The LT1640AL/LT1640AH are 8-pin, negative voltage Hot SwapTM controllers that allow a board to be safely inserted and removed from a live –48V backplane. Inrush current is limited to a programmable value by controlling the gate voltage of an external N-channel pass transistor. The pass transistor is turned off if the input voltage is less than the programmable undervoltage threshold or greater than the overvoltage threshold. A programmable electronic circuit breaker protects the system against shorts. The PWRGD (LT1640AL) or PWRGD (LT1640AH) signal can be used to directly enable a power module. The LT1640AL is designed for modules with a low enable input and the LT1640AH for modules with a high enable input. The LT1640AL/LT1640AH are available in 8-pin PDIP and SO packages.
The LT1640AL and LT1640AH are 8‑pin negative‑voltage hot‑swap controllers that enable safe insertion and removal of boards from a live –48 V backplane. They limit inrush current, protect against over‑ and under‑voltage conditions, and provide a programmable electronic circuit breaker.
The handbook details the device features, electrical characteristics, pin functions, typical application circuits, timing diagrams, and package dimensions, giving designers the information needed to integrate the controller into power‑sequencing designs.
| Supply Current | 1.3 mA to 5 mA |
|---|---|
| Power Good Threshold | 14 V (typical) |
| Drain Input Bias Current | 10 pA to 500 pA |
| PWRGD Output Low Voltage (LT1640AL) | 0.48 V to 0.8 V |
The LT1640AL is designed for modules with a low enable input, while the LT1640AH is designed for modules with a high enable input.
Inrush current is limited by programming a value that controls the gate voltage of an external N‑channel pass transistor.
The PWRGD pin provides a Power‑Good output that can be connected directly to the enable pin of a power module.