Features and Benefits
- 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
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.
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|
|LT4256-3||Latch Off or Retry||UV/OV, Open Circuit Detect||SSOP-16|
- 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
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (3)
Demonstration circuit 1354B is a positive high voltage hot swap controller featuring either the LT®1641-1, LT1641-2, LT4256-1, or LT4256-2.
The board facilitates measurement of transient conditions, steady state operation with different loads, and fault conditions. The Controller responds to fault conditions such as input undervoltage(UV), output power good (PWRGD) fault, and overcurrent and response can be verified by the output voltage (VOUT) LED state and PWRGD pin signal. The LT1641-1 and LT4256-1 latch off if MOSFET shuts off under overcurrent condition, while LT1641-2 and LT4256-2 automatically restart after time-out delay.
The DC1354B contains one hot swap controller, power MOSFET, current sense resistor, enable circuit, input voltage clamp, gate protection circuit, resistive output voltage divider for feedback signal, and three LEDs to indicate the presence of input and output voltages and power good condition.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
LT4256-1 Companion Parts
Recommended Related Parts
Product Selector Card (1)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.