National Semiconductor Introduces the LP3985 LDO Regulator
National Semiconductor (Santa Clara, CA) has announced the LP3985, a new CMOS LDO regulator designed to improve talk and standby times in GSM, TDMA and CDMA cellular phones.
The company claims that the LDO's low voltage will increase the operating times battery-powered portable equipment like personal digital assistants, palm devices, digital cameras and watches, as well as Bluetooth and GPS modules. The LP3985 also offers signal-to-noise performance. It is housed in a micro-SMD package and uses ceramic capacitors.
At a full load of 150mA, National Semiconductor cites the LP3985 as having a typical voltage drop of 60mV between its input and output voltage. The IC's quiescent current is 163 microamps, and this drops to 1 microamp in shutdown mode. A logic-controlled on/off input allows for turn-on times of 200 microseconds.
The LP3985 has a power supply rejection ratio of 60dB at 1kHz and 50dB at 10kHz. Low noise, rated at 30 microVrms over 10Hz to 100kHz, allows the use of a 1-microfarad output capacitor, which can be either ceramic or tantalum. The company claims that a bypass capacitor will further reduce the output noise without slowing down the load-transient response. The five-bump package measures 0.828mm x 1.387mm, with a profile of 0.85mm.
"Performance and size are extremely critical issues in the dynamic world of wireless and digital consumer designs," said Steven Hunt, director of marketing and applications for National's portable power systems group. "National's LP3985 LDO voltage regulators offer low dropout and other performance features. The icing on the cake is the innovative package it's wrapped in. As micro-SMD packages are integrated into system designs, they shorten production cycles, increase product reliability and ultimately change the way products go to market."
A variety of standard output voltage options ar available, including 2.5V, 2.8V and 3.0V. Output voltage accuracy is two percent at room temperature and four percent over all load, line and temperature conditions. Available in the five I/O micro-SMD package, the LP3985IBP is priced at $0.56 each in quantities of 1,000. The LP3985IM5, in the SOT23-5 package, is $0.50 each in quantities of 1,000.