LT4256-1 and LT4256-2 - Positive High Voltage Hot Swap Controllers
Features
- Allows Safe Board Insertion and Removal from a Live Backplane
- Controls Supply Voltage from 10.8V to 80V
- Foldback Current Limiting
- Overcurrent Fault Detection
- Drives an External N-Channel MOSFET
- Programmable Supply Voltage Power-Up Rate
- Undervoltage Protection
- Latch Off Operation Mode (LT4256-1)
- Automatic Retry (LT4256-2)
- Available in an 8-Pin SO Package
Typical Application
Description
The LT4256-1/LT4256-2 are high voltage Hot Swap™ controllers that allow a board to be safely inserted and removed from a live backplane. An internal driver drives an external N-channel MOSFET switch to control supply voltages ranging from 10.8V to 80V.
The LT4256-1/LT4256-2 features an adjustable analog foldback current limit. If the supply remains in current limit for more than a programmable time, the N-channel MOSFET shuts off and the PWRGD output asserts low. The LT4256-2 automatically restarts after a time-out delay. The LT4256-1 latches off until the UV pin is cycled low.
The PWRGD output indicates when the output voltage rises above a programmed level. An external resistor string from VCC provides programmable undervoltage protection.
The LT4256 can be used as an upgrade to LT1641 designs. See Table 1 on page 14 for upgraded specifications.
The LT4256-1 and LT4256-2 are available in an 8-pin SO package that is pin compatible with the LT1641.
| Retry / Latch Off |
Features | Package | |
| LT4256-1 | Latch Off | UV | SO-8 |
| LT4256-2 | Retry | UV | SO-8 |
| LT4256-3 | Latch Off or Retry | UV/OV, Open Circuit Detect | SSOP-16 |
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 |
|---|---|---|---|---|---|
| LT4256-1CS8#PBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT4256-1CS8#TRPBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT4256-1IS8#PBF | SO-8 | S8 | I | 05-08-1610 (S8) | Yes |
| LT4256-1IS8#TRPBF | SO-8 | S8 | I | 05-08-1610 (S8) | Yes |
| LT4256-2CS8#PBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT4256-2CS8#TRPBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT4256-2IS8#PBF | SO-8 | S8 | I | 05-08-1610 (S8) | Yes |
| LT4256-2IS8#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 | |
|---|---|---|---|---|---|---|
| LT4256-1CS8#PBF | SO-8 | C | $2.50 | $1.75 | Yes | |
| LT4256-1CS8#TRPBF | SO-8 | C | $1.81 | Yes | ||
| LT4256-1IS8#PBF | SO-8 | I | $2.86 | $2.00 | Yes | |
| LT4256-1IS8#TRPBF | SO-8 | I | $2.06 | Yes | ||
| LT4256-2CS8#PBF | SO-8 | C | $2.50 | $1.75 | Yes | |
| LT4256-2CS8#TRPBF | SO-8 | C | $1.81 | Yes | ||
| LT4256-2IS8#PBF | SO-8 | I | $2.86 | $2.00 | Yes | |
| LT4256-2IS8#TRPBF | SO-8 | I | $2.06 | 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 |
|---|---|---|---|
| DC1354A-A | LT4256-1 Positive High Voltage Hot Swap Controllers with Latch-off (-1) | $50.00 | |
| DC1354A-B | LT4256-2 Positive High Voltage Hot Swap Controllers with Auto-Retry(-2) | $50.00 | |
| Buy Now | |||
Applications
- Hot Board Insertion
- Electronic Circuit Breaker/Power Bussing
- Industrial High Side Switch/Circuit Breaker
- 24V/48V Industrial/Alarm Systems
- Ideally Suited for 12V, 24V and 48V Distributed Power Systems
- 48V Telecom Systems
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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
To launch a ready to run LTspice demonstration circuit for this part:
- Step 1: If you have not installed LTspice on this computer, download and install LTspice
- Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
- Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu
To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.
Models for the following parts are available in LTspice:
LT4256-1
LT4256-2
LT4256-3
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.
