Date: 12/02/2009

Configurable dual output step-down converter delivers 3A/1A or 2A/2A

Linear Technology introduced the LTC3546, a dual channel, synchronous buck regulator which can deliver either dual 2A outputs or 3A from one channel and 1A from the other, with up to 96% efficiency. Using a constant frequency, current mode architecture, the LTC3546 operates from an input voltage range of 2.25V to 5V, making it ideal for single cell Li-Ion/polymer, or multi-cell alkaline/NiCad/NiMH applications.

Other features include:

1. Each output is adjustable from 0.6V to 5V and has turn-on supply tracking.
2. Separate RUN and Power Good Pins enable independent control of each channel.
3. The LTC3546's switching frequency can be set at 2.25MHz or is programmable from 750 kHz to 4MHz helping to optimize efficiency while avoiding critical noise-sensitive frequency bands.
4. Its design consists of 2A and 1A primary synchronous switches and a 1A dependent synchronous output switch which can be externally connected to either of the primary outputs to produce either 3A and 1A outputs or dual 2A outputs.
5. The 2A primary switch can be run either in phase with the additional switches or 180deg out of phase via an external phase pin.
6. Its Burst Mode operation minimizes quiescent current to 160uA (both channels on) in no load conditions.
7. The current threshold at which Burst Mode operation begins can be independently programmed for each channel.
8. It can also be run in pulse skipping or forced continuous modes to minimize output ripple.
9. The LTC3546 offers a Power Good indicator and is synchronizable to an external clock.
10. Provides external synchronization capability, over-temperature and short-circuit protection.
11. No Schottky diodes required
12. Low ripple burst mode operation (<30mVP-P), IQ = 125uA
13. Low shutdown current: IQ < 1uA
14. Low Dropout Operation: 100% duty cycle
15. Externally or internally programmable burst level
16. External or internal soft-start or supply tracking

Package: 4mm x 5mm QFN-28 package

Price:
1. LTC3546EUFD is priced $3.75 each in 1,000-piece quantities
2. LTC3546IUFD is priced at $4.41 in 1,000-piece quantities

Availability: All versions are available from stock

For more information visit www.linear.com