National Semi Intros LM2685 Dual-Output Switched Capacitor Regulator

The new LM2685 from National Semiconductor Corp. (Santa Clara, CA) is a dual-output switched capacitor regulator that integrates a switched capacitor doubler, a low dropout (LDO) regulator and a switched capacitor inverter in a low profile TSSOP-14 package. The LM2685 provides a dual output (+5V regulated and -5V unregulated) power supply by using switched capacitor and LDO techniques. The +5V regulated power supply is suited for components such as audio CODECs, amplifiers and SIMs, while the -5V can be used for contrast bias for LCDs, and to increase the dynamic range of operational amplifiers used for analog inputs. The LM2685 is considered an ideal adjunct to the main dc/dc conversion for many portable devices, especially those that incorporate audio I/O and LCDs. The device's 50mA output current is said to be 10 times higher than competitive solutions. The LM2685 accommodates an input voltage range from 2.85V to 5.5V, matching the voltage delivered from lithium-ion batteries. The regulator uses five capacitors and no inductors to achieve its functionality. The absence of inductors is claimed to offer higher manufacturing reliability and lower radiated EMI as compared to inductive switching techniques. The LM2685 is priced at $1.75 in 1,000-piece quantities.

National Semiconductor Corp.
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