cellular devices, integrates 11 low-dropout regulators along with an RGB LED driver, battery charger, backup battery charger and I2C interface. It comes in an LLP-48.
The battery-charging and-management units, the LP3945 and 3946, integrate the pass transistor, thus offering a complete small, high-performance discrete charger. The LP3945 is programmable via an I2C interface for setting charging and end-of-charge current and output voltage; the LP3946 is preprogrammed at the factory (no interface). Two LED drivers indicate battery charge status. These chips come in a 14-pin LLP.
The LP3933 white-LED driver is particularly suited to so-called "clamshell" handsets. The chip, basically a 300-milliamp dc/dc magnetic-boost converter working off a 3- to 6-volt input, includes four 25-mA white-LED drivers and two general LED drivers that are 8-bit programmable. It can be controlled over an SPI serial interface and comes in a 32-pin, 4.5 x 5.5-mm laminate chip-scale plastic package. The second light-management IC, the LP3936, also in a CSP-32, has six white-LED drivers, one RGB driver and an 8-bit A/D converter to sense ambient light. Its combined Micro Wire and I2C-compatible interface can link to a microprocessor or microcontroller.
All devices will ultimately become available in the company's Microfil package. The Microfil uses a patented underfill material applied at the wafer level to increase the reliability for high-pin-count devices and cut package sizes by a claimed factor of four to seven. Microfil packages having pin counts of 64 and below are scheduled to appear in the third quarter, and higher pin counts in the fourth quarter.
The LP3935, -36, -38, -41, -45 and -46 are sampling now. The 3933 will be available in the second quarter. The 3935 and 3945/3946 are scheduled for production quantities in Q2, with the LP3933, 3936, 3938 and 3941 available for production in Q3.
The LP3933 lighting-management ICs will be priced at $1.35 each, and the LP3936 at $1.20. The LP3935 power-management IC will be $1.75, the LP3938 $1.85 and the LP3941 $2.05. The LP3945 and LP3946 Li-ion/NiMH charger chips will sell for $1 and 90 cents, respectively. All chips are priced in lots of 500,000.
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