LT1959 - 4.5A, 500kHz Step-Down Switching Regulator
Features
- Operates with Input as Low as 4V
- Output Range Down to 1.21V
- Constant 500kHz Switching Frequency
- Uses All Surface Mount Components
- Inductor Size Reduced to 1.8µH
- Saturating Switch Design: 0.07 Ohms
- Shutdown Current: 20µA
- Easily Synchronizable
- Cycle-by-Cycle Current Limiting
- 4.5A Switch
- Current Mode Control
Typical Application
Description
The LT1959 is a 500kHz monolithic buck mode switching regulator functionally identical to the LT1506 but optimized for lower output voltage applications. It will operate down to 1.21V output compared to 2.42V for the LT1506. A 4.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. High switching frequency allows a considerable reduction in the size of external components. The topology is current mode for fast transient response and good loop stability.A special high speed bipolar process and new design techniques achieve high efficiency at high switching frequency. Efficiency is maintained over a wide output current range by keeping quiescent supply current to 4mA and by utilizing a supply boost capacitor to saturate the power switch.
The LT1959 fits into standard 7-pin DD and fused lead SO-8 packages. Full cycle-by-cycle short-circuit protection and thermal shutdown are provided. Standard surface mount external parts are used, including the inductor and capacitors. There is the optional function of shutdown or synchronization. A shutdown signal reduces supply current to 20µA. Synchronization allows an external logic level signal to increase the internal oscillator from 580kHz to 1MHz.
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 |
|---|---|---|---|---|---|
| LT1959CR#PBF | DDPAK-7 | R | C | 05-08-1462 | Yes |
| LT1959CR#TRPBF | DDPAK-7 | R | C | 05-08-1462 | Yes |
| LT1959CS8#PBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT1959CS8#TRPBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT1959IR#PBF | DDPAK-7 | R | I | 05-08-1462 | Yes |
| LT1959IR#TRPBF | DDPAK-7 | R | I | 05-08-1462 | Yes |
| LT1959IS8#PBF | SO-8 | S8 | I | 05-08-1610 (S8) | Yes |
| LT1959IS8#TRPBF | SO-8 | S8 | I | 05-08-1610 (S8) | 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 | |
|---|---|---|---|---|---|---|
| LT1959CR#PBF | DDPAK-7 | C | $5.61 | $4.74 | Yes | |
| LT1959CR#TRPBF | DDPAK-7 | C | $4.86 | Yes | ||
| LT1959CS8#PBF | SO-8 | C | $5.19 | $4.39 | Yes | |
| LT1959CS8#TRPBF | SO-8 | C | $4.45 | Yes | ||
| LT1959IR#PBF | DDPAK-7 | I | $6.39 | $5.40 | Yes | |
| LT1959IR#TRPBF | DDPAK-7 | I | $5.52 | Yes | ||
| LT1959IS8#PBF | SO-8 | I | $5.98 | $5.05 | Yes | |
| LT1959IS8#TRPBF | SO-8 | I | $5.11 | 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 |
|---|---|---|---|
| DC355A | LT1959CS8 | 4.5A Switch, 500kHz Step-Down Regulator, 5V to 15Vin, 1.8Vout @ 4A | $150.00 | |
| DC356A | LT1959CR | 4.5A Switch, 500kHz Step-Down Regulator, 5V to 15Vin, 1.8Vout @ 4A | $150.00 | |
| Buy Now | |||
Applications
- Portable Computers
- Battery-Powered Systems
- Battery Chargers
- Distributed Power
- 5V to 3.3V Conversion
- 5V to 2.5V Conversion
- 5V to 1.8V Conversion
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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:
LT1959
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.
