Product category: Power Supply ICs and Controllers
News Release from: National Semiconductor | Subject: LM3670 and LM3671
Edited by the Electronicstalk Editorial Team on 27 January 2005
Convertors switch modes to save portable
power
Two new miniature, high-efficiency synchronous step-down DC/DC convertors aim to optimise the efficiency and size of portable devices.
National Semiconductor has released the first two products in a family of miniature, high efficiency synchronous step-down DC/DC convertors for portable systems The LM3670 and LM3671 optimise the efficiency and size of portable devices including wireless handsets, digital still cameras, MP3 players, PDAs, hard disk drives, wireless LAN and other low-power, small form-factor products
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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The LM3670 and LM3671 feature automatic PFM/PWM (pulse-frequency-modulation/pulsewidth-modulation) mode operation which delivers the highest efficiency over the entire load.
The synchronous rectification attribute of the LM3670 and LM3671 achieves up to 95% efficiency during continuous switching operation.
These devices feature world-class quiescent current at 16uA typical, resulting in excellent standby times that further extend battery life.
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The LM3670 and LM3671 have outstanding noise characteristics, generating less than 5mV peak-to-peak output voltage ripple, making them ideal for RF-based portable systems.
The small 2.2uH inductor, 10uF output capacitors and SOT-23 package minimise the footprint size.
"Today's feature-rich portable electronics need more efficient power management to maintain peak performance at all power levels", said Peter Henry, Vice President of National Semiconductor's Portable Power Products Group.
"The LM3670 and LM3671 accomplish this by combining a tiny solution size with the highest efficiency and longest standby times to offer the most effective buck regulator solution for portable power solutions".
The LM3671 powers low-voltage circuits operating from a lithium-ion battery or 2.8 to 5.5V voltage rails.
It has a load capability of up to 600mA.
The LM3671's 2MHz oscillator frequency enables the use of three very small external components for operation, including a 2.2uH inductor and two 10uF capacitors.
The LM3671's high-output voltage accuracy, low-output voltage ripple and fast transient response enable peak processor performance.
The LM3671 offers superior features and performance for powering digital cores and peripherals in portable systems.
Automatic switching between PWM low-noise and PFM low-current modes lead to high-efficiency performance over the complete load range.
Fixed-frequency PWM mode drives loads from approximately 70 to 600mA, and the PFM mode takes over at lower loads.
PFM mode extends battery life through the reduction of quiescent current to typically 16uA under light loads and during system standby.
In shutdown mode (enable pin pulled low), the device turns off and reduces battery consumption to 0.1uA typically.
The LM3671 is available with output voltage options of 3.3, 1.875, 1.8, 1.6, 1.5, 1.375, 1.25 and 1.2V as well as an adjustable option for other voltages.
The LM3670 is the low-power version of the LM3671 and is optimised for systems and applications with lower output current requirements.
It switches at 1MHz and has a load capability up to 300mA.
The LM3670 requires a very small 10uH inductor and two 4.7uF capacitors for operation.
The LM3670 is available with output voltage options of 1.8, 1.875 and 1.5V and an adjustable option for other voltages.
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