Simplified Block Diagram
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- Dual USB Switch with Auxiliary Input
- Autoreset from Fault Condition
- Guaranteed 500mA Load per Channel
- Programmable Current Limits on Auxiliary Inputs
- Reverse Current Protection
- Thermal Overload Protection
- Built-In 20ms Fault-Blanking
- 4V to 5.5V Range
- Independent FAULT Indicator Outputs
The MAX1838 has multiple protection features, including independent thermal-shutdown on each channel to limit junction temperature in case of a prolonged short or overload condition. The device has accurate internal current-limit and reverse-current protection to safeguard the input supply against overload. When powered from the auxiliary supply, the current limit on each channel is set independently with an external resistor.
An autoreset feature latches the switch off if the output is shorted, thereby saving system power. When the short is removed, the switch automatically turns back on. Independent fault signals (active-low FAULTA and active-low FAULTB) notify the microprocessor (µP) that the internal current limit has been reached. A 20ms fault-blanking feature prevents the MAX1838 from issuing false alarms to the host during power-up or when hot-swapping into a capacitive load.
The MAX1838 is available in a space-saving 16-pin QSOP. For other USB current-limited switches, refer to the MAX1693, MAX1694, MAX1812, and MAX1823.