LTC3446 - Monolithic Buck Regulator with Dual VLDO Regulators
Features
- High Efficiency Triple Step-Down Outputs from a Single Input Supply
- 1A Synchronous Buck Regulator Provides Main Step-Down Output and Powers Two 300mA VLDO Linear Regulators
- Output Voltages as Low as 400mV (VLDO Outputs)
- Power Good Output
- Input Voltage Range: 2.7V to 5.5V
- Independent Internal Soft-Start for Each Supply
- Independent Enable Pin for Each Supply
- Low (140µA Typ) No-Load Quiescent Current with all Outputs Enabled
- Constant Frequency Current Mode Operation
- 2.25MHz Switching Frequency Uses Small Inductors
- Defeatable Automatic Burst Mode® Operation for High Efficiency at Light Loads
- ±1.5% Reference Accuracy
- Overtemperature Protection
- Thermally Enhanced 4mm × 3mm 14-Pin DFN Package
AEC-Q100 data available for specific packages
Typical Application
Description
The LTC3446 combines a synchronous buck DC/DC converter with two very low dropout (VLDO) linear regulators to provide up to three stepped-down output voltages from a single input voltage. The input voltage range is ideally suited for Li-Ion battery-powered applications, as well as powering low voltage logic from 5V or 3.3V rails. The output voltage range extends down to 0.4V for the VLDO regulators and 0.8V for the buck.The 1A synchronous buck converter provides the main output with high efficiency, typically 85%. The two 300mA VLDO regulators can run off the main output to provide two additional lower voltage outputs. A built-in supply monitor provides a power good indication.
The buck converter switches at 2.25MHz, allowing the use of small surface mount inductors and capacitors. Constant frequency current mode operation produces controlled output spectrum and fast transient response. A mode-select pin allows automatic Burst Mode operation to be enabled for higher efficiency at light load, or disabled for lower noise operation down to very light loads. The two VLDO regulators are stable with ceramic output capacitors as small as 1µF.
Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LTC3446EDE#PBF | 4x3 DFN-14 | DE | E | 05-08-1708 | Yes |
| LTC3446EDE#TRPBF | 4x3 DFN-14 | DE | E | 05-08-1708 | Yes |
| LTC3446IDE#PBF | 4x3 DFN-14 | DE | I | 05-08-1708 | Yes |
| LTC3446IDE#TRPBF | 4x3 DFN-14 | DE | I | 05-08-1708 | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LTC3446EDE#PBF | 4x3 DFN-14 | E | $3.93 | $2.75 | Yes | |
| LTC3446EDE#TRPBF | 4x3 DFN-14 | E | $2.81 | Yes | ||
| LTC3446IDE#PBF | 4x3 DFN-14 | I | $4.71 | $3.30 | Yes | |
| LTC3446IDE#TRPBF | 4x3 DFN-14 | I | $3.36 | Yes | ||
| Buy Now • Request Samples | ||||||
Demo Boards
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 |
|---|---|---|---|
| DC893A | LTC3446EDE Demo Board | 2.9V ≤ VIN ≤ 5.5V, Vout1 = 1.8V @ 400mA, Vout2/Vout3 = 1.2V/1.5V @ 300mA | $100.00 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LTC3446IDE#PBF | 4x3 DFN-14 | I | $4.71 | $3.30 | Yes | |
| LTC3446IDE#TRPBF | 4x3 DFN-14 | I | $3.36 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Low Power Handheld Devices
- Low Voltage and Multivoltage Power for Digital Logic, I/O, FPGAs, CPLDs, ASICs and CPUs
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Design Tools
LTspice
LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice
Models for the following parts are available in LTspice:
LTC3446
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
