DocumentationDatasheet
Reliability Data
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Features
- High Efficiency, 500mA Buck Plus 300mA VLDOTM Regulator
Auto Start-Up Powers VLDO/Linear Regulator
Output Prior to Buck Regulator Output - Independent High Effi ciency, 500mA Buck (VIN: 2.7V to 5.5V)
- 300mA VLDO Regulator with 30mA Standalone Mode
- No External Schottky Diodes Required
- Buck Output Voltage Range: 0.8V to 5V
- VLDO Input Voltage Range (LVIN): 0.9V to 5.5V
- VLDO Output Voltage Range VLDO: 0.4V to 4.1V
- Selectable Fixed Frequency, Pulse-Skip Operation or Burst Mode® Operation
- Short-Circuit Protected
- Current Mode Operation for Excellent Line and Load Transient Response
- Constant Frequency Operation: 2.25MHz
- Low Dropout Buck Operation: 100% Duty Cycle
- Small, Thermally Enhanced, 10-Lead (3mm × 3mm) DFN Package
Typical Application
Description
The LTC3541-1 combines a synchronous buck DC/ DC converter with a very low dropout linear regulator (VLDO) to provide up to two output voltages from a single input voltage with minimal external components. When configured for dual output operation, the LTC3541-1’s auto start-up feature will bring the VLDO/linear regulator output into regulation in a controlled manner prior to enabling the Buck regulator output without the need for external pin control. Buck output prior to VLDO/linear regulator output sequencing may also be obtained via external pin control. The input voltage range is ideally suited for Li-Ion batterypowered applications, as well as powering sub-3.3V logic from 5V or 3.3V rails.
The synchronous buck converter provides a high efficiency output, typically 90%, capable of providing up to 500mA of continuous output current while switching at 2.25MHz, allowing the use of small surface mount inductors and capacitors. A mode-select pin allows Burst Mode operation to be enabled for higher efficiency at light load currents, or disabled for lower noise, constant frequency operation.
The VLDO regulator provides a low noise, low voltage output capable of providing up to 300mA of continuous output current using only a 2.2µF ceramic capacitor. The input supply voltage of the VLDO regulator (LVIN) may come from the buck regulator or a separate supply.
| Options | Vout Switcher (V) | Vout VLDO | Auto Start Up Sequencing |
|---|---|---|---|
| LTC3541 | Adj down to 0.8V | Adj down to 0.4V | Switcher, then VLDO |
| LTC3541-1 | Adj down to 0.8V | Adj down to 0.4V | VLDO, then switcher |
| LTC3541-2 | 1.875V fixed | 1.5V fixed | Switcher, then VLDO |
| LTC3541-3 | 1.8V fixed | 1.575 fixed | VLDO, then switcher |
3x3 DFN-10
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LTC3541EDD#PBF | DFN | 10 | E | $2.70 | $1.89 |
| LTC3541EDD#TRPBF | DFN | 10 | E | $1.95 | |
| LTC3541EDD-1#PBF | DFN | 10 | E | $2.70 | $1.89 |
| LTC3541EDD-1#TRPBF | DFN | 10 | E | $1.95 | |
| LTC3541EDD-2#PBF | DFN | 10 | E | $2.70 | $1.89 |
| LTC3541EDD-2#TRPBF | DFN | 10 | E | $1.95 | |
| LTC3541EDD-3#PBF | DFN | 10 | E | $2.70 | $1.89 |
| LTC3541EDD-3#TRPBF | DFN | 10 | E | $1.95 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.
| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC970A-B | LTC3541-1 Demo Board | 3V ≤ VIN ≤ 5.5V, Vout1 (Buck) = 1.8V or 2.5V @ 500mA, Vout2 (VLDO) = 0.8V/1.2V/1.5V/1.8V @ 300mA | $100.00 |