DocumentationDatasheet
Reliability Data
Product Selector Card
LT Journal
cad_symbol
ltspice
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 |
SO-8,
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LT4256-1CS8#PBF | SO | 8 | C | $2.50 | $1.75 |
| LT4256-1CS8#TRPBF | SO | 8 | C | $1.81 | |
| LT4256-1IS8#PBF | SO | 8 | I | $2.86 | $2.00 |
| LT4256-1IS8#TRPBF | SO | 8 | I | $2.06 | |
| LT4256-2CS8#PBF | SO | 8 | C | $2.50 | $1.75 |
| LT4256-2CS8#TRPBF | SO | 8 | C | $1.81 | |
| LT4256-2IS8#PBF | SO | 8 | I | $2.86 | $2.00 |
| LT4256-2IS8#TRPBF | SO | 8 | I | $2.06 | |
| LT4256-3CGN#PBF | SSOP | 16 | C | $2.95 | $2.10 |
| LT4256-3CGN#TRPBF | SSOP | 16 | C | $2.16 | |
| LT4256-3IGN#PBF | SSOP | 16 | I | $3.48 | $2.45 |
| LT4256-3IGN#TRPBF | SSOP | 16 | I | $2.51 | |
| LT4256-1CS8 | SO | 8 | C | $5.00 | $3.50 |
| LT4256-2CS8 | SO | 8 | C | $5.00 | $3.50 |
| LT4256-2CS8#TR | SO | 8 | C | $3.62 | |
| LT4256-2IS8 | SO | 8 | I | $5.72 | $4.00 |
| LT4256-2IS8#TR | SO | 8 | I | $4.12 | |
| LT4256-1CS8#TR | SO | 8 | C | $3.62 | |
| LT4256-1IS8 | SO | 8 | I | $5.72 | $4.00 |
| LT4256-1IS8#TR | SO | 8 | I | $4.12 | |
| LT4256-3CGN | SSOP | 16 | C | $5.90 | $4.20 |
| LT4256-3CGN#TR | SSOP | 16 | C | $4.32 | |
| LT4256-3IGN | SSOP | 16 | I | $6.96 | $4.90 |
| LT4256-3IGN#TR | SSOP | 16 | I | $5.02 |
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 |