This is known as adjustable soft-start or slew-rate control and is implemented in HS2950P. So, it is not a good idea to turn on the switch instantly instead, turn it on gently by limiting the inrush current. If the voltage drops below the required specification, the circuit may fail to turn on. Also, the voltage in the circuit may be dropped to cater to the current spike demand. Due to this vast spike, the current can exceed the absolute maximum ratings of the circuit components and eventually damage them. Basic features of HS2950P Inrush Current ControlĪ substantial current spike can flow into the uncharged output capacitors when the load switch turns on. Let's review the basic features of a HotSwitch device shown in Figure 3.įigure 3. The MOSFET connects the input line to the output interface. A charge pump circuit is used to boost the gate voltage to the proper level to drive the N-channel MOSFET. ![]() In specific scenarios, the MOSFET may need to operate at a voltage near the lower limit of the operating voltage range. The MOSFET can be turned on or off by controlling the gate to source voltage. The MOSFET is a voltage-controlled device. The main element in a HotSwitch device is an N-channel MOSFET which is used as a switch. HotSwitch incorporates several advanced features desirable by a circuit designer. System protection with Semtech’s HS2950P Functioning of HotSwitch Bundled in a tiny 3x3mm 12-pin DFN package, HotSwitch HS2950P also includes various adjustable protection features, including soft-start, turn-on-delay, overvoltage, undervoltage, and overcurrent limit.įigure 2. It is a single-channel integrated eFuse with a wide input voltage range of 2.7V to 29V, supporting up to 5A output current and a low 25mΩ (typical) Rds(on). Semtech recently released an eFuse product, HotSwitch HS2950P. An eFuse can replace a fragile conventional fuse and integrate all the protection features into one product. Due to all these protection features, the load switch is also called an electronic fuse or eFuse. ![]() It also protects the load from a power supply in abnormal power situations such as inrush current and electrical transients.Īlong with inrush current control, a load switch protects the electrical circuit from overvoltage, undervoltage, over-temperature, short-to-the-battery, and short-to-ground conditions. Turning the load on and off and power sequencing are not the only functions carried out by a load switch. This ordering called power sequencing is done by load switches. To ensure turn on and turn off happens appropriately, a specific order needs to follow in distributing power in the circuit. Multiple power sources are used in some applications, such as microprocessors, FPGAs, network switches, or industrial controllers. ![]() A load switch can automatically turn off and turn on a load as needed, significantly reducing overall power consumption. These circuits can consume power even in sleep mode. For an electronic gadget, not all circuitry needs to be active all the time. But in recent years, power saving has become crucial for any electronic device, whether it is battery-powered or not. For a portable battery-powered device, saving power means longer battery life. Being power efficient means consuming power only when needed by the system. ![]() Modern-day power electronic devices are designed to be smaller, more innovative and more efficient. System protection with a HotSwitch device Figure 1 shows how a system is protected by a HotSwitch device.įigure 1. At the same time, the devices in Semtech’s HotSwitch portfolio provide an enhanced shield against inrush current, overvoltage, under voltage, reverse current, short circuit, and over-temperature faults. It detects electrical surges and secures the downstream subsystem by disconnecting the load from the power source. Primarily, the HotSwitch device turns on or off the current flow to a power rail as-needed. HotSwitch® is a new product line of devices from Semtech with an integrated load switch or eFuse that protects electronics systems against typical electrical transients and steady-state fault conditions.
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